Experimental and numerical aspects of cavitation

Rubber isolation systems represent an effective method to isolate the super structure from seismic ground accelerations. In this study, two sets of hig h-damping natural rubber bearings are subjected to characterization tests t o determine the corresponding stiffness parameters, Bearings with flat stee l laminae represent the first set, while the second one has inclined steel plates necessary to obtain a transversely nonisotropic response. During she ar deformation a negative hydrostatic stress state and irreversible materia l damage in the form of internal rupture develops. The cavitation region is not visible from the outside and thus not recognized or accounted for duri ng experimentation. Numerical simulation using a cavitation damage model ba sed on a variable bulk modulus quantifies the amount of stiffness reduction attributed to internal rupture in the material. It is shown that the amoun t and extension of damage is much more severe for elastomeric bearings when inclined steel plates are used to generate anisotropy in the in-plane resp onse.