Effect of interconnected reinforcement and its content on the damping capacity of aluminium matrix studied by a new circle-fit approach

In this study, samples of aluminium alloy, AA1050, are reinforced with different volume fraction of interconnected, galvanized iron wire preforms using conventional casting technique followed by hot extrusion. Further, a new methodology of using free-free type suspended beam arrangement, coupled with circle-fit approach is used to determine damping characteristics. 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 verify the test method, test results of monolithic aluminium sample are compared against other test methods from published literature. Results of this study shows that addition of about 1.6, 3.1 and 4.7% of interconnected reinforcement increases the overall damping capacity of the aluminium matrix by 17%, 35% and 65%, respectively. An attempt is made to rationalize the increase in damping capability of the composites in terms of associated microstructure variation of aluminium matrix.