Simulation Of Mechanical Properties Of Foam Aluminum Based On Finite Element Method

The porous material is widely used in automobile manufacturing, railway, aviation structural design and other aspects because of its high specific modulus and strength. In addition, in the course of compressive deformation, the stress of the porous material almost remains constant to improve the efficiency in absorbing the energy, therefore the porous material can be equipped to components subjected to high-speed impact as energy-absorbing devices to protect the passengers and other components from damage when subjected to high-speed impact. As a result, while studying the static mechanical behavior of porous material, it is particularly important to do its dynamic mechanical behavior research. The study of compressive deformation behavior of porous metal material at high strain rates and its mechanical properties is of more practical significance.According to the geometrical relationship, the paper draws the relationship between the relative density and structure of aluminum foam model and establishes the openings model. By changing the size of the strain rate, the finite element analysis software ANSYS / LS-DYNA is used to conduct the compression simulation test of the model under quasi-static and dynamic conditions, comparing the curves of mechanical properties under different loading rates to analyze the deformation mechanism and strain rate effect. The results show that with the increase of the strain rate, Young’s modulus and flow stress increase, and densification strain decreases. The open-cell foam aluminum is more sensitive to the strain rate, with strain rate sensitivity as 0.106 and 0.245 respectively under quasi-static compression process, and strain rate sensitivity as 0.416 and 0.169 respectively under dynamic compression.Select two simple cubic open-cell foam aluminum models, namely models with certain aperture but different relative density and models with certain relative density but different aperture, then the paper conducts the simulation study of the dynamic mechanical properties of these two aluminum foam models with different structural parameters. From the simulation, we can see that during the dynamic compression, elastic modulus and yield strength increase with increasing relative density, and decrease with increasing radius, thus the mechanical properties of the aluminum foam metal with small aperture are better than that of the aluminum foam metal with large aperture.Under certain relative density and pore size, the finite element simulation software is used to exert quasi-static and dynamic loading to CCAF at different strain rates. By studying the curve of its mechanical properties, we can see the mechanical properties of CCAF under quasi-static conditions don’t change significantly with the change of strain rate, and strain rate sensitivity are 0.0017 and 0.0026 respectively. During the dynamic compression, with increasing strain rate, the elastic modulus and yield stress increase, and strain rate sensitivity are 0.068 and 0.0135 respectively, from which we can see CCAF has a more significant strain rate effect during dynamic compression.With certain relative density, tetradecahedral obturator model of different base material are established, namely aluminum, aluminum-silicon alloy and aluminum-magnesium alloy. Based on the compression test under four strain rates and analysis of its curve of the mechanical properties, we can see that the stress- strain curves of aluminum foam metal with three base materials have linear elastic, plastic platform and densification in either quasi-static or dynamic compression. With increasing strain rate, platform stress of aluminum and aluminum-magnesium alloy with pure plastic material rises significantly, and strain rate sensitivity are 0.273, 0.431 and 0.479, 0.404 respectively; flow stress of aluminum-silicon alloy with brittle material changes less, and strain rate sensitivity are 0.0956 and 0.0955 respectively, among which the elastic modulus and yield stress of magnesium alloy is higher than that of aluminum and aluminum-silicon alloy, indicating that the strain rate sensitivity of metal foam is not only related to localization, microscopic inertia and compactness, but the matrix material is also a main factor to affect it.