Numerical Simulation Of PBXs’ Mesomechanical Behaviors Based On CZM

In this thesis,ABAQUS software was used to simulate the mechanical behaviors,deformation and failure of polymer-bonded explosives(PBXs)under quasi-static loading conditions at meso-scale level.Based on Tyson polygons,combined with digital image processing technology,a PBX meso-model with high particle volume fraction is built.A mesoscopic finite element model based on a cohesive zone model for PBXs was created using a self-programming program to embed cohesive elements into it.The damage,failure and crack propagation of the PBXs are simulated by the deformation,damage and failure of the cohesive elements.The quasi-static uniaxial tension and compression experiments on the model were numerically simulated.The stress-strain curves obtained from numerical simulations under quasi-static uniaxial tension and compression were compared with corresponding experimental and literature data to verify the correctness of the model and material parameters.The meso-deformation,damage evolution and failure mechanism of PBX explosives were analyzed.It was found that and the damage mode of PBX under uniaxial tension is the tensile failure caused by interface debonding,while the damage mode of PBX under uniaxial compression is tangential failure along the grain-binder interface,with some interface debonding and particle breakage.And the influence of the strain rate on the mechanical behavior and damage and failure mechanism of PBX was analyzed.Based on the same material parameters and loads,the meso-scale models with different number of particles were calculated.The calculated stress-strain curves and damage process were consistent,and the number of model particles was verified to be within the valid range.The failure of the meso-scale model with different particle size distributions and interfacial bond strengths under uniaxial tension and compressive loading was calculated.The influence of particle size distribution and interface bond strength on the mechanical properties,failure process and damage and failure mechanism of PBX explosive under uniaxial and uniaxial compression was obtained and analyzed.The results show that I and II types of cracks are more likely to be generated near large-size particles;the PBX meso-model with uniform particle distribution has better mechanical properties;and within a certain range,the mechanical properties of the PBX increase with the increase of the bond strength.