基于CT图像的Al/PTFE反应材料冲击压缩行为的三维细观模拟研究

3D Meso-scale Simulation on the Shock Compression Behaviors of Al/PTFE Reactive Materials Based on the CT Slices

为了研究铝/聚四氟乙烯(Al/PTFE)反应材料的细观冲击响应,采用理论与数值模拟的方法对Al/PTFE反应材料的冲击压缩行为进行了研究。基于三项式物态方程和混合物叠加原理,计算了Al/PTFE反应材料的冲击Hugoniot曲线及Al与PTFE材料的冲击压力—冲击温升关系;采用纳米CT获得了材料的三维细观图像,并采用数字图像处理和网格映射方法,建立了基于材料真实细观结构的三维有限元模型,计算获得的冲击Hugoniot关系与理论结果吻合较好。数值模拟研究结果表明,Al/PTFE反应材料在细观冲击压缩过程中,材料细观尺度上的波阵面呈不平整状态;铝颗粒主要受到沿冲击方向上的压缩作用,形状并未发生明显改变,W颗粒的加入使邻近的Al颗粒剧烈变形;冲击压缩后PTFE基体的温度明显高于Al颗粒的温度。当撞击速度为1500m/s时,PTFE基体的温度达3000K以上,而铝颗粒仅为400K左右。

To investigate the meso-scale responses of aluminum/polytetrafluoroethylene(Al/PTFE)reactive materials under shock loading,the shock compression behaviors of Al/PTFE reactive materials were investigated via theoretical and numerical approaches.The shock Hugoniot of Al/PTFE materials and the pressure—temperature relation for single Al and PTFE were calculated by the trinomial theory of the equation of state and the mixing theory.Three dimensional(3D)heterogeneous slices for Al/PTFE materials were obtained from nano-CT,and image processing and mesh mapping methods were used to obtain the 3D finite element model of the material structures.The numerical Hugoniot results agree well with the theoretical results.The numerical modeling results indicate that the shock-wave front in the meso-scale range is uneven when the Al/PTFE materials are compacted by shock waves.Additionally,no obvious shape change is observed when the Al granules are compressed along the impact direction.Whereas the addition of W particles lead,to the severe deformation of the neighboring Al granules.The temperature of the PTFE matrix is higher than that for the Al granules.When the impact velocity is 1500m/s,the temperature of the PTFE matrix exceeds 3000K,but the temperature of the Al particle is only around 400K.