Improvement of viscoelastic damping by using manganese bronze with indium

Many engineering structures are required to minimize vibrations. Vibrations in a system can be reduced by changing the design of the structure or by using a new material which has better mechanical damping. Damping materials are desirable as they convert mechanical energy to heat. As most engineering structures are load bearing, the material used needs to have high stiffness as well. Hence, a new material developed for the use of engineering structures should have both high stiffness and high damping. This paper discusses a variety of materials that were uniquely developed to achieve the aforementioned objectives. The new manganese bronze C86500 based samples were alloyed with different indium alloys (In, InSn, and BiSn) and classified according to the type of heat treatment, amount of cold working, and alloy composition by weight percentage. A dynamic mechanical analyzer (DMA) was used to find the complex modulus and loss tangent (tanδ) values of the created samples. These values were then used to evaluate and compare the various samples and their relative damping capacities across different frequencies at a particular temperature and strain. Most of the alloying compounds showed an average increase of 120 % in the low frequency range (0.01-0.1 Hz), without significantly compromising its stiffness. BiSn was found to be the most effective alloying compound for the new manganese bronze C86500 with 30 % cold working.