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1
Kurguzov, Konstantin V., and Igor K. Fomenko. "Piles and lateral loads: comparison of calculation methods." Vestnik MGSU, no. 10 (October 2019): 1280–91. http://dx.doi.org/10.22227/1997-0935.2019.10.1280-1291.
Повний текст джерелаАнотація:
Introduction. Calculation and analysis of pile resistance to loads remains to be a relevant problem in geoengineering. The design of pile foundations is currently performed using diverse analytical, empirical and numerical methods. However, the reliability of these methods remains to be a topic of interest among researchers and designers. This research paper analyses methods used for calculating the lateral-load capacity of piles in comparison with field-test data.
Materials and methods. The paper dwells upon the development of reliable analytical expressions based on mathematical models of the pile–soil interaction. Main existing mathematical models of the soil environment, including the Mohr – Coulomb elastic ideal plastic model and the hardening soil model (HSM) were analysed. A particular attention was paid to a variety of factors affecting the pile–soil interaction, such as natural factors, pile types, pile sinking depth and technology, configurations of loads, as well as time-changed processes. A comparison of methods for calculating the lateral-load capacity of piles was conducted. To that end, calculations using the Mohr – Coulomb model and the local elastic strain theory (still required by building codes) were performed. High-level solid elements were used to develop and compute a finite-element pile-in-soil model in a spatial setting. Another model on the basis of parametric pile elements was designed using the MIDAS software.
Results. It is established that the use of numerical calculation methods for evaluating the capacity and movements of pile foundations provides results comparable to those of field tests. These methods demonstrate a higher reliability compared to standardized analytical techniques.
Conclusions. The reliability of numerical calculations of pile resistance to lateral impact is shown to be sufficiently high, thus being feasible for use in geoengineering. The use of these methods should be based on advanced non-linear soil models, such as HS, CamClay, etc.
2
H. Maneetes and A. M. Memari. "Finite Element Modeling of Reinforced Concrete Cladding Panels H." Electronic Journal of Structural Engineering 9 (June 1, 2009): 62–72. http://dx.doi.org/10.56748/ejse.9118.
Повний текст джерелаАнотація:
Architectural precast concrete cladding systems are considered non-load bearing wall systems and are designed primarily to transfer their self-weight and out-of-plane lateral loads to the supporting building structure. They are typically not designed for significant structural in-plane forces resulting from cladding-structure interaction. In fact, modern earthquake-resistant design requires that these cladding panels be isolated from the lateral force-resisting system. Finite element technique was employed to study precast concrete panels and special modeling strategies were developed for panel connections to the structural frame. The precast concrete panel was designed to participate in the building lateral force-resisting. Finite element modeling techniques were adopted to better understand the strength and stiffness characteristics of these concrete cladding panels subjected to significant in-plane loading. Good correlation was obtained between finite element modeling results and existing experimental results. The analytical results were used to develop a simplified mathematical model that can be incorporated into suitable building models to evaluate its performance as a lateral force-resisting system to withstand earthquake-induced lateral loads.
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Timurağaoğlu, Mehmet Ömer, Adem Doğangün, and Ramazan Livaoğlu. "Comparison and assessment of material models for simulation of infilled RC frames under lateral loads." Journal of the Croatian Association of Civil Engineers 71, no. 1 (January 8, 2019): 49–56. http://dx.doi.org/10.14256/jce.2307.2017.
Повний текст джерелаАнотація:
In the present study, the behaviour of infilled RC frames under earthquake loading is investigated numerically, and the influence of three different concrete material models on the in-plane behaviour of infilled RC frames is evaluated using the finite element analysis (FEA). For this reason, the efficiency of infilled walls is examined on full scale models. Finite element analysis results show that mathematical model of concrete may change behaviour of infilled RC frames. The post-peak behaviour is especially influenced.
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Krysko, A. V., J. Awrejcewicz, K. S. Bodyagina, M. V. Zhigalov, and V. A. Krysko. "Mathematical modeling of physically nonlinear 3D beams and plates made of multimodulus materials." Acta Mechanica 232, no. 9 (June 26, 2021): 3441–69. http://dx.doi.org/10.1007/s00707-021-03010-8.
Повний текст джерелаАнотація:
AbstractIn this work, mathematical models of physically nonlinear plates and beams made from multimodulus materials are constructed. Our considerations are based on the 3D deformation theory of plasticity, the von Mises plasticity criterion and the method of variable parameters of the theory of elasticity developed by Birger. The proposed theory and computational algorithm enable for solving problems of three types of boundary conditions, edge conditions and arbitrary lateral load distribution. The problem is solved by the finite element method (FEM), and its convergence and the reliability of the results are investigated. Based on numerical experiments, the influence of multimodulus characteristics of the material of the beam and the plate on their stress–strain states under the action of transverse loads is illustrated and discussed.
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Cardei, Petru, Raluca Sfiru, and Vergil Muraru. "A mathematical model for the accumulation of fatigue in bars subjected to lateral vibrations." E3S Web of Conferences 112 (2019): 03002. http://dx.doi.org/10.1051/e3sconf/201911203002.
Повний текст джерелаАнотація:
The article presents a mathematical model for the phenomenon of fatigue accumulation in the slender bar subjected to lateral bending. The model is based on the Euler-Bernoulli type bar, a bi-linear elastic-plastic model and, for simulation of fatigue, a system of equations describing the decrease resistance parameters of the material: the ultimate strain and stress. In the article is exposes the bar response to two types of dynamic loads, as well as a fatigue test simulating process using the proposed model, which results in the Wöhler diagram of the material for the bending vibrations. The conclusions outline the outlook of the model as well as its shortcomings. The author expounds the advantages of the model, but the reader is also challenged to reflect on the opportunity of using mathematical models of great complexity.
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Sánchez-Martinez, Roberto, J. Enrique Sierra-García, and Matilde Santos. "Performance and Extreme Conditions Analysis Based on Iterative Modelling Algorithm for Multi-Trailer AGVs." Mathematics 10, no. 24 (December 15, 2022): 4783. http://dx.doi.org/10.3390/math10244783.
Повний текст джерелаАнотація:
Automatic guidance vehicles (AGV) are industrial vehicles that play an important role in the development of smart manufacturing systems and Industry 4.0. To provide these autonomous systems with the flexibility that is required today in these industrial workspaces, AGV computational models are necessary in order to analyze their performance and design efficient planning and control strategies. To address these issues, in this work, the mathematical model and the algorithm that implement a computational control-oriented simulation model of a hybrid tricycle-differential AGV with multi-trailers have been developed. Physical factors, such as wheel-ground interaction and the effect of vertical and lateral loads on its dynamics, have been incorporated into the model. The model has been tested in simulation with two different controllers and three trajectories: a circumference, a square, and an s-shaped curve. Furthermore, it has been used to analyze extreme situations of slipping and capsizing and the influence of the number of trailers on the tracking error and the control effort. This way, the minimum lateral friction coefficient to avoid slipping and the minimum ratio between the lateral and height displacement of the center of gravity to avoid capsizing have been obtained. In addition, the effect of a change in the friction coefficient has also been simulated.
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Yang, Mengying, Dingding Xiang, Song Wang, and Weiqiang Liu. "The Radial Bulging and Axial Strains of Intervertebral Discs during Creep Obtained with the 3D-DIC System." Biomolecules 12, no. 8 (August 10, 2022): 1097. http://dx.doi.org/10.3390/biom12081097.
Повний текст джерелаАнотація:
Creep-associated changes in disc bulging and axial strains are essential for the research and development of mechano-bionic biomaterials and have been assessed in various ways in ex vivo creep studies. Nonetheless, the reported methods for measurement were limited by location inaccuracy, a lack of synchronousness, and destructiveness. To this end, this study focuses on the accurate, synchronous, and noninvasive assessment of bugling and strains using the 3D digital image correlation (3D-DIC) system and the impact of creep on them. After a preload of 30 min, the porcine cervical discs were loaded with different loads for 4 h of creep. Axial strains and lateral bulging of three locations on the discs were synchronously measured. The three-parameter solid model and the newly proposed horizontal asymptote models were used to fit the acquired data. The results showed that the load application reduced disc strains by 6.39% under 300 N, 11.28% under 400 N, and 12.59% under 500 N. Meanwhile, the largest protrusion occurred in the middle of discs with a bugling of 1.50 mm, 1.67 mm, and 1.87 mm. Comparison of the peer results showed that the 3D-DIC system could be used in ex vivo biomechanical studies with reliability and had potential in the assessment of the mechanical behavior of novel biomaterials. The phenomenon of the largest middle protrusion enlightened further the strength of spinal implants in this area. The mathematical characterizations of bulging and strains under different loads yielded various model parameters, which are prerequisites for developing implanted biomaterials.
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Campione, Giuseppe. "The effects of fibers on the confinement models for concrete columns." Canadian Journal of Civil Engineering 29, no. 5 (October 1, 2002): 742–50. http://dx.doi.org/10.1139/l02-066.
Повний текст джерелаАнотація:
A mathematical model is developed to express the stressstrain relationships in compression of fiber-reinforced concrete (FRC) columns for both normal- and high-strength concrete, with and without conventional steel reinforcement. This model allows one to determine the maximum strength and strain capacity by determining the effective concrete core of the confining devices at rupture. Analytical expressions are also given for the ultimate load corresponding to the complete formation of the concrete failure plane. The proposed model incorporates the most relevant parameters of confinement, i.e., type of confinement, volumetric ratio, spacing, yielding strength, shape of the member cross section, type of fiber (length, diameter, shape), and fiber volume. The model has been verified against data obtained from concentric compressive tests on concrete specimens reinforced with transverse steel and fibers.Key words: high-strength concrete, fiber-reinforced concrete, lateral reinforcement, stressstrain curves.
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Ün, Kerem, İbrahim D. Akçalı, and Mahir Gülşen. "A Theoretical and Experimental Investigation of Lateral Deformations in a Unilateral External Fixator." Journal of Medical Devices 1, no. 2 (September 11, 2006): 165–72. http://dx.doi.org/10.1115/1.2735972.
Повний текст джерелаАнотація:
The objective of this work is to set up, validate, and analyze a theoretical model of an external fixator for its deformation characteristics in order to draw reliable conclusions relevant to the design and effective clinical implementation of such medical devices. External fixators are mechanical devices widely used in the treatment of fractured bones and correction of limb deformities. Lateral deformation at the fracture site is known to delay bone healing, and investigation of lateral deformation characteristics of such devices experiencing forces acting perpendicular to the bone axis is important from the standpoint of their design as well as their clinical effectiveness. A mathematical model of a three-dimensional (3D) unilateral fixator with multipin fragment attachments has been developed using Castigliano’s method. The relative lateral deformations of the fragment ends at the fracture site induced by loads applied perpendicular to bone axes are calculated with the model. The model has been subjected to experimental verification for a uniplanar unilateral external fixator under comparable conditions with the theory. It has been found out that the effects of fixator size, shape, and geometry on the level of relative lateral displacement of the fracture site are similar in both the theoretical and experimental models. Stiffness is a maximum if the force is applied in the same plane as the proximal pin plane. Placing the distal pin group at a 90deg position relative to the proximal pin plane has been observed to increase the stiffness about 10%. In loading directions perpendicular to proximal the pin plane, stiffness is minimum. The angle difference between the load direction and the resulting displacement direction follows a sinusoidal pattern with an amplitude of 10deg for loading angles in the 0–180deg range. Selecting the distance of proximal pins to the fracture site smaller than the distance of distal pins to the fracture site has been found to decrease relative lateral deformation. The model and the experiment have simultaneously demonstrated that lower values of effective pin lengths and higher values of pin connector lengths lead to higher stiffness. Increasing the number of pins also contributes to the higher values of fixator stiffness.
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Wu, Xi, and Jim Meagher. "A Two-Disk Extended Jeffcott Rotor Model Distinguishing a Shaft Crack from Other Rotating Asymmetries." International Journal of Rotating Machinery 2008 (2008): 1–11. http://dx.doi.org/10.1155/2008/846365.
Повний текст джерелаАнотація:
A mathematical model of a cracked rotor and an asymmetric rotor with two disks representing a turbine and a generator is utilized to study the vibrations due to imbalance and side load. Nonlinearities typically related with a “breathing” crack are included using a Mayes steering function. Numerical simulations demonstrate how the variations of rotor parameters affect the vibration response and the effect of coupling between torsional and lateral modes. Bode, spectrum, and orbit plots are used to show the differences between the vibration signatures associated with cracked shafts versus asymmetric shafts. Results show how nonlinear lateral-torsional coupling shifts the resonance peaks in the torsional vibration response for cracked shafts and asymmetric rotors. The resonance peaks shift depending on the ratio of the lateral-to-torsional natural frequencies with the peak responses occurring at noninteger values of the lateral natural frequency. When the general nonlinear models used in this study are constrained to reduce to linear torsional vibration, the peak responses occur at commonly reported integer ratios. Full spectrum analyses of theXandYvibrations reveal distinct vibration characteristics of both cracked and asymmetric rotors including reverse vibration components. Critical speeds and vibration orders predicted using the models presented herein include and extend diagnostic indicators commonly reported.
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Pruchnicki, Erick. "Two New Models for Dynamic Linear Elastic Beams and Simplifications for Double Symmetric Cross-Sections." Symmetry 14, no. 6 (May 26, 2022): 1093. http://dx.doi.org/10.3390/sym14061093.
Повний текст джерелаАнотація:
We present two new models for dynamic beams deduced from three dimensional theory of linear elasticity. The first model is deduced from virtual work considered for small beam sections. For the second model, we suppose a Taylor-Young expansion of the displacement field up to the fourth order in transverse dimensions of the beam. We consider the Fourier series expansion for considering Neumann lateral boundary conditions together with dynamical equations, we obtain a system of fifteen vector equations with the fifteen coefficients vector unknown of the displacement field. For beams with two fold symmetric cross sections commonly used (for example circular, square, rectangular, elliptical…), a unique decomposition of any three-dimensional loads is proposed and the symmetries of these loads is introduced. For these two theories, we show that the initial problem decouples into four subproblems. For an orthotropic material, these four subproblems are completely independent. For a monoclinic material, two subproblems are coupled and independent of the two other coupled subproblems. For the first model, we also give the detailed expression of these four subproblems when we consider the approximation of the displacement field used in the second model.
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Bedon, Chiara. "Simplified Lateral Torsional Buckling (LTB) Analysis of Glass Fins with Continuous Lateral Restraints at the Tensioned Edge." Mathematical Problems in Engineering 2021 (March 24, 2021): 1–21. http://dx.doi.org/10.1155/2021/6667373.
Повний текст джерелаАнотація:
Within multiple design challenges, the lateral torsional buckling (LTB) analysis and stability check of structural glass members is a well-known issue for design. Typical examples can be found not only in glass slabs with slender bracing members but also in facades and walls, where glass fins are used to brace the vertical panels against input pressures. Design loads such as wind suction give place to possible LTB of fins with LR at the tensioned edge and thus require dedicated tools. In the present investigation, the LTB analysis of structural glass fins that are intended to act as bracers for facade panels and restrained via continuous, flexible joints acting as lateral restraints (LRs) is addressed. Geometrically simplified but refined numerical models developed in Abaqus are used to perform a wide parametric study and validate the proposed analytical formulations. Special care is spent for the prediction of the elastic critical buckling moment with LRs, given that it represents the first fundamental parameter for buckling design. However, the LR stiffness and resistance on the one side and the geometrical/mechanical features of the LR glass members on the other side are mutually affected in the final LTB prediction. In the case of laminated glass (LG) members composed of two or more glass panels, moreover, further design challenges arise from the bonding level of the constituent layers. A simplified but rational analytical procedure is thus presented in this paper to support the development of a conservative and standardized LTB stability check for glass fins with LR at the tensioned edge.
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Rezvani Sharif, Mostafa, and Seyed Mohammad Reza Sadri Tabaei Zavareh. "Numerical analysis of the shear strength of circular reinforced concrete columns subjected to cyclic lateral loads using linear genetic programming." Engineering Computations 37, no. 7 (March 18, 2020): 2517–37. http://dx.doi.org/10.1108/ec-10-2018-0453.
Повний текст джерелаАнотація:
Purpose The shear strength of reinforced concrete (RC) columns under cyclic lateral loading is a crucial concern, particularly, in the seismic design of RC structures. Considering the costly procedure of testing methods for measuring the real value of the shear strength factor and the existence of several parameters impacting the system behavior, numerical modeling techniques have been very much appreciated by engineers and researchers. This study aims to propose a new model for estimation of the shear strength of cyclically loaded circular RC columns through a robust computational intelligence approach, namely, linear genetic programming (LGP). Design/methodology/approach LGP is a data-driven self-adaptive algorithm recently used for classification, pattern recognition and numerical modeling of engineering problems. A reliable database consisting of 64 experimental data is collected for the development of shear strength LGP models here. The obtained models are evaluated from both engineering and accuracy perspectives by means of several indicators and supplementary studies and the optimal model is presented for further purposes. Additionally, the capability of LGP is examined to be used as an alternative approach for the numerical analysis of engineering problems. Findings A new predictive model is proposed for the estimation of the shear strength of cyclically loaded circular RC columns using the LGP approach. To demonstrate the capability of the proposed model, the analysis results are compared to those obtained by some well-known models recommended in the existing literature. The results confirm the potential of the LGP approach for numerical analysis of engineering problems in addition to the fact that the obtained LGP model outperforms existing models in estimation and predictability. Originality/value This paper mainly represents the capability of the LGP approach as a robust alternative approach among existing analytical and numerical methods for modeling and analysis of relevant engineering approximation and estimation problems. The authors are confident that the shear strength model proposed can be used for design and pre-design aims. The authors also declare that they have no conflict of interest.
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Qiu, Tian-Xia, and Ee-Chon Teo. "FINITE ELEMENT MODELING OF HUMAN THORACIC SPINE." Journal of Musculoskeletal Research 08, no. 04 (December 2004): 133–44. http://dx.doi.org/10.1142/s0218957704001302.
Повний текст джерелаАнотація:
Mathematical models, which can accurately represent the geometric, material and physical characteristics of the human spine structure, are useful in predicting biomechanical behaviors of the spine. In this study, a three-dimensional finite element (FE) model of thoracic spine (T1–T12) was developed, based on geometrical data of embalmed thoracic vertebrae (T1–T12) obtained from a precise flexible digitizer, and validated against published thoracolumbar experimental results in terms of the torsional stiffness of the whole thoracic spine (T1–T12) under axial torque alone and combined with distraction and compression loads. The torsional stiffness was increased by over 60% with application of a 425 N distraction force. A trend in increasing torsional stiffness with increasing distraction forces was detected. The validated model was then loaded under moment rotation in three anatomical planes to determine the ranges of motion (ROMs). The ROMs were approximately 37°, 31°, 32°, 51° for flexion, extension, lateral bending and axial rotation, respectively. These results may offer an insight to better understanding the kinematics of the human thoracic spine and provide clinically relevant fundamental information for the evaluation of spinal stability and instrumented devices functionality for optimal scoliosis correction.
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Xu, Huabo, Huihui Song, and Rui Hou. "Central Bulge Ferrite Core for Efficient Wireless Power Transfer." Energies 14, no. 16 (August 19, 2021): 5111. http://dx.doi.org/10.3390/en14165111.
Повний текст джерелаАнотація:
To improve the efficiency of the wireless power transfer (WPT) system without increasing the system size, a central bulge ferrite core with a novel configuration is proposed. The mutual inductance between magnetic coupling structures is able to increase obviously, which is approved by eigenfunction expansion method. In this paper, the mathematical models of the planar core and the central bulge core are established, respectively, as two types of the mutual inductance are calculated in same condition. The structure parameters of the central bulge ferrite core are further optimized by Maxwell magnetic field simulation. Experiments are conducted to compare the WPT efficiency of two types of ferrite cores in improving the efficiency of WPT system, in which the influence of transmission distance, lateral misalignment, and load variation are taken into account. The results show that central bulge ferrite core has better performance in WPT efficiency than the planar one, even in the case of long power transfer distance and lateral misalignment.
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Abdallah, Wael J., Khurram Hashmi, Muhammad Talib Faiz, Aymen Flah, Sittiporn Channumsin, Mohamed A. Mohamed, and Denis Anatolievich Ustinov. "A Novel Control Method for Active Power Sharing in Renewable-Energy-Based Micro Distribution Networks." Sustainability 15, no. 2 (January 13, 2023): 1579. http://dx.doi.org/10.3390/su15021579.
Повний текст джерелаАнотація:
The microgrid is an emerging trend in modern power systems. Microgrids consist of controllable power sources, storage, and loads. An elaborate control infrastructure is established to regulate and synchronize the interaction of these components. The control scheme is divided into a hierarchy of several layers, where each layer is composed of multi-agents performing their dedicated functions and arriving at a consensus of corrective values. Lateral and horizontal interaction of such multi-agents forms a comprehensive hierarchical control structure that regulates the microgrid operation to achieve a compendium of objectives, including power sharing, voltage, and frequency regulation. The success of a multi-agent-based control scheme is dependent on the health of the communication media that is used to relay measurements and control signals. Delays in the transmission of control signals result in an overall deterioration of the control performance and non-convergence. This paper proposes novel multi-agent moving average estimators to mitigate the effect of latent communication links and establishes a hierarchical control scheme incorporating these average estimators to accurately arrive at system values during communication delays. Mathematical models are established for the complete microgrid system to test the stability of the proposed method against conventional consensus-based methods. Case-wise simulation studies and lab-scale experimental verification further establish the efficacy and superiority of the proposed control scheme in comparison with other conventionally used control methods.
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Jaaz, Hussein Abad Gazi, Ali Fadhil Naser, Hussam Ali Mohammed, and Ayad Ali Mohammed. "Earthquake Resistance Optimization and Evaluation of Bridge Piers Structural Form and Dimensions Based on Demand to Capacity Ratio and Yielding Points of Force-Displacement." Mathematical Modelling of Engineering Problems 8, no. 6 (December 22, 2021): 945–54. http://dx.doi.org/10.18280/mmep.080614.
Повний текст джерелаАнотація:
The evaluation of structural safety must be taken after each earthquake. The importance losses of life and materials carries the significance of the works in the field of earthquake engineering. The purpose of this study was to optimize and evaluate the earthquake resistance of bridge piers by adopting different cross-section forms and dimensions for bridge supports under earthquake action. Two methods of seismic design were used in the optimization and evaluation process. These methods were demand to capacity ratio (DCR) and yielding point. The results of demand to capacity ratio shown that the values of DCR for all piers forms models were increased when the dimension of pier cross section were increased and the values of DCR became less than 1.0, indicating that the increasing in dimensions leading to rise the capacity of bridge supports to carry the earthquake loads in transverse and longitudinal direction. Comparing with models, solid wall pier form had the lower value of DCR, indicating that solid wall piers were suitable in the design of bridge supports to resist the lateral loads of earthquake and it has enough stiffness and capacity under earthquake action. The results of performance points shown that the yielding points were increased when the dimensions of piers were increased for all piers form in transverse and longitudinal direction. The maximum values were appeared within support No. 1 and support No. 4. Solid wall form of pier had the higher values of yielding points, meaning that this type of piers form had higher seismic capacity and it will resist the earthquake action more than others piers form. This study recommended that to use third model for each pier form in the design of bridges structures to resist the earthquake load. Also this study was recommended to use solid wall piers as supports in construction of bridge structure within areas had earthquake action.
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Muszynska, Agnes. "Vibrational Diagnostics of Rotating Machinery Malfunctions." International Journal of Rotating Machinery 1, no. 3-4 (1995): 237–66. http://dx.doi.org/10.1155/s1023621x95000108.
Повний текст джерелаАнотація:
This paper outlines rotating machinery malfunction diagnostics using vibration data in correlation with operational process data. The advantages of vibration monitoring systems as a part of preventive/predictive maintenance programs are emphasized. After presenting basic principles of machinery diagnostics, several specific malfunction symptoms supported by simple mathematical models are given. These malfunctions include unbalance, excessive radial load, rotor-to-stator rubbing, fluid-induced vibrations, loose stationary and rotating parts, coupled torsional/lateral vibration excitation, and rotor cracking. The experimental results and actual field data illustrate the rotor vibration responses for individual malfunctions. Application of synchronous and nonsynchronous perturbation testing used for identification of basic dynamic characteristics of rotors is presented. Future advancements in vibration monitoring and diagnostics of rotating machinery health are discussed. In the Appendix, basic instrumentation for machine monitoring is outlined.
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Ghannadpour, S. A. M., A. Kurkaani Barvaj, and H. R. Ovesy. "Predicting the Nonlinear Damage Response of Imperfect Laminates Using Linear Material Degradation Model and a Semi-Analytical Technique." International Journal of Structural Stability and Dynamics 21, no. 10 (June 23, 2021): 2150141. http://dx.doi.org/10.1142/s0219455421501418.
Повний текст джерелаАнотація:
This paper investigates nonlinear damage response and ultimate collapse of laminates under in-plane and lateral pressure loadings. The in-plane loading was in the form of end-shortening strain, while the lateral pressure was sinusoidal. The plates had initial geometric imperfection to which simply-supported boundary conditions were applied. Ritz techniques with nonlinear strain terms in kinematic relations as well as the first-order shear deformation theory were applied. Hashin and Rotem failure criteria were used for failure analysis. Two models were also employed for degradation of material properties in the plates. The complete ply degradation model was implemented along with the ply region degradation model, in which stiffness reduction was applied only to one region of the ply in which failure had occurred. Note that the stiffness degradation after the failure was investigated as both instantaneous and linear models. In both complete ply and region ply degradation models with instantaneous degradation of material properties, at any location in a ply or region, which has exceeded the given stress criterion, the corresponding stiffness properties are instantaneously degraded throughout that ply or region but with linear material degradation model, the stiffness diminishes gradually and linearly. Finally, the results were then validated against the findings of different references as well as finite element analysis. According to the results, it was seen that in the ply region degradation model, last ply failure loads are generally larger than those of the complete ply degradation model.
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Tang, Jiwei, Shumin Pu, Peixi Yu, Weicheng Xie, Yunfei Li, and Binxing Hu. "Research on Trajectory Prediction of a High-Altitude Zero-Pressure Balloon System to Assist Rapid Recovery." Aerospace 9, no. 10 (October 19, 2022): 622. http://dx.doi.org/10.3390/aerospace9100622.
Повний текст джерелаАнотація:
A comprehensive simulation model is established to predict the trajectory of a high-altitude zero-pressure balloon flight system with no parachute that is required to carry the load floating at the designated altitude for several hours or less. A series of mathematical models, including thermal dynamic, atmospheric, earth, wind, geometry, and exhaust models, are developed to predict the trajectory of the balloon flight system. Based on these models, the uncertainties of the launch parameters and the corresponding flight performance are simulated. Combined with the control strategy, the entire flight trajectory is simulated and discussed in detail, including the ascending, floating, and descending phases. The results show that the vertical velocity takes on a W shape during the ascent process. Furthermore, the balloon begins to gradually descend with weakening solar radiation after noon. Moreover, the landing vertical speed of the balloon flight system can approach zero with the control strategy applied, whereas the lateral drift range is more limited relative to the uncontrolled flight mode. The results and conclusions presented herein contribute to the design and operation of a zero-pressure balloon flight system within limited airspace to improve the rapid recovery ability of the flight system.
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Brailko, N. N., and I. M. Tkachenko. "STUDY OF THE STRESS-STRAIN STATE OF THE "FILLING-TOOTH" SYSTEM IN CERVICAL DEFECTS OF THE TEETH." Актуальні проблеми сучасної медицини: Вісник Української медичної стоматологічної академії 20, no. 4 (December 30, 2020): 108–14. http://dx.doi.org/10.31718/2077-1096.20.4.108.
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The problem of preserving restorations in defects in the cervical region, even with high-quality preparation and restoration, is also relevant in the modern world. The tensions in the teeth lead to the formation of cracks in the enamel and dentin, loss of tightness and marginal adhesion of the fillings, resorption and loss. Therefore, to ensure high-quality results of treatment of hard tissue defects in the cervical region of the teeth, it is appropriate to take into account the physical processes occurring around the "filling-tooth" system, namely, the stress-strain state. To assess the stress-strain state of the coronal part of the teeth with restorations, given the tightness and extreme cumbersomeness of using traditional analytical methods of theoretical mechanics and resistance of materials through a variety of geometric shapes and physical and mechanical characteristics of hard tissues of the dentition and filling material, it seems most appropriate to conduct research with using finite element modeling. The purpose of this biomechanical analysis is to study the influence of the size and location of defects of the cervical region on the stress-strain state of the obturation material in cases of restoration of these defects. Biomechanical analysis of the stress-strain state of the filling material was performed using elastic three-dimensional models of single-rooted teeth (first premolar and canine) fixed in the alveolar bone with periodontal ligaments surrounding the tooth root. Mathematical modeling was performed using the well-known modeling package and finite element analysis FEMAP 10.2.0, designed for implementation in the Windows environment on a personal computer. In order to reduce the number of finite elements, and as a consequence, reduce the amount of computational procedures and the amount of time spent on the calculation while increasing the accuracy of calculations, further research seems appropriate not on the full model of the mandible, but on its fragment isolated from the mandible. the first premolar and canine. Biomechanical analysis of the stress-strain state was performed on a fragment of the jawbone with overall dimensions of the cross section, which corresponds to some average dimensions: height h = 22 mm and width b = 16 mm. The program, which is used to build and analyze the considered models on the basis of the finite element procedure, determines the displacement of each node of the finite element along three coordinate axes, normal and tangential stresses, as well as equivalent Huber-Mises stresses. As the main criteria for assessing the stress-strain state of the obturation material, it is advisable to take the maximum values of tangential stresses at the adhesion boundary, which shift the filling material relative to the boundary of the restored cavity and thus determine the strength of the adhesive layer and, consequently, durability. The most unfavorable of the considered combinations of loads was the joint action of the vertical component of the load with the horizontal in the lingual-vestibular direction (corresponding to the maximum value of tangential stresses at the adhesion of the filling material) in the localization of restoration on the vestibular surface in the cervical premolar. When localizing the restoration on the oral side of the cervical premolar, the most unfavorable of the considered combinations of loads was the joint action of the vertical component of the load with the horizontal in the vestibular-lingual direction. Thus, the direction of action of the horizontal component of the functional load, in the most unfavorable combination with the vertical, is determined by the localization of the restoration on the lateral surface of the premolar.
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Valentino, Tobias, Marian Höhmann, Kevin Schünemann, Jonas Wentzler, Tim Wünderlich, Tim Radel, and Frank Vollertsen. "Time-Resolved Force Measurements to Determine Positioning Tolerances for Impulse-Based Indentations." Lasers in Manufacturing and Materials Processing 8, no. 2 (May 31, 2021): 216–35. http://dx.doi.org/10.1007/s40516-021-00140-8.
Повний текст джерелаАнотація:
AbstractHigh-throughput experimentation methods determine characteristic values, which are correlated with material properties by means of mathematical models. Here, an indentation method based on laser-induced shock waves is presented, which predicts the material properties, such as hardness and tensile strength, by the induced plastic deformation in the substrate material. The shock wave pushes a spherical indenter inside a substrate material. For reproducible indentations, the applied load is of importance. To compare different processes and process parameters, the measured plastic deformation is normalized by the applied load. However, eccentric irradiation leads to altered beam profiles on the surface of spherical indenters and the angle of incidence is changed. Thus, the influence of eccentric irradiation is studied with an adapted time-resolved force measurement setup to determine the required positioning tolerances. The spherical indenter is placed inside a cylindrical pressure cell to increase the laser-induced shock pressure. From the validated time-resolved force measurement method we derive that deviations from the indentation forces are acceptable, when the lateral deviation of the beam center, which depends only on the alignment of the setup, does not exceed ± 0.4 mm. A vertical displacement from the focus position between -3.0 mm and + 2.0 mm still leads to acceptable deviations from the indentation force.
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Cheng, Yung-Chang, Chern-Hwa Chen, and Chin-Te Hsu. "Derailment and Dynamic Analysis of Tilting Railway Vehicles Moving Over Irregular Tracks Under Environment Forces." International Journal of Structural Stability and Dynamics 17, no. 09 (October 23, 2017): 1750098. http://dx.doi.org/10.1142/s0219455417500985.
Повний текст джерелаАнотація:
Utilizing a nonlinear creep model, the dynamic behavior of tilting railway vehicles moving over curved tracks with rail irregularities and under earthquakes and wind loads is studied. The car model adopted consists of 28 degrees of freedom, capable of simulating the lateral, vertical, roll and yaw motions for the wheelsets, truck frames and car body. The derailment quotient is investigated to analyze the running safety of a tilting railway vehicle using the linear and nonlinear creep models, while considering the rail irregularities and environmental forces for various tilting angles. Generally, the derailment risk of the tilting railway vehicle is higher than that of non-tilting railway vehicle with or without rail irregularities and environmental forces. The derailment quotients calculated by the linear creep model are underestimated for a tilting railway vehicle. In addition, the derailment quotients evaluated for rough rails and under environmental forces are higher than those obtained for smooth rails with no environmental forces. It is confirmed that rail irregularities and each type of environmental forces have decisive effects on derailment quotients. They are compared and ranked according to their significance.
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Liu-Barba, David, M. L. Hull, and S. M. Howell. "Coupled Motions Under Compressive Load in Intact and ACL-Deficient Knees: A Cadaveric Study." Journal of Biomechanical Engineering 129, no. 6 (May 14, 2007): 818–24. http://dx.doi.org/10.1115/1.2800762.
Повний текст джерелаАнотація:
Knowledge of the coupled motions, which develop under compressive loading of the knee, is useful to determine which degrees of freedom should be included in the study of tibiofemoral contact and also to understand the role of the anterior cruciate ligament (ACL) in coupled motions. The objectives of this study were to measure the coupled motions of the intact knee and ACL-deficient knee under compression and to compare the coupled motions of the ACL-deficient knee with those of the intact knee. Ten intact cadaveric knees were tested by applying a 1600N compressive load and measuring coupled internal-external and varus-valgus rotations and anterior-posterior and medial-lateral translations at 0deg, 15deg, and 30deg of flexion. Compressive loads were applied along the functional axis of axial rotation, which coincides approximately with the mechanical axis of the tibia. The ACL was excised and the knees were tested again. In the intact knee, the peak coupled motions were 3.8deg internal rotation at 0deg flexion changing to −4.9deg external rotation at 30deg of flexion, 1.4deg of varus rotation at 0deg flexion changing to −1.9deg valgus rotation at 30deg of flexion, 1.4mm of medial translation at 0deg flexion increasing to 2.3mm at 30deg of flexion, and 5.3mm of anterior translation at 0deg flexion increasing to 10.2mm at 30deg of flexion. All changes in the peak coupled motions from 0degto30deg flexion were statistically significant (p<0.05). In ACL-deficient knees, there was a strong trend (marginally not significant, p=0.07) toward greater anterior translation (12.7mm) than that in intact knees (8.0mm), whereas coupled motions in the other degrees of freedom were comparable. Because the coupled motions in all four degrees of freedom in the intact knee and ACL-deficient knee are sufficiently large to substantially affect the tibiofemoral contact area, all degrees of freedom should be included when either developing mathematical models or designing mechanical testing equipment for study of tibiofemoral contact. The increase in coupled anterior translation in ACL-deficient knees indicates the important role played by the ACL in constraining anterior translation during compressive loading.
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Ertekin, R. C., H. R. Riggs, X. L. Che, and S. X. Du. "Efficient Methods for Hydroelastic Analysis of Very Large Floating Structures." Journal of Ship Research 37, no. 01 (March 1, 1993): 58–76. http://dx.doi.org/10.5957/jsr.1993.37.1.58.
Повний текст джерелаАнотація:
The linear hydroelastic response of a very large floating structure (VLFS) consisting of multiple modules is studied theoretically, following a review of the past work on hydroelasticity in fluid-structure interaction. The 3-dimensional Green function method and Morison's equation approach are used to determine the fluid loading in conjunction with two different hydroelastic models. The first method uses a rigid module, flexible connector model in which the hydrodynamic interaction between rigid modules is taken into account. The double composite source distribution method, which is a numerically efficient implementation of the Green function method that exploits double symmetry of the structure in the longitudinal and lateral directions, is used to reduce computations. In the second method, fully elastic modules are considered. In this approach, the fluid loading is obtained by Morison's equation, and the structure is modeled by frame finite elements. The predictions for the rigid-body motions and structural deformations, as well as module-connector loads, obtained by the two different methods are compared. The proposed methods of hydroelasticity have been used to predict the response of a 16-module VLFS, 100 m by 1600 m. Both methods are sufficiently efficient to allow the analysis of even larger VLFS.
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Dihtiar, V. A., M. O. Kaminska, and O. V. Yaresko. "Mathematical calculation and coefficient value of chest shape recovery for planning thoracoplasty of pectus excavatum." TRAUMA 22, no. 1 (April 9, 2021): 26–32. http://dx.doi.org/10.22141/1608-1706.1.22.2021.226408.
Повний текст джерелаАнотація:
Background. Pectus excavatum is characterized by retraction of the sternum and anterior ribs of different depth and width. The formation, its prediction, calculation of chest deformity, and their study when planning thoracoplasty using the Nuss procedure for this pathology is an important problem of orthopedics and thoracic surgery. The purpose of the work was to calculate the coefficient of restoration of the chest shape by the ratio of the pectus excavatum depth and the chest size in the frontal plane before and after mathematical modeling of thoracoplasty using the Nuss procedure. Methods. To assess displacement of ribs depen-ding on depth deformity of chest h, two models were built. The first model is a flat frame on supports, the elements of which consist of cartilaginous parts of ribs and sternum. For this model, the dependence of the force F was determined, which is necessary to correct the depth of chest deformity. The second model is a curved bar that simulates a rib, to one of the ends of which a support load is applied, calculated during the analysis of the first model. For this model, the displacement of the plate fixation point under the action of a given force was determined. To obtain more accurate results, a finite element study was performed on a chest model. Results. The correction of pectus excavatum depth without fixing plate to ribs was simulated. The displacements of rib sections in the place of plate fixation at different depths of pectus excavatum was assessed: h = 2 cm, h = 3 cm, h = 4 cm, h = 5 cm. The analysis of calculation results showed that after correction of the depth of chest deformity, its size in the frontal plane decreases. So, at the maximum deformation depth h = 5 cm, the deviation of the rib sections at the plate fixation point occurred by 2.4 cm. Conclusions. The relationship between the pectus excavatum depth and chest size in the frontal plane was established when modeling the newly formed chest form during for Nuss procedure. The coefficient of restoring the chest shape was mathematically calculated, which is 2 (2∆ = h), where h is the depth of pectus excavatum. The practical significance of the coefficient is that when planning thoracoplasty and shaping plate, the distance between its lateral ends, which corresponds to the chest shape and adjoin ribs, must be reduced by ½ h (where h is the depth of pectus excavatum) before correcting the pectus excavatum full adherence to the ribs in the postoperative period.
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N. F. Meador. "MATHEMATICAL MODELS FOR LATERAL RESISTANCE OF POST FOUNDATIONS." Transactions of the ASAE 40, no. 1 (1997): 191–201. http://dx.doi.org/10.13031/2013.21245.
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Kasal, B., M. S. Collins, P. Paevere, and G. C. Foliente. "Design Models of Light Frame Wood Buildings under Lateral Loads." Journal of Structural Engineering 130, no. 8 (August 2004): 1263–71. http://dx.doi.org/10.1061/(asce)0733-9445(2004)130:8(1263).
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Nurjannah, Siti Aisyah, Saloma Saloma, Yulindasari Yulindasari, Kiagus Muhammad Aminuddin, and Gilbert Chuhairy. "The analysis of numerical self-compacting concrete wall panel models with variations of shear reinforcement." Engineering Solid Mechanics 11, no. 1 (2023): 89–102. http://dx.doi.org/10.5267/j.esm.2022.8.002.
Повний текст джерелаАнотація:
Reinforced concrete wall critical zones are the responsive areas of dissipated earthquake loads. They are formed in the connection of the wall panels and the fixed restraints. The longitudinal and transversal steel reinforcements with certain spacing are designed according to the required nominal strength at the connections. Under certain conditions, the reinforcement distance becomes very tight, making working on castings using normal concrete difficult. This condition also occurs in boundary elements consisting of longitudinal and transversal reinforcements in tight spaces. A concrete material that flows easily and solidifies itself is required to avoid segregation. One type of this material is Self-Compacting Concrete (SCC). The SCC performance as a wall panel material that withstands gravity and cyclic lateral loads still require further research. This study aimed to analyze the hysteretic performance of reinforced SCC wall panels with variations of shear reinforcement in resisting cyclic lateral loads. The analysis used software based on numerical analysis. The drift ratios, hysteretic curves, stress patterns, ductility, and stiffness of the wall panels were analyzed. The SCC wall panel with ordinary shear reinforcement resisted lateral positive and negative loads of 152.32 kN and 143.09 kN, respectively. In comparison, the wall panel with boundary elements and tighter shear reinforcements could withstand the positive and negative lateral loads of 187.62 kN and 145.98 kN, respectively. The SCC wall panel reached the best ductility of 21.38 with ordinary shear reinforcement because the yield occurred faster than in other wall panels. The results showed that the boundary elements and shear reinforcements of reinforced SCC wall panels affected the performance in resisting cyclic lateral loads.
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Jamil, Irfan, Irshad Ahmad, Wali Ullah, Mahmood Ahmad, Mohanad Muayad Sabri Sabri, and Ali Majdi. "Experimental Study on Lateral and Vertical Capacity of Piled Raft and Pile Group System in Sandy Soil." Applied Sciences 12, no. 17 (September 2, 2022): 8853. http://dx.doi.org/10.3390/app12178853.
Повний текст джерелаАнотація:
In deep foundations, the pile group and the pile raft are generally used. To date, the contribution of the raft is not taken into account in the design, even when the raft is in contact with the soil and the whole system is therefore considered to work as a pile group foundation. In a combined pile raft system, the raft takes a considerable portion of the applied load, depending upon the number of piles, the spacing to diameter ratio of the piles, and the length to diameter ratio. In this paper, an experimental investigation is carried out to study the response of small-scale pile group and piled raft models with a varying number of piles subjected to both vertical and lateral loads. Additionally, the response mechanism of these models to both types of loads is also studied. A comparison was made between these models. It was found that, unlike the pile group, the piled raft provides considerably high stiffness to both types of loads, and the difference between the stiffness of both systems decreases as the number of piles increases. By comparing the response of the piled raft and the pile group with the same number of piles under the same vertical and lateral load, it was concluded that the piled raft response to the lateral and vertical loads was much stiffer than the pile group response. The lateral deflection and the vertical settlement of the piled raft were less than those of the pile group with the same pile configuration. This effective response of the piled raft to the vertical and lateral loads was due to the raft contribution in resisting the vertical and lateral loads. Moreover, with the increase in the number of piles, the vertical and lateral contribution of the raft decreases.
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Anjana, Elsa Alexander, R. Renjith, and Binu M. Issac. "Analytical Study on Effect of Geometry of Tall Buildings on Diagrid Structural Systems Subjected to Lateral Loads." Applied Mechanics and Materials 857 (November 2016): 47–52. http://dx.doi.org/10.4028/www.scientific.net/amm.857.47.
Повний текст джерелаАнотація:
Structural design of high rise buildings is governed by lateral loads due to wind or earthquake. As the height of building increases, the lateral load resisting system becomes more important than the structural system that resists the gravitational loads. Recently, diagrid structural system are widely used for tall buildings due to its structural efficiency and flexibility in architectural planning. Diagrid structural system is made around the perimeter of building in the form of a triangulated truss system by intersecting the diagonal and horizontal members. Diagonal members in diagrid structural systems can carry gravity loads as well as lateral loads. Lateral loads are resisted by axial action of the diagonals compared to bending of vertical columns in framed tube structure. The structural efficiency of diagrid system also helps in avoiding interior and corner columns, thereby allowing significant flexibility with the floor plan. In this paper, effect of lateral loads on steel diagrid buildings are studied. Square and rectangular buildings of same plan area with diagrid structural system is considered for the study. Diagrid modules extending upto 2,4,6,8 and 12 storeys are evaluated. Static analysis for the gravity loads, wind and earthquake and response spectrum analysis are carried out for these different combinations of plan shape and diagrid modules and performance of all these diagrid models i.e., storey displacement, storey drift and modal time period are evaluated and compared in this study.
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Delprete, C., and M. M. Gola. "Mechanical Performance of External Fixators With Wires for the Treatment of Bone Fractures—Part I: Load-Displacement Behavior." Journal of Biomechanical Engineering 115, no. 1 (February 1, 1993): 29–36. http://dx.doi.org/10.1115/1.2895467.
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Using matrix algebra, a mathematical model is formulated for a particular type of external fixator with wires (system developed by Ilizarov) for the treatment of bone fractures. The mathematical model is used to give a linear estimate of the stiffness under lateral and axial loads in a representative number of practical conditions. Relative displacements of the bone ends at the fracture site are calculated not only in the common case of a gap, but also for various angles of inclined sliding contact; in this case, a realistic load is applied and nonlinear stiffening of the wires under transversal loads is iteratively taken into account.
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Belenkiy, L., and Y. Raskin. "Estimate of the Ultimate Load on Structural Members Subjected to Lateral Loads." Marine Technology and SNAME News 38, no. 03 (July 1, 2001): 169–76. http://dx.doi.org/10.5957/mt1.2001.38.3.169.
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This paper examines plastic behavior of typical ship structures, specifically beams, grillages, and plates subjected to predominantly lateral loads. The ultimate loads, determined on the basis of the theorems of limit analysis [1,2], are evaluated using nonlinear finite-element plastic analysis. The relationships between analytical and finite-element models for prediction of ultimate loads of beams, stiffened panels, and grillages are illustrated. It has been shown that the ultimate loads, obtained from the theorems of limit analysis, can be successfully used for strength assessment of stiffened ship structures subjected to lateral loads. The effect of shear force on ultimate load is analyzed using the finite-element method. This paper confirms that in the case of beams and grillages under lateral loading, the ultimate load may characterize the threshold of the load at which a stiffened ship's structure fails by the development of excessive deflections. For plate elements, on the other hand, the plastic deflections represent the permissible limit of external load better than the ultimate limit load.
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Song, Kejian, Yuan Long, Chong Ji, and Fuyin Gao. "Plastic Deformation of Metal Tubes Subjected to Lateral Blast Loads." Mathematical Problems in Engineering 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/250379.
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When subjected to the dynamic load, the behavior of the structures is complex and makes it difficult to describe the process of the deformation. In the paper, an analytical model is presented to analyze the plastic deformation of the steel circular tubes. The aim of the research is to calculate the deflection and the deformation angle of the tubes. A series of assumptions are made to achieve the objective. During the research, we build a mathematical model for simply supported thin-walled metal tubes with finite length. At a specified distance above the tube, a TNT charge explodes and generates a plastic shock wave. The wave can be seen as uniformly distributed over the upper semicircle of the cross-section. The simplified Tresca yield domain can be used to describe the plastic flow of the circular tube. The yield domain together with the plastic flow law and other assumptions can finally lead to the solving of the deflection. In the end, tubes with different dimensions subjected to blast wave induced by the TNT charge are observed in experiments. Comparison shows that the numerical results agree well with experiment observations.
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Menegozzo, Marco, Andrés Cecchini, Frederick A. Just-Agosto, David Serrano Acevedo, Orlando J. Flores Velez, Isaac Acevedo-Figueroa, and Jancary De Jesús Ruiz. "A 3D-Printed Honeycomb Cell Geometry Design with Enhanced Energy Absorption under Axial and Lateral Quasi-Static Compression Loads." Applied Mechanics 3, no. 1 (March 14, 2022): 296–312. http://dx.doi.org/10.3390/applmech3010019.
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This work presents an innovative honeycomb cell geometry design with enhanced in-plane energy absorption under quasi-static lateral loads. Numerical and experimental compression tests results under axial and lateral loads are analyzed. The proposed cell geometry was designed to overcome the limitations posed by standard hexagonal honeycombs, which show relatively low stiffness and energy absorption under loads that have a significant lateral component. To achieve this, the new cell geometry was designed with internal diagonal walls to support the external walls, increasing its stiffness and impact energy absorption in comparison with the hexagonal cell. 3D-printed unit-cell specimens made from ABS thermoplastic material were subjected to experimental quasi-static compression tests, in both lateral and axial directions. Energy absorption was compared to that of the standard hexagonal cell, with the same mass and height. Finite element models were developed and validated using experimental data. Results show that the innovative geometry absorbs approximately 15% more energy under lateral compression, while maintaining the same level of energy absorption of the standard hexagonal cell in the axial direction. The present study demonstrates that the proposed cell geometry has the potential to substitute the standard hexagonal honeycomb in applications where significant lateral loads are present.
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Liu, Ai-rong, Yong-hui Huang, Qi-cai Yu, and Rui Rao. "An Analytical Solution for Lateral Buckling Critical Load Calculation of Leaning-Type Arch Bridge." Mathematical Problems in Engineering 2014 (2014): 1–14. http://dx.doi.org/10.1155/2014/578473.
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An analytical solution for lateral buckling critical load of leaning-type arch bridge was presented in this paper. New tangential and radial buckling models of the transverse brace between the main and stable arch ribs are established. Based on the Ritz method, the analytical solution for lateral buckling critical load of the leaning-type arch bridge with different central angles of main arch ribs and leaning arch ribs under different boundary conditions is derived for the first time. Comparison between the analytical results and the FEM calculated results shows that the analytical solution presented in this paper is sufficiently accurate. The parametric analysis results show that the lateral buckling critical load of the arch bridge with fixed boundary conditions is about 1.14 to 1.16 times as large as that of the arch bridge with hinged boundary condition. The lateral buckling critical load increases by approximately 31.5% to 41.2% when stable arch ribs are added, and the critical load increases as the inclined angle of stable arch rib increases. The differences in the center angles of the main arch rib and the stable arch rib have little effect on the lateral buckling critical load.
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Nuțu, Emil, and Horia Miron Gheorghiu. "Simulation of Bone Mechanical Adaptation Using Different Mathematical Models: A Comparative Numerical Study." Key Engineering Materials 638 (March 2015): 183–88. http://dx.doi.org/10.4028/www.scientific.net/kem.638.183.
Повний текст джерелаАнотація:
The adaptation of bones to mechanical loads or bone remodeling can be simulated using specific mathematical models in conjunction with the finite element method. There are several theories proposed within the literature for the prediction of the bone behavior under mechanical loads and all have been used successfully, within certain limits of prediction details, but no unanimous acceptance have been reported yet. Within this context, it is important to know the differences and similarities between the results which these theories can produce, in order to improve their interpretation. On the basics of the above observation, the paper presents the comparison between density distributions achieved using three different models of bone remodeling: the original strain energy density equation developed at the University of Nijmegen, the principle of cellular accommodation incorporated into the Nijmegen model and the variant developed at the University of Manchester obtained by adding the quadric term which eliminates the density accumulation at physiologically unrealistic high loads. It is shown, using a suggestive test problem, that the three models generate significantly different results.
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Li, Yi, Chao Li, Qiu-Sheng Li, Yong-Gui Li, and Fu-Bin Chen. "Refined Mathematical Models for Across-Wind Loads of Rectangular Tall Buildings with Aerodynamic Modifications." International Journal of Structural Stability and Dynamics 21, no. 09 (May 20, 2021): 2150131. http://dx.doi.org/10.1142/s0219455421501315.
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This paper aims to systematically study the across-wind loads of rectangular-shaped tall buildings with aerodynamic modifications and propose refined mathematic models accordingly. This study takes the CAARC (Commonwealth Advisory Aeronautical Research Council) standard tall building as a benchmark model and conducts a series of pressure measurements on the benchmark model and four CAARC models with different round corner rates (5%, 10%, 15% and 20%) in a boundary layer wind tunnel to investigate the across-wind dynamic loads of the typical tall building with different corner modifications. Based on the experimental results of the five models, base moment coefficients, power spectral densities and vertical correlation coefficients of the across-wind loads are compared and discussed. The analyzed results shown that the across-wind aerodynamic performance of the tall buildings can be effectively improved as the rounded corner rate increases. Taking the corner round rate and terrain category as two basic variables, empirical formulas for estimating the across-wind dynamic loads of CAARC standard tall buildings with various rounded corners are proposed on the basis of the wind tunnel testing results. The accuracy and applicability of the proposed formulas are verified by comparisons between the empirical formulas and the experimental results.
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Mahdi, Taha K., Mohammed A. Al-Neami, and Falah H. Rahil. "Experimental and Numerical Study on the Winged Pile-Soil Interaction under Lateral Loads." IOP Conference Series: Earth and Environmental Science 961, no. 1 (January 1, 2022): 012063. http://dx.doi.org/10.1088/1755-1315/961/1/012063.
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Abstract Increasing the cross-sectional area of piles leads to an increase in the lateral bearing resistance and reduces displacements near ground level. This increase compensates for the reduction in soil stiffness at the seabed level. Installing wings near the mudline level is one approach for increasing the area of the pile in mudline level. This research paper discusses a number of small-scale laboratory models and FEM models to study the benefit of adding wings on the variation of bearing capacity of laterally pile loaded embedded in sandy soil. To determine the advantages of adding wings to the pile, four embedded ratios (4, 6, 8, 10) were used to model both flexible and rigid pile types with various wing numbers and dimensions. The results revealed that adding wings to the pile improves lateral load resistance and greatly reduces lateral deflection. So, to achieve better resistance, wings must be linked with the pile shaft perpendicular to the lateral load applied nearer the top of the pile head. Increasing the number of wings results in a large increase in lateral pile capacity. The ultimate lateral applied load is proportional to the rise in relative density at the same (L/D) ratio.
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Zaya, Neven E., Lokman H. Hassan, and Halis Bilgil. "Mathematical Modeling for Prediction of Heating and Air-Conditioning Energies of Multistory Buildings in Duhok City." Academic Journal of Nawroz University 7, no. 4 (December 21, 2018): 153. http://dx.doi.org/10.25007/ajnu.v7n4a284.
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Present endeavor is devoted to estimate the air-conditioning and heating energies or loads of modern buildings in Duhok City, Iraq using new mathematical models. Many parameters have been considered in current modeling, namely, area of building, number of storeys and types of the common materials of the building walls. Regression analysis is performed to formulate new mathematical linear and nonlinear models for the loads. In addition, Fuzzy logic is utilized in the third model employing Sugeno's regulation. The outcomes reveal that the reasonable matching is achieved between the proposed models and mechanical engineering analytical solutions of heating and air-conditioning standards. Consequently, high correlation coefficient as more than 85% is determined between the predicted values of the models and analytical results. The linear model shows perfect matching with the analytical outputs more than the other proposed mathematical formulations.
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Lipecki, T., and A. Flaga. "Application of Simulation Methods of Stochastic Processes to Vortex Excitation." Archives of Civil Engineering 63, no. 1 (March 28, 2017): 77–98. http://dx.doi.org/10.1515/ace-2017-0006.
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AbstractA description of direct simulation of crosswind loads caused by critical vortex excitation and the response of the structure to these loads are presented in this paper. Tower-like structures of circular cross-sections are considered. A proposed mathematical model of vortex excitation has been numerically implemented and a selfserving computer program was created for the purpose. This software, cooperating with the FEM system, allows for a simulation of a crosswind load and lateral response in real time, meaning that at each time step of the calculations the load is generated using information regarding displacements seen beforehand. A detailed description of the mathematical model is neglected in this paper, which is focused on numerical simulations. WAWS and AR methods are used in simulations.
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Ruggieri, Claudio, and Jose´ Alfredo Ferrari,. "Structural Behavior of Dented Tubular Members Under Lateral Loads." Journal of Offshore Mechanics and Arctic Engineering 126, no. 2 (May 1, 2004): 191–97. http://dx.doi.org/10.1115/1.1712979.
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Structural behavior of tubular members with dent damaged caused by local indentation remains a key issue for the safety and failure assessment of critical structures, including marine facilities, oil and gas pipelines. This failure mode most often arises from very large localized plastic deformations caused mainly by excessive or accidental loads such as, for example, during the collision of adjacent risers in deepwater floating production systems (FPS). The complex interaction between the local deformation in the dented region and global bending of the tubular member may severely reduce the plastic collapse load which strongly affects its load-deflection behavior. This study presents an experimental and numerical investigation of the structural behavior of a dented tubular member under lateral load which is applicable to marine risers. Experimental load-deflection curves measured using a 412″O.D. (114 mm) API N80 pipe (580 MPa yield stress) with varying length characterize the plastic response during local indentation and global bending. 3D finite element models are employed to generate numerical solutions describing the large deformation, non-linear behavior for the tested pipes. The experimental results agree well with the numerical results. The analyses provide further insight into the structural response of tubular members and risers with dent damage effects.
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Hwang, Jaejin, Gregory G. Knapik, Jonathan S. Dufour, and William S. Marras. "A Comparison of Performance Between Straight-Line Muscle and Curved Muscle Models." Proceedings of the Human Factors and Ergonomics Society Annual Meeting 61, no. 1 (September 2017): 1339–40. http://dx.doi.org/10.1177/1541931213601817.
Повний текст джерелаАнотація:
The straight-line muscle biomechanical models of the lumbar spine have been utilized to predict spinal loads to assess the potential risk of work-related injuries. The curved muscle paths have been suggested to realistically simulate muscles’ behavior in complex lumbar motions. However, the effect of curved muscle paths on the modeling performances and spinal loads in the lumbar spine model during complex lifting exertions has not been fully investigated. The objective of this study was to characterize the differences in modeling performances and spinal loads between the conventional straight-line muscle model and the curved muscle model of the lumbar spine. Twelve subjects (6 males and 6 females) participated in this study. Mean values and standard deviations of age, body mass, and height of all subjects were 26.6 (5.3) years, 73.6 (13.3) kg, and 172.7 (5.4) cm, respectively. Electromyographic (EMG) activities with surface electrodes (Motion Lab Systems MA300-XVI, Baton Rouge, Louisiana, USA) were collected over 10 trunk muscles (pair of the latissimus dorsi, erector spinae, rectus abdominis, external oblique, and internal oblique) with 1000 Hz sampling rate. The OptiTrack optical motion capture system (NaturalPoint, Corvallis, OR, USA) with 24 Flex 3 infrared cameras was used to monitor whole body kinematics with 100 Hz sampling rate. A Bertec 4060A force plate (Bertec, Worthington, OH, USA) was used to measure ground reaction forces with 1000 Hz sampling rate. Customized Laboratory software via a National Instruments USB-6225 data acquisition board (National Instruments, Austin, TX, USA) was utilized to collect all signals simultaneously and efficiently run the model. Subjects performed complex lifting tasks by various load weight (9.1kg and 15.9kg), load origins (counterclockwise 90⁰, counterclockwise 45⁰, 0⁰, clockwise 45⁰, and clockwise 90⁰), and load height (mid-calf, mid-thigh, and shoulder). Both curved muscle model and straight-line muscle model were tested under same experiment conditions, respectively. The curved muscle model showed better model fidelity (average coefficient of determination (R2) = 0.83; average absolute error (AAE) = 14.4%) than the straight-line muscle model (R2 = 0.79; AAE = 20.7%), especially in upper levels of the lumbar spine. The curved muscle model showed higher R2 than the straight-line muscle model, and the T12/L1 level showed the biggest difference as 0.1. The curved muscle model had lower AAE than the straight-line muscle model, and the T12/L1 showed the biggest difference as 18%. The curved muscle model generally showed higher compression (up to 640N at T12/L1), lower anterior-posterior shear loads (up to 575N at T12/L1), and lower lateral shear loads (up to 521N at T12/L1) than the straight-line muscle model. The biggest difference in spinal loads between two models (especially in anterior-posterior shear and lateral shear loads) occurred at upper levels of the lumbar spine, which could be related to the amount of muscle curvatures at each spine level. The curved muscle model generally showed higher compression and lower anterior-posterior and lateral shear loads than the straight-line muscle model. It might be partially related to the muscle paths of the erector spinae (major power producing muscle). In curved muscle model, erector spinae was placed more parallel with the lumbar spine curvature than the straight-line muscle model. It could affect the spinal load distributions such as higher compression and lower shears loads in the curved muscle model compared to the straight-line muscle model. In conclusion, the improved performance of the curved muscle model indicated that the curved muscle approach would be advantageous to estimate precise spinal loads in complex lifting jobs compared to the straight-line muscle approach.
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Sadakov, Sergey, Fabio Villone, Guglielmo Rubinacci, and Salvatore Ventre. "Simple Parametric Model for Calculation of Lateral Electromagnetic Loads in Tokamaks at Asymmetric Vertical Displacement Events (AVDE)." Plasma 5, no. 3 (July 25, 2022): 306–23. http://dx.doi.org/10.3390/plasma5030024.
Повний текст джерелаАнотація:
This paper describes a family of relatively simple numerical models for calculation of asymmetric electromagnetic (EM) loads at all tokamak structures and coils at asymmetric vertical plasma displacement events (AVDE). Unlike currently known AVDE studies concentrated on plasma physics, these models have a practical purpose to calculate detailed time-dependent patterns of AVDE-induced EM loads everywhere in the tokamak. They are built to intrinsically assure good-enough EM load balance (opposite net forces and torques for the Vacuum Vessel and the Magnets with zero total for the entire tokamak), as needed for consequent simulation of the tokamak’s dynamic response to AVDE, as well as for the development of tokamak monitoring algorithms and tokamak simulators. To achieve these practical goals, the models work in a manner of parametric study. They do not intervene in details of plasma physics, but run at widely varied input assumptions on AVDE evolution and severity. Their outputs will fill a library of ready-for-use lateral EM loads for multiple variants of AVDE evolution and severity. The tokamak physics community can select any variant from the library, and engineers can pick ready-for-use AVDE loads. Investigated here, EM models represent one already known approach and one newly suggested. The latter attempts to reflect the helical pattern of halo currents in plasma and delivers richer outcomes and, thus, can be preferred as the single practical model for parametric calculations.
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Molina Herrera, Maritzabel, and Javier Alberto Ortíz Porras. "Behavior of cold-formed thin steel sections (MM) under concentrated loads." Ingeniería e Investigación 26, no. 3 (September 1, 2006): 12–25. http://dx.doi.org/10.15446/ing.investig.v26n3.14744.
Повний текст джерелаАнотація:
New sections are continually being developed in the cold-formed steel world to improve the performance of existing sections. M-section development provides an example of improving C-sections’ shear resistance and web crippling resistance against C-sections’ concentrated loads. C-sections’ shear nominal strength can be achieved through locating tow web intermediate stiffeners (M-sections) even though web crippling resistance cannot be increased in the same way. Such intermediate stiffeners mean that M-section stresses and deflections cannot be analysed with traditional material mechanics. Concentrated loads cause this behavior to become increased; 4 different models and 3 tests for each of them were thus developed, as well as determining M-sections’ theoretical resistance (based on 1996 AISI). The values obtained corresponded to maximum resistance load, visual identification of any possible type of failure, deflections (at middle span) and deformations (εx, εy, εxy). Mathematical models were also used for comparing the finite element method and simplified mathematical models’ test results for a detailed review of MM-section stress and deformation. These models were calibrated on the test results. After the failure mode was identified for each model, MM-section maximum resistance load was compared to nominal load (according to AISI formulation, also aiding formulating nominal strength calculation). The information obtained from tests and mathematical models was analysed to observe parameter (∆, σ y T) tendencies respecting applied load (P). Cyclic tests under pseudo-static loads were performed to study MM-sections’ hysteretic behavior.
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Kang, Heesuk, Paul Park, Frank La Marca, Scott J. Hollister, and Chia-Ying Lin. "Analysis of load sharing on uncovertebral and facet joints at the C5–6 level with implantation of the Bryan, Prestige LP, or ProDisc-C cervical disc prosthesis: an in vivo image-based finite element study." Neurosurgical Focus 28, no. 6 (June 2010): E9. http://dx.doi.org/10.3171/2010.3.focus1046.
Повний текст джерелаАнотація:
Object The goal of this study was to evaluate and compare load sharing of the facet and uncovertebral joints after total cervical disc arthroplasty using 3 different implant designs. Methods Three-dimensional voxel finite element models were built for the C5–6 spine unit based on CT images acquired from a candidate patient for cervical disc arthroplasty. Models of facet and uncovertebral joints were added and artificial discs were placed in the intervertebral disc space. Finite element analyses were conducted under normal physiological loads for flexion, extension, and lateral bending to evaluate von Mises stresses and strain energy density (SED) levels at the joints. Results The Bryan disc imposed the greatest average stress and SED levels at facet and uncovertebral joints with flexion-extension and lateral bending, while the ProDisc-C and Prestige LP discs transferred less load due to their rigid cores. However, all artificial discs showed increased loads at the joints in lateral bending, which may be attributed to direct impinging contact force. Conclusions In unconstrained/semiconstrained prostheses with different core rigidity, the shared loads at the joints differ, and greater flexibility may result in greater joint loads. With respect to the 3 artificial discs studied, load sharing of the Bryan disc was highest and was closest to normal load sharing with the facet and uncovertebral joints. The Prestige LP and ProDisc-C carried more load through their rigid core, resulting in decreased load transmission to the facet and uncovertebral joints.
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Qasim, Tuka Mohammed, and Salah Rohaima Al-Zaidee. "Experimental Investigation for Non and Partially Composite Cold-Formed Steel Floor Beams." Civil Engineering Journal 5, no. 6 (June 23, 2019): 1407–23. http://dx.doi.org/10.28991/cej-2019-03091341.
Повний текст джерелаАнотація:
In this study, six full-scaled models of RC floors supported by cold-form steel sections have been tested. Each model consists of RC 75mm thick slab supported on two parallel cold-formed steel beams with a span of 3m and spacing of 500mm. The slab has an overhang part of 250mm on each side. In the first and fourth models, the slab has been casted directly on the top flanges with no shear connector to simulate the effectiveness of friction in resisting of the lateral-torsional buckling. Shear studs have been drilled in the second and fifth models to ensure the composite action. Finally, the flanges have been embedded for the third and sixth models. A single channel beam is used in the first, second, and third models while a built-up beam is used in the fourth, fifth, and sixth models. Each model has been loaded up to failure under a pure bending with two-line loads located at the third points. Data for loads, deformations, and strains have been gathered. Except the fourth and the sixth models that failed in local buckling modes, all other models failed in global lateral-torsional buckling modes. For the single beam models; the load carrying capacity of the non-composite model is 82.9% less than the capacity of the composite models with shear studs and embedded flange. For the built-up models; the load carrying capacity of the non-composite model is 44.2 % less than the loads of the composite model with shear stud and 48.7% less than the model with the embedded flange.
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Sarhan, Osamah, and Mahdy Raslan. "Study of the elastic stiffness factor of steel structures with different lateral load resisting systems." International Journal of Advanced Engineering, Sciences and Applications 1, no. 2 (April 30, 2020): 6–11. http://dx.doi.org/10.47346/ijaesa.v1i2.26.
Повний текст джерелаАнотація:
Steel structures, like other types of structures, are exposed to different types of loads, including lateral loads such as earthquake and wind. To resist such loading, lateral stiffness has a significant role. In this paper, the elastic stiffness factor (K) for different models of steel structure with various bracing systems and different parameters are compared. The comparison has been performed by analysing and studying the formation of plastic hinges applying the pushover analysis. The results illustrate that the increase in the number of stories reduces the K value, while the increase of span length increases it. Besides, the usage of the bracing system significantly increases the K value.
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Uddin, Syed Zubair. "Comparative Study of Tube in Tube Flat Slab with Tube in Tube Waffle Slab, Structures Under the Sesmic Loads." International Journal for Research in Applied Science and Engineering Technology 9, no. 9 (September 30, 2021): 2113–21. http://dx.doi.org/10.22214/ijraset.2021.38329.
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Abstract: The tube in tube structure is one of the type that is been broadly used as structural system for tall structures. Considering the lateral loads due to the seismic force it gives more stiffness and gives more strength to the high-rise structures. Lateral loads are shared between the inner and outer tubes our aim is to make the structure stiff by its connectivity and comparing them by providing drops to the waffle. By adding tube in tube to the flat slab and waffle slab, concept is they both does not have the beams such that to know the comparison of both the models. This both models have been designed using e-tabs software and the dimensions, limitations are been taken from the provision Indian standard code book. Keywords: High-rise building, tube in tube, Response spectrum analysis.
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Azzam, H. "Mathematical networks for thermal transient and non-transient progressive fatigue of engine components." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 212, no. 2 (February 1, 1998): 125–36. http://dx.doi.org/10.1243/0954410981532199.
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Engine components can experience varying centrifugal loads, gas loads, oxidation, micro- structure transformation at high temperatures and stresses induced by temperature gradients. The life consumption of hot engine components depends not only on these factors but also on the time spent at constant-amplitude loads. The damage mechanism of engine components is therefore complex and requires formidable models. These models are not suitable for fatigue management or on-board systems because of their high computational costs. There is a need for efficient simulations that can accurately portray this complex damage mechanism and, at the same time, can be embedded in fatigue management and on-board systems. Mathematical networks were developed to fulfil this need and successfully synthesized the fatigue damage of aircraft structural components from flight parameters. In this paper, the feasibility of training the mathematical networks to synthesize fatigue of engine components is demonstrated. The mathematical attributes of the networks were based on information supplied by Rolls-Royce. The networks’ training mechanism was targeted at the minimization of errors in synthesized accumulative damage values. The mathematical networks synthesized the accumulative fatigue damage of three engine components successfully. One component was subject to non-thermal transient stresses and two components were subject to thermal transient stresses.