Fatigue Crack Simulation Of WFD By Ordinary State-based Peridynamics

Widespread fatigue damage(WFD)in a structure was characterized by the multiple cracks which can interfere with each other.WFD was widely happened in aircraft and shipments,so it had great practical significance to do the research of WFD.Existing numerical analysis methods of WFD included boundary element method and alternating direction finite element method,but these methods required high mesh density around the crack tip and the crack tip area need re-meshed when the crack propagates,which make the modeling more complex and the calculation more time,therefore the application in engineering was seriously restricted.Peridynamic theory was developed in recent years,the motion equation in peridynamics is in integral form and it's different from the differential form motion equation in traditional mechanics theory,therefore avoiding the singularity problem around the crack tip area and provided a new idea to solve the problem of WFD.This study focused on Peridynamics fatigue theory,a peridynamics model for fatigue cracking was presented by using ordinary state-based peridynamics theory for plane stress,and the model can be applied for crack initiation and propagation analysis.It is impossible to simulate every cyclic loading procedure,so a parameter called “critical broken bonds number” is introduced in the model to speed the calculation process of the model.A computational software of fatigue crack initiation and propagation was developed in the developing environment of Microsoft Visual Studio 2010,and the OpenMP techniques was applied to achieve multi-threading parallel computing function.Visualization of the calculation results was achieved by matlab.In particular,fatigue crack of panel containing multiple cracks and finite plate with multiple collinear holes was simulated by the peridynamics fatigue model,the fatigue crack paths and a-N curve of the simulation results agreed well with the experimental results.The result of single edge-cracked plate shown that the calculation was speeded,and computational efficiency was still reasonable when an appropriate “critical broken bonds number” was chosen.Thus,fatigue failure problem can be effectively simulated by the peridynamics fatigue model.