Investigation Of Metal Material Damping Measurement

Material damping is the most essential form of damping. As material damping is dependent on many factors, it's rather difficult to develop exact and comprehensive expressions to describe material damping. In engineering, the general approach to evaluate material damping is to measure the vibration responses of the standard specimens which are made of a certain material and to identify material damping factor on the basis of vibration theories and data processing techniques. Material damping capacity is critical to many fields, including the building of exact structural dynamics models, analysis on the stability of structure, prediction of response and investigation on new materials.Because material damping is achieved by measuring vibration response of standard specimens, this problem is usually classified to a problem of parameter identification of vibration system. Generally, the measurement of material damping has lower testing precision and worse repeatness than that of other modal parameters auch as modal frequency and modal mass, this fact limits the progress of many vibration issues related to damping .The research on developing high precise and stable material damping measuring technique is of great significance and it is the aim of this paper.On the scale of data processing, the method connecting measurement and numerical analysis is ultilized comparing different damping identification means and improving in some extent. Two kinds of alloy, LY-12 and Ti6-4, are taken as testing materials. In this paper, their material damping capacity and damping testing methods are investigated in two damping models which are linear viscous damping model and frequency-amplitude dependent damping model.In the linear viscous damping model, three classes of damping identification techniques such as frequency domain methods time domain methods and wavelet transform methods are studied. In different situation, the identification precision of three frequency domain methods, such as half power band width method, frequency refining and correction for power spectrum, are compared to each other and material dampings of two kinds of metal at room temperature in the air are measured. For time...