Application Of CZM And VCCT Methods In Crack Propagation Numerical Simulation

In engineering practice,crack propagation often leads to catastrophic consequences,so the study of crack propagation is of great value and significance.With the rapid development of computer,numerical simulation technology has been applied to the field of crack propagation research,and it favored because of its low cost,high computational efficiency,capability of dealing with complex problems and many other advantages.In this paper,the crack propagation of the bonded structure and the double cantilever beam structure are studied by using the cohesive zone model and virtual crack closure method.The main research contents and research results are as follows:(1)The method of creating finite thickness cohesive zone model is analyzed and its advantages and disadvantages are expounded.The crack propagation process and the peel force of the bonded structure under the loading condition of type?are simulated by the cohesive zone model with finite thickness,the stress cloud,the load displacement response curve and the peel force are obtained.The effect of the damage evolution behavior,fracture strength and fracture energy on load displacement curve are studied,the results show that the damage evolution behavior has little effect on the load displacement response curve;the fracture strength only affects the slope of ascending branch of load displacement response curve and the peak load;the fracture energy only affects the descending branch of the load displacement response curve.The accuracy of the cohesive zone model with linear damage evolution behavior and the cohesive zone model with exponential damage evolution behavior in simulating peel force is researched,comparing with the experimental value,we can conclude that both of them can better predict the peel force and the predictive precision of the cohesive zone model with exponential damage evolution behavior is more high than the cohesive zone model with linear damage evolution behavior.The effect of mesh size of bonding pieces on the numerical solution of the peeling force are analyzed,the result shows: the mesh size has a significant influence on the numerical solution and the closer the mesh size to the area of the intermediate bond layer,the closer the numerical solution to the experimental value.(2)The implementation of the specification of initial condition,the activation of the crack propagation ability and the creation of the fracture criterion in ABAQUS are studied when the crack propagation is simulated by the virtual crack closure method.The crack propagation process and the debond initiation value of the double cantilever beam under the loading of type?are simulated by the virtual crack closure method,The stress cloud,the load displacement response curve and the value of the debond initiation are obtained.The effect of the maximum allowable step size,the reduction tolerance of the strain energy release rate and the load size on debond initiation of the double cantilever beam are analyzed,The results show that the reduction tolerance of the strain energy release rate has no effect on the value of debond initiation;The maximum allowable step size and the load size has little effect on the value of debond initiation,and the error between the numerical solution and the experimental value of the debond initiation are within 3%.(3)The finite element model of the bonded structure and double cantilever beam are established by the virtual crack closure method and the cohesive zone model respectively,the numerical solution of peel force and debond initiation are obtained.By comparing with the experimental data,we can draw a conclusion that the cohesive zone model should be preferentially used to simulate the crack propagation of the bonded structure;When the crack propagation of the double cantilever beam is simulated,the virtual crack closure method should be preferentially used.