旋转部件SGBEM-FEM耦合热弹性断裂分析

SGBEM-FEM coupling for thermoelastic fracture mechanics analysis of rotational components

旋转部件载荷复杂,易萌生裂纹,引发疲劳断裂失效。针对含裂纹受热旋转部件,在全局无裂纹区域使用有限元法(FEM),发挥其在大型结构仿真分析方面的优势;在裂纹附近局部子域使用对称伽辽金边界单元法(SGBEM),发挥其在结构断裂分析方面的优势。构造考虑旋转惯性载荷和热载荷影响的SGBEM超单元,该超单元刚度矩阵对称半正定,且施加的旋转惯性载荷和热载荷仅影响等效力向量,可实现与有限元刚度矩阵和力向量的直接装配,从而耦合求解旋转部件的热弹性断裂问题。采用构造的SGBEM超单元FEM耦合法计算了含裂纹受热旋转圆盘的应力强度因子,验证了该方法的有效性。

Rotational components undergo complex loads which can easily initiate cracks,resulting in fatigue and fracture failures.For thermal-loaded rotational components with cracks,the finite element method(FEM)was applied to the global structure without cracks,thus exerting the advantage of FEM in numerical analysis of large-scale structure;meanwhile,the symmetric Galerkin boundary element method(SGBEM)was employed to the subdomain around the crack,thereby developing the advantage of SGBEM in fracture analysis.The SGBEM super element,which took the influence of the rotational inertia loading and the thermal loading into consideration,was developed in this paper.The stiffness matrix of the obtained SGBEM super element was symmetric and positive semidefinite,where the rotational inertia loading and the thermal loading only influence the equivalent force vector.Thus,the SGBEM super element can be directly assembled with the stiffness matrix and the equivalent force vector of the FEM,and be coupled with the FEM to solve the thermoelastic fracture problem of rotational components.Stress intensity factors of the cracked rotational disk undergoing the thermal loading were computed,which validates the effectiveness of SGBEM super element and FEM coupling method.