The Initial Imperfection Amplified Criterion is applied toinvestigate the geometric nonlinear dynamic buckling of staticallypreloaded ring-stiffened cylindrical shells under axial fluid-solidimpact. Tak- ing account o...The Initial Imperfection Amplified Criterion is applied toinvestigate the geometric nonlinear dynamic buckling of staticallypreloaded ring-stiffened cylindrical shells under axial fluid-solidimpact. Tak- ing account of the effects of large deformation andinitial geometric imperfection, the governing equations are obtainedby the Galerkin method and solved by the Runge-Kutta method. Theeffects of static preloading (uniform external radial pressure) onthe buckling features and the load-carrying ability of ring-stiffenedcy- lindrical shells against axial impact are discussed.展开更多
We studied consecutive impact loading on woven high-modulus polyethylene rope, which is used in robotics fields. An impact tester was developed to conduct the experiments. Five consecutive impact loads (five drops) we...We studied consecutive impact loading on woven high-modulus polyethylene rope, which is used in robotics fields. An impact tester was developed to conduct the experiments. Five consecutive impact loads (five drops) were applied to the rope and the stiffness of the loading part that corresponds to each drop was evaluated. The stiffness of the woven ropes was affected strongly by consecutive impact loading. The change in stiffness is undesirable in some applications such as in robotic fields. Therefore, we have proposed a method that can optimize changes in stiffness by applying a preload before impact testing (preload treatment). The experimental results show that preload is an efficient way to reduce changing rope stiffness. We have also proposed an empirical equation that can estimate the rope stiffness after arbitrary preload treatment, and this equation is a function of the number of drops and the static preload level. The equation can be used to determine the preload treatment conditions to stabilize the stiffness of the woven ropes before they are used in engineering fields.展开更多
客车制动缸膜板的稳定工作对制动系统的安全性和可靠性具有决定性意义。制动缸膜板直径较大,密封圈处螺栓数量较多且工况复杂,分析表明其安装方式及温度对密封性能影响显著。文中采用有限元分析方法研究顺次加载、ASME PCC-1加载、JIS B...客车制动缸膜板的稳定工作对制动系统的安全性和可靠性具有决定性意义。制动缸膜板直径较大,密封圈处螺栓数量较多且工况复杂,分析表明其安装方式及温度对密封性能影响显著。文中采用有限元分析方法研究顺次加载、ASME PCC-1加载、JIS B 2251加载方式对螺栓预紧力的影响。同时分析了温度变化对螺栓预紧力以及膜板密封面应力分布的影响,并且对制动缸进行了不同温度下的密封性能试验。结果表明,3种加载方式最后都能得到较为均匀的载荷,其中JIS B 2251加载方式最接近目标载荷,加载过程最简易;随着温度的升高,螺栓预紧力上升,密封面上的接触应力增大;低温状态下制动缸内压力下降最快,高温次之,常温最慢。展开更多
基金the National Natural Sciences Foundation of China(No.19802017)
文摘The Initial Imperfection Amplified Criterion is applied toinvestigate the geometric nonlinear dynamic buckling of staticallypreloaded ring-stiffened cylindrical shells under axial fluid-solidimpact. Tak- ing account of the effects of large deformation andinitial geometric imperfection, the governing equations are obtainedby the Galerkin method and solved by the Runge-Kutta method. Theeffects of static preloading (uniform external radial pressure) onthe buckling features and the load-carrying ability of ring-stiffenedcy- lindrical shells against axial impact are discussed.
文摘We studied consecutive impact loading on woven high-modulus polyethylene rope, which is used in robotics fields. An impact tester was developed to conduct the experiments. Five consecutive impact loads (five drops) were applied to the rope and the stiffness of the loading part that corresponds to each drop was evaluated. The stiffness of the woven ropes was affected strongly by consecutive impact loading. The change in stiffness is undesirable in some applications such as in robotic fields. Therefore, we have proposed a method that can optimize changes in stiffness by applying a preload before impact testing (preload treatment). The experimental results show that preload is an efficient way to reduce changing rope stiffness. We have also proposed an empirical equation that can estimate the rope stiffness after arbitrary preload treatment, and this equation is a function of the number of drops and the static preload level. The equation can be used to determine the preload treatment conditions to stabilize the stiffness of the woven ropes before they are used in engineering fields.
文摘客车制动缸膜板的稳定工作对制动系统的安全性和可靠性具有决定性意义。制动缸膜板直径较大,密封圈处螺栓数量较多且工况复杂,分析表明其安装方式及温度对密封性能影响显著。文中采用有限元分析方法研究顺次加载、ASME PCC-1加载、JIS B 2251加载方式对螺栓预紧力的影响。同时分析了温度变化对螺栓预紧力以及膜板密封面应力分布的影响,并且对制动缸进行了不同温度下的密封性能试验。结果表明,3种加载方式最后都能得到较为均匀的载荷,其中JIS B 2251加载方式最接近目标载荷,加载过程最简易;随着温度的升高,螺栓预紧力上升,密封面上的接触应力增大;低温状态下制动缸内压力下降最快,高温次之,常温最慢。
