New Method for the Evaluation of Material Damping Using the Wavelet Transform

Abstract

Material damping is a fundamental parameter required for dynamic analysis of geotechnical and civil infrastructure. The material damping ratio is very difficult to measure in situ. A new methodology for in situ measuring of material damping using surface waves is presented in this work. This methodology is successfully evaluated on laboratory scale models and numerical simulations. Ultrasonic waves are used in this work because of the size of the laboratory models. The output force of an ultrasonic piezoelectric transmitter is modeled by using a Morlet function. The wave attenuation and phase variation of propagating surface waves with distance are analyzed using the wavelet transform. Numerical results show that the material damping ratio calculated using the wavelet transform gives a global value that represents an average damping ratio for the frequency bandwidth imposed by the seismic or ultrasonic source. Experimental results, from tests on a cemented sand and a concrete plate, show good agreement with published damping values.