Experimental Studies On Dynamic Fracture Properties Of 205A Aluminium Alloy

This paper focuses on the 205A aluminum alloy material commonly used in the aerospace industry, and studies its dynamic fracture properties by the dynamic fracture toughness experiment, the SHTB dynamic tensile experiment and the light gas gun spall experiment.(1) Based on Split Hopkinson Bar (SHB) loading technique, we have designed experimental device for the dynamic fracture toughness of the three point bend specimen, analyzed the testing mechanisms and developed the experiment technology for the test. The dynamic fracture toughness of 40Cr alloy steel is tested using this technology, and the result shows that this experiment technology is effective and feasible. Using this technology the dynamic fracture toughness of 205A aluminum alloy is tested under the loading conditions of 10 m/s and 15 m/s. The experimental result indicates that the relevance between the dynamic fracture toughness of the alloy and the loadind rate is not obvious.(2) The dynamic tensile failure performance of 205A aluminum alloy is studied using SHTB loading technique, and its strain-rate effect is not obvious. Experimental results show that the dynamic tensile strength of this material is 377.98 MPa. Its average dynamic destruction energy density is 14.23MPa from the energy analysis.(3) The spall performance of 205A aluminum alloy is studied using the light gas gun loading techniques. The material spall growth evolutionary process is analyzed using the free surface test specimen recollecting method and the PMMA back board stress wave cross section method. The calculation results show that the spall strength of this material is 1.21 GPa.The analysis of the microscopic appearance character of the fracture on the testing samples recollected from the fracture testing experiments for dynamic fracture toughness, the dynamic tensile and the spall shows that the dynamic fracture of the 205A aluminum alloy is brittle fracture. The comparison analysis of the energy rate shows that the dynamic fracture performance of 205A material in the dynamic tensile failure experiment and the dynamic fracture toughness experiment are equivalent. There is intrinsic connections between fraction performances beyond the dynamic tensile strength point in dynamic tension stress-strain curve and the evolution process of spall.