Elastomer based isolators are used in Launch vehicles to protect sensitive equipments from vibration environments. Issues in predicting vibration responses accurately are addressed and a modified Hyper-elastic model for elastomers proposed to model such materials in FE domain. Two types of isolators formulations and configurations are studied through modelling and experiments. Isolators are subjected to pre-stress due to the assembly and static acceleration. A displacement based four node axi-symmetric element is used having mixed u-p formulation. Elastomer is modelled with Yeoh material model, whose constants were obtained from uni-axial tension test data. To study the dynamic response of the isolator under pre-stressed state, elastomeric constants obtained for different strain amplitude through Dynamic Mechanical Aalyzer (DMA). The approach to model static loading effects and damping through Yeoh material model with frequency dependant complex coefficients is explained. Isolators in statically deformed state are further analyzed for harmonic, random and transient loads. The results obtained with the present Finite Element Formulation are compared with experiments for harmonic and random excitations.