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1
Erkmen, R. Emre, and Magdi Mohareb. "Nonorthogonal solution for thin-walled members – applications and modelling considerations." Canadian Journal of Civil Engineering 33, no. 4 (April 1, 2006): 440–50. http://dx.doi.org/10.1139/l06-027.
Повний текст джерелаАнотація:
In a companion paper (R.E. Erkmen and M. Mohareb. 2006. Canadian Journal of Civil Engineering, 33: 421–439.), three finite elements based on the Vlasov thin-walled beam theory were formulated using a nonorthogonal coordinate system. Although the associated derivations are more elaborate than in more conventional solutions based on orthogonal coordinates, the new elements offer more modelling capabilities and flexibility in modelling structural steel members, a feature that is illustrated in this paper. In this context, the current paper presents four details in steel construction that were conveniently modelled within the new solution scheme. The applications involve thin-walled members with coped flanges, rectangular holes reinforced with longitudinal stiffeners, and eccentric supports. Comparisons with established shell finite element models using ABAQUS suggest the validity of the new solution. Key words: open sections, finite element analysis, thin-walled members, coped flanges, rectangular holes, eccentric supports.
2
Rosmanit, Miroslav, Přemysl Pařenica, Oldřich Sucharda, and Petr Lehner. "Physical Tests of Alternative Connections of Different High Roof Purlins Regarding Upward Loading." Buildings 11, no. 11 (October 29, 2021): 512. http://dx.doi.org/10.3390/buildings11110512.
Повний текст джерелаАнотація:
Thin-walled cold-rolled sections are used in the construction industry, especially in the roofing of large-span halls. The load-bearing capacity of a thin-walled structure depends to a large extent on the load-bearing capacity of the details at the point of attachment to the structure and the interconnection of the individual thin-walled elements. Therefore, in the case of thin-walled structures, it is necessary to use additional structural elements such as local reinforcement, stabilising elements, supports, and other structural measures such as the doubling of profiles. This paper focused on the behaviour of tall Z300 and Z350 mm thin-walled trusses at the connection to the superstructure regarding upward loading (e.g., wind suction and so on). Two section thicknesses, 1.89 mm and 2.85 mm, were experimentally analysed. Furthermore, two types of connections were prepared, more precisely without and with a reinforced buckle. The experiments aimed to investigate the behaviour and load-carrying capacity of the detail of the roof truss connections to the supporting structure. The resulting load capacity values were compared with normative approaches. Analyses of the details of the bolt in the connection are also presented. The paper presents a practical evaluation of the physical test on real structural members.
3
Wang, J., D. Qin, and Q. Zhang. "Mathematical model for predicting the blade behaviour of horizontal axis wind turbine." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 222, no. 9 (September 1, 2008): 1681–94. http://dx.doi.org/10.1243/09544062jmes733.
Повний текст джерелаАнотація:
A mathematical model using both beam finite element and thin-walled structure theory is developed to predict the natural frequency and blade behaviour of a horizontal axis wind turbine under constant wind speed and turbulence condition. First of all, the deformation pattern of the blade is defined on the basis of thin-walled structure theory and Timoshenko beam theory, and by considering the blade as a rotation cantilever beam, the governing equation is obtained using the principle of virtual work. Then, it is discreted by a beam element. Constraints are applied to define boundary conditions and coupling of flapwise, edgewise, and elongation deformations on the governing equation using the penalty method. Finally, natural frequencies of the blade are analysed. Detailed expressions for centrifugal and Coriolis forces are obtained. The stress on the root and displacement at the tip are also analysed in detail. The blade's deflection in turbulent conditions is simulated and shown to mostly influence flapwise blade deformation.
4
Sha, Yun Dong, Ji Yong Li, and Zhi Jun Gao. "Dynamic Response of Pre/Post Buckled Thin-Walled Structure under Thermo-Acoustic Loading." Applied Mechanics and Materials 80-81 (July 2011): 536–41. http://dx.doi.org/10.4028/www.scientific.net/amm.80-81.536.
Повний текст джерелаАнотація:
Advanced aircraft and spacecraft structures are exposed to increasingly severe operating environments, including a combination of mechanical, aerodynamic, acoustic and thermal loads. Such loading conditions can cause thin-walled structures to respond in a nonlinear fashion and exhibit complex response characteristics. This paper investigates the dynamic response of pre/post buckled thin-walled structure under high level random acoustic loading. Firstly, different orders of critical buckling temperatures and modal frequencies under alternative temperatures are obtained using Finite Element Method (FEM), and the modal frequency changes in a disorder fashion are discussed in detail. Then with coupled BEM/FEM method, the dynamic responses including transverse displacement, strain and stress of a stiffened rectangular plate under thermo-acoustic loading are simulated. By comparing the response characteristics of the plate in pre/post buckled conditions, some valuable conclusions are derived, which can be used to explain the response behaviours of thin-walled structures.
5
Kang, Yong Gang, Zhong Qi Wang, J. J. Wu, and Cheng Yu Jiang. "Efficient Algorithms for Calculations of the Maximum Surface Form Errors in Peripheral Milling." Applied Mechanics and Materials 10-12 (December 2007): 757–61. http://dx.doi.org/10.4028/www.scientific.net/amm.10-12.757.
Повний текст джерелаАнотація:
An efficient flexible iterative algorithm with a general approach is presented for calculations of surface form errors in peripheral milling of thin-walled workpiece. An efficient finite-element model for tool/workpiece is presented to analyze the surface dimensional errors in peripheral milling of aerospace thin-walled workpieces. The efficient flexible iterative algorithm is proposed to calculate the deflections and the maximum surface form errors as contrasted with the rigid iterative algorithm used in the literatures. Meanwhile, some key techniques such as the finite-element modeling of the tool-workpiece system; the determinant algorithm to judge instantaneous immersion boundaries between a cutter element and the workpiece; iterative scheme for the calculations of tool-workpiece deflections considering the former convergence cutting position are developed and the method for calculating the position and magnitude of the maximum surface form errors are developed and presented in detail. The proposed approach is validated and proved to be efficient through comparing the obtained numerical results with the test results.
6
Voronov, S. A., and I. A. Kiselev. "Dynamics of flexible detail milling." Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics 225, no. 4 (September 23, 2011): 299–309. http://dx.doi.org/10.1177/1464419311418735.
Повний текст джерелаАнотація:
The five-axis milling operations are commonly used in aerospace industry. For example, this operation is the base for the machining process of the turbine blade production. The milling operations of thin-walled structures cause the vibrations of the tool and the workpiece and this turn affect the quality of the workpiece surface. Modelling of the milling process is necessary to determine the proper cutting conditions for the required productivity and the surface quality. In this article, the geometry modelling algorithm for five-axis milling process is proposed. Dynamics of the machined surface is modelled using the finite-element method. The obtained results make possible to conclude about the stability of milling process and to calculate the efficient processing conditions at which the amplitude of the generated vibrations does not exceed the admissible level. The results of this research can be used while the milling process technologies are designed. Especially, it is significant for the machining of hard-to-machine materials and processing of heat-resistant alloys in space and aircraft industries.
7
Bruschelli, L., and V. Latorrata. "The Influence of “Shell Behavior” on Load Distribution for Thin-Walled Conical Joints." Journal of Applied Mechanics 67, no. 2 (April 12, 1999): 298–306. http://dx.doi.org/10.1115/1.1304841.
Повний текст джерелаАнотація:
This article presents a new analytical method with a numerical solution to calculate load distribution in threaded connections. Our departure model was that suggested by D. G. Sopwith who has proposed the most recent and most tested theory. Our research consists in the introduction of conicity and, above all, in the development of the influence of boundary geometry (i.e. the nonthreaded section) on load distribution. Pipe joints are analyzed in special detail, supplying us with useful finite element method comparative results. [S0021-8936(00)02002-X]
8
Pařenica, Přemysl, Petr Lehner, Jiří Brožovský, and Martin Krejsa. "Numerical Models of the Connection of Thin-Walled Z-Profile Roof Purlins." Materials 14, no. 21 (November 1, 2021): 6573. http://dx.doi.org/10.3390/ma14216573.
Повний текст джерелаАнотація:
High thin-walled purlins of Z cross-section are important elements in steel wide-span structures. Their behaviour is influenced by many variables that need to be examined for every specific case. Their practical design thus requires extended knowledge of their behaviour for the possible configurations and dimensions. Numerical analysis verified by experimental investigation can thus enrich such knowledge. Numerical models have the advantage of repeatability and the ability to offer parametric changes. The parametric study presented shows a detailed description of a finite element model of thin-walled cross-sectional roof purlins connected to other roof elements. Models include various approaches to modelling bolt connection. Two schemes of purlins, with and without cleats, are presented. The results of different approaches in numerical modelling are compared with the results of a physical test on a real structure. The article shows a significant agreement in the case of specific approaches and points out the differences with others. The results can be helpful in terms of how to approach the modelling of thin-walled structures and the effective approach to experimental preparation.
9
Chen, Fuh Kuo, and Shin Gee Chen. "Press Forging of Thin-Walled AZ31 Magnesium-Alloy Components." Advanced Materials Research 189-193 (February 2011): 1401–5. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.1401.
Повний текст джерелаАнотація:
The press forging of AZ31 magnesium-alloy sheets for producing thin-walled structural components used in the electronics industry was examined by both the finite element analysis and the experimental approach in the present study. The experimental results obtained from the compression tests and ring compression tests were employed in the finite element simulations to investigate the effects of process parameters, such as forming temperature, friction condition, embossment location, and sheet thickness on the formation of embossments in a press forging process. The finite element simulation results reveal that a cost-effective press forging process of AZ31 magnesium-alloy requires an optimum combination of the above parameters. The detailed examination of the effects of the process parameters on the formation of embossments made in the present study could provide a design guideline for a press forging process of AZ31 magnesium-alloy sheets.
10
Yidris, Noorfaizal, J. Loughlan, Mohamed Thariq Hameed Sultan, and Azmin Shakrine Mohd Rafie. "Failure Mechanics of Uniformly Compressed Thin-Walled Box-Section Struts." Applied Mechanics and Materials 225 (November 2012): 172–77. http://dx.doi.org/10.4028/www.scientific.net/amm.225.172.
Повний текст джерелаАнотація:
It is well known that the structural performance of thin-walled compression members is subject to the effects of local buckling and material yielding. Due to these effects, the compressive carrying capability of short strut members can be significantly reduced. This paper employs finite element simulation to examine the post-buckled response of thin-walled box-sections that covers complete loading history of the compression struts from the onset of elastic local buckling through the nonlinear elastic and elasto-plastic post-buckling phases of behaviour up to final collapse and unloading. A detailed account of the growth and redistribution of stresses on the surfaces is given in the paper. The results from finite element simulations are shown to compare well with the analytical method of analysis.
11
Turlier, D., M. L. Facchinetti, S. Wolf, I. Raoult, B. Delattre, A. Magnin, and N. Grimonprez. "Seam weld shell element model for thin walled structure FE fatigue design." MATEC Web of Conferences 165 (2018): 21007. http://dx.doi.org/10.1051/matecconf/201816521007.
Повний текст джерелаАнотація:
In automotive industry, the FE fatigue analysis of mechanical structures made of steel thin walled parts and seam welded assemblies uses a dedicated technique based on shell element modelling for components and on 1D rigid elements for welds. This method has been validated with several intensive fatigue test campaigns using gas metal arc welded samples with different assemblies, for both bending and torsional loads. The fatigue results are relative to crack initiation at the weld toe with bending normal stress or with longitudinal shear stress for several load ratios. The purpose of the current work is the transposition of the initial method to another FE welded model. In a recent IIW guideline for the assessment of weld root fatigue, a shell element weld model has been proposed for seam weld fatigue assessment in case of weld root crack initiation. The idea is to analyse the possible extension of this FEA weld element model for weld toe fatigue analysis and several comparisons of stress results are detailed and discussed. Different fatigue criteria are used to verify the correlation with the fatigue test results. First, the approach is based on maximum shear stress, then structural stress is calculated and results are compared to IIW S/N curves.
12
White, C. S. "An Analysis of the Thin-Walled Torsion Specimen." Journal of Engineering Materials and Technology 114, no. 4 (October 1, 1992): 384–89. http://dx.doi.org/10.1115/1.2904189.
Повний текст джерелаАнотація:
A detailed finite element analysis has been conducted of the thin-walled torsion specimen. This specimen, when properly gripped, provides an approximation to the simple shear deformation field. Variations through the thickness of the specimen are small for the shear stress but can be large for the axial normal stress. Plastic deformation extends into the shoulder region requiring a correction factor to be used when converting the applied twist at the grips to average shear strain across the gauge section. This correction factor can be numerically quantified and used in data reduction.
13
Xu, Xun, Haidong Yu, Yunyong Li, and Xinmin Lai. "Compliant assembly deviation analysis of large-scale thin-walled structures in different clamping schemes via ANCF." Assembly Automation 40, no. 2 (November 3, 2019): 305–17. http://dx.doi.org/10.1108/aa-01-2019-0018.
Повний текст джерелаАнотація:
Purpose The structure stiffness is greatly affected by the fixture constraints during assembly due to the flexibility of large-scale thin-walled structures. The compliant deformation of structures is usually not consistent for the non-uniform stiffness in various clamping schemes. The purpose of this paper is to investigate the correlation between the assembly quality and the clamping schemes of structures with various initial deviations and geometrical parameters, which is based on the proposed irregular quadrilateral plate element via absolute nodal coordinate formulation (ANCF). Design/methodology/approach Two typical clamping schemes are specified for the large-scale thin-walled structures. Two typical deviation modes are defined in both free and clamping states in the corresponding clamping schemes. The new irregular quadrilateral plate element via ANCF is validated to analyze the compliant deformation of assembled structures. The quasi-static force equilibrium equations are extended considering the factors of clamping constraints and geometric deviations. Findings The initial deviations and geometrical parameters strongly affect the assembly deviations of structures in two clamping schemes. The variation tendencies of assembly deviations are demonstrated in details with the circumferential clamping position and axial clamping position in two clamping schemes, providing guidance to optimize the fixture configuration. The assembly quality of structures with deviations can be improved by configuration synthesis of the clamping schemes. Originality/value Typical over-constraint clamping schemes and deviation modes in clamping states are defined for large-scale thin-walled structures. The plate element via ANCF is extended to analyze the assembly deviations of thin-walled structures in various clamping schemes. Based on the proposed theoretical model, the effects of clamping schemes and initial deviations on the deformation and assembly deviation propagation of structures are investigated.
14
Hario Yudhanto, Ashando, Bambang Piscesa, Mario M. Attard, Budi Suswanto, and Priyo Suprobo. "Finite element modeling of concrete confined with circular thin-walled steel sheet." E3S Web of Conferences 156 (2020): 05009. http://dx.doi.org/10.1051/e3sconf/202015605009.
Повний текст джерелаАнотація:
For a reinforced concrete column to behave in a ductile manner without much loss on strength requires sufficient confinement to the concrete core. One way to provide confinement to the concrete core is to use external confining devices such as a series of thin-walled circular steel sheet tube to confine the concrete. This type of external confining device falls off on the categories of Steel Tube Confined Concrete (STCC). With the presence of a gap between the steel sheet, the buckling on the tube due to high axial stresses can be avoided. On the other hand, STCC also offers great advantages to strengthen a non-code conforming reinforced concrete column to achieve better resistance to withstand earthquake load. From the numerical analysis point of view, the important task to successfully model the STCC specimen lies in the modeling of the interface behavior between concrete and steel tube. For that purpose, in this paper, the 3D-NLFEA package is used to study the response of STCC. The analysis result is further compared with the available test results in the literature. From the analysis, the predicted response is excellent. Detailed discussion on the parameter of the interface behavior between concrete and steel tube is presented.
15
Čítek, David, Jiří Kolísko, Petr Tej, Tomáš Mandlík, and Stanislav Řeháček. "Prefabrication of the Thin-Walled U-Profile UHPFRC Footbridge." Key Engineering Materials 760 (January 2018): 152–57. http://dx.doi.org/10.4028/www.scientific.net/kem.760.152.
Повний текст джерелаАнотація:
This article presents a mix design, preparation and production of thin-walled footbridge made from UHPFRC. Optimization of UHPFRC matrix and parameters of this material leads to the design of very thin structures. In this case an experimental pedestrian bridge was designed and prepared. Single-span bridge with span of 10 m and the clear width of 1.50 m with the total thickness of shell structure 30 - 45 mm was cast as a prefabricated element in one piece. Self-compacting character of UHPFRC with high flowability allows the production of the final structure. Extensive research was done before production of footbridge. Two versions of large scale mock-ups were casted and tested. According to the complexity of whole experiment a casting technology and production of formwork were tested and optimized many times. Experimental reached data were compared with extensive numerical analysis and the final design of structure and UHPFRC matrix were optimized in many details.
16
Ma, Wei, Yong Chao Lu, Yong Gang Liu, Ji Shun Li, and Yu Jun Xue. "Influence of Sandwich Damping on the Loss Factor of Multi-Plies Bellows." Applied Mechanics and Materials 44-47 (December 2010): 2998–3002. http://dx.doi.org/10.4028/www.scientific.net/amm.44-47.2998.
Повний текст джерелаАнотація:
Multi-plies bellows is a kind of cylindrical thin-walled container with curved shape. It is effective in seal, energy storage and vibration isolation. In the paper, the modal loss factor of multi-plies bellows was analyzed based on the modal strain energy method. Then the finite element models of multi-piles bellows were given by ANSYS. The mechanical performance of bellows was analyzed in detail. The strain energy distribution of multi-plies bellows and viscoelsticity layer were given. According to the strain energy, the influence of sandwich damping on the loss factor was studied. The results show that the loss factor can be improved by employing the sandwich damping with big thickness and elastic modulus 200MPa.
17
Mortazavi Moghaddam, Alireza, Atefeh Kheradpisheh, and Masoud Asgari. "A basic design for automotive crash boxes using an efficient corrugated conical tube." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 235, no. 7 (February 5, 2021): 1835–48. http://dx.doi.org/10.1177/0954407021990921.
Повний текст джерелаАнотація:
Frontal vehicle structure is of high importance through crash energy managements and crash boxes are the fundamental structural component for vehicle safety as well as after sales issues. Similar to many other vehicle components, the detail design of crash box is usually part of manufacture knowhow. However, some guide lines are always available. In this article a general procedure is introduced for designing of crash box with the aid of novel thin walled structures and according to conventional crash scenarios. The problem is followed through some basic steps. Firstly, the crash box idea is selected through a wide range of previous investigated elements and is packaged in a real bench vehicle. Then thanks to the protection provided by the new crash box on the other more expensive components (e.g. headlamp, cooling pack, etc.), the effectiveness of this element are acknowledged through the low speed offset crash. Further on the robustness of new proposed crash box is approved by high speed crash simulations. The quasi-static simulations implemented during the analyses are carried out by finite element explicit code (Abaqus) and the FE modeling and dynamic simulation through the next steps are also performed in ANSA and PAM CRASH respectively. Finally in addition to the general crash box design proposed procedure, the achieved results demonstrated that the corrugated conical thin walled tubes deforms in regular and rather stable shape under both axial and oblique loadings. They also produced a reasonable reaction force versus deformations which leads to stiff and crashworthy energy absorber in comparison to traditional rectangular and even some special models like as origami shapes, and so they could be a valuable selection for crash box implementations in passenger cars.
18
De Melo, F. J. M. Q., and M. A. P. Vaz. "The linear elastic in-plane bending of curved hollow profiles having a thin-walled rectangular section." Journal of Strain Analysis for Engineering Design 27, no. 3 (July 1, 1992): 145–49. http://dx.doi.org/10.1243/03093247v273145.
Повний текст джерелаАнотація:
This paper presents a simple solution for the flexibility calculation of curved profiles having a rectangular thin-walled cross-section. Some assumptions related to geometric details about the shape of the deformed structure are included in the present analysis, aiming at an economic and accurate solution. Results concerning the distortion of the transverse section are compared with the corresponding data from the solution with a thin shell finite element analysis. A flexibility factor for the structure analysed here is presented as a graphical result.
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Chen, Changpeng, Jie Yin, Haihong Zhu, Xiaoyan Zeng, Guoqing Wang, Linda Ke, Junjie Zhu, and Shijie Chang. "The effect of process parameters on the residual stress of selective laser melted Inconel 718 thin-walled part." Rapid Prototyping Journal 25, no. 8 (September 9, 2019): 1359–69. http://dx.doi.org/10.1108/rpj-09-2018-0249.
Повний текст джерелаАнотація:
Purpose High residual stress caused by the high temperature gradient brings undesired effects such as shrinkage and cracking in selective laser melting (SLM). The purpose of this study is to predict the residual stress distribution and the effect of process parameters on the residual stress of selective laser melted (SLMed) Inconel 718 thin-walled part. Design/methodology/approach A three-dimensional (3D) indirect sequentially coupled thermal–mechanical finite element model was developed to predict the residual stress distribution of SLMed Inconel 718 thin-walled part. The material properties dependent on temperature were taken into account in both thermal and mechanical analyses, and the thermal elastic–plastic behavior of the material was also considered. Findings The residual stress changes from compressive stress to tensile stress along the deposition direction, and the residual stress increases with the deposition height. The maximum stress occurs at both ends of the interface between the part and substrate, while the second largest stress occurs near the top center of the part. The residual stress increases with the laser power, with the maximum equivalent stress increasing by 21.79 per cent as the laser power increases from 250 to 450 W. The residual stress decreases with an increase in scan speed with a reduction in the maximum equivalent stress of 13.67 per cent, as the scan speed increases from 500 to 1,000 mm/s. The residual stress decreases with an increase in layer thickness, and the maximum equivalent stress reduces by 33.12 per cent as the layer thickness increases from 20 to 60µm. Originality/value The residual stress distribution and effect of process parameters on the residual stress of SLMed Inconel 718 thin-walled part are investigated in detail. This study provides a better understanding of the residual stress in SLM and constructive guidance for process parameters optimization.
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Faes, Koen, Rishabh Shotri, and Amitava De. "Probing Magnetic Pulse Welding of Thin-Walled Tubes." Journal of Manufacturing and Materials Processing 4, no. 4 (December 11, 2020): 118. http://dx.doi.org/10.3390/jmmp4040118.
Повний текст джерелаАнотація:
Magnetic pulse welding is a solid-state joining technology, based on the use of electromagnetic forces to deform and to weld workpieces. Since no external heat sources are used during the magnetic pulse welding process, it offers important advantages for the joining of dissimilar material combinations. Although magnetic pulse welding has emerged as a novel technique to join metallic tubes, the dimensional consistency of the joint assembly due to the strong impact of the flyer tube onto the target tube and the resulting plastic deformation is a major concern. Often, an internal support inside the target tube is considered as a solution to improve the stiffness of the joint assembly. A detailed investigation of magnetic pulse welding of Cu-DHP flyer tubes and 11SMnPb30 steel target tubes is performed, with and without an internal support inside the target tubes, and using a range of experimental conditions. The influence of the key process conditions on the evolution of the joint between the tubes with progress in time has been determined using experimental investigations and numerical modelling. As the process is extremely fast, real-time monitoring of the process conditions and evolution of important responses such as impact velocity and angle, and collision velocity, which determine the formation of a metallic bond, is impossible. Therefore, an integrated approach using a computational model using a finite-element method is developed to predict the progress of the impact of the flyer onto the target, the resulting flyer impact velocity and angle, the collision velocity between the flyer and the target, and the evolution of the welded joint, which are usually impossible to measure using experimental observations.
21
Li, Kangjie, Yixiong Feng, Yicong Gao, Hao Zheng, and Hao Qiu. "Crashworthiness Optimization Design of Aluminum Alloy Thin-Walled Triangle Column Based on Bioinspired Strategy." Materials 13, no. 3 (February 2, 2020): 666. http://dx.doi.org/10.3390/ma13030666.
Повний текст джерелаАнотація:
Aluminum alloy thin-walled structures have been well used in applications of energy absorption. In the present work, a bioinspired design strategy for aluminum alloy thin-walled structures is proposed to improve the performance of out-of-plane crashworthiness by altering the material distribution. According to the proposed strategy, a novel fractal thin-walled triangle column (FTTC) is designed, which is composed by iteratively applying the affine transformation of a base triangle up to 2nd-order. The finite element model is established to investigate the out-of-plane crashworthiness of FTTC and validated by experiment results. The numerical analysis of the crashworthiness of FTTC with different fractal orders (0th, 1st and 2nd) are performed, and the results show that 1st- and 2nd-order FTTC enhance the energy absorption of structures and crush force efficiency. In particular, 2nd-order FTTC has better energy absorption ability due to the optimal distribution of materials, which are efficiently organized by the proposed bioinspired design strategy. In addition, a parameter study is performed to investigate the effect of FTTC geometric details on the crushing procedure. The collapse mode shows that it tends to change from unstable to stable with the increase in thickness and side length and the decrease in height. Moreover, a positive relevant relationship is identified between the thickness and the crashworthiness for FTTC.
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Zhang, Puyang, Yunlong Xu, Conghuan Le, Hongyan Ding, and Yaohua Guo. "Structural Optimization Method for the Transition Section in Composite Bucket Foundations of Offshore Wind Turbines." Energies 11, no. 11 (November 21, 2018): 3230. http://dx.doi.org/10.3390/en11113230.
Повний текст джерелаАнотація:
A two-step structural optimization method was proposed to select the transition section of a composite bucket foundation (CBF). In the first step, based on the variable density method, a solid isotropic microstructures with penalization (SIMP) interpolation model was established under specific load conditions and boundary conditions. The solution of force transmission path and the topology of the transition section in six forms (e.g., linear, arc-shaped, linear thin-walled, and arc-shaped thin-walled) were optimized. Afterwards, finite element software ABAQUS was used to verify this model. Results show that the utilization rate of the arc-shaped thin-walled structure was the largest, and its basic transmission force was more straightforward together with smaller cross-section size at the same height and smaller influence on spoiler flow. In the second step, the detailed optimization of CBF was carried out using mathematical programming. Under the premise of minimum total construction cost, the body shape parameters of each part were set as design variables satisfying the corresponding strength, stiffness, and stability conditions; meanwhile, the minimum total structure weight was set as the objective function. MATLAB was used to solve the sequence quadratic programming (SQP) algorithm and hybrid genetic algorithm, and the optimal body parameters were obtained.
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Malekshahi, A., K. H. Shirazi, and M. Shishehsaz. "Axial Crushing of Prismatic Multi-Corner Metal Columns Considering Plastic Hardening and Curvature." Journal of Mechanics 35, no. 3 (February 28, 2018): 315–26. http://dx.doi.org/10.1017/jmech.2018.2.
Повний текст джерелаАнотація:
ABSTRACTIn this paper, progressive crushing of prismatic multi-corner thin walled metal tubes under quasi-static axial load is investigated in detail. The novelty of the paper is mainly in considering strain hardening effect during plastic deformation instead of rigid plastic model and also the effect of curvature in forming the folds instead of plastic hinges. For this purpose, a new geometric model based on FEM and experimental observations is used which is capable of being adapted with new crushing configurations during crushing. Based on this model, the instantaneous energy associated with plastic deformation of different regions are calculated and finally by summing all energies and using minimum absorbed energy, mean crushing force and collapse parameters are determined. To evaluate the results, a detailed finite element study using ABAQUS and LS-Dyna solver is conducted on some regular polygonal mild steel tubes under axial crushing. Comparing the results of the new theoretical approach with FEM results show very good capability of that in predicting collapse behavior of these structures.
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Szychowski, Andrzej, and Karolina Brzezińska. "Local Buckling and Resistance of Continuous Steel Beams with Thin-Walled I-Shaped Cross-Sections." Applied Sciences 10, no. 13 (June 28, 2020): 4461. http://dx.doi.org/10.3390/app10134461.
Повний текст джерелаАнотація:
In modern steel construction, thin-walled elements with Class 4 cross-sections are commonly used. For the sake of the computation of such elements according to European Eurocode 3 (EC3), simplified computational models are applied. These models do not account for important parameters that affect the behavior of a structure susceptible to local stability loss. This study discussed the effect of local buckling on the design ultimate resistance of a continuous beam with a thin-walled Class 4 I-shaped cross-section. In the investigations, a more accurate computational model was employed. A new calculation model was proposed, based on the analysis of local buckling separately for the span segment and the support segment of the first span, which are characterized by different distributions of bending moments. Critical stress was determined using the critical plate method (CPM), taking into account the effect of the mutual elastic restraint of the cross-section walls. The stability analysis also accounted for the effect of longitudinal stress variation resulting from the varied distribution of bending moments along the continuous beam length. The results of the calculations were compared with the numerical simulations using the finite element method. The obtained results showed very good congruence. The phenomena mentioned above are not taken into consideration in the computational model provided in EC3. Based on the critical stress calculated as above, “local” critical moments were determined. These constitute a limit on the validity of the Vlasov theory of thin-walled bars. Design ultimate resistance of the I-shaped cross-section was determined from the plastic yield condition of the most compressed edge under the assumptions specified in the study. Detailed calculations were performed for I-sections welded from thin metal sheets, and for sections made from two cold-formed channels (2C). The impact of the following factors on the critical resistance and design ultimate resistance of the midspan and support cross-sections was analyzed: (1) longitudinal stress variation, (2) relative plate slenderness of the flange, and (3) span length of the continuous beam. The results were compared with the outcomes obtained for box sections with the same contour dimensions, and also with those produced acc. EC3. It was shown that compared with calculations acc. EC3, those performed in accordance with the CPM described much more accurately the behavior of the uniformly loaded continuous beam with a thin-walled section. This could lead to a more effective design of structures of this class.
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Yidris, Noorfaizal, Mohamed Thariq Hameed Sultan, Mohammad Yazdi Harmin, and Azmin Shakrine Mohd Rafie. "Local-Overall Flexural Interaction of Pinned-Ended Thin-Walled I-Section Columns." Applied Mechanics and Materials 564 (June 2014): 444–48. http://dx.doi.org/10.4028/www.scientific.net/amm.564.444.
Повний текст джерелаАнотація:
The structural performance of thin-walled compression members are subject to the effects of local buckling, interaction between buckling modes, loading end conditions and material yielding and that due to these effects the compressive carrying capability of thin-walled members can be significantly diminished. This paper employs the finite element simulation to examine the local-overall flexural interaction response of pinned-ended thin-walled I-section columns that covers the complete compressed loading history from the onset of elastic local buckling through the nonlinear elastic and elasto-plastic post-buckling interactive phases of behaviour to final collapse and unloading. A detailed account of the growth and redistribution of stresses on the surfaces is given in the paper. Pinned-ended conditions means, of course, simply supported conditions at the column ends with respect to global rotations and the ends of the constituent plates of the cross-section can be treated as either locally rotationally constrained or locally rotationally free. The numerical simulations take into account the influence of material nonlinearity and geometrical imperfections on the compressive ultimate failures of the sections, however, the study is limited to the interaction of local buckling with overall flexural bending as well as locally rotationally constrained condition. This paper shows that the ultimate failure of the columns is related with yielding on the compression sides of the outer surfaces of the section walls at the web, flanges and section junctions mostly located along the length of the columns.
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Djavanroodi, Faramarz, and Fahd Almufadi. "Numerical Modeling of Nanostructured Tube Produced by ECAP." Key Engineering Materials 780 (September 2018): 25–31. http://dx.doi.org/10.4028/www.scientific.net/kem.780.25.
Повний текст джерелаАнотація:
— tailoring material properties to specific application requirements is one of the major challenges in materials engineering. Grain size is a key factor affecting physical and mechanical properties of polycrystals materials. Grain size reduction in the metals and alloys can be achieved using Equal channel angular pressing (ECAP) method. In this work, Nanostructure thin walled copper tube specimens with 1 mm wall thickness and 23mm diameter have been produced successfully with ECAP method using flexible polyurethane rubber pad to prevent the tube walls from collapsing. Furthermore, this paper details the development of a numerical simulation to analyse the fabrication of thin walled tube through ECAP process. A copper tube was pushed through a channel with a series of 90° bends. During each successive bend, the magnitude of plastic strains accumulate in the copper tube. A three dimensional numerical simulation was used to model the process and determine the extent of plastic deformation that takes place during each bend process. The numerical simulation was developed using the finite element (FE) code, ABAQUS V6.13, and analysed using the explicit solver.
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Mutafi, Ayad, Noorfaizal Yidris, Seyed Saeid Rahimian Koloor, and Michal Petrů. "Numerical Prediction of Residual Stresses Distribution in Thin-Walled Press-Braked Stainless Steel Sections." Materials 13, no. 23 (November 26, 2020): 5378. http://dx.doi.org/10.3390/ma13235378.
Повний текст джерелаАнотація:
Stainless steels are increasingly used in construction today, especially in harsh environments, in which steel corrosion commonly occurs. Cold-formed stainless steel structures are currently increasing in popularity because of its efficiency in load-bearing capacity and its appealing architectural appearance. Cold-rolling and press-braking are the cold-working processes used in the forming of stainless steel sections. Press braking can produce large cross-sections from thin to thick-walled sections compared to cold-rolling. Cold-forming in press-braked sections significantly affect member behaviour and joints; therefore, they have attained great attention from many researchers to initiate investigations on those effects. This paper examines the behaviour of residual stress distribution of stainless steel press-braked sections by implementing three-dimensional finite element (3D-FE) technique. The study proposed a full finite element procedure to predict the residual stresses starting from coiling-uncoiling to press-braking. This work considered material anisotropy to examine its effect on the residual stress distribution. The technique adopted was compared with different finite element techniques in the literature. This study also provided a parametric study for three corner radius-to-thickness ratios looking at the through-thickness residual stress distribution of four stainless steels (i.e., ferritic, austenitic, duplex, lean duplex) in which have their own chemical composition. In conclusion, the comparison showed that the adopted technique provides a detailed prediction of residual stress distribution. The influence of geometrical aspects is more pronounced than the material properties. Neglecting the material anisotropy shows higher shifting in the neutral axis. The parametric study showed that all stainless steel types have the same stress through-thickness distribution. Moreover, R/t ratios’ effect is insignificant in all transverse residual stress distributions, but a slight change to R/t ratios can affect the longitudinal residual stress distribution.
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SILVESTRE, N., and D. CAMOTIM. "NONLINEAR GENERALIZED BEAM THEORY FOR COLD-FORMED STEEL MEMBERS." International Journal of Structural Stability and Dynamics 03, no. 04 (December 2003): 461–90. http://dx.doi.org/10.1142/s0219455403001002.
Повний текст джерелаАнотація:
A geometrically nonlinear Generalized Beam Theory (GBT) is formulated and its application leads to a system of equilibrium equations which are valid in the large deformation range but still retain and take advantage of the unique GBT mode decomposition feature. The proposed GBT formulation, for the elastic post-buckling analysis of isotropic thin-walled members, is able to handle various types of loading and arbitrary initial geometrical imperfections and, in particular, it can be used to perform "exact" or "approximate" (i.e., including only a few deformation modes) analyses. Concerning the solution of the system of GBT nonlinear equilibrium equations, the finite element method (FEM) constitutes the most efficient and versatile numerical technique and, thus, a beam FE is specifically developed for this purpose. The FEM implementation of the GBT post-buckling formulation is reported in some detail and then employed to obtain numerical results, which validate and illustrate the application and capabilities of the theory.
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Mikhnev, M. M., I. V. Kudryavtsev, and P. N. Silchenko. "Theoretical Justification and Analysis of Technology for Manufacturing Waveguide-and-Distribution Systems of Spacecraft Communication Devices." Proceedings of Higher Educational Institutions. Маchine Building, no. 06 (723) (June 2020): 51–66. http://dx.doi.org/10.18698/0536-1044-2020-6-51-66.
Повний текст джерелаАнотація:
Manufacturing of extended thin-walled waveguide-and-distribution system (WDS) by soldering separate elements is associated with force, strain and temperature impacts leading to undesirable deformations both in local areas as well as in the whole structure. Each element and the system in general are subjected to local thermal exposure that results in temperature stresses and strains. The stresses that occur due to heating can cause irreversible deformations of the structure manifested as local deflections and distortions of the cross section geometry. When assembling waveguide-and-distribution systems, even minor angular and linear displacements in the places where the elements are joined result in disruption of the overall geometry of the structure and therefore, a displacement of the mounting points relative to the desired location. Forced alignment of these points would create internal stresses, which combined with external impacts, could violate the conditions of strength, rigidity and location of the control mounting points. To achieve the required strength, rigidity and accuracy parameters of the system, it is necessary to perform a theoretical and calculation analysis of the manufacturing process parameters, steps, actions and methods. The paper presents a method of calculating waveguide-and-distribution systems that can be used to promptly determine the stress-strain state with a required accuracy in order to ensure strength, rigidity and sufficient geometrical accuracy of the WDS structure. The WDS is treated as a rod model in the global formulation and as a shell structure when a separate local area is analyzed in detail. This approach enables the assessment of the stress-strain state in general and more precise calculations of the stresses and strains in defined local areas with nearly any required accuracy. An example showing calculations of the dynamics of variation of the gap between thin-walled elements in the process of soldering is given. An analysis of the stress-strain state of the mounting soldered seam between the elements is performed. The results obtained using the proposed two-step calculation method provide the required quality throughout the whole process of manufacturing an extended waveguide-and-distribution system for a spacecraft.
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Feng, Liangyuan. "Resolving Common Element Problem by Using Different Lines in Fundamental Parameters Method Multilayer Thin Film Analysis." Advances in X-ray Analysis 37 (1993): 213–18. http://dx.doi.org/10.1154/s0376030800015718.
Повний текст джерелаАнотація:
The presence of one or more common elements in different layers often complicates or hampers the analysis of a multilayer thin film system. Some constraints or preconditions are usually required in order to reach a mathematical solution. For example, either the concentration(s) of the common element(s) in, or the thickness(es) of one of the relevant layers must be known.An alternative approach is the use of more than one analyzing line for the element in question. Although this approach has long been proposed, there have been no detailed studies seen in literature. An attraction of using this approach is that it requires no prior knowledge of either the concentration or the thickness. The author has implemented this approach, and studied in detail its feasibility and pitfalls for practical applications.
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Потянихин, Д. А., А. А. Синельщиков, and Ко Х. Мин. "Simulation of the stress-strain state of a tubular billet during the expansion of its middle part using rigid die." MORSKIE INTELLEKTUAL`NYE TEHNOLOGII), no. 2(52) (June 20, 2021): 105–10. http://dx.doi.org/10.37220/mit.2021.52.2.059.
Повний текст джерелаАнотація:
В работе представлены результаты моделирования в конечно-элементном программном комплексе ANSYS напряженно-деформированного состояния тонкостенной трубчатой заготовки из титанового сплава ОТ4 в процессе раздачи эластичной средой по жесткой матрице. Рассматривается осесимметричная матрица в виде тела вращения с криволинейной образующей. Задача решается в осесимметричной квазистационарной постановке. Конечно-элементная модель включает пуансон, матрицу, трубчатую заготовку, и эластичное рабочее тело. Пуансон перемещается в вертикальном направлении вниз, передавая усилие на деформируемую деталь через рабочее тело. Фрикционное взаимодействие происходит по закону Кулона. Проведен анализ напряженно-деформированного состояния детали в процессе формообразования. Исследовано распределение остаточных напряжений, упругое пружинение после снятия нагрузки и утонение стенок детали. Показана возможность получения детали типа «переходник» из титанового сплава ОТ4 холодным пластическим деформированием без нагрева заготовки. In this paper, the results of simulation of the stress-strain state of a thin-walled tubular blank made from titanium alloy OT4 in the ANSYS finite element software package in the process of expansion by an elastic medium in the rigid die are presented. The axisymmetric die in the form of a body of revolution with a curvilinear generatrix is considered. The problem is solved in an axisymmetric quasi-stationary setting. The finite element model includes a punch, a die, a tubular blank, and an elastic working body. The punch moves vertically downward, transmitting the force to the deformed tube through the working body. Frictional interaction occurs according to the Coulomb's law. The analysis of the stress-strain state of the deformed detail in the process of shaping is carried out. Distribution of residual stresses, elastic spring back after removal of the load and wall thinning of the detail are investigated. The possibility of obtaining the "adapter" type detail from titanium alloy OT4 by cold plastic deformation without heating the blank is shown.
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De Gaetano, G., D. Mundo, F. I. Cosco, C. Maletta, and S. Donders. "Concept Modelling of Vehicle Joints and Beam-Like Structures through Dynamic FE-Based Methods." Shock and Vibration 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/303567.
Повний текст джерелаАнотація:
This paper presents dynamic methodologies able to obtain concept models of automotive beams and joints, which compare favourably with the existing literature methods, in terms of accuracy, easiness of implementation, and computational loads. For the concept beams, the proposed method is based on a dynamic finite element (FE) approach, which estimates the stiffness characteristics of equivalent 1D beam elements using the natural frequencies, computed by a modal analysis of the detailed 3D FE model of the structure. Concept beams are then connected to each other by a concept joint, which is obtained through a dynamic reduction technique that makes use of its vibration normal modes. The joint reduction is improved through the application of a new interface beam-to-joint element, able to interpolate accurately the nodal displacements of the outer contour of the section, to obtain displacements and rotations of the central connection node. The proposed approach is validated through an application case that is typical in vehicle body engineering: the analysis of a structure formed by three spot-welded thin-walled beams, connected by a joint.
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Chen, Jiehao, Xifeng Liang, Ping Xu, and Shuguang Yao. "Crashworthiness Analysis and Multi-Objective Optimisation of Multi-Cell Windowed Structures under Dynamic Impact Loading." Shock and Vibration 2022 (January 31, 2022): 1–17. http://dx.doi.org/10.1155/2022/2263308.
Повний текст джерелаАнотація:
Applying a windowed design in a thin-walled structure is a method to further enhance the crashworthiness of the structure. In this study, two kinds of windowed designs were introduced into different regions of a multi-cell energy absorption structure to form a multi-cell windowed structure, and its crashworthiness under dynamic impact was studied. Dynamic impact testing and LS-DYNA finite element modelling were combined to calculate the crashworthiness response of the structure. The simulation results show that the use of the windowed multi-cell structure can improve the crashworthiness response of the multi-cell structure. The influence of the windowed design on the structural deformation mode was analysed in detail. In addition, the multi-objective optimization design of different windowed structures was carried out to obtain a comprehensive crashworthiness evaluation, and the results show that the windowed design at the front end of the structure yields good results regarding the initial peak force (PCF), while the windowed design in the middle of the structure can effectively improve the specific energy absorption (SEA) and energy absorption (EA).
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Teter, Andrzej, and Zbigniew Kolakowski. "Catastrophic Influence of Global Distortional Modes on the Post-Buckling Behavior of Opened Columns." Materials 13, no. 15 (July 25, 2020): 3314. http://dx.doi.org/10.3390/ma13153314.
Повний текст джерелаАнотація:
The multimodal buckling of thin-walled isotropic columns with open cross-sections under uniform compression is discussed. Column lengths were selected to enable strong interactions between selected eigenmodes. In the case of short columns or very long ones subjected to compression, single-mode buckling can be observed only and the effect under discussion does not occur. In the present study, the influence of higher global modes on the load-carrying capacity and behavior in the post-buckling state of thin-walled structures with open cross-sections is analyzed in detail. In the literature known to the authors, higher global modes are always neglected practically in the analysis due to their very high values of bifurcation loads. However, the phenomenon of an unexpected loss in the load-carrying capacity of opened columns can be observed in the experimental investigations. It might be explained using multimode buckling when the higher global distortional-flexural buckling modes are taken into account. In the conducted numerical simulations, a significant influence of higher global distortional-flexural buckling modes on the post-buckling equilibrium path of uniformly compressed columns with C- and TH-shaped (the so-called “top-hat”) cross-sections was observed. The columns of two lengths, for which strong interactions between selected eigenmodes were seen, were subject to consideration. Two numerical methods were applied, namely, the semi-analytical method (SAM) using Koiter’s perturbation approach and the finite element method (FEM), to solve the problem. The SAM results showed that the third mode had a considerable impact on the load-carrying capacity, whereas the FEM results confirmed a catastrophic effect of the modes on the behavior of the structures under analysis, which led to a lack of convergence of numerical calculations despite an application of the Riks algorithm. All elastic-plastic effects were neglected.
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Beglov, I. A., V. V. Rustamyan, and R. A. Verbitskiy. "Application of quasi-rotation surface segments in architectural prototyping." Journal of Physics: Conference Series 2182, no. 1 (March 1, 2022): 012002. http://dx.doi.org/10.1088/1742-6596/2182/1/012002.
Повний текст джерелаАнотація:
Abstract The present paper details an approach to modeling of quasi-rotation surface segments with pre-defined conditions. The desired surfaces and their segments are formed parametrically through Maple computer algebra system. Various analytical approaches to trimming of the excessive parts of quasi-rotation surfaces are indicated. Geometric modeling is performed with use of a previously developed algorithm. An example illustrating the initial stage of design of an overpass between two separate buildings is provided. The design objective contains the basic geometric parameters of the desired architectural element. Three control models were created with the same initial parameters through basic CAD software methods. All of the constructed models are thin-walled. Mechanical properties of the scale 3D models of the target element were compared in equal conditions by means of CAD software. The prototype created through the use of a quasi-rotation surface segment was the most resistant to load. The paper also features a rendered concept of a complex of three towers connected with three overpasses. The acquired results allow us to conclude that quasi-rotation is an effective method of formation of models of architectural elements.
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RAJASEKARAN, S., and K. NALINAA. "STABILITY AND VIBRATION ANALYSIS OF NON-PRISMATIC THIN-WALLED COMPOSITE SPATIAL MEMBERS OF GENERIC SECTION." International Journal of Structural Stability and Dynamics 05, no. 04 (December 2005): 489–520. http://dx.doi.org/10.1142/s0219455405001714.
Повний текст джерелаАнотація:
This paper presents a detailed treatment of the formulation of static, bucking and vibration analysis of non-prismatic thin-walled composite spatial members of generic section. The theory is limited to small strains, moderate deflections and small rotations. The torsional shear strain on the middle surface of the beam wall is zero for an open contour while it corresponds to constant shear flow for a closed contour. Rigorous expressions for strains based on membrane theory of shells are obtained through which the effect of nonlinear tapering is considered. Solutions for classical buckling and vibration analysis by the finite element method are discussed. Numerical integration by using Gaussian quadrature on the cross-sections for the computation of sectorial properties and stress resultants and over the length for the computation of flexural, geometric and mass matrices is suggested. Some examples are solved and critical bucking loads, natural frequencies and the corresponding buckled and mode shapes are obtained by the Jacobi iteration procedure.
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Singer, Andrej, and Ivan A. Vartanyants. "Coherence properties of focused X-ray beams at high-brilliance synchrotron sources." Journal of Synchrotron Radiation 21, no. 1 (November 2, 2013): 5–15. http://dx.doi.org/10.1107/s1600577513023850.
Повний текст джерелаАнотація:
An analytical approach describing properties of focused partially coherent X-ray beams is presented. The method is based on the results of statistical optics and gives both the beam size and transverse coherence length at any distance behind an optical element. In particular, here Gaussian Schell-model beams and thin optical elements are considered. Limiting cases of incoherent and fully coherent illumination of the focusing element are discussed. The effect of the beam-defining aperture, typically used in combination with focusing elements at synchrotron sources to improve transverse coherence, is also analyzed in detail. As an example, the coherence properties in the focal region of compound refractive lenses at the PETRA III synchrotron source are analyzed.
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Katrňák, Tomáš, Jaroslav Juračka, and Ivo Jebáček. "RESEARCH OF EFFECTS OF DEFECTS ON STABILITY FAILURES OF SEMI-MONOCOQUE STIFFENERS." Aviation 23, no. 3 (January 29, 2020): 83–90. http://dx.doi.org/10.3846/aviation.2019.11903.
Повний текст джерелаАнотація:
This article presents further results of the research of effects of model defects on the local buckling of compressed stiffeners in nonlinear finite element (FE) analyses. The main outcomes are confirmation of trends for 10 sets of profile dimensions, final validations of various sets of FE simulations, and designs of practical types of defects with appropriate ratio values. A single node defect and then complex types of defects with alternating distributions of node shifts along one edge, two free flange edges, one flange surface and both flange surfaces are analyzed in this research project. First parts of this paper describe designed FE models with defects, their effects on simulation results, colored graphic visualizations with stress scales and determinations of the sudden failure of stability in the local mode. Then, particular results of FE analyses are validated by a comparison with the results of analytical methods of stability failure. Final detail comparisons of analytical and FE simulation results with data of experimental tests confirm predicted critical buckling forces. The validation of results and design parameters together with the knowledge of effects of model defects on buckling behaviors allows more accurate simulations of internal stiffeners of thin-walled semi-monocoque structures.
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SILVA, N. FREITAS, and N. SILVESTRE. "ON THE INFLUENCE OF MATERIAL COUPLINGS ON THE LINEAR AND BUCKLING BEHAVIOR OF I-SECTION COMPOSITE COLUMNS." International Journal of Structural Stability and Dynamics 07, no. 02 (June 2007): 243–72. http://dx.doi.org/10.1142/s0219455407002307.
Повний текст джерелаАнотація:
This paper presents the incorporation of shear deformation effects into a Generalized Beam Theory (GBT) developed to analyze the structural behavior of composite thin-walled columns made of laminated plates and displaying arbitrary orthotropy. Unlike other existing beam theories, the present GBT formulation incorporates in a unified fashion (i) elastic coupling effects, (ii) warping effects, (iii) cross-section in-plane deformation and (iv) shear deformation. The main concepts and procedures involved in the available GBT are adapted/modified to account for the specific aspects related to the member shear deformation. In particular, the GBT fundamental equilibrium equations are presented and their terms are physically interpreted. An I-section is used to illustrate the performance of GBT cross-section analysis and the mechanical properties are explained in detail. With the purpose of solving the GBT system of differential equilibrium equations, a finite element formulation is briefly presented. Finally, in order to clarify the concepts involved in the formulated GBT and illustrate its application and capabilities, the linear (first-order) and stability behavior of three composite I-section members displaying non-aligned orthotropy are analyzed and the results obtained are thoroughly discussed and compared with estimates available in the literature.
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Jie, Yi, Li Can, and Zhong Gang Sun. "Influence of Welding Sequence on Residual Stress and Distortion in Rectangular Welding of 6061 Aluminum Alloy." Advanced Materials Research 668 (March 2013): 890–97. http://dx.doi.org/10.4028/www.scientific.net/amr.668.890.
Повний текст джерелаАнотація:
This paper presented a detailed finite element simulation on the basis of elastic-plastic method combined with thermo-mechannical coupling algorithm，and the software abaqus was used for the welding simulation of thin-walled 6061-T6 aluminum. The residual stress and distortion with various types of welding sequence were investigated and the optimal welding sequence was gained through comparison and analysis. The results showed that the maximum residual stress on the plane of the welds was tensile stress after welding in a rectangular. The method of symmetry welding got smaller residual stress which could enhance the stability of the weldments, and starting from a longer welding path got smaller residual distortion of aluminum alloy.
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Timalsina, Asim, Gene Hou, and Jin Wang. "Computing Fluid-Structure Interaction by the Partitioned Approach with Direct Forcing." Communications in Computational Physics 21, no. 1 (December 5, 2016): 182–210. http://dx.doi.org/10.4208/cicp.080815.090516a.
Повний текст джерелаАнотація:
AbstractIn this paper, we propose a new partitioned approach to compute fluid-structure interaction (FSI) by extending the original direct-forcing technique and integrating it with the immersed boundary method. The fluid and structural equations are calculated separately via their respective disciplinary algorithms, with the fluid motion solved by the immersed boundary method on a uniform Cartesian mesh and the structural motion solved by a finite element method, and their solution data only communicate at the fluid-structure interface. This computational framework is capable of handling FSI problems with sophisticated structures described by detailed constitutive laws. The proposed methods are thoroughly tested through numerical simulations involving viscous fluid flow interacting with rigid, elastic solid, and elastic thin-walled structures.
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Shah, Zahir, Ebraheem O. Alzahrani, Abdullah Dawar, Wajdi Alghamdi, and Malik Zaka Ullah. "Entropy Generation in MHD Second-Grade Nanofluid Thin Film Flow Containing CNTs with Cattaneo-Christov Heat Flux Model Past an Unsteady Stretching Sheet." Applied Sciences 10, no. 8 (April 15, 2020): 2720. http://dx.doi.org/10.3390/app10082720.
Повний текст джерелаАнотація:
Entropy generation plays a significant role in several complex processes, extending from cosmology to biology. The entropy generation minimization procedure can be applied for the optimization of mechanical systems including heat exchangers, elements of nuclear and thermal power plants, ventilation and air-conditioning systems. In order to present our analysis, entropy generation in a thin film flow of second grade nanofluid holding single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) with a Cattaneo–Christov heat flux model is studied in this article. The flow is considered passing a linearly extending surface. A variable magnetic field with aligned angle ε is functioned along the extending sheet. With the aid of the homotopy analysis method (HAM), the fluid flow model is elucidated. The impressions of embedded factors on the flow are obtainable through figures and discussed in detail. It is observed that the velocity profile escalated with the increasing values of volume fraction of nanoparticles and second grade fluid parameter. The higher values of volume fraction of nanoparticles, second grade fluid parameter, non-linear heat source/sink, and thermal radiation parameter intensified the temperature profile. Surface drag force escalated with heightening values of nanoparticles volume fraction, unsteadiness, film thickness, magnetic, and second grade fluid parameters. Entropy generation increased with enhancing values of magnetic parameter, Brinkman number, and Reynolds number.
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Klaerner, Matthias, Mario Wuehrl, Lothar Kroll, and Steffen Marburg. "Metal–plastic composites with amplitude-dependent constraint layer damping." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 233, no. 18 (April 18, 2019): 6425–35. http://dx.doi.org/10.1177/0954406219840681.
Повний текст джерелаАнотація:
For metal–plastic composites with thin shear-sensitive cores, high damping can be determined. These materials were developed to reduce the structure-borne noise and are therefore used for thin-walled components with bending loads. In addition to the known sensitivity due to the temperature and frequency, these materials show a significant dependency on vibration amplitudes. Within the framework of this study, the nonlinear damping of metal–plastic composites was determined experimentally using free-vibrating cantilever beams. A detailed analysis of the derived velocity–time curves showed a nonlinear damping within the decay. An exponential approach was successfully used to describe the relation between damping and current deflection. Furthermore, a strain energy-based evaluation is introduced to quantify the share of the core contributions. For this purpose, the strain energy of several acoustically sensitive car components as well as the beams with varying supports and vibration lengths were determined numerically with a finite element analysis. The strain energy ratio of the cores was then derived as a comparative measurement and within a finite element-based design of experiments. A cantilever beam setup with a component-specific beam length representing similar core strain energy ratios was retested and showed a similar exponential amplitude dependence but higher damping parameters.
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Ghorbanpour-Arani, AH, A. Rastgoo, M. Sh Zarei, A. Ghorbanpour Arani, and E. Haghparast. "Nonlocal elastic medium modeling for vibration analysis of asymmetric conveyed-fluid Y-shaped single-walled carbon nanotube considering viscothermal effects." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 231, no. 3 (August 9, 2016): 574–95. http://dx.doi.org/10.1177/0954406215617194.
Повний текст джерелаАнотація:
In the present research, vibration and instability analysis of a viscoelastic Y-shaped single-walled carbon nanotube conveying fluid is carried out. The surrounding viscoelastic medium is simulated by various models such as Kelvin–Voigt, Maxwell, standard linear solid Reissner, and nonlocal models. The size effects are considered based on modified couple stress theory. In order to achieve more accurate results, fourth-order beam theory is utilized. Surface stress effects are considered based on Gurtin–Murdoch theory. In addition, effects of the asymmetry of Y-shaped single-walled carbon nanotube are also taken into account. Regarding fluid–structure interaction, the equations of motion as well as boundary conditions are derived using Hamilton’s principle and solved by means of hybrid analytical–numerical method. Regarding the temperature changes on visco-Pasternak foundation, the effects of different surrounding medium models are discussed in detail. The overall results indicated that the stability and vibration characteristics of Y-shaped single-walled carbon nanotube conveying fluid are strongly dependent on damping coefficient. The results of this work are hoped to be useful in design and manufacturing of nanodevices where Y-shaped nanotubes act as a basic element.
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Bhatt, Megha, and Sandip Vasanwala. "Comparison of Ultimate Capacities of RC Chimney Sections under Wind Loading." Trends in Sciences 19, no. 1 (January 1, 2022): 1722. http://dx.doi.org/10.48048/tis.2022.1722.
Повний текст джерелаАнотація:
Diffusion of gaseous and particulate pollutants from tall stacks has formed an important element in the control of air pollution since the industrial revolution began. These tall reinforced concrete chimneys are considered to be cantilever columns subjected to axial load resulted from the self-weight of the shell, linings and other accessories and bending moments which are resulted from the lateral loads like wind forces and earthquake forces.
The recently published IS: 4998 – 2015 adopted a limit state design concept which requires well defined stress-strain relationship for concrete and steel. It has been seen that there are many disparities lies between the stress-strain relationships of constituent materials adopted by IS: 4998 – 2015 and other design standards.
This paper discusses various methods pertaining to the estimation of the ultimate strength of thin-walled hollow circular sections of reinforced concrete chimneys, subjected to wind loading. A comparative study of various methods based on the prevalent codes reveals considerable disparity in the predicted ultimate strength values. These differences have been critically analyzed and results are discussed in this paper in terms of ultimate strength along with the contribution of concrete and steel, ultimate curvature and depth of neutral axis. For the comparison of above-mentioned parameters, design recommendations of IS 4998 – 2015, CICIND 2011, ACI 307 – 08 are used.
HIGHLIGHTS
The recently published IS: 4998 – 2015 adopted a limit state design concept which requires well defined stress-strain relationship for concrete and steel which differs in terms of strain and stress limits when compared with other well established RC chimney design codes
Various methods pertaining to the estimation of the ultimate strength of thin-walled hollow circular sections of reinforced concrete chimneys, subjected to wind loading are discussed using a comparative study with different parameters of RC chimney
For the comparison of above-mentioned parameters, design recommendations of IS 4998 – 2015, CICIND 2011, ACI 307 – 08 are used
Stress-strain relationship of concrete and steel also discussed with the bases of the same is also discussed in detail for each of the above codes
GRAPHICAL ABSTRACT
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Maudlin, Daniel. "Architecture and Identity on the Edge of Empire: The Early Domestic Architecture of Scottish Settlers in Nova Scotia, Canada, 1800–1850." Architectural History 50 (2007): 95–123. http://dx.doi.org/10.1017/s0066622x00002896.
Повний текст джерелаАнотація:
In the early nineteenth century thousands of Scots emigrated to Nova Scotia, Canada, settling there principally in Pictou and Antigonish Counties. This article considers the transformation of the domestic architecture of emigrants from the Scottish Highlands, from earth and random-rubble-walled ‘black houses’ to Classically ornamented and proportioned timber-framed houses. It demonstrates that, in contrast to the transferable traditions of Lowland Scottish settlers, virtually no element of the Scottish Highland vernacular building tradition was established in Nova Scotia, and that Scottish Highland emigrants adopted a new architecture with near total uniformity. These changes in architectural practice are described here in some detail, and then interpreted as indicators of changed social practice within the immigrant Highland community.
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Truong-Thi, T., T. Vo-Duy, V. Ho-Huu, and T. Nguyen-Thoi. "Static and Free Vibration Analyses of Functionally Graded Carbon Nanotube Reinforced Composite Plates using CS-DSG3." International Journal of Computational Methods 17, no. 03 (November 20, 2019): 1850133. http://dx.doi.org/10.1142/s0219876218501335.
Повний текст джерелаАнотація:
This study presents an extension of the cell-based smoothed discrete shear gap method (CS-DSG3) using three-node triangular elements for the static and free vibration analyses of carbon nanotube reinforced composite (CNTRC) plates. The single-walled carbon nanotubes (SWCNTs) are assumed to be uniformly distributed (UD) and functionally graded (FG) distributed along the thickness direction. The material properties of carbon nanotube-reinforced composite plates are estimated according to the rule of mixture. The governing equations are developed based on the first-order shear deformation plate theory (FSDT). In the CS-DSG3, each triangular element will be divided into three sub-triangles, and in each sub-triangle, the stabilized discrete shear gap method is used to compute the strains and to avoid the transverse shear locking. Then the strain smoothing technique on the whole triangular element is used to smooth the strains on these three sub-triangles. Effects of several parameters, such as the different distribution of carbon nanotubes (CNTs), nanotube volume fraction, boundary condition and width-to-thickness ratio of plates are investigated. In addition, the effect of various orientation angles of CNTs is also examined in detail. The accuracy and reliability of the proposed method are verified by comparing its numerical solutions with those of other available results in the literature.
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Kolakowski, Zbigniew, and Andrzej Teter. "Eigenproblem Versus the Load-Carrying Capacity of Hybrid Thin-Walled Columns with Open Cross-Sections in the Elastic Range." Materials 14, no. 13 (June 22, 2021): 3468. http://dx.doi.org/10.3390/ma14133468.
Повний текст джерелаАнотація:
The phenomena that occur during compression of hybrid thin-walled columns with open cross-sections in the elastic range are discussed. Nonlinear buckling problems were solved within Koiter’s approximation theory. A multimodal approach was assumed to investigate an effect of symmetrical and anti-symmetrical buckling modes on the ultimate load-carrying capacity. Detailed simulations were carried out for freely supported columns with a C-section and a top-hat type section of medium lengths. The columns under analysis were made of two layers of isotropic materials characterized by various mechanical properties. The results attained were verified with the finite element method (FEM). The boundary conditions applied in the FEM allowed us to confirm the eigensolutions obtained within Koiter’s theory with very high accuracy. Nonlinear solutions comply within these two approaches for low and medium overloads. To trace the correctness of the solutions, the Riks algorithm, which allows for investigating unsteady paths, was used in the FEM. The results for the ultimate load-carrying capacity obtained within the FEM are higher than those attained with Koiter’s approximation method, but the leap takes place on the identical equilibrium path as the one determined from Koiter’s theory.
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Engbert, T., T. Heymann, D. Biermann, and A. Zabel. "Flow drilling and thread forming of continuously reinforced aluminium extrusions." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 225, no. 3 (March 1, 2011): 398–407. http://dx.doi.org/10.1243/2041297510394104.
Повний текст джерелаАнотація:
Light-metal extrusions are widely used as frame-structure elements. Joining these profiles via screw coupling is a challenging task due to the small wall thickness of the extrusions and the missing accessibility within a frame structure. The combination of flow drilling and thread forming offers a possibility to cope with this task. These processing techniques allow the manufacture of stable threads in thin-walled structures with the profile accessible from one side only. Nowadays, aluminium profiles can be continuously reinforced through composite extrusion. Mechanical properties, like increased tensile strength compared with homogeneous profiles, make reinforced profiles preferable for applications such as safety-relevant components. However, the reinforcement can seriously affect machining processes as well as the machining results. Therefore, the flow-drilling operation, the thread-forming operation, and the process results have been analysed in detail with a new, difficult-to-machine material combination, namely steel-wire-reinforced aluminium extrusions. The crucial factor when machining lightweight extrusions are the forces acting perpendicular to the thin walls, so the influence of the reinforcement and the processing parameters on the feed force during flow drilling is presented. To examine the effect of the reinforcement on the thread-forming result and to quantify the benefit of flow drilling, the threads are stressed with a defined tensile load until failure.
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Drosg, B., W. Fuchs, K. Meixner, R. Waltenberger, R. Kirchmayr, R. Braun, and G. Bochmann. "Anaerobic digestion of stillage fractions – estimation of the potential for energy recovery in bioethanol plants." Water Science and Technology 67, no. 3 (February 1, 2013): 494–505. http://dx.doi.org/10.2166/wst.2012.574.
Повний текст джерелаАнотація:
Stillage processing can require more than one third of the thermal energy demand of a dry-grind bioethanol production plant. Therefore, for every stillage fraction occurring in stillage processing the potential of energy recovery by anaerobic digestion (AD) was estimated. In the case of whole stillage up to 128% of the thermal energy demand in the process can be provided, so even an energetically self-sufficient bioethanol production process is possible. For wet cake the recovery potential of thermal energy is 57%, for thin stillage 41%, for syrup 40% and for the evaporation condensate 2.5%. Specific issues for establishing AD of stillage fractions are evaluated in detail; these are high nitrogen concentrations, digestate treatment and trace element supply. If animal feed is co-produced at the bioethanol plant and digestate fractions are to be reused as process water, a sufficient quality is necessary. Most interesting stillage fractions as substrates for AD are whole stillage, thin stillage and the evaporation condensate. For these fractions process details are presented.