Theoretical Analysis And Numerical Simulation Of The Dynamic Response Of Metal Foam Under Impact Loading

Metal foam is a new structural and functional materials composed by metalskeleton, large aperture and high porosity, it has been widely used in automobile,aerospace, railway transportation and building fields etc, because of its excellentproperties such as light weighty, energy absorption capacity, vibration-reducing,sound-insulation, heating-insulation and electromagnetic shielding and so on. Some ofthese applications, for example, car’s bumper of foam aluminum, foam metalmaterials used on spacecraft to absorb energy and used for protection packing and soon, metal foam is often subjected to impact loading. Therefore, understanding itsdynamic properties so as to provide reference for material manufacturing andengineering application has important signification and application value. In this paper,the quasi-static and dynamic compression experiment of open-cell aluminum foam isconducted, then we assumed the constitutive relation of metal foam is ideal accordingto the compression curves of the aluminum foam and proposed a one-dimensionalsteady shock model to analyze the dynamic response and deformation mechanism ofmetal foam under impact loading, as well as a corresponding numerical simulation.Firstly, the quasi-static and dynamic compression experiment of open-cellaluminum foam is conducted by Servo-Hydraulic material universal testing machineand SHPB device respectively. The results showed that the quasi-static and dynamiccompression curves of open-cell aluminum all show three regions: elastic region, yieldregion and densification region, its yield stress and plateau stress would becomegreater with increasing strain rate, but the densification strain would decrease. Sothe open-cell aluminum foam is strain-rate sensitive.Secondly, we proposed a rigid perfectly-plastic locking idealization of metalfoam according to the experiment results, and with one-dimensional stress wavetheory we analyzed the process of metal foam impacting a free mass. In order to verifythe theoretical analysis, explicit finite element analysis is performed using LS-DYNA.The results showed that the initial contact pressure between the metal foam and freemass was not be influenced by their mass, and increased quadratically with theincreasing impact velocity. The final undeformed length of metal foam decreasedexponentially according to the increasing impact velocity.Finally, we established a theoretical model of metal foam impacting a rigid wallas well as a numerical simulation. By the solution of this model, we gave the analysis of how the material parameters of metal foam affect the critical velocity and time forfull crushing of metal foam. The numerical prediction was found to be in goodagreement with the analytical results.