FACTORS AFFECTING THE DAMPING CAPACITY OF CAST ALUMINUM-MATRIX COMPOSITES

The damping capacity of stir-cast aluminium-matrix composites containi ng graphite and silicon carbide particles, were studied using a cantil ever beam specimen and an HP 5423A Structural Dynamics Analyser, Dampi ng data were determined in the first mode of vibration. Aluminium-matr ix composites containing 5-10 vol % graphite particles and 10 vol % si licon carbide particles were prepared by the stir-casting technique an d die cast to obtain standard samples (6 mm x 25 mm 100 mm). Graphite particles were found to be more effective in enhancing the damping cap acity of composites compared to silicon carbide particles. The damping capacity of composites increased with the volume percentage of graphi te within the range studied. However, no notable improvements in dampi ng capacity were observed by dispersion of silicon carbide in aluminiu m alloy. The results have been analysed in terms of the effect of size , shape, nature and volume fraction of particles on the damping capaci ty of the aluminium matrix particulate composites and compared with th e damping capacity data available in the literature. The effects of fr equency, strain amplitude, temperature and processing on damping capac ity of the aluminium matrix composites are reviewed.