泡沫金属夹芯梁在重复冲击下的动态响应

Dynamic responses of metal foam sandwich beams to repeated impacts

为了研究重复冲击载荷作用下泡沫金属夹芯梁的动态响应,采用Abaqus数值仿真软件,基于可压碎泡沫模型(crushable foam),建立了泡沫金属夹芯梁遭受楔形质量块冲击的有限元模型。通过将仿真获得的夹芯梁上下面板最终挠度与重复冲击实验结果进行对比,验证仿真方法的准确性。在此基础之上,分析了泡沫金属夹芯梁在楔形质量块重复冲击作用下的变形模式、加卸载过程以及能量耗散特性。结果表明,在重复冲击载荷作用下,夹芯梁的变形不断累积,上面板主要出现局部凹陷和整体弯曲,而芯层则是局部压缩,下面板表现为整体弯曲。在重复加卸载过程中,加卸载刚度随着冲击次数的增加而增大。随着冲击次数的增加,上面板和芯层的能量吸收增量不断减小,而下面板的能量吸收增量不断增加,且最终均趋于稳定。泡沫金属夹芯梁的塑性变形能增量不断减小,而回弹系数随着冲击次数逐渐增加,最后趋于稳定值。

The phenomena of repeated impacts are very common,especial in the field of ship and ocean engineering.When the ship structures suffering from repeated impact loadings,the deformation and damages will accumulate,leading to failure even damage of the structures,which may cause serious accident.In order to study the dynamic behaviors of metal foam sandwich beams(MFSBs)under repeated impact loadings,the nonlinear finite element model was established based on the material model of crushable foam by using Abaqus-Explicit,and the approach to achieve repeated impacts in the software was proposed.The accuracy of the numerical simulation was verified by comparing the permanent deflections of front and back face sheets.Based on the results of the numerical simulations,the deformation modes,loading and unloading process as well as the energy absorption behavior of the MFSBs under repeated impacts were analyzed.Results show that during repeated impacts,the deformation of the MFSBs is accumulated gradually,the front face sheet mainly experiences global bending and local indentation,and the metal foam core suffers from local compression,while the back face sheet is subjected to global bending.During the repeated impacts,the loading and unloading stiffness increases with the impact number.The energy absorption of front face is larger than that of back face and metal foam core in all the impacts.As the impact number increases,the energy absorbed by front face sheet and foam core declines gradually,while that of the back face sheet increases,approaching a constant value.The plastic deformation energy of the MFSBs decreases with the impact number,on the opposite,the rebound energy of the MFSBs increases gradually with the impact number,while both of them trends to be stable.The proposed finite element method can be applied to accurately predict the dynamic responses of the MFSBs suffering from repeated impact loadings,and provide technical supports for the anti-impact design of metal foam sandwich structures.