冲击荷载作用下单层网壳结构动力稳定性研究

摘要

针对冲击荷载不同于地震作用，而常规动力稳定性判定准则不适用问题，阐述求解冲击问题的基本理论及冲击荷载取值；据冲击荷载特性提出适合冲击碰撞问题的单层网壳结构动力稳定性判定准则；选 K6型单层网壳结构模型，利用非线性有限元软件 ANSYS ／LS －DYNA 进行结构冲击作用下动力稳定性分析，通过大量算例，分析其在不同冲击物质量比及速度作用下全过程动力响应，结合动力响应模式获得冲击荷载作用下单层网壳动力失稳的临界能量区域，并从矢跨比、跨度、杆件截面三方面对结构进行参数分析。结果表明，基于网壳动力响应模式与冲击能量相结合方法对单层网壳进行动力稳定性判定合理；结构刚度越小，冲击作用下动力稳定性越差；加大主肋利于提高结构动力稳定性。%Unlike for the case of seismic action,the conventional dynamic stability criteria are no longer applicable for the case of impact load.The basic theory of solving the impact problem and the problem of how to take resonably the value of impact load were expounded.According to the impact load characteristics,the dynamic stability criterion suitable for impact collision problem of single-layer reticulated shell structure was proposed.Taking a K6 single-layer reticulated shell model as an object,the dynamic stability analysis under impact was carried out by using the nonlinear finite element software ANSYS /LS-DYNA.The whole process of dynamic response under the action of different quality and speed of impact loads was analyzed.The critical energy region of dynamic instability of the single-layer reticulated shell under impact loads was obtained based on the dynamic response model.The dynamic stability under earthquake was also analysed in order to get the instability critical load which was then compared with that under impact action.From the aspects of rise-span ratio,span and bar cross-section,a parameter analysis was carried out.The results show the dynamic stability discriminant method for single-layer reticulated shell structures,which combines the dynamic response model with the impact energy is reasonable.The smaller the structure stiffness,the worse the dynamic stability under impact load. Increasing the main bar section is most conducive to improve the structure dynamic stability.