闭孔泡沫铝的动态压缩性能试验研究

Tests for dynamic compressive performance of closed-cell aluminum foams

为了研究闭孔泡沫铝动态压缩性能的应变率效应,采用改进的INSTRON高速动力加载系统,对不同应变率下闭孔泡沫铝试件进行动态压缩试验研究。首先利用正向试验和反向试验技术对不同厚度的闭孔泡沫铝试件在同一加载速率下的动态压缩性能进行了研究,得到了在一定速率下消除泡沫铝动态压缩试验中惯性效应的合理试件厚度。进一步开展了闭孔泡沫铝试件在不同加载速率下的高速压缩试验,研究了其动态压缩性能随应变率的变化规律。结果表明在高速压缩下,闭孔泡沫铝的应力-应变曲线与准静态条件相同,具有明显的弹性段、平台段及压实段的3阶段特征。闭孔泡沫铝的平台应力具有明显的应变率效应,而致密应变在不同的应变率下表现出了不同的变化趋势,初步解释为泡沫铝孔壁塑性变形机制的改变以及波动效应的相互影响。闭孔泡沫铝的吸能能力随应变率的增加而明显提升。

To investigate the strain rate effect on dynamic compressive performance of closed-cell aluminum foam,the improved INSTRON High speed loading system was used to conduct dynamic compression tests of closed-cell aluminum foam specimens under different strain rate. Firstly, the forward and reverse test methods were adopted to study the dynamic compressive performance of closed-cell aluminum foam specimens with different thicknesses under the same loading velocity, and the specimen thickness to eliminate the inertia effect at a certain speed was obtained. A series of closed-cell aluminum foams were further tested under different loading rates to study the change law of their dynamic compression performances versus strain rate. The results showed that the dynamic stress-strain curve of closed-cell aluminum foam has three regions including an elastic region, a stress platform one and a compressive one, it is the same as that in the quasi-static case; platform stress of closed-cell aluminum foam has an obvious strain rate effect under high speed compressive loads, and its densification strain under different strain rates has different varying trends ; this phenomenon is explained as the interaction effects between the change of plastic deformation mechanism of aluminum foam cell wall and fluctuations effect; the energy absorption capability of closed-cell aluminum foam is improved significantly with in crease in strain rate.