Three-dimensional finite element analysis of circular fiber-reinforced elastomeric bearings under compression

Fiber reinforced elastomeric isolators (FREIs) are a relatively new type of elastomeric bearing. FREIs utilize fiber material for the reinforcing layers instead of steel which is used in conventional steel reinforced elastomeric isolators (SREIs). Unlike SREIs, where the steel reinforcing material is usually assumed to be rigid in extension, the reinforcing fiber layers are considered to be flexible in extension. As a result, the vertical response characteristics of FREIs differ from those of SREIs. In this study, a 3D parametric numerical finite element analysis (FEA) is carried out on sixteen circular FREI bearings. All bearings investigated have the same overall dimensions, while the thickness of elastomer layers and the axial stiffness of reinforcement are the parameters that are varied. FEA results, in terms of deformed shape, stiffness, stress and/or strain in reinforcing and elastomer layers are compared with predicted values obtained using the pressure solution and the pressure approach methods. Good overall agreement was observed between the FEA results and the results obtained from analytical solutions. It was concluded that the end boundary effect, which is often neglected, becomes a contributing factor on the vertical response for bearings reinforced with flexible reinforcements, or bearings with low shape factor values.