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1
Zinco, Adamo, Fernando Fraternali, Gianmario Benzoni i Enzo Martinelli. "On the Distribution in Height of Base Shear Forces in Linear Static Analysis of Base-Isolated Structures". Buildings 10, nr 11 (1.11.2020): 197. http://dx.doi.org/10.3390/buildings10110197.
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Although base isolation is nowadays a well-established seismic-protection technique for both buildings and bridges, and several issues are still open and attract the interest of the research community. Among them, the formulation of computationally efficient and accurate analysis methods is a relevant aspect in structural design of seismic-isolated buildings. In fact, codes and guidelines currently in force in various parts of the world generally include the possibility for designers to utilize linear-elastic analysis methods based on equivalent linearization of the non-linear force-displacement response of isolators. This paper proposes a formula for defining the force distribution in height that should be considered in linear-static analyses to obtain a more accurate approximation of the actual structural response, supposedly simulated by means of non-linear time history analysis. To do that, it summarizes the results of a wide parametric analysis carried out on a batch of structures characterized by three different heights and various properties of base isolators. The reported results highlight that the equivalent static force distribution provided by both Italian and European codes tend to underestimate the actual seismic lateral forces acting on base-isolated buildings, whereas the inverted triangular distribution, proposed in various American codes and standards, is often conservative.
2
Figliolini, Giorgio, i Massimo Sorli. "Open-loop Force Control of A Three-finger Gripper Through PWM Modulated Pneumatic Digital Valves". Journal of Robotics and Mechatronics 12, nr 4 (20.08.2000): 480–93. http://dx.doi.org/10.20965/jrm.2000.p0480.
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This paper proposes an open-loop force control system for a three-finger gripper using small digital solenoid valves modulated using PWM (Pulse-Width-Modulation) technique. These valves are good candidates for this robotic application because of their small dimensions, low weight and cost, simple structure and easy operation by means of on/off signals. A linear model for pressure control in the pneumatic actuator's thrust chamber was developed and tested experimentally. A large dead-band was introduced in the PWM driver in order to investigate a suitable method for its correction. Good results were obtained by correcting the static characteristic curve of the three-way equivalent valve that controls the flow rate exchanged with the pneumatic cylinder thrust chamber. These results can be applied to similar solutions with larger digital valves. Gripping mechanism efficiency and the effects of friction forces were taken into account in developing the force control.
3
Jiang, Shan, Fude Sun, Jiansheng Dai, Jun Liu i Zhiyong Yang. "Design and analysis of a tendon-based MRI-compatible surgery robot for transperineal prostate needle placement". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 229, nr 2 (7.05.2014): 335–48. http://dx.doi.org/10.1177/0954406214533783.
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Tendon-based transmission has significant advantages in the development of a surgical robot, which is fully magnetic resonance imaging compatible and can work dexterously in the very limited space inside magnetic resonance imaging core. According to the requirements of magnetic resonance imaging compatibility, a novel 6 degrees of freedom tendon-based surgical robot composed of three independent modules is developed in this paper. After a brief introduction to the robot, the direct and inverse kinematic equations are deduced by applying the concept of screw displacements, and the reachable workspace of the robot is calculated. As to the static force analysis, we apply the principle of virtual work to derive a transmission between the equivalent joint torques and the tendon forces. By the use of the pseudoinverse technique, a systematic method is developed for the resolution of redundant tendon forces.
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Singh, A., N. Nawayseh, L. P. Singh, S. Singh i H. Singh. "Investigation of Compressive Stress on Lumbar Spine due to Whole Body Vibration Exposure in Rotary Tillage Operation". International Journal of Automotive and Mechanical Engineering 16, nr 2 (4.07.2019): 6684–96. http://dx.doi.org/10.15282/ijame.16.2.2019.16.0503.
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The aim of this study is to investigate the compressive stress on lumbar spine due to whole body vibration (WBV) exposure in real field rotary soil tillage operation. The spinal stress was evaluated in terms of daily equivalent static compression dose (Sed) with respect to various ride conditions (i.e. forward speed, pulling force and tilling depth). Taguchi's L9 orthogonal array was used to form a systematic set of experiments by varying each ride condition over three levels. Signal-to-noise (S/N) ratios were computed to analyse the holistic effect of ride conditions among all the experimental conditions. In addition, the power spectral density (PSD) of the acceleration at the seat pan was measured along the dominant axis for each experiment. A second order regression model was developed to predict the real experimental Sed response. Further, the ride conditions were optimised by using desirability technique with the aim of minimizing Sed response. The magnitude of daily equivalent static compression dose was found between 0.38 and 0.76 MPa which shows a moderate probability of an adverse health effects as per ISO2631-5: 2004. Statistically, forward speed and pulling force are found to significantly affect the Sed response with a contribution of 64.43% and 24.73%, respectively. The PSD indicated that the vibration energy of the acceleration measured on the seat pan depend on the ride conditions. The predicted response of regression model showed 4.56% error in obtaining the actual experimental values. The optimised forward speed, pulling force and tilling depth levels were found to be 0.6 m/s, 2 kN, and 0.10 m, respectively.
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Hu, Botao, Linan Cheng, Xiaobo Sun i Fanchen Deng. "Design Technique of the Test Static for Large Curvature Composite Radome". Journal of Physics: Conference Series 2553, nr 1 (1.08.2023): 012019. http://dx.doi.org/10.1088/1742-6596/2553/1/012019.
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Abstract The radome is an important component that maintains the aerodynamic shape of the aircraft, makes the electrical property stable, and ensures flight safety. Composite is used in most aircraft radome in the world to reduce the weight of the aircraft. For the sake of safety, a static strength test was usually conducted on the radome to verify whether its strength and stiffness meet the requirements. In this paper, the load was treated equivalently, and a lever loading system of nonparallel force was put forward considering the characteristics of the large curvature of the radome structure and that it was difficult to apply load. All test cases were completed successfully, and the test results indicate that the test system works stably and reliably, and the strength and stiffness of the radome meet the design requirements.
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Meena, Balveer Singh, Atul Kumar Shrivastava i Kunal Bhelave. "A Finite-element Method of Solution for Optimization of Frame of Tractor Operated Single Row Maize Cobs Picker". International Journal of Plant & Soil Science 35, nr 3 (2.03.2023): 154–59. http://dx.doi.org/10.9734/ijpss/2023/v35i32787.
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Finite element analysis (FEA) is a computational technique that divides complex structures into small elements and solves them numerically using various partial differential equations. In agriculture, engineers can use numerical simulation based on the FEA technique to study the behaviour of various input products in order to optimise the design of any machine without developing a prototype. The present study focused to design and simulates the frame of tractor operated single row maize cobs picker by employing the FEA technique. A 3D-CAD model of the frame of a tractor-operated single row maize cobs picker was created using the Solid Works software, and a static structural test was performed using the FEA technique in the ANSYS version 15.0 workbench software. A special fixture has been developed to calculate the force required to scrape the pulpy material of the leaves in the Universal Testing Machine. According to the simulation results, maximum deformation was observed as 0.051mm while maximum shear stress and Von Mises equivalent stress were found to be 0.246 MPaPa and 1. 47 MPa, respectively at 250 N scraping forces. Additionally, it was noted that the stress values fall within the material's yield strength. The FEA approach was found to be a scientific and highly effective method for designing and simulating the frame of a tractor-operated single row maize cobs picker.
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Boulkhiout, Radhwane. "Soil Densification Effect on The Seismic Response of Structures Taking into Consideration Soil-Structure Interaction". Civil Engineering Beyond Limits 2, nr 4 (21.09.2021): 13–17. http://dx.doi.org/10.36937/cebel.2021.004.003.
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Soil compaction is a considerable construction activity to ensure safety and durability, notably in the transportation industry. This technique of compaction increases soil bulk density and soil strength, while decreases porosity, aggregate stability index, soil hydraulic conductivity, and nutrient availability, thus reduces soil health. Consequently, it lowers crop performance via stunted aboveground growth coupled with reduced root growth. Therefore, if the characteristics of the soil are changed, it will affect the response of the structures. In this work, the effect of improving soil characteristics by compaction techniques on the dynamic response of foundations and structures, taking into consideration the effect of soil-structure interaction was determined. The dynamic response of foundations is presented by the impedances functions, which are determined numerically by the CONAN program, based on the cone method. In addition, the response of the structure will be presented according to the lateral displacement in each level of it. This motion vector is a function of the forces in each level; for this, the equivalent static method was applied, which allows to calculate the seismic force at the base and its distribution on the height of the structure. The results obtained show the efficiency of soil densification on the seismic response of MDOF frames.
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Ahmad, Naveed, Qaisar Ali i Muhammad Umar. "Seismic Vulnerability Assessment of Multistory Timber Braced Frame Traditional Masonry Structures". Advanced Materials Research 601 (grudzień 2012): 168–72. http://dx.doi.org/10.4028/www.scientific.net/amr.601.168.
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Research carried out on the seismic investigation of timber braced frame (TBF) masonry structures of traditional construction practice is presented, essential for seismic performance evaluation of such construction type using engineering approaches. An innovative simplified equivalent frame method (EFM) based on macro modelling approach is presented for nonlinear dynamic seismic analysis of TBF masonry structures. The modelling include EFM idealization of wall using stiff elastic beam-column element assigned with moment-rotation (M-θ) nonlinear lumped plasticity hinges. Earlier, the approach i.e. the EFM idealization and M-θ constitutive law, is calibrated with the experimental results obtained through quasi-static cyclic test on full scale walls. The technique is further extended herein for seismic dynamic analysis of multistory structures. Generalization of the technique for modelling walls of various geometry and loading is performed. It included nonlinear static pushover analysis of various case study walls, by means of SAP2000 calibrated earlier with experimental results, for the derivation of lateral force-deformability behavior towards the development of generalized M-θ constitutive law for TBF masonry walls. Three representative structures, from one to three storeys, are analyzed using a suite of ten natural accelerograms and incremental dynamic analysis technique. Structure fragility and resilience functions are derived using a fully probabilistic and dynamic approach. The structures analyzed in the present study represent TBF masonry wall structures, called as Dhajji-Dewari structures, common in Northern areas of Pakistan.
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Yazdani, Aref. "Field Equations and Radial Solutions in a Noncommutative Spherically Symmetric Geometry". Advances in High Energy Physics 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/349659.
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We study a noncommutative theory of gravity in the framework of torsional spacetime. This theory is based on a Lagrangian obtained by applying the technique of dimensional reduction of noncommutative gauge theory and that the yielded diffeomorphism invariant field theory can be made equivalent to a teleparallel formulation of gravity. Field equations are derived in the framework of teleparallel gravity through Weitzenbock geometry. We solve these field equations by considering a mass that is distributed spherically symmetrically in a stationary static spacetime in order to obtain a noncommutative line element. This new line element interestingly reaffirms the coherent state theory for a noncommutative Schwarzschild black hole. For the first time, we derive the Newtonian gravitational force equation in the commutative relativity framework, and this result could provide the possibility to investigate examples in various topics in quantum and ordinary theories of gravity.
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Qureshi, Ramla Karim, Negar Elhami-Khorasani i Thomas Gernay. "Adaption of active boundary conditions in structural fire testing". Journal of Structural Fire Engineering 10, nr 4 (9.12.2019): 504–28. http://dx.doi.org/10.1108/jsfe-12-2018-0042.
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Purpose This paper aims to investigate the need for active boundary conditions during fire testing of structural elements, review existing studies on hybrid fire testing (HFT), a technique that would ensure updating of boundary conditions during a fire test, and propose a compensation scheme to mitigate instabilities in the hybrid testing procedure. Design/methodology/approach The paper focuses on structural steel columns and starts with a detailed literature review of steel column fire tests in the past few decades with varying axial and rotational end restraints. The review is followed with new results from comparative numerical analyses of structural steel columns with various end constraints. HFT is then discussed as a potential solution to be adapted for fire testing of structural elements. Challenges in contemporary HFT procedures are discussed, and application of stiffness updating approaches is demonstrated. Findings The reviewed studies indicate that axial and rotational restraints at the boundaries considerably influence the fire response of steel columns. Equivalent static spring technique for simulating effect of surrounding frame on an isolated column behavior does not depict accurate buckling and post-buckling response. Additionally, numerical models that simulate fire performance of a column situated in a full-frame do follow the trends observed in actual test results up until failure occurs, but these simulations do not necessarily capture post-failure performance accurately. HFT can be used to capture proper boundary conditions during testing of isolated elements, as well as correct failure modes. However, existing studies showed cases with instabilities during HFT. This paper demonstrates that a different stiffness updates calculated from the force-displacement response history of test specimen at elevated temperature can be used to resolve stability issues. Originality/value The paper has two contributions: it suggests that the provision of active boundary conditions is needed in structural fire testing, as equivalent static spring does not necessarily capture the effect of surrounding frame on an isolated element during a fire test, and it shows that force-displacement response history of test specimen during HFT can be used in the form of a stiffness update to ensure test stability.
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Bhelave, Kunal, Atul Kumar Shrivastava i Balveer Singh Meena. "A Finite-Element Method for Enhancement Issues of Frame of Battery Operated Ridge Planter with Drip Line Installer". International Journal of Environment and Climate Change 13, nr 9 (18.07.2023): 1355–62. http://dx.doi.org/10.9734/ijecc/2023/v13i92364.
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Using distinct partial differential equations, complicated structures breaks down into small elements using the computational approach known as finite element analysis (FEA). Engineers in agriculture can investigate the behavior of numerous input products using numerical simulation based on the FEA technique in order to enhance the design of any machine without constructing a prototype. The current study employed the FEA technique to develop and simulate the frame of a battery-operated ridge planter with a drip line installer. A static structural test was performed through using the FEA technique in the ANSYS version 15.0 workbench software, and a 3D-CAD model of the frame of a battery-operated ridge planter with drip line installer was made using the Solid Works software. To determine the force necessary in the universal testing machine and the applied forces, respectively, on the frame, a specific fixture has been generated.
Total deformation was measured at 23313 mm, and the simulation revealed that the maximum shear stress, equivalent stress, normal stress, stress intensity, and strain energy were, respectively, 8.40 MPa, 16.68 MPa, 16.4 MPa, 16.8 MPa, and 3.55 MPa at 1817.5 N of total load acting on the frame.
The stress values are within the material's yield strength, it was also observed. The FEA methodology was discovered to be a way for creating and simulating the frame of a battery-operated ridge planter with drip line installer that is very effective and scientific.
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Naraghi, Tahereh, i Ali S. Nobari. "A novel method for the identification of a model for the nonlinear characteristic of a bolted lap-joint". Journal of Vibration and Control 23, nr 3 (9.08.2016): 484–500. http://dx.doi.org/10.1177/1077546315581238.
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Joints are the main source of nonlinearity and energy dissipation in large assembled structures which could be otherwise considered as linear. Consequently, modeling and parameter identification of joints play a significant role in any successful design and finite element (FE) modeling of structures. In the present research, an identification procedure is proposed for the modeling of the nonlinear behavior of a bolted joint. The main emphasis are placed on the simplicity of the experimental procedures involved as well as ease of incorporation of the identified model in the FE model of the structure. Using the concept of the optimum equivalent linear frequency response function, structure was excited by two levels of random force, at two bolt preload levels, and then the eigen values of the nonlinear structure and the inverse eigen-sensitivity identification technique are used, in order to identify the nonlinear properties of bolted joints. The results of implementing the method are promising and indicative of the fact that, in contrast to static Iwan’s model of a bolted joint, the equivalent dynamic characteristics of a bolted joint may be frequency dependent, as the different modes will affect the interface zone of the jointed structures in a different manner.
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Utegenova, Shinara. "Implementation of the sliding-line technique in a MEC model of a linear bistable actuator". COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 41, nr 1 (2.12.2021): 517–27. http://dx.doi.org/10.1108/compel-07-2021-0230.
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Purpose The aim of this study is to investigate the implementation of the sliding-line technique (SLT) in a generic two-dimensional (2D) nonlinear adaptive magnetic equivalent circuit (MEC) model predicting the electromagnetic force evolution of a linear bistable electromagnetic actuator technology. Design/methodology/approach The developed MEC model considers the saturation effect and the auto-adjustability of the spatial discretisation. The connection between static and mobile zones is ensured by an approach known as “air-gap sliding-line technique”, which is widely used for rotary electric motor models. To the best of the author’s knowledge, that is the first time that the SLT is implemented on an electromagnetic structure with linear motion. Findings It was found that, in case of a linear actuator with a relatively small working stroke, the implementation of the SLT could lead to some non-negligible inaccuracies. Originality/value To solve the above-mentioned problem, it was proposed to investigate the implementation of a single SLT vs double SLT. The results of the MEC models were compared with the 2D finite-element analysis (FEA) as well as with the experimental test results. The developed semi-analytical models can be easily adapted to other topologies of linear electromagnetic machines.
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Tayebi, Noureddine, Thomas F. Conry i Andreas A. Polycarpou. "Reconciliation of nanoscratch hardness with nanoindentation hardness including the effects of interface shear stress". Journal of Materials Research 19, nr 11 (1.11.2004): 3316–23. http://dx.doi.org/10.1557/jmr.2004.0425.
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The definitions of hardness from nanoscratch and nanoindentation analyses with a spherical indenter were compared and shown to be mathematically equivalent for the case of zero interface shear stress (surface traction). The definition of nanoindentation hardness was taken as the ratio of the resultant force to the area of contact projected on a plane normal to the line of action of the resultant force, whereas in the case of the nanoscratch technique, the hardness and interfacial shear stress were related to the measured normal and lateral forces in a nanoscratch experiment, as well as to the cross-sectional area of the groove. The two definitions of hardness were then applied to nanoscratch experimental data from material systems covering a wide range of hardness values. The calculated values of hardness from the two definitions were based on the contact area, determined from the scratch residual profile and the elastic recovery of the plastically deformed surface, and yielded the same values of hardness within experimental error. The contact angle, and thus the contact area, was shown experimentally to be sensitive to interface shear stress: a positive increase in interface shear stress led to a reduction in contact area as compared to the case of a frictionless contact. For a material with given hardness, normal indenter force, and contact area, a positive or negative interface shear stress is balanced by a positive or negative change, respectively, in the lateral force about the value needed to maintain a static balance for a frictionless nanoscratch contact. A comparison of these effects with experimental data indicates that very hard materials tend to have negative to zero interface shear stress, which correlates to a sink-in effect, whereas the soft materials tend to have positive interface shear stress, which correlates to a pileup effect.
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Zhang, Ruijie, Dan Ye, Jianting Zhou i Dengzhou Quan. "Seismic Analysis Method for Underground Structure in Loess Area Based on the Modified Displacement-Based Method". Applied Sciences 11, nr 23 (26.11.2021): 11245. http://dx.doi.org/10.3390/app112311245.
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At present, the seismic design research of underground structures in loess areas is lagging behind compared with practical engineering requirements. The selection of seismic calculation methods and parameters does not consider the influences of the special geological conditions in various regions, so their usefulness is limited. Based on the above problems, a modified displacement-based method (DBM) was proposed and its application was compared with the most commonly used methods of analysis (force-based design method, displacement-based design method, detailed equivalent static analysis numerical method, and the full dynamic time-history method). The results were also validated by considering data from shaking table tests conducted on a case study involving the underground Feitian Road subway station in Xi’an. The results show that compared with DBM, the average accuracy of the modified DBM technique is improved by 41.65%. The modified DBM offers good accuracy, simplicity in its model, a rapid analysis time, and easy convergence.
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Deng, M. L., i B. Z. Yue. "Attitude Dynamics and Control of Liquid Filled Spacecraft with Large Amplitude Fuel Slosh". Journal of Mechanics 33, nr 1 (15.07.2016): 125–36. http://dx.doi.org/10.1017/jmech.2016.60.
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AbstractThis paper focuses on the attitude dynamics and control of liquid filled spacecraft, and the large amplitude fuel slosh dynamics is included by using an improved moving pulsating ball model. The moving pulsating ball model is an equivalent mechanical model that is capable of imitating the whole liquid reorientation process, specifically for the occurrence of large amplitude slosh. This model is improved by incorporating a static capillary force and an effective mass factor. The improvements on this model are validated with previously published experiment results. The spacecraft attitude maneuver is implemented by the momentum transfer technique, and the feedback control strategy is designed based on Lyapunov theory. The effects of liquid viscosity, tank location and desired steady time on sloshing torque and control torque are investigated. The attitude control strategy applied in this paper is proved to be applicable for the coupled liquid filled spacecraft system. The obtained conclusions are useful to aid in liquid filled spacecraft overall design.
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Zeng, Qing Na, Sheng Li Lv, Lei Jiang Yao i Xiao Yan Tong. "Damage Mechanism of Plain Weave C/SiC Composites Subjected to Quasi-Static Indentation Loading". Advanced Materials Research 211-212 (luty 2011): 217–21. http://dx.doi.org/10.4028/www.scientific.net/amr.211-212.217.
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Quasi-static indentation (QSI) tests on plain weave carbon fiber reinforced silicon carbide (C/SiC) ceramic matrix composites (CMC) have been performed to study the damage evolution law and damage modes. Acoustic emission (AE) and Ultrasonic C-scan techniques are creatively used to monitor the damage process and detect the indented damage, respectively. The damage development process could be described by three evidently different stages: initial crack tips spreading along within the matrix, matrix cracking and delamination as well as fiber bundles breakage of different layers. The AE activity indicated that the main damage modes are matrix cracking and delamination in the first two stages, once the pressing force exceeds the peak load the damage mode will change into fiber bundles breakage. Moreover, the damage procured in the QSI test is slightly lower than that produced in the low velocity impact (LVI) test under the equivalent energy, the correspondence between the two test methods is reasonably good.
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Hariri-Ardebili, Mohammad Amin, i Victor E. Saouma. "Random Response Spectrum Analysis of Gravity Dam Classes: Simplified, Practical, and Fast Approach". Earthquake Spectra 34, nr 2 (maj 2018): 941–75. http://dx.doi.org/10.1193/021517eqs033m.
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The seismic risk of concrete dams may be assessed using various numerical techniques, ranging from simplified methods to linear and nonlinear ones. Such methods should be combined with probabilistic concepts to account for the randomness in both demand and capacity. This paper proposes a random version of a simplified response spectrum method (involving equivalent static lateral forces [ESLFs]) for gravity dams by means of propagating uncertainties through the input parameters. Input parameter sensitivity is quantified and the extended procedure is explained step by step. Results are then generalized for the different dam classes. The impacts of sampling size and technique (i.e., pseudo-random and quasi-random) are also discussed. A time-based performance is evaluated and fragility curves are derived. This method may be used during the initial stages of a design process or safety analysis for existing dams.
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Yu, Muchun, Xue Gao i Qian Chen. "Study of the Mechanical Properties and Vibration Isolation Performance of a Molecular Spring Isolator". Shock and Vibration 2016 (2016): 1–10. http://dx.doi.org/10.1155/2016/6451829.
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Molecular Spring Isolator(MSI) is a novel passive vibration isolation technique, providingHigh-Static-Low-Dynamic(HSLD) stiffness based on the use ofmolecular springmaterial. Themolecular springmaterial is a solid-liquid mixture consisting of water and hydrophobic nanoporous materials. Under a certain level of external pressure, water molecules can intrude into the hydrophobic pores of nanoporous materials, developing an additional solid-liquid interface. Such interfaces are able to store, release, and transform mechanical energy, providing properties like mechanical spring. Having been only recently developed, the basic mechanic properties of a MSI have not been studied in depth. This paper focuses on the stiffness influence factors, the dynamic frequency response, and the vibration isolation performance of a MSI; these properties help engineers to design MSIs for different engineering applications. First, the working mechanism of a MSI is introduced from a three-dimensional general view of the water infiltration massive hydrophobic nanoporous pores. Next, a wide range of influence factors on the stiffness properties of MSI are studied. In addition, thefrequency response functions(FRFs) of the MSI vibration isolation system are studied utilizing the matching method based on equivalent piecewise linear (EPL) system. Finally, the vibration isolation properties of MSI are evaluated by force transmissibility.
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Tiwari, Anubhav, Ishfaq A. Ahmed, Vijay Kumar Gupta, Rakesh Kumar Haldkar i Ivan A. Parinov. "Customised Implant for Temporomandibular Joint: New Technique to Design and Stress Analysis to Balance the Loading at Both Ends". Micromachines 14, nr 8 (20.08.2023): 1646. http://dx.doi.org/10.3390/mi14081646.
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The temporomandibular joint (TMJ) is a critical joint for the opening and closing of the mouth. The generation of customised TMJs according to individuals’ dental anatomy is needed. Currently, the implants available on the market lack consideration of the patient’s dental anatomy. This leads to the creation of an imbalance in the reaction forces on both ends of the TMJ. This requires a slight structural change in the design parameters to give a solution. The purpose of this study is to propose a new design that includes the geometry and materials for a TMJ implant. Stress analysis was carried out on the TMJ to balance the reaction forces at both TMJ ends. A static analysis was performed using ANSYS Workbench, to compare the results of two customised designs of TMJ implants, in order to better balance the reaction forces at both ends. The model in the study showed that the reaction forces for both the patient-specific TMJ implants were nearly balanced. The reaction forces were better balanced, and almost equivalent to the intact conditions. The stresses in the mandible were more uniformly distributed in the customised design of the TMJ implant. The two types of design showed that the custom design took up less space in the patient’s region of surgery, making it a better option compared to a stock TMJ implant. The custom implant would allow faster patient rehabilitation, as the reaction forces would be close to those in intact conditions.
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Paull, A., R. J. Stalker i D. J. Mee. "Experiments on supersonic combustion ramjet propulsion in a shock tunnel". Journal of Fluid Mechanics 296 (10.08.1995): 159–83. http://dx.doi.org/10.1017/s0022112095002096.
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Measurements have been made of the propulsive effect of supersonic combustion ramjets incorporated into a simple axisymmetric model in a free piston shock tunnel. The nominal Mach number was 6, and the stagnation enthalpy varied from 2.8 to 8.5 MJ kg−1. A mixture of 13% silane and 87% hydrogen was used as fuel, and experiments were conducted at equivalence ratios up to approximately 0.8. The measurements involved the axial force on the model, and were made using a stress wave force balance, which is a recently developed technique for measuring forces in shock tunnels. A net thrust was experienced up to a stagnation enthalpy of 3.7 MJ kg−1, but as the stagnation enthalpy increased, an increasing net drag was recorded. Pilot and static pressure measurements showed that the combustion was supersonic.The results were found to compare satisfactorily with predictions based on established theoretical models, used with some simplifying approximations. The rapid reduction of net thrust with increasing stagnation enthalpy was seen to arise from increasing precombustion temperature, showing the need to control this variable if thrust performance was to be maintained over a range of stagnation enthalpies. Both the inviscid and viscous drag were seen to be relatively insensitive to stagnation enthalpy, with the combustion chambers making a particularly significant contribution to drag. The maximum fuel specific impulse achieved in the experiments was only 175 s, but the theory indicates that there is considerable scope for improvement on this through aerodynamic design.
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Thenappan, Shanmugasekar. "Investigation of Dynamic Factor, Rail Stress and Track Foundation Modulus of Ballasted Railway Track for Different Bed Conditions Using Numerical Methods". IOP Conference Series: Materials Science and Engineering 1200, nr 1 (1.11.2021): 012018. http://dx.doi.org/10.1088/1757-899x/1200/1/012018.
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Abstract The track stiffness is the primary function of roadbeds thickness and subgrade characteristics. For this purpose, numerical scale track finite element technique representing the ballasted track with multi layered substructure founded on subgrade was simulated. The track deflection, stress was abstracted in static and dynamic conditions. The track significant design parameters: Foundation modulus, rail fatigue strength, rail bending stress and stress on subgrade levels were evaluated by using improved current track design numerical methods and compared against field test results which were carried out on part of MG Double track high speed main line (1600 km). Mathematical equations were developed to correlate the variables; ballast thickness, settlement, track stiffness, rail bending stress and rail fatigue strength on varying subgrade soil modulus. Incorporation of this parametric study will improve and optimise the conventional track design and maintenance standard. A simple improved track design was introduced by using single track stiffness parameter from conventional plate bearing test (PBT) on Force Displacement (FD) conventional curve method. The improved method with deriving equivalent track stiffness from rail pad and track substructure tested C value are accurate and simple. The current test method to determine the track stiffness in live track condition is expensive and unsafe with operational requirements. This PBT is simple, cost saving on labour, safe and without applying live train load.
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Cocchi, Lorenzo, Alessio Picchi i Bruno Facchini. "Effect of Rotation and Hole Arrangement in Cold Bridge-Type Impingement Cooling Systems". International Journal of Turbomachinery, Propulsion and Power 4, nr 2 (29.05.2019): 13. http://dx.doi.org/10.3390/ijtpp4020013.
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Experimental activity has been performed to study different impingement cooling schemes in static and rotating conditions. Geometry replicates a leading-edge cold bridge system, including a radial supply channel and five rows of film-cooling and showerhead holes. Two impingement geometries have been studied, with different numbers of holes and diameters but with equal overall passage area. Reynolds numbers up to 13,800 and rotation numbers up to 0.002 have been investigated (based on an equivalent slot width). Tests have been performed using a novel implementation of transient heat transfer technique, which allows correct replication of the sign of buoyancy forces by flowing ambient temperature air into a preheated test article. Results show that complex interactions occur between the different features of the system, with a particularly strong effect of jet supply condition. Rotation further interacts with these phenomena, generally leading to a slight decrease in heat transfer.
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Khedr, Mohamed A., i Ghyslaine McClure. "A simplified method for seismic analysis of lattice telecommunication towers". Canadian Journal of Civil Engineering 27, nr 3 (1.06.2000): 533–42. http://dx.doi.org/10.1139/l99-090.
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A simplified static method for estimating the member forces in self-supporting lattice telecommunication towers due to both horizontal and vertical earthquake excitations is presented in this paper. The method is based on the modal superposition technique and the response spectrum approach, which are widely used for seismic analysis of linear structures. It is assumed that the lowest three flexural modes of vibration are sufficient to correctly estimate the tower's response to horizontal excitation, while only the lowest axial mode is sufficient to capture the response to vertical excitation. An acceleration profile along the height of the tower is defined using estimates of the lowest three flexural modes or the lowest axial mode, as appropriate, together with the spectral acceleration values corresponding to the associated natural periods. After the mass of the tower is calculated and lumped at the leg joints, a set of equivalent static lateral or vertical loads can be determined by simply multiplying the mass profile by the acceleration profile. The tower is then analyzed statically under the effect of these loads to evaluate the member forces. This procedure was developed on the basis of detailed dynamic analysis of ten existing three-legged self-supporting telecommunication towers with height range of 30-120 m. The maximum differences in member forces obtained with the proposed method and the detailed seismic analysis are of the order of ±25% in the extreme cases, with an average difference of ±7%. The results obtained for two towers with heights of 66 and 83 m are presented in this paper to demonstrate the accuracy and practicality of the proposed method.Key words: self-supporting tower, earthquake, vertical excitation, dynamic analysis.
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ЧУРИЛОВ, Д. Г., И. С. АРАПОВ, А. В. СТАРУНСКИЙ i С. Д. ПОЛИЩУК. "JUSTIFICATION OF APPLICATION MODES OF MACHINING ATTACHMENTS FOR PROCESSING PARTS BY THE METHOD OF PLASTIC DEFORMATION". VESTNIK RIAZANSKOGO GOSUDARSTVENNOGO AGROTEHNOLOGICHESKOGO UNIVERSITETA IM P A KOSTYCHEVA, nr 2(50) (30.06.2021): 136–41. http://dx.doi.org/10.36508/rsatu.2021.50.2.019.
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Проблема и цель. Установлено, что функциональное действие машин в значительной мере определяется параметрами качества их поверхностного слоя. Цель работы – обеспечение качества поверхностного слоя деталей одним из наиболее эффективных способов, обеспечивающих управление в широком диапазоне показателями качества обработки деталей поверхностным пластическим деформированием (ОУО ППД). Одни и те же параметры качества поверхностного слоя можно получить, используя различные методы и режимы ОУО ППД. Для их оценки необходимо определение трудоемкости операции. Следовательно, имеет место совокупность научно-технических задач, решение которых позволяет разработать методологию, алгоритм и программу выбора оптимального метода и условий ОУО ППД, обеспечивающих требуемые параметры качества поверхности при минимальной технологической себестоимости, что дает значительный экономический эффект. Методология. Одним из способов обработки деталей при восстановлении служит алмазное выглаживание после процесса шлифования. Выглаживатель – кристаллический алмаз – перераспределят металл поверхностного слоя, при этом меняется микрорельеф. После алмазного выглаживания увеличивается надежность, долговечность деталей, износостойкость. Для достижения цели предлагается использование двухзвенных оправок, которые позволяют исключить биение обрабатываемой поверхности. Структурный эквивалент механизма близок к кривошипно-шатунному механизму, в отличие от которого радиус обрабатываемой детали распределяется по дуге. Изменения силы выглаживания устанавливают связь между статической силой и силой инерции. Статическую силу сглаживания можно определить, зная основные технологические параметры и процессы. Сила инерции зависит от массы подвижного звена оправки. Результаты. Результаты настоящего исследования показали: к числу задаваемых параметров относятся масса подвижного звена оправки, диаметр детали, скорость скольжения, эксцентриситет, постоянная механизма и сила инерции. Найдены разрешенные частоты вращения в зависимости от диаметра детали. Заключение. Данная методика может быть применена для восстановления рабочих поверхностей поршневых пальцев автотракторных дизельных двигателей сельскохозяйственного назначения и позволяет снизить уровень шероховатости поверхности обрабатываемых деталей. Problem and purpose. Problem and purpose. It has been established that the functional action of machines is largely determined by the quality parameters of their surface layer. The purpose of the work is to ensure the quality of the surface layer of parts by one of the most effective methods that provides control over a wide range of quality indicators for processing parts by surface plastic deformation (SPD). The same parameters of the quality of the surface layer can be obtained using different methods and modes of SPD. To assess them, it is necessary to determine the complexity of the operation. Consequently, there is a set of scientific and technical problems, the solution of which makes it possible to develop a methodology, an algorithm and a program for choosing the optimal method and conditions for SPD, which provide the required surface quality parameters at a minimum technological cost, that gives a significant economic effect. Methodology. One of the methods of processing parts during restoration is diamond burnishing after the grinding process. The smoother or the crystal diamond will redistribute the metal of the surface layer, thus changing the microrelief. After diamond burnishing, reliability, durability of parts, and wear resistance increase. To achieve the goal, it is proposed to use two-link mandrels, which allow to exclude the beating of the treated surface. The structural equivalent of the mechanism is close to the crank gear, in contrast to which the radius of the workpiece is distributed along the arc. Changes in the smoothing force establish a relationship between static force and inertial force. The static smoothing force can be determined by knowing the basic technological parameters and processes. The force of inertia depends on the mass of the moving link of the mandrel. Results. The results of this study showed that the parameters set included the mass of the movable link of the mandrel, the diameter of the part, the sliding speed, the eccentricity, the constant of the mechanism and the force of inertia. The permitted speeds were found depending on the diameter of the part. Conclusion. This technique can be used to restore the working surfaces of the piston pins of automotive diesel engines for agricultural purposes and can reduce the level of surface roughness of the processed parts
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Ramos, Leandro Ito, Douglas Jhon Ramos i Gregory Bregion Daniel. "Evaluation of textured journal bearings under dynamic operating conditions in rotating machinery". Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 234, nr 6 (5.11.2019): 842–57. http://dx.doi.org/10.1177/1350650119887568.
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In order to obtain rotating machinery with improved energy efficiency, the approach of surface texturing journal bearings has been adopted to reduce the viscous dissipation in the lubricant. A possible reduction in shear viscous forces in the bearings of rotating machines could reduce the amount of heat released along its operation, resulting in a lower operating temperature that tends to improve journal bearings performance and the machine’s energetic efficiency. Thus, this work aims to investigate the texturing of journal bearings under dynamic loading conditions, considering the application in rotating systems. For this, computational simulations are performed through a rotating system model constructed by means of the finite element method in which the hydrodynamic journal bearings that support the rotor are modeled by Reynolds’ equation using the finite volume method and the full multigrid technique. The numerical results show that textured journal bearings can be applied to rotating machines, providing reductions in shear viscous forces. However, the magnitude of this reduction should be carefully evaluated, as the Reynolds cavitation model was applied to ensure a lower computational spent time and thus enable the simulations involved in this study. The novelty of this study is related to determining the appropriate distributions and geometric parameters of the textures for the journal bearing under dynamic load condition considering its equivalent static load condition what tends to drastically reduce computational time to perform this procedure, representing an important alternative for industrial application.
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Kudryavtsev, I. V., M. M. Mikhnev i P. N. Silchenko. "A Calculation Procedure for Strength Analysis of Wave Guides for Ensuring Improved Mass-Dimensional Parameters". Proceedings of Higher Educational Institutions. Маchine Building, nr 05 (722) (maj 2020): 50–61. http://dx.doi.org/10.18698/0536-1044-2020-5-50-61.
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This paper presents a calculation procedure for designing waveguides with iproved mass-dimensional parameters, which ensures the required strength and stiffness characteristics under static, dynamic and deformational loads. The procedure is based on the analysis of methods for determining the stress-strain state of the waveguide-and-distribution systems of spacecraft. The first stage of the procedure involves modelling the waveguide-and-distribution systems in a general formulation by a rod structure with equivalent loading and fixing conditions and determining the stress-strain state of such a system. At the second stage, local areas with the maximum stress-strain state values are selected for a further refined analysis in the rod system. An evaluation of the influence of the waveguide wall thickness on the general stress-strain state is performed. It is shown that when the waveguide wall thickness varies in the range of 0.25 – 2.50 mm, the strength and stiffness of its sections under static loads basically follow the linear law. It is established that under dynamic loading the wall thickness has almost no effect on the resultant stress-strain state of the waveguide arising under the influence of forced fluctuations and quasi-static loading owing to its dependence on the ratios of mass, moments of inertia and resistance, which for some standard sizes of the waveguides will be almost constant. The equations obtained for the rod system cannot be used for evaluating the influence of the wall thickness on local stress-strain state in the form of wall deflection, local loss of stability, etc. In view of this, at the second stage of modelling local areas of interest are selected and transformed into 3D thin-walled structures, with translation into finite element method programs for a more exact analysis. In the future, the proposed technique can be used to solve connected problems of interrelation and the influence of cross-sectional deformations in local zones of the waveguide on the changes in electromagnetic fields with the formation of parasite waves. This will significantly improve the quality of radio engineering characteristics of the waveguide and distribution systems while ensuring their strength, stiffness and minimal mass-dimensional parameters.
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Гребеников, А. Г., И. В. Малков, С. П. Светличный, И. Н. Москаленко i О. Ю. Кривых. "МЕТОД ПІДТВЕРДЖЕННЯ РЕСУРСНИХ ХАРАКТЕРИСТИК МЕТАЛЕВОЇ ЛОПАТІ НЕСУЧОГО ГВИНТА ВЕРТОЛЬОТА ЗА РЕЗУЛЬТАТАМИ ВИПРОБУВАНЬ". Open Information and Computer Integrated Technologies, nr 96 (23.02.2023): 34–96. http://dx.doi.org/10.32620/oikit.2022.96.03.
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The helicopter main rotor blade is the basic product that determines the reliability and service life of the helicopter as a whole. The problem of predicting and ensuring the specified blade life is an urgent problem considered at the stage of its design. The analysis of the design, structural materials and design and technological solutions of the main rotor blade (RB) of the Mi-8 helicopter has been carried out. A brief description of the main rotor blade of the Mi-8 helicopter is presented. The analysis was carried out and a standard flight cycle (SFC) of the helicopter was developed. The type of bench equipment for carrying out bench fatigue tests of the blade has been selected and justified. The loads on the main rotor blade for the SFC are determined. To determine the fatigue life of a blade, it is necessary to know the characteristics of the stress-strain state. The calculation of the stress-strain state (SSS) of a blade by the finite element method (FEM) using the ANSYS system is presented. The characteristics of the stress-strain state of the spar of the regular and irregular parts of the rotor blade of a helicopter are determined using the ANSYS system. The use of numerical methods for calculating the characteristics of the stress-strain state can significantly reduce the time and cost of designing a blade. The paper presents the results of calculating the regular part of the main rotor blade of the Mi-8 helicopter in the hover mode in the case of its loading with aerodynamic and inertial load from rotation, as well as the force from its own weight. With the help of the ANSYS system, a finite element model of the regular part of the blade was developed, consisting of a set of beam elements of variable section, a calculation was carried out taking into account the geometric nonlinearity of the structure's behavior, and an analysis of the results obtained was carried out. To describe the response of materials to an external action, a model of an elastically deformable isotropic body was used with the assignment of the corresponding elastic constants of the material. The analysis of the calculation results includes the determination of reactions at the attachment points, the values of the maximum displacements of structural elements and stresses in dangerous sections. Dangerous sections are determined and the values of the longitudinal force and bending moment in these sections are calculated. The assessment of the static strength of the blade by the safety factor was carried out. When evaluating the static strength, the equivalent stresses according to Mises were considered as the maximum design stresses. To assess the fatigue strength, we analyzed the distribution of the main tensile stresses in the power elements over typical stress concentrators. The maximum level of the main tensile stresses in the dangerous section indicates that the blade material operates in the zone of high-cycle fatigue. A technique for calibrating strain gauge channels has been developed. The calculation of the characteristics of the rotor blade of a helicopter is based on the requirements set forth in the technical literature, regulatory documents. When performing work, the requirements of the Aviation Rules, Part 29 (AP - 29) were taken into account. These studies were the basis for the development of a method for confirming the resource characteristics of a helicopter main rotor blade based on the results of flight and bench tests.
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Krot, Pavlo, Radoslaw Zimroz, Anna Michalak, Jacek Wodecki, Szymon Ogonowski, Michal Drozda i Marek Jach. "Development and Verification of the Diagnostic Model of the Sieving Screen". Shock and Vibration 2020 (18.06.2020): 1–14. http://dx.doi.org/10.1155/2020/8015465.
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The minerals processing enterprises are widely using vibrating machines to separate different fractions of materials. Sieving efficiency is greatly dependent on particle trajectories, or orbit, of periodical motion over the sieving decks. A screening process is very dependable on design parameters such as the vibrator power, synchronisation of their drives, and oscillation frequency as well as the stiffness of supporting springs. Deterioration of supporting springs (stiffness reduction and cracks) due to cyclic loading and fatigue is difficult to determine by the visual inspection, static loading tests, or nondestructive testing techniques. Vibration monitoring systems of different vendors are analysed where vibration sensors usually installed on the bearings of vibrators are as well used for supporting springs diagnostics. However, strong cyclic components from the unbalanced exciters and stochastic disturbances from the input stream and vibrating pieces of the material make analysis a not trivial task. The considered vibrating screen is investigated on the 6-DOF (degree-of-freedom) dynamical model to reflect all linear and rotational components of spatial motion. Besides the main periodic motion, the model accounts for stochastic alpha-stable distributed impacts from the material. Instead, the Gaussian normal distribution is considered for the position of equivalent force application point. Supporting springs are represented by the bilinear stiffness characteristics. Specific features of vibration signals (angle of orbit inclination, natural frequency change, harmonics of natural frequency, and phase space plots) are analysed to recognise the weak nonlinear features of a system under conditions of small stiffness changes in springs. The extensive measurements are conducted on the industrial vibrating screen, and the dynamic model is verified by the measurement data. Recommendations are given on failure diagnostics of springs in the industrial vibrating screens.
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Ma, Yanhua, Xueqian Chen i Wenjie Zuo. "Equivalent static displacements method for contact force optimization". Structural and Multidisciplinary Optimization 62, nr 1 (30.01.2020): 323–36. http://dx.doi.org/10.1007/s00158-020-02500-y.
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Zhang, Xiang Ming, Li Bao Zhu, An Wen Wang, Shao Hong Yang i Ming Yong Hu. "Superficial Discussion on New Framework of Static Equilibrium". Applied Mechanics and Materials 670-671 (październik 2014): 691–95. http://dx.doi.org/10.4028/www.scientific.net/amm.670-671.691.
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Statics is set up on the basis of 4 axioms of statics. Although these axioms are distillate and summarizing of the accumulated humankind's experience in long-range production and life, introduction of these axioms to statics seems a bit abrupt, especially the critical axiom "resultant of two forces" far fetched. This article was an attempt to present the embodying description of the effect of force and force system, based on the nature of effect of force and the equivalent and equilibrium of force systems. On this basis, theorem of two forces resultant and the theorem of two forces balance were proved, and the theorem of force systems equivalent was brought up. A new framework of static equilibrium system was built up to try to make a more perfect and more reasonable description for static equilibrium.
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Qi, Xin, Qianqian Deng, Lei Zhao, Song Yuan, Zhenliang Li, Xibao Wang i Zhixiang Yu. "Equivalent Relationship of the Mechanical Behavior of Ring Nets under Static Punching and Dynamic Impact Conditions". Buildings 13, nr 3 (22.02.2023): 588. http://dx.doi.org/10.3390/buildings13030588.
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To build the equivalent relationship of the mechanical behavior of ring nets under static punching and dynamic impact conditions, a series of tests with different parameters were conducted. The equivalent coefficients of breaking force, breaking displacement, and net energy dissipation were defined to describe the potential relationship. Besides, sensitivity analyses were made. The results showed that, with the increase of impact velocity, the equivalent coefficients of breaking force decreased as a power function, and the equivalent coefficients of breaking displacement and net energy dissipation both decreased linearly. As the ring diameter increased, the equivalent coefficients of breaking force increased linearly, but the equivalent coefficients of breaking displacement and net energy dissipation both decreased linearly. With the increase of the aspect ratio of ring net, the equivalent coefficients of breaking force and breaking displacement decreased linearly and exponentially, respectively, and the equivalent coefficients of net energy dissipation decreased as a power function. With the increase of the ratio of loading head area to ring net area, the equivalent coefficients of breaking force increased as a power function, and the equivalent coefficients of breaking displacement and net energy dissipation decreased and increased linearly, respectively. The influence degrees of these parameters are as follows: impact velocity > ring diameter > aspect ratio of ring net > ratio of loading area to ring net area. Based on these four parameters, the equivalent coefficient formulas of static punching and dynamic impact were established.
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Xu, Jie, Keiji Yamada, Katsuhiko Seikiya, Ryutaro Tanaka i Yasuo Yamane. "A Basic Study on the Relations Between Machining Conditions and the Static and Dynamic Components of Forces in Drilling". International Journal of Automation Technology 7, nr 3 (5.05.2013): 345–52. http://dx.doi.org/10.20965/ijat.2013.p0345.
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This paper discusses a method of converting thrust and torque detected during drilling, which transforms thrust and torque into equivalent thrust force and principal force. The static and dynamic components defined according to this method are used to evaluate instability. The effects of different conditions on the static and dynamic components are investigated through experiments.
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Song, Meng Yan, Ge Tian, Ming Wu Yuan, Li Na Ge, Jing Jing Song i Xiang Rong Fu. "Dynamic Characteristic Analysis of the 3D Spring Model of Column with Triangular Section". Applied Mechanics and Materials 353-356 (sierpień 2013): 3304–7. http://dx.doi.org/10.4028/www.scientific.net/amm.353-356.3304.
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In this paper, the equivalent mechanical spring model of the three-dimensional continuum is studied. By using stiffness calculation formulas of three-dimensional continuum column under axial force and bending force, which are primary force states in the column, a mechanical equivalent trusses model with the same width and height is derived. The equivalent model is statically indeterminate trusses system of spring. The 3D spring calculation model can be used in the dynamic characteristic analysis. With the comparison of the first four order frequency values between the solid model and the equivalent spring model, it shows that the equivalent spring model not only have the equivalent stiffness in the static analysis but also have the equivalent dynamic characteristics in the dynamic analysis.
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Maguire, James R., Lip H. Teh, G. Charles Clifton i Timothy J. McCarthy. "Equivalent static force method for selective storage racks with uplifting baseplates". Journal of Constructional Steel Research 165 (luty 2020): 105821. http://dx.doi.org/10.1016/j.jcsr.2019.105821.
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Wang, Liang. "Gear Shaft Optimization Design". Academic Journal of Science and Technology 3, nr 2 (28.10.2022): 92–95. http://dx.doi.org/10.54097/ajst.v3i2.2099.
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Multi-objective optimization design of gear shaft, first determine the design variables, gear shaft structure size mainly includes length size and radius size, gear shaft shaft diameter as the optimization variable, the equivalent force of gear shaft is an important indicator of static performance, and the gear shaft is optimized with the maximum equivalent force of gear shaft as the optimization goal.
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Eidukynas, Rimantas, i Valdas Barauskas. "ANALYSIS OF CONTACT PROBLEMS IN ELASTIC—PLASTIC METAL SEALS/TAMPRIŲJŲ METALINIŲ SANDARIKLIŲ KONTAKTINĖS SĄVEIKOS TYRIMAS". JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 3, nr 10 (30.06.1997): 37–42. http://dx.doi.org/10.3846/13921525.1997.10531682.
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One of the most important problems in the design of seal joints is the optimisation of their shape and the material properties. This paper presents the results of the numerical simulation of conical and cantilever seal joints contact problems by using the finite element system ANSYS 5.0A. The temperature and friction have been taken into account. The sealing principle of conical seals, which are usually used as flange joints in networks of pipes, is based on large plastic deformations of seal edges and maintaining the highly elastic property of the whole construction of the seal. Fig 1 presents the scheme of the conical seal used as a base for numerical simulations. The relation between the contact force and displacement in conical seals with various material hardening shows that the contact force is not proportional to the displacement. The latter statement is demonstrated by Fig 2, presenting the results of the numerical simulations, where the curves 1, 2, 3 correspond to the following numerical values of material properties curve 1- E = 2,1.105 MPa, σy = 280 MPa, Eκ1 = 7000 MPa (ε ≤ 0,0125), E&kappa2 = 2500 MPa (0,0125 < ε ≤ 0,0125), Eκ3 = 600 MPa (0,1 < ε ≤ 0,3), Eκ4 = 1000 MPa (ε > 0,3), curve 2—E=2,1.105 MPa, σy = 200 MPa, Eκ = 5.103 MPa; curve 3—E = 2,1.105 MPa, σy = 500 MPa, Eκ = 3.103 MPa. Under displacement 0,7—1,3 mm, the cone seal usually loses stability by exhibiting the second form of instability. Such a sealing joint is not suitable for the practical application as it is not hermetic. Fig 3 shows the deformed shape and contours of the equivalent plastic strains of the above-mentioned conical seal (RAD1=0,153 m, RAD2=0,159 m, h=0,001 m, A=0,0007m, α = 60°, β=0°, ϕ = 10°, γ = 45°, E = 2,1.105 MPa, σy=280 MPa, Eκ1 =7000 MPa (ε ≤ 0,0125), Eκ2 =2500 MPa (0,0125 < ε ≤ 0,0125), Eκ3 = 1600 MPa (0,1 < ε ≤ 0,3), Eκ4 = 1000 MPa (ε > 0,3), ν = 0,3) in one of the loading steps of the solution process. Numerous numerical simulations have shown that the second form of instability is caused by unfavourable loading and boundary conditions for the first instability form. Such numeric results correspond exactly to the experiments. Under high pressure of the working medium (over 40 MPa), such seals collapse by exhibiting the first form of instability. The contact force increases only by 10%, and the collapse occurs when the seal is loaded more than 1,4 mm. V—and λ—form (cantilever) seals may recover from static and 0,1—0,4 mm dynamic displacements due to their high elasticity. Usually such seals possess soft metallic or polymeric coats. The process of the seal deformation is very complex because the contact surface slides and rolls upon the basic surface. In this paper the problem has been solved be using the submodelling techniques of ANSYS. The submodelling involves analysing a coarse model and by subsequently creating the finely meshed “submodel” of the region of interest. The coarse model displacements are applied as constraints on the cut boundary of submodel. In this problem, we will use the region of the whole cantilever seal as the coarse model. The region of interest is the contact zone, so we create the submodel of this region. Due to symmetry, only half a seal needs to be modelled (Fig 4), where RADX = 3 mm,S1 = 5 mm, H1 = 1,7 mm, H2 = 0,5 mm,S2 = 0,5 mm,3 = 2,8 mm, S3=5,5 mm, RAD1 = RAD2 = RAD3 = 1 mm, RADY = 4mm, RADC=30 mm, DD=0,1 mm, δ=0,12 mm, E= 2,1.105 MPa, ν = 0,3. After numerous numerical simulations, the base relations were defined. The maximum stress intensity dependence against the parameters of the arms of the cantilever spring seal elastic zone (Fig 6); ratio of relative seal radius against maximal stress intensity σI, pressure force F and contact pressure q1 (Fig 7). The analysis enabled to obtain the optimised construction of the seal. The elastic-plastic deformation analysis of the coating has been performed. When the loads are small, the stress and strain contours are characteristic of classic Hertzian [1] contact theory. With higher loads, the picture changes significantly. After increasing the contact area width, the plastic zone grows and develops through to the boundaries of the interacting region. By summarising the simulation results were obtained: the relations between the contact width, the approach of the contact surfaces δ, relative contact force Fk and ratio q/σy, when coating thickness is 0,14 mm and radius of the indenter 0,5 mm. The relation q/σy in this case is constant, approximately equal to 16. With the increase of the indenter radius, the ratio q/σy is not constant and increases with an increase of the contact force. The numerical simulations of various seals allow to arrive to the following conclusions: For cone seals the geometric instability (usually in the second form) is exhibited even at computatively small loads. When the loading exceeds 1,2 mm, the elastic structure may acquire an unaxisymmetric form. In the usage of such seals, the following points should be taken into account: it is necessary to match the materials properly. Best suitable materials have higher yield point and higher stiffness hardening; try to keep axisymmetric form of a seal even under the collapse. For this reason it is necessary to keep high requirements; good results are obtained by covering the seals with soft coatings, thus reducing the force. In such way only the coating is subjected to the plastic deformation, while the whole structure remains elastic. Cantilever seals have good elastic properties and do not loose stability. After summarising the numerical simulations results, the suggestions for the rational geometric shape of the cantilever seal have been made. In the design of coated seals it is necessary to take into account that the equivalent plastic strains in the coat layers close to the indenter increase with increasing contact force, decreasing the indenter radius and the coat thickness
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Song, Zhiqiang, Fei Wang, Yujie Liu i Chenhui Su. "Infinite Element Static-Dynamic Unified Artificial Boundary". Shock and Vibration 2018 (5.07.2018): 1–14. http://dx.doi.org/10.1155/2018/7828267.
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The method, which obtains a static-dynamic comprehensive effect from superposing static and dynamic effects, is inapplicable to large deformation and nonlinear elastic problems under strong earthquake action. The static and dynamic effects must be analyzed in a unified way. These effects involve a static-dynamic boundary transformation problem or a static-dynamic boundary unified problem. The static-dynamic boundary conversion method is tedious. If the node restraint reaction force caused by a static boundary condition is not applied, then the model is not balanced at zero moment, and the calculation result is distorted. The static numerical solution error is large when the structure possesses tangential static force in a viscoelastic static-dynamic unified boundary. This paper proposed a new static-dynamic unified artificial boundary based on an infinite element in ABAQUS to solve static-dynamic synthesis effects conveniently and accurately. The static and dynamic mapping theories of infinite elements were introduced. The characteristic of the infinite element, which has zero displacement at faraway infinity, was discussed in theory. The equivalent nodal force calculation formula of infinite element unified boundary was deduced from an external wave input. A calculation and application program of equivalent nodal forces was developed using the Python language to complete external wave inputting. This new method does not require a static and dynamic boundary transformation and import of stress field and constraint counterforce of boundary nodes. The static calculation precision of the infinite element unified boundary is more improved than the viscoelastic static-dynamic unified boundary, especially when the static load is in the tangential direction. In addition, the foundation simulation range of finite field can be significantly reduced given the utilization of the infinite element static dynamic unified boundary. The preciseness of static calculation and dynamic calculation and static-dynamic comprehensive analysis are unaffected.
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Paultre, Patrick, Éric Lapointe, Sébastien Mousseau i Yannick Boivin. "On calculating equivalent static seismic forces in the 2005 National Building Code of Canada". Canadian Journal of Civil Engineering 38, nr 4 (kwiecień 2011): 476–81. http://dx.doi.org/10.1139/l11-021.
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Several major changes were introduced in the seismic design provisions of the 2005 edition of the National Building Code of Canada (NBCC). The lateral earthquake design force at the base and the lateral force distribution along the building height depend on the design spectra and on modification factors that, in most cases, require a large number of interpolations and calculations. This note presents a spreadsheet that facilitates determination of the 2005 NBCC seismic design forces from the equivalent static force procedure.
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Ningrum, Diana, Albertus Nahak i Nawir Rasidi. "Comparison Analysis of Equivalent Static Earthquake and Spectrum Response Dynamics on Steel Structure". Asian Journal Science and Engineering 1, nr 2 (26.01.2023): 103. http://dx.doi.org/10.51278/ajse.v1i2.548.
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The purpose of this study is to compare two methods of seismic load analysis, namely the static equivalent method and the dynamic response spectrum method. The case study is the integrated service building of Tribhuwana Tunggadewi University, Malang City which has 5 levels and is located in the 4 (medium) earthquake zone with moderate soil conditions. The research method used is descriptive quantitative. Collecting data of project drawings, as well as observations and interviews. Analysis method Equivalent static and dynamic response spectrum using software Staad Pro. The results compared are the base shear force (V), the floor lateral force (F), and the displacement or displacement. The result in the form of maximum internal force is analyzed to determine the capacity or ability of the profile to withstand combined loads. The comparison of base shear and displacement does not differ much from the two seismic analysis methods used. This insignificant difference is in accordance with the SNI that for structures with a height below 40m can be analyzed using equivalent statics, while in the case study it only has a height of 30m. So that the equivalent static analysis becomes more accurate to use because the analysis process is simpler than dynamic analysis, but for structures with a height above 5 floors it is recommended to use dynamic analysis. The results of the analysis of the ability of the steel profile on the cross section of the column and beam indicate a safe condition in carrying combined loads.
Keywords: Volume Fraction, Cannabis Sativa Fibers, Fiber Composites
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ZHOU, XUANYI, i MING GU. "AN APPROXIMATION METHOD FOR COMPUTING THE DYNAMIC RESPONSES AND EQUIVALENT STATIC WIND LOADS OF LARGE-SPAN ROOF STRUCTURES". International Journal of Structural Stability and Dynamics 10, nr 05 (grudzień 2010): 1141–65. http://dx.doi.org/10.1142/s0219455410003944.
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Due to their sensitivity to wind, the design of large-span roofs is generally governed by wind loads. For some flexible large-span roofs with low damping and concentrated modes, the effect of multi-mode coupling should be taken into account in computing the resonant buffeting response and equivalent static wind loads. Such an effect is considered by the modified SRSS method in this paper via the modal coupling factor. Based on the same SRSS method, the equivalent static wind loads combining the mean, background, and resonant components, are computed. Particularly, the background and resonant components are computed by the LRC method and the equivalent inertia force method considering the modal coupling effects by the modified SRSS method, respectively. The method is then applied to the computation of wind-induced vibration responses and equivalent static wind load distributions of a real large-span roof. The results show that the modal coupling effect on the resonant component can be identified by the present method with high accuracy.
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Li, Jing Fu, i Zhi Jun Long. "A New Structure of a Force Sensor Based on the Analysis of Electromechanical Impedance". Advanced Materials Research 179-180 (styczeń 2011): 793–800. http://dx.doi.org/10.4028/www.scientific.net/amr.179-180.793.
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In this article a new structure of a force sensor based on piezoelectric materials is proposed. The design and choice of measuring principle is based on the direct piezoelectric effect, for the measurement of the dynamic force, and on the analysis of the electromechanical impedance technique, for measuring the static force. This technique is based on the measurement of modes of the structure. Indeed, the application of stress on the structure will cause changes in the modes of the structure and appearance of new eigenmodes. Thus far these methods should allow for measurement of static force applied.
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Fiore, Alessandra, i Pietro Monaco. "POD-based representation of the alongwind Equivalent Static Force for long-span bridges". Wind and Structures An International Journal 12, nr 3 (25.05.2009): 239–57. http://dx.doi.org/10.12989/was.2009.12.3.239.
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Heng, Kai, Tianli Chen, Ruiwen Li i Hao Wu. "Dynamic behaviors and equivalent static force of double-column pier under horizontal impact". Structures 49 (marzec 2023): 1093–111. http://dx.doi.org/10.1016/j.istruc.2023.02.016.
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Meng, Qingyi, Xiaoqian Chen i Huang Zhang. "Dynamic characteristics analysis of magnetorheological semi-active vibration isolator with high-static-low-dynamic stiffness". Journal of Physics: Conference Series 2343, nr 1 (1.09.2022): 012003. http://dx.doi.org/10.1088/1742-6596/2343/1/012003.
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High static and low dynamic stiffness vibration isolators have the advantages of high load-bearing capacity and small static displacement, but their negative stiffness components will cause a jump phenomenon at the resonance frequency. A semi-active vibration isolator with high-static-low-dynamic stiffness based on magnetorheological (MR) damper is proposed. The equivalent dynamic model of the MR semi-active vibration isolator is established, and the main resonance steady solution and stability conditions of the vibration isolation system are obtained using the average method. The influences of the basic excitation amplitude, excitation frequency, coulomb force, viscous damping coefficient, load-bearing mass, nonlinear elastic force coefficient and linear elastic force coefficient on the stability and performance of vibration isolation systems are analyzed. The results will provide a certain theoretical basis for the design of semi-active control strategies.
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Lu, Yun, Wei Jia Li, Wen Zhuo Tian i Kai Zhou. "Study on Measurement of Six-DOF Force/Torque for Loading Experiment on Heavy Load Equipment". Applied Mechanics and Materials 543-547 (marzec 2014): 1115–18. http://dx.doi.org/10.4028/www.scientific.net/amm.543-547.1115.
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According to the requirements of fatigue test of aircraft cabin, large engine and mining machinery for heavy-duty six dimensional generalized force sensors, a new method of using piezoelectric quartz as force-sensitive element on the basis of the theory of heavy force division and equivalent capacity compression is proposed in this study. Furthermore, in order to minimize the force-coupling for the six-dimension force sensor, the optimization objective function is devised and the calculation method for decoupling is also proposed, on the basis of which, the generalized force sensor with high sensitivity, high stiffness, high linearity but light in its weight is designed. At last, the static calibration experiment is carried out the result shows that the sensor has a good ability of heavy force division and capacity for equivalent compression it can be well used in large tonnage six component force loading device and fatigue test system.
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Wang, Junjie, Yanchen Song i Zhiran Yu. "Impact factor method for design of bridge foundations under ship collisions". Advances in Structural Engineering 20, nr 4 (1.08.2016): 534–48. http://dx.doi.org/10.1177/1369433216655923.
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Due to the complexity involved and limited study on the topic, the equivalent static method, adopted in the current codes for structural design of bridges under ship collisions, does not take into account the dynamic amplification effect correctly. In this article, impact factor method is proposed to estimate the response of bridge’s piers and foundations, as a better alternative of the equivalent static method. Through refined numerical simulations of ship-rigid wall collisions for nine typical ships under various impact velocities, 81 impact force time-histories are obtained. The period-dependent impact factor is defined, and empirical function of it is proposed and parameters in the empirical function are determined by the 81 sample impact force time-histories. Finally, both impact factor method and dynamic time-history method are used to estimate the responses of piers and foundations of two example bridges, and the precision of impact factor method is discussed.
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Platz, Daniel, Daniel Forchheimer, Erik A. Tholén i David B. Haviland. "Interpreting motion and force for narrow-band intermodulation atomic force microscopy". Beilstein Journal of Nanotechnology 4 (21.01.2013): 45–56. http://dx.doi.org/10.3762/bjnano.4.5.
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Intermodulation atomic force microscopy (ImAFM) is a mode of dynamic atomic force microscopy that probes the nonlinear tip–surface force by measurement of the mixing of multiple modes in a frequency comb. A high-quality factor cantilever resonance and a suitable drive comb will result in tip motion described by a narrow-band frequency comb. We show, by a separation of time scales, that such motion is equivalent to rapid oscillations at the cantilever resonance with a slow amplitude and phase or frequency modulation. With this time-domain perspective, we analyze single oscillation cycles in ImAFM to extract the Fourier components of the tip–surface force that are in-phase with the tip motion (F I ) and quadrature to the motion (F Q ). Traditionally, these force components have been considered as a function of the static-probe height only. Here we show that F I and F Q actually depend on both static-probe height and oscillation amplitude. We demonstrate on simulated data how to reconstruct the amplitude dependence of F I and F Q from a single ImAFM measurement. Furthermore, we introduce ImAFM approach measurements with which we reconstruct the full amplitude and probe-height dependence of the force components F I and F Q , providing deeper insight into the tip–surface interaction. We demonstrate the capabilities of ImAFM approach measurements on a polystyrene polymer surface.
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Zhang, Jun, Qing Yang Cai, Hong Mei Tang i Bang Zeng Guo. "The Experimental Research on the Static-Loaded Beam Based on the Artificial Neural Network Technique". Applied Mechanics and Materials 423-426 (wrzesień 2013): 2610–13. http://dx.doi.org/10.4028/www.scientific.net/amm.423-426.2610.
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In order to identify the force on coupling beam, the study of static-loaded diagnosis based on the EMI and ANN techniques is introduced. The theory of EMI and ANN techniques was introduced. The experimental platform was build. The situation of coupling beam was diagnosed by the different curves. The static-load was diagnosed by the ANN technique subsequently. The experiments show we can through the EMI and ANN techniques to identify the force on coupling beam.
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VIRGALA, IVAN, ERIK PRADA i MAREK VAGAS. "POWER AND FORCE LIMITING TECHNIQUE AT COLLABORATIVE WORKPLACE". MM Science Journal 2021, nr 2 (2.06.2021): 4424–27. http://dx.doi.org/10.17973/mmsj.2021_6_2021037.
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Nowadays, the automotive industry still incorporates collaborative robots and their applications into the less traditional processes to automate them. The purpose is to make up for the skill gap, retain skilled staff, attract the younger generation, and increase quality. The paper brings a short overview of the automated collaborative workplace, including the PFL technique description and possibilities. Also, human-robot collaboration (HRC) is elaborated together with the example of such an automated workplace (with dual-arm robotic system participation). The specific contact (transient, quasi-static) between the human body and robotic system is described to fulfill the HRC and PFL technique. It also summarizes and explains ISO / TS 15066 details to apply this technique at automated assembly process example.