Effect Of Residual Al And Pores On Dynamic Mechanical Properties Of Ti-Al₃Ti Laminated Composites

With the development of aerospace,military industry and other fields,the performance of protective materials have been proposed higher requirements.Ti-Al₃Ti laminated composites have attracted much attention because of its characteristics of low density,high hardness and high specific strength.At present,the preparation technology and mechanical properties of Ti-Al₃Ti laminated composites have been extensively studied.However,the effects of Al layer and pore defects on the mechanical properties of Ti-Al₃Ti laminated composites are relatively few.In this paper,the finite element model of Ti-Al₃Ti laminated composites containing Al layer and pores was established by combining the split Hopkinson pressure bar experimental technology and finite element simulation technology.The impact process of a Hopkinson pressure bar on Ti-Al₃Ti laminated composites was simulated.The influence of the residual Al layer and holes on the dynamic mechanical properties of the laminated materials was studied,and the failure mechanism was analyzed.The results were as follows:1.Ti-Al₃Ti laminated composites containing 0%,15%,30%Al were prepared.The dynamic impact test results showed that under the same impact load,the laminated composite with 15%Al content had the best mechanical properties,only one main crack was observed after SHPB test.While the laminated composite with 30%Al content had the highest fracture strain and multiple cracking was observed after SHPB test.2.The finite element simulation results show that When the Al content in Ti-Al₃Ti laminated composite was 10%,the compressive strength of the material was the highest(1181.4 MPa).As the volume fraction of Al continues to increase,the compressive strength of the material decreased but the fracture strain increased.3.When Ti-Al₃Ti laminated composites without Al were subjected to compression stress,stress concentration occurred in the specimens due to the mismatched deformation between different layers,which lead to the generation of a large number of microcracks between layers.However,the stress distribution of Ti-Al₃Ti laminated composites containing Al was more uniform,the distribution of microcracks is more dispersed,and the interlaminar stress value was lower than that of the laminated composites without Al.4.When the pore densities was 0%,1%,3%and 5%,the compressive strength of Ti-Al₃Ti laminated composites decreased by 9.6%,17.2%and 21.4%,respectively.With the increase of pore densities,the dynamic mechanical properties of the material decreased greatly.5.For Ti-Al₃Ti laminated composites containing both Al layer and pores,with the increase of pore densities from 0%to 1%,3%and 5%,the compressive strength of the material decreased by 8.5%,8.8%and 19.7%,respectively,and the decrease rate was less than that of Ti-Al₃Ti laminated composites without Al layer.This indicated that the presence of Al can reduce the adverse effect caused by pores.