冲击载荷下径向密度排布对泡沫金属力学性能影响的研究

Influence of radial density arrangement on mechanical properties of metal foam under impact loading

参照层状密度梯度泡沫模型实现方法,利用3D-Voronoi技术设计了新型径向密度梯度泡沫模型,并用有限元软件,对它在不同冲击载荷下的力学行为进行数值模拟。研究冲击速度、密度梯度和平均相对密度对金属泡沫冲击端、支撑端应力和能量吸收能力的影响,发现:径向正梯度泡沫与层状正、负梯度泡沫相比,其两端的应力值均较小,可同时保护冲击端、支撑端物体;径向负梯度泡沫两端应力变化幅度较小,能够保证物体受力稳定;几种泡沫金属的能量吸收能力在不同冲击速度下发生交替变化。对于径向梯度泡沫,能量吸收能力对密度梯度大小不敏感,对梯度方向敏感,径向负梯度泡沫的能量吸收能力始终大于径向正梯度泡沫;平均相对密度越大,径向正、负梯度泡沫两端应力越大、吸能效果越好。

Based on the generation method of layered density graded foam,new radial density graded foam models were designed by 3D-Voronoi technique,and their mechanical behavior under different impact loads was numerically simulated by finite element software.By analyzing the effects of impact velocity,density gradient and average relative density on the stress of impact end and support end,and energy absorption capacity of metal foams,it is found that the radial positive graded foam has smaller stress values at both ends than the layered positive and negative graded foams,which can simultaneously protect objects at any ends.The stress fluctuation of radial negative graded foam is small,which can ensure the stability of the force received by the object,and the energy absorption values of four metal foams vary alternately at different impact velocities.For the radial graded foam,energy absorption capacity is insensitive to density gradient,but sensitive to gradient direction.The energy absorption capacity of radial negative graded foam is always greater than radial positive graded foam.The larger the average relative density,the greater the stress at both ends,and the energy absorption effect is also enhanced.