基于离散元的杆件断裂全过程数值模拟

杆件的断裂会涉及到大变形、非线性以及不连续等问题,通常的数值计算方法模拟这种复杂力学行为具有局限性。本文基于颗粒离散元法DEM,将接触粘结处的分布式弹簧用梁纤维进行等效,提出了一种适于结构弹塑性分析的DEM纤维梁模型,然后在此基础上构建了构件断裂模拟算法以及纤维破环准则。将该模型应用于悬臂梁结构,模拟了悬臂梁从弹性到弹塑性阶段,再到断裂破坏的全过程,数值模拟得到的结构响应和截面开裂破坏形态均较合理。最后将该方法应用于单层网壳倒塌破坏模拟,并与网壳振动台倒塌试验进行对比,结果表明,数值模拟得到的杆件断裂过程及结构倒塌模式与试验现象一致,验证了该模型的正确性和适用性。

Numerical simulation on entire-process of member fracture by discrete element method

The fracture of members is involved in some problems like large deformation,nonlinearity,and discontinuity,so there are limitations to simulating this complex mechanical behavior using the common numerical methods.Firstly,based on particle discrete element method (DEM),a DEM fiber beam model is proposed for structural elastoplastic analysis,where the beam fiber is equivalent to distributed springs of contact bonding.Then the fracture simulation algorithm of members and a crack criterion of fibers are established on the basis of the above model.The given model is applied in a cantilever beam and the entire process for the beam from elastic to elastoplastic stage,and further to fracture failure stage is studied.The results show that the response of a structure and cracking failure modes of the cross section obtained from the numerical simulation are well reasonable.Finally,the present method is used to simulate the collapse of a single-layer reticulated shell.The simulation results,including the process of member fracture and the structural failure mode,are consistent with the response of shaking table test of the shell.The comparisons made verify the accuracy and validity of this method.