Experimental Study On Mechanical Properties Of The Open-cell And Closed-cell Aluminum Foams

Aluminum foam is a kind of engineering material, which has relatively high stiffness and strength achievable at low density. According to the cell structure, aluminum foams have open cells and closed cells. Closed cells are that each cell is sealed off from its neighbors by membrane-like faces, and open cells are that the cells interconnect. Due to their unique structure, mechanical properties and energy absorbing capacity, aluminum foams have found applications in a number of fields as an excellent energy absorber and impact-protector and are regarded as the most promising materials in the automobile, railway and aerospace industries. For these reasons, the mechanical properties of aluminum foams have drawn much attention in recent years and become one of the most attractive topics in mechanics and materials sciences.In the present paper, the mechanical properties of aluminum foams with various densities including open cells and closed cells have been researched by combining experimental study with theoretical analysis. The conclusion will make an important role in production methods and its application.Firstly, quasi-static compressive tests are conducted using a displacement controlled CMT5305 at the strain rates of 10-3 s-1. Based on the experimental results, the effects of relative density, strain rate and cell structure on the compressive properties of aluminum foams are analyzed, and energy absorption capacity of aluminum foams are also studied. The energy absorption efficiency and ideality are used to evaluate its capacity of foams. The efficiency reflects material property, and high efficiency indicates that aluminum foam is a kind of excellent material of energy absorption.Secondly, the dynamic compression tests are carried out at strain rate (102~103 s-1) by Split Hopkinson Pressure Bar (SHPB). Futher jobs of effects of relative density and strain rate on the stress-strain curve are discussed and the deformation mechanism of the foam is revealed. Two aluminum foams with different cell structures exhibit different deforming models in the compressive tests.Thirdly, The uniaxial tensile behaviors of aluminum foam are investigated and a series of stress- strain curves are obtained. Compared with compressive properties, the tensile strength is lower than compressive strength, however Young's modulus is larger in tension. Tensile and compressive constitutive relations of aluminum foam are given.