Finite Element Analysis Of Elasto-Plastic Cracked Beams

Most engineering materials are solid materials and their destruction processes' solutions are one of difficult mechanical problems, so the research on stress and strain fields near the crack tip is meaningful, but this problem is extremely complex. Cracks in engineering are often microscopic, traditional methods can only approximately calculate the theoretical stress intensity factor(SIF), J integral etc., but it can't be used in describing cracks in complex shapes, expansion of crack and stress field around crack tip. At the same time, experimental methods are costly and constrained by experimental facility.For the characteristics of fracture mechanics, FEM simplifies the research process. SIF and J integral along different paths can be easily calculated by operating the elements around the crack tip. The path of crack propagation can be predicted by XFEM method, the stress and displacement filed can be also easily approached which can't be obtained by experimental or theoretical method directly.In this paper, calculation and simulation of crack beam's SIF, J integral, crack propagation and mode information are researched. Describe an elastic-plastic crack beam element with FEM theory and the plastic zone around crack tip is simplified to spring element, then show how the crack influence the stiffness of the beam, and deduce a method to calculate the frequency of the crack beam. Then research on the influence to the natural frequency which is caused by the crack location, crack size and the load on the beam ends using the gotten method. Finally, the stress and displacement field is calculated by FEM software, from which the basic principles of the classical theory of elastic-plastic fracture mechanics are verified. FEM results are compared with theoretical results in order to analysis the influence to the stress distribution caused by the plastic zone, besides, different types of crack propagation under different dynamic load are also researched.