Three-dimensional cohesive finite element simulations of mechanical behavior of polymer-bonded explosives under quasi-static tensile loading

Microstructural features such as voids, microcracks and interfaces play an important role in the mechanical properties of polymer-bonded explosives, which significantly decide the performance, safety and reliability. A series of micron-scale 3D models were constructed, and a 3D cohesive finite element method in a commercial software was used to study the elastic properties and fracture development of HMX/Estane polymer-bonded explosives under quasi-static tension. The predicted Young's modulus of HMX/Estane PBX with particle volume fraction of 92.7 % at 0.01 s-1 is 2.24 GPa, which is only 7.4 % different from the experimental result. 3D models perform better than 2D models in the prediction of Young's modulus and Poisson's ratio, and the difference between 2D and 3D results can be up to 40 %. In addition, the effect of particle size on the mechanical properties is investigated. It is shown that 3D models can correctly describe the relationship of particle size with stress-strain curves and fracture development of PBX. Results demonstrate that a 3D model is necessary in the study to delineate the relationships between microstructural features and the mechanical behavior of polymer-bonded explosives. image