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Li Z.-M.,Shanghai Key Laboratory of Digital Manufacture for Thin walled Structures | Li Z.-M.,Shanghai JiaoTong University
Composite Structures | Year: 2014

Thermal postbuckling analysis for 3D (three-dimension) braided beams to initial geometrical imperfection in general modes subjected to uniform, linear and non-linear temperature distribution through the thickness are presented. The cross-section of 3D braided composite beam may be treated as a cell system and the geometry of each cell is deeply dependent on its position. A generic imperfection function for one-dimensional composite beam is introduced to model various possible initial geometrical imperfection including sine type, local type, and global type imperfections. Based on first-order shear deformation beam theory incorporating von Kármán nonlinear strain displacement relations, the governing equation is nonlinear integral-differential equations. An analytical solution for thermal postbuckling of 3D braided beams with and without imperfection obtained as a function of the applied thermal load is employed to determine buckling temperatures and postbuckling equilibrium paths of 3D braided beams. The results reveal that the temperature dependent properties, temperature distribution, geometric parameter, fiber volume fraction, initial geometrical imperfections and braiding angle have a significant effect on thermal postbuckling behavior of braided composite beams. © 2013 Elsevier Ltd. Source


Li Y.B.,Shanghai JiaoTong University | Li Y.B.,Shanghai Key Laboratory of Digital Manufacture for Thin walled Structures | Li D.L.,Shanghai JiaoTong University | Li D.L.,Shanghai Key Laboratory of Digital Manufacture for Thin walled Structures | And 3 more authors.
Science and Technology of Welding and Joining | Year: 2016

Traditional spot welds and magnetically assisted spot welds were made in 2.25 mm thick galvanised dual-phase steel, and the weld microstructures were compared. The magnetically assisted weld nugget had a ‘dog bone’ shape, and it had an increased diameter, which indicates a larger load-bearing area that will improve mechanical performance. The fusion zone of the magnetically assisted welds had a finer and less-directional grain structure than the conventional welds, which would improve weld strength, plastic strains, and ductility. Both types of welds contained an unusual soft zone very close to the fusion zone that is thought to be an integral part of the fusion zone. The soft zone of the magnetically assisted welds was wider than the conventional welds. © 2016 Institute of Materials, Minerals and Mining Source


Yu W.-W.,Shanghai Key Laboratory of Digital Manufacture for Thin walled Structures | Zhao Y.-X.,Shanghai Key Laboratory of Digital Manufacture for Thin walled Structures | Shi L.,Baosteel | Chao C.,Shanghai Key Laboratory of Digital Manufacture for Thin walled Structures
Journal of Iron and Steel Research | Year: 2013

MS980 is one of advanced high-strength steels, which has a great potential for producing square tubes. Residual stress plays a significant role in determining roll-formed members behavior and strength. An experimental study on transverse residual stress of roll-formed shape with square section was conducted via X-ray diffraction method. The distribution of transverse residual stresses at different position in sections was measured and studied, and influence of cold-rolled-sheet and hot-rolled-sheet, different fillet radius, different processes, and different pickling time on circumferential residual stress distribution for square section was investigated. The experimental results show the transverse residual stresses are compressive stress in the corner portion and the tensile stress in the straight edge. Fillet radius, sheet, and process have a significant impact on the distribution of residual stress, but the conventional pickling hardly affects residual stress. Source


Zhao C.,Xian Jiaotong University | Zhao C.,Shanghai Key Laboratory of Digital Manufacture for Thin walled Structures | Yu H.,Shanghai Key Laboratory of Digital Manufacture for Thin walled Structures | Lin Z.,Xian Jiaotong University | And 2 more authors.
Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics | Year: 2015

Viscoelastic material is widely used in mechanisms and its properties have a great influence on the dynamic behaviors of structures. In this study, a modified viscoelastic constitutive model is developed by introducing the nonlinear strain-displacement relation of materials to the classical Kelvin-Voigt model. The new model can be implemented into the finite element absolute nodal coordinate formulation directly, which can be applied to investigate the large rotation and the large deformation problem. The mass matrix and the viscoelastic stiffness matrix of a two-dimensional viscoelastic beam with shear deformation are derived with the absolute nodal coordinate formulation. The dynamic model of the beam is presented based on Newton equations. The dynamic equations are transformed from a set of differential algebraic equations to a set of first-order ordinary differential equations, which are calculated by using the fourth-order explicit Runge-Kutta method. A free falling flexible pendulum is employed to study the correlation between the dynamic behaviors of structures and the mechanical behaviors of materials. The results indicate that the modified constitutive model is able to describe the nonlinear deformation behavior of the structure, which undergoes large rotation and large deformation. The flexible deformation of the beam is related to the elastic modulus, the density and the viscosity coefficient of the material. The viscous behavior of material reduces the elastic deformation of the structure during its movement, which is beneficial to the kinematic accuracy of the multibody system. IMechE 2014. Source


Yu H.,Xian Jiaotong University | Yu H.,Shanghai Key Laboratory of Digital Manufacture for Thin walled Structures | Zhao C.,Xian Jiaotong University | Zhao C.,Shanghai Key Laboratory of Digital Manufacture for Thin walled Structures | And 6 more authors.
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2015

The assemble precision of thin-walled structures are very important in engineering, which affects the performance of the mechanism. Large rotations are easy to occur in these structures during assembling process due to their geometric features. So it is necessary to establish a precise model of the thin-walled structure to predict its deformation. In this study, the absolute nodal coordinate formulation (ANCF) method is used to describe initial curved thin-walled structure and to study the compatibility of deformation of thin-walled structures during assembling process. A four-node shell element of ANCF with 48DOFs is employed to discrete the thin-walled structure. The vector of the element elastic forces and the stiffness matrix are derived based on continuum mechanics. Static deformation tests of a cantilever plate and the modal analysis of free square plate are used to validate the formulations for the plate element of ANCF. The statics equilibrium equations are deduced and the compatibility of deformation of two thin-walled structures is investigated. © Springer International Publishing Switzerland 2015. Source

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