Papers by Keyword: Dynamic Energy Absorption

Abstract: In order to gain a deep understanding of energy absorption property and failure mechanism of closed-cell foam metals, the dynamic energy absorption property of closed-cell foam metals with matrix Al, matrix Al-Si6, matrix Al-Si12 CCAF, Mg matrix, aluminum-fiber and RE-Al alloys are discussed based on the compression and energy absorption test. The influence of different basis materials on absorption property of closed-cell foam metals is discussed, too. It also shows the micro topography of CCAF during the compression process. In addition, micro-mechanics failure mechanism of CCAF is discussed. Results obtained in this research include: (1) the compression deformation curves of different foam metals indicate that matrix Al CCAF is better for energy absorption materials, because of the best energy absorption property and the high strength. (2) the strength of metal foams with matrix Al-Si6, matrix Al-Si12 and matrix Mg are higher than that of matrix Al CCAF, and also have better energy absorption property. However, the failure characteristics of brittle fracture indicate obvious in matrix Al-Si6, matrix Al-Si12 and matrix Mg. (3) the micro-topography of CCAF with matrix Al is simple and uniform. Also the fracture has obvious tear trace. Aluminum-fiber and RE-Al alloys have better compression property, but lower strength and no strength increasing stage lead to destroy suddenly. (4) the curves of energy absorption for matrix Al and matrix Al-Si6CCAF are on the rise. And the maximum of energy absorption is about 2.1MJ/m³. (5) micropore and crack of closed-cell foam metals provide a good space for the compression and energy absorption. Meanwhile, it is the main failure parts of damage. Keywords: closed-cell foam metal; dynamic energy absorption; micro-topography; micro-mechanics

Abstract: Compressive stress-strain loops of selected polymers at strain rates up to nearly 800/s are determined in a strain range of nearly 8% on the standard split Hopkinson pressure bar. Four different commercially available extruded polymers are tested at room temperature. The compressive stress-strain loops at low and intermediate strain rates are measured on an Instron testing machine. The effects of strain rate on the Young's modulus, flow stress and dissipation energy are discussed. It is shown that the area included within the stress-strain loop increases with increasing strain rate as well as a given strain, that is, all four extruded polymers tested exhibit intrinsic strain-rate dependent viscoelastic behavior and a high elastic aftereffect following complete unloading.