Impact Properties of Porous Structures Formed by Laser Powder Bed Melting
Porous structures have been widely used in aerospace devices and biomedical instruments because of their good specific strength and energy absorption.The mechanical properties of porous structures largely depend on the deformation mechanism of structural units,so it is very important to fully understand the structural evolution of porous structures in the process of impact loading.In this paper,the 3D Voronoi technology was used to design the decahedron(Octa)with 80％and 90％porosity.The samples of porous aluminum alloy with two kinds of porosity were prepared by selective laser melting(SLM)forming technology.The drop hammer impact experiment was carried out to explore the energy absorption of porous structures with different porosity under the impact load.In the finite element simulation,X-ray transmission computed tomography(X-CT)was used to reconstruct the geometry model of the porous structure to explore the actual deformation mechanism and pore fracture mechanism of the porous result.The results show that the energy absorption of porous structures decreases with the increase of pores,and porous structures with high porosity are more likely to form multiple local dense regions in weaker locations.Meanwhile,the bending and yielding of cell walls generally occur during the collapse of pores,and the deformation is often propagated through the formation of several narrow collapse zones.In this paper,we have a new understanding of the deformation mechanism of Octa structures under impact load,which is of great significance to the impact resistance design and energy absorption evaluation of porous structures.
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