In order to reduce casualties and property losses in a collision accident, thin-walled structure has been extensively used as energy absorber in crashworthiness design of train. With the help of energy absorber, colli...In order to reduce casualties and property losses in a collision accident, thin-walled structure has been extensively used as energy absorber in crashworthiness design of train. With the help of energy absorber, collision kinetic energy can be controllably dissipated by the plastic deformation of structures. A new kind of multi-cell thin-walled structure called as bitubular polygonal tubes with internal walls(BPTIW) was constructed. The crashworthiness characteristics of BPTIWs were investigated by LS-DYNA. It can be found that the BPTIW with 12 sides has the most excellent crashworthiness characteristics. Therefore, based on response surface method(RSM) and multiobjective particle optimization(MOPSO) algorithm, the BPTIW with 12 sides was selected to optimize the dimensions of cross-sectional configuration under different constraints of energy absorption(EA) and crushing peak force(CPF). The results show that the optimal designs of BPTIW12 under different constraints present excellent crashworthiness characteristics and can be used in the practical engineering.展开更多
The thin-walled tube flexure（TWTF） hinges have important potential application value in the deployment mechanisms of satellite and solar array, but the optimal design of the TWTF hinges haven＇t been completely solv...The thin-walled tube flexure（TWTF） hinges have important potential application value in the deployment mechanisms of satellite and solar array, but the optimal design of the TWTF hinges haven＇t been completely solved, which restricts their applications. An optimal design method for the qusai-static folding and deploying of TWTF hinges with double slots is presented based on the response surface theory. Firstly, the full factorial method is employed to design of the experiments. Then, the finite element models of the TWTF hinges with double slots are constructed to simulate the qusai-static folding and deploying non-linear analysis. What＇s more, the mathematical model of the TWTF flexure hinge quasi-static folding and deploying properties are derived by the response surface method. Considering of small mass and high stability, the peak moment of quasi-static folding and deploying as well as the lightless are set as the objectives to get the optimal performances. The relative errors of the objectives between the optimal design results and the FE analysis results are less than 7%, which demonstrates the precision of the surrogate models. Lastly, the parameter study shows that both the slots length and the slots width both have significant effects to the peak moment of quasi-static folding and deploying of TWTF hinges with double slots. However, the maximum Mises stress of quasi-static folding is more sensitive to the slots length than the slots width. The proposed research can be applied to optimize other thin-walled flexure hinges under quasi-static folding and deploying, which is of great importance to design of flexure hinges with high stability and low stress.展开更多
At present,limit equilibrium method is often adopted in the design of reinforced earth retaining wall. Geotechnical engineers home and abroad have done a lot of work to improve the traditional calculation methods in r...At present,limit equilibrium method is often adopted in the design of reinforced earth retaining wall. Geotechnical engineers home and abroad have done a lot of work to improve the traditional calculation methods in recent years,while there are lots of defects. This paper first identifies the location of failure surface and safety factor through the finite element program of PLAXIS and then analyses the influencing factors of the stability of reinforced earth retaining wall with geogrid. The authors adopt strength reduction FEM (finite element method)in the design and stability analysis of reinforced earth retaining wall and have achieved some satisfying results. Without any assumptions,the new design method can automatically judge the failure mode of reinforced earth retaining wall,consider the influence of axial tensile stiffness of the reinforcement stripe on the stability of retaining wall,identify reasonable distance and length of the reinforcement stripe,and choose suitable parameters of reinforcement stripe,including strength,stiffness and pseudo-friction coefficient which makes the design optimal. It is proved through the calculation examples that this method is more reasonable,reliable and economical in the design of reinforced earth retaining wall.展开更多
以弹性地基梁法为基础,运用动态施工反演分析的思想,即在常规的反分析过程中引入隧步开挖和隧道支撑的动态施工因素,反算反映基坑土体性态的 m 值,以求仿真模拟深基坑工程实际施工情况,进而为下一工况的变形预报提供可靠保证。最后通过...以弹性地基梁法为基础,运用动态施工反演分析的思想,即在常规的反分析过程中引入隧步开挖和隧道支撑的动态施工因素,反算反映基坑土体性态的 m 值,以求仿真模拟深基坑工程实际施工情况,进而为下一工况的变形预报提供可靠保证。最后通过一个工程实例的计算值与实测值对比分析,验证了该法在基坑支护结构设计和施工过程中是合理可行性的。展开更多
基金Project(CX2016B047)supported by Hunan Provincial Innovation Foundation For Postgraduate,ChinaProjects(U1334208,51405516,51275532)supported by the National Natural Science Foundation of ChinaProject(2016YFB1200403)supported by the National Key Research and Development Proguam of China
文摘In order to reduce casualties and property losses in a collision accident, thin-walled structure has been extensively used as energy absorber in crashworthiness design of train. With the help of energy absorber, collision kinetic energy can be controllably dissipated by the plastic deformation of structures. A new kind of multi-cell thin-walled structure called as bitubular polygonal tubes with internal walls(BPTIW) was constructed. The crashworthiness characteristics of BPTIWs were investigated by LS-DYNA. It can be found that the BPTIW with 12 sides has the most excellent crashworthiness characteristics. Therefore, based on response surface method(RSM) and multiobjective particle optimization(MOPSO) algorithm, the BPTIW with 12 sides was selected to optimize the dimensions of cross-sectional configuration under different constraints of energy absorption(EA) and crushing peak force(CPF). The results show that the optimal designs of BPTIW12 under different constraints present excellent crashworthiness characteristics and can be used in the practical engineering.
基金supported by National Natural Science Foundation ofChina(Grant No.50935002)
文摘The thin-walled tube flexure（TWTF） hinges have important potential application value in the deployment mechanisms of satellite and solar array, but the optimal design of the TWTF hinges haven＇t been completely solved, which restricts their applications. An optimal design method for the qusai-static folding and deploying of TWTF hinges with double slots is presented based on the response surface theory. Firstly, the full factorial method is employed to design of the experiments. Then, the finite element models of the TWTF hinges with double slots are constructed to simulate the qusai-static folding and deploying non-linear analysis. What＇s more, the mathematical model of the TWTF flexure hinge quasi-static folding and deploying properties are derived by the response surface method. Considering of small mass and high stability, the peak moment of quasi-static folding and deploying as well as the lightless are set as the objectives to get the optimal performances. The relative errors of the objectives between the optimal design results and the FE analysis results are less than 7%, which demonstrates the precision of the surrogate models. Lastly, the parameter study shows that both the slots length and the slots width both have significant effects to the peak moment of quasi-static folding and deploying of TWTF hinges with double slots. However, the maximum Mises stress of quasi-static folding is more sensitive to the slots length than the slots width. The proposed research can be applied to optimize other thin-walled flexure hinges under quasi-static folding and deploying, which is of great importance to design of flexure hinges with high stability and low stress.
基金This research was funded by the Constructional Science and Technology Project of West Transportation,Ministry of Transport of People’s Republic of China(2003-318-799-17)
文摘At present,limit equilibrium method is often adopted in the design of reinforced earth retaining wall. Geotechnical engineers home and abroad have done a lot of work to improve the traditional calculation methods in recent years,while there are lots of defects. This paper first identifies the location of failure surface and safety factor through the finite element program of PLAXIS and then analyses the influencing factors of the stability of reinforced earth retaining wall with geogrid. The authors adopt strength reduction FEM (finite element method)in the design and stability analysis of reinforced earth retaining wall and have achieved some satisfying results. Without any assumptions,the new design method can automatically judge the failure mode of reinforced earth retaining wall,consider the influence of axial tensile stiffness of the reinforcement stripe on the stability of retaining wall,identify reasonable distance and length of the reinforcement stripe,and choose suitable parameters of reinforcement stripe,including strength,stiffness and pseudo-friction coefficient which makes the design optimal. It is proved through the calculation examples that this method is more reasonable,reliable and economical in the design of reinforced earth retaining wall.
文摘以弹性地基梁法为基础,运用动态施工反演分析的思想,即在常规的反分析过程中引入隧步开挖和隧道支撑的动态施工因素,反算反映基坑土体性态的 m 值,以求仿真模拟深基坑工程实际施工情况,进而为下一工况的变形预报提供可靠保证。最后通过一个工程实例的计算值与实测值对比分析,验证了该法在基坑支护结构设计和施工过程中是合理可行性的。
