冲击荷载作用下单层网壳结构动力稳定性研究

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。

Dynamic stability of single-layer reticulated shell structures subjected to impact loads

Unlike seismic action，conventional dynamic stability criteria are no longer applicable for impact load. Firstly, the basic theory of solving the impact problem and value of impact load were expounded; Secondly, according to the impact load characteristics, dynamic stability criterion which is suitable for impact collision problem of single-layer reticulated shell structure is proposed. Lastly, choose a K6 single-layer reticulated shell model, dynamic stability analysis under impact is done by internationally computing dynamic nonlinear finite element software ANSYS / LS-DYNA. The whole process dynamic response under the action of different impact quality and speed is analyzed through a lot of examples. Dynamic instability critical energy region of single-layer reticulated shell under impact loads are got according to the dynamic response model; By analyzing the dynamic stability under earthquake to get instability critical load which is compared with the impact action. From the rise-span ratio, span, bar cross-section to do parameters analysis. The results show: Dynamic stability discriminant method of single-layer reticulated shell structures which combining the dynamic response model and impact energy is reasonable; The smaller the structure stiffness, the worse the dynamic stability under impact load; Increase the main bar section is most conducive to improving the structure dynamic stability.