Papers by Author: Tao Zhu

Abstract: Three typical finite element models (FEM) of spot-welds have been created as analysis objects, and the relationship between force and displacement of the specimens were obtained under shear and tensile forces through the elastic-plastic finite element analysis. Simulation results and the shear-tensile test curves of TG301L and SUS301L stainless steel specimens which were obtained based on JIS Z 3136 shear-tensile test methods were compared. The results showed that: No matter what type of nuclear simulation, stiffness of simulation models are less than the actual stiffness of the specimen; and when the specimen was stretched and sheared, with solid element to simulate the nugget can get maximum stiffness, it is most close to the actual stiffness, umbrella model is followed, and a stiff beam model is the worst.

Abstract: For high-speed railway carbody structure durability analysis problems in China, one integrated method based on MBS (multibody simulation) is proposed here. Firstly, one EMU (Electricity Multiple Unit) full vehicle was performed to dynamic modeling and simulation. The numerical simulation results were applied to illustrate the vehicle dynamic characteristics. And the relationships between structural strength, stiffness, and frequency characteristics were also studied. Secondly, the multidisciplinary design technique was used to solve multi-mode coupled vibration of carbody structure on the cumulative effects of local vibration and damage effects, as well as structure light-weighting and other parallel optimization problems. Finally, the effective measures were proposed to control carbody structure’s physical failure.

Abstract: In order to accurately and conveniently simulate spot-weld in FEA, based on the typical specimen of stainless steel, three typical finite element models (FEM) of spot-welds have been created as analysis objects. Firstly, based on the calculation theory of the spot-weld fatigue, two sets of analytical solution, which were the maximum principle stress of the specimen around the spot-weld nugget, were obtained under the action of stretching and shearing, respectively. Then, their linear elastic FEM were established, and the stress states around the spot-weld nugget and the adjacent sheets were analyzed. Finally, according to the results compared between the analytical solution and simulation solution, it can be seen that, when the specimen was stretched, using the brick model to simulate the nugget can get the smallest absolute error of the principle stress, so its spot-weld fatigue damage is the most consistent with the actual situation, a stiff beam model followed, and an umbrella model is the worst; when the specimen was sheared, using the brick model to simulate the nugget can also get the smallest absolute error of the principle stress, so its spot-weld fatigue damage is also the most consistent with the actual situation, the umbrella model is followed, and the stiff beam model is the worst. The results show that appropriate selection of spot-weld FEM is extremely essential for fatigue life prediction under the initial design of products.