摘要
基于传统离散单元法的接触模型,通过能量守恒定律推导适用于杆系结构的离散元模型接触刚度。将分层梁理论引入到离散单元法中,给出接触的塑性判断准则以及推导接触进入塑性后的刚度系数,从而可以应用离散元方法解决杆系结构的弹塑性问题。通过定义离散单元法基于应变的断裂准则,将其应用于解决杆件的断裂问题。选取适用于碰撞问题的赫兹模型,给出赫兹模型刚度的设置方法。最后应用改进后的离散单元法对单层网壳冲击试验进行了考虑弹塑性、断裂、碰撞的全过程模拟,验证了该方法的正确性。并对Kiewitt单层球面网壳单点冲击和多点冲击进行数值模拟研究,分析了单点和多点冲击下单层网壳的破坏模式、冲击力、节点位移和支座反力的异同点。
In this study, the contact stiffness of discrete element model for beam structure is deduced by energy conservation law based on the contact model of traditional discrete element method. By introducing the layered beam theory into the discrete element method, the judging criterion of plasticity of contact is given and the stiffness coefficient of contact after going into plasticity is derived, so that the discrete element method can be used to solve the elasto-plastic problem of beam structures. The strain-based fracture criterion of the discrete element method is defined, and then it is applied to solving the fracture problem of beam structure. The Hertz model suitable for collision problem is selected, and the setting method of Hertz model stiffness is given. Finally,the improved discrete element method is used to simulate the whole impact testing process of single-layer reticulated shell with elastoplasticity, fracture and collision considered, so that this method can be verified.Numerical simulations on single point and multi-point impacts of Kiewitt single-layer spherical reticulated shells are carried out. The differences in failure mode, impact force, joint displacement and support reaction of single-layer reticulated shell subjected to single point and multi-point impact are analyzed.
引文
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