Microslip Induced Damping in the Contact of Nominally Flat Surfaces with Geometric Defects
It is well known that the friction between interfaces at bolted joints plays a major role in the characterization of damping. Friction can be either induced by macroslip or microslip. The aim of this chapter is to model and quantify the dissipated energy by microslip in the joints in order to compute the damping ratio. It is assumed that the coefficient of friction between the nominally flat surfaces is constant and that friction is the only source of energy dissipation. An experimental study is reported to measure static normal load and dynamic tangential load without any coupling between these two main directions. A rheological contact model, Extended Greenwood Model (EGM), based on microcontacts and statistical distributions is developed and studied. Experimental results and simulations are compared in order to assess and discuss the model.
SUMMARY ::: ::: A complete set of expressions is presented for the computation of elastic dynamic stress in plane-layered media. We use a discrete-wavenumber reflectivity method to compute the stress field radiated by arbitrary moment-tensor sources. The expressions derived here represent an interesting tool for both-the observational and theoretical analysis of dynamic stress changes associated with earthquake phenomena. Dynamic stress changes associated with a strike-slip fault having unilateral rupture are shown. This modelling, which is similar to the 1992 Landers California earthquake, illustrates the effects of distance, directivity and depth on transient stress changes.