材料缺陷对泡沫铝准静态压缩力学性能的影响

A Study on the Effect of Material Defects on Quasi-static Compression Mechanical Properties of Aluminum Foam

为揭示材料缺陷(包括局部大孔、孔壁缺失和波纹孔壁)在泡沫铝准静态压缩过程中的作用机理,研究材料缺陷对泡沫铝屈服应力和平台应力(10%~30%压缩应变区间的平均应力)的影响,基于二维随机Voronoi模型建立含缺陷泡沫铝的二维有限元模型,采用非线性有限元法模拟泡沫铝准静态压缩过程,通过将模拟结果与泡沫铝准静态压缩试验结果相对比,验证该数值方法的可靠性。研究结果表明:材料缺陷导致泡沫铝屈服应力和平台应力减小,局部大孔和孔壁缺失缺陷造成的应力降幅较大,波纹孔壁缺陷造成的应力降幅较小;材料缺陷造成的应力降幅与泡沫铝孔隙率有关,局部大孔和孔壁缺失缺陷造成的应力降幅受孔隙率的影响较大。材料缺陷是影响泡沫铝准静态压缩力学性能的重要因素,由其造成的泡沫铝屈服应力和平台应力的降幅受孔隙率的影响,在含泡沫铝材料的结构设计中应予以关注。

In order to reveal the mechanism of material defects(local large pores,missing pore walls and corrugated pore walls)in the quasi-static compression of aluminum foam so as to study the effect of material defects on the yield stress and platform stress(average stress within the 10%~30%compression strain range)of aluminum foam,a two-dimensional finite element model of aluminum foam with defects is established based on the two-dimensional random Voronoi model,and the non-linear finite element method is used to simulate the quasi-static compression process of aluminum foam.The simulation results are compared with the results of the quasi-static compression test of aluminum foam to verify the reliability of the numerical method.The result of the study shows that the material defects will lead to the decrease of the yield stress and platform stress of the aluminum foam.The stress reduction caused by the local large pores and pore wall defects is larger than the stress reduction caused by the corrugated pore wall defects.The stress drop caused by material defects is related to the porosity of foamed aluminum,and the stress drop caused by local macropores and pore wall defects is greatly affected by porosity.Material defects are important factors affecting the quasi-static compressive mechanical properties of aluminum foam.The reduction of material defects on the yield stress and platform stress of aluminum foam is affected by porosity and should be considered in the structural design of aluminum foam materials.