玻璃纤维增强气凝胶在动态压缩下的变形行为

采用Hopkinson压杆对玻璃纤维增强气凝胶进行动态压缩实验,通过精确控制试样应变"冻结"气凝胶压缩过程,对不同应变下的实验材料进行孔结构测试和显微分析. 结果表明,在动态变形过程中玻璃纤维增强气凝胶的纳米多孔网状结构遭到破坏,玻璃纤维逐渐断裂,气孔缩小以致孔穴坍塌,气孔之间的连通性变差,胶体粒子之间的排列更加紧密. 玻璃纤维增强气凝胶在动态压缩下破坏的临界应变约为0.80,并具有明显的应变率强化效应. 动态压缩过程中孔壁受到横向张应力的升高和胶体粒子之间的高速碰撞导致玻璃纤维增强气凝胶的破坏.

Deformation Behavior of Glass Fiber Reinforced AerogelUnder Dynamic Compression

Dynamic compression test on glass fiber reinforced aerogel has been done by Hopkinson pressure bar. Method of accurately controlled strain was used to freeze different stages of compression process. Failure process of glass fiber reinforced aerogel has been studied by microanalysis and porosity analysis of aerogel under different strain. The results showed that under dynamic compression, the nano-porous network structure of aerogel is destroyed, the glass fibers break down gradually, the pores shrink and even result in pore collapse, the connectivity of pores becomes worse, colloidal particles are squeezed closer to one another. Under dynamic compression condition, the critical failure strain of aerogel is about 0.80. The mechanical behavior of aerogel displays a marked strain rate strengthening effect. Under dynamic compression, the failure is due to the increase of lateral tensile stress of pore wall and high speed collision between colloidal particles.