闭孔泡沫铝压缩力学性能的实验和三维有限元模拟

基于X射线电子计算机断层扫描技术，建立了反映闭孔泡沫铝真实结构的三维有限元模型.对闭孔泡沫铝准静态和动态压缩力学性能进行了实验和数值模拟，分析了闭孔泡沫铝的变形特性及力学性能，验证了模型的可靠性.结果表明，准静态压缩下，试件主要沿加载轴45°方向产生塑性变形.压缩速率为低速时，其变形模式与准静态相同.闭孔泡沫铝试件截面上结构薄弱处首先出现应力集中，材料达到塑性屈服.在高速压缩下，试件加载端首先达到塑性屈服.比较闭孔泡沫铝不同应变率下的屈服强度，动态压缩下的屈服强度远高于准静态压缩下的.应变率280~700 s-1下，其屈服强度变化不明显，应变率继续升高至2 000 s-1，屈服强度略微提高. 

Experiments and Three-Dimensional Finite Element Simulations on the Compressive Mechanical Properties of Closed-Cell Aluminum Foam

Based on X-ray electronic computed tomography technology,a three-dimensional finite element model was established to reflect the true structure of closed-cell aluminum foam.Firstly,the quasi-static and dynamic compressive mechanical properties of closed-cell aluminum foam were analyzed based on experiments and numerical simulations.Then the deformation characteristics and mechanical properties of closed-cell aluminum foam were analyzed.Finally,the reliability of the model was verified.The results show that a long platform stage appears on the stress-strain curve of closed-cell aluminum foam under quasi-static and dynamic loading.Under quasi-static compression,the specimens exhibit local plastic deformation mainly along the loading axis at 45°.At low compression rate,the deformation mode is the same as under quasi-static compression,stress concentration occurs first in the structural weakness of the closed-cell aluminum foam specimen,until material plasticity bend.Under high-speed compression,the loading end of the specimen first reaches the yield stress.Comparing the yield strength at different strain rates,the yield strength of closed-cell aluminum foam under dynamic compression is higher than that of quasi-static compression.When the strain rate of closed-cell aluminum foam specimen is 280~700 s^-1,the change of yield strength is not obvious.The strain rate increases to 2 000 s^-1,and the yield strength increases slightly.