基于泡沫材料的动态刚性-线性硬化塑性-刚性卸载(D-R-LHP-R)模型,结合连续性方程,动量守恒方程及刚体的运动方程,得到了激波在泡沫材料中的量纲一消失位置Xs/L0和动态屈服应力Yi、激波波速cp、冲击初始应变εi之间的如下关系式:Xs/Lo=exp(- ρ0cpv/Y)=exp(1-σi/Y)=exp(-ρ0c2pεi/Y)(a)采用Taylor-Hopkinson装置进行实验,当直接测得泡沫铝试样密度ρ0、边界初始应力σi、初始打击速度vi、泡沫铝杆原长L0及激波在泡沫铝杆中消失长度Xs后,利用方程式(a)可反演求得D-R-LHP-R模型下的泡沫铝动态应力应变曲线。最后通过与泡沫铝准静态实验数据对比,表明该泡沫铝是应变率敏感性材料。
Based on the dynamic Rigid-Linear Hardening Plastic-Rigid Unloading (D-R LHP-R) model of foam materials and starting from the displacement continuity equation, the momentum conserva tion equation and the motion equation of rigid part, the relation between the critical position for shock disappearance Xs' the yield stress Y, the shock velocity cp as well as the impact boundary strain εi can be determined as follows:Xs/Lo=exp(- ρ0cpv/Y)=exp(1-σi/Y)=exp(-ρ0c2pεi/Y)(a)Among the parameters in the above equation, the specimen density ρ0, the boundary stress σi, the im pact velocity υi, the undeformed length of the specimen Xs, and the original length of the specimen L0, can be easily measured from the Taylor cylinder-Hopkinson bar impact experiments. Therefore, the constitutive parameters strees and strain of the R-LHP-R model can be finally reversely deter mined for the tested aluminum foam by using the above experimental parameters and Eq(a). The comparison of stress-strain between the quasi-static compressive curve and the R-LHP R model indi cares the strain rate sensitivity of the tested aluminum foams.