Damping characterisation of aluminium containing interconnected wire reinforcement using a novel frequency domain based method

Abstract

In this study, an aluminium alloy, AA 1050, was reinforced with an interconnected, axisymmetrical, galvanised iron wire preform. The composite was synthesised using a conventional casting technique followed by hot extrusion. The composite was tested in a free - free type suspended beam arrangement, coupled with circle fit approach to determine damping characteristics. This testing method is based on classical vibration theory, by which the geometry and material properties of the metal matrix composites are related to the resonant frequency and structural damping of the test specimen. Using the fact that the ratio of the vibration response to the applied force fits to a circle in the Argand plane for each resonant frequency of the test specimen, the damping factor and natural frequency is predicted accurately for the test specimen. To demonstrate the accuracy of the test method, test results of a pure aluminium sample are compared against results from other test methods from published literature. Results of this study show that addition of about 5% of interconnected reinforcement increases the overall damping capacity of the aluminium matrix by ~ 17%. An attempt is made to correlate the increase in damping with the reinforcement associated microstructure variation of the aluminium matrix.