Transient vibration response study of moulded and pre-stressed silicone elastomer vibration isolators

Moulded elastomeric vibration isolators used in aerospace applications are studied for predicting transient vibration response to typical excitations. Vibration isolators used in the present study undergo non-linear static deformations followed by transient dynamic loads. Static deformation is imposed by the specified displacement during assembly of metallic steel parts of isolator, and a static inertial load is applied as the load rating of the isolators. Statically deformed state is obtained using total Lagrangian approach assuming Hookean material model for metallic parts and Yeoh material model for elastomers. Steel properties are used from the literature, and Yeoh material constants are obtained from uni-axial tension test data of elastomer specimen. For transient response study, dynamic elastomeric constants are obtained from test in a Dynamic Mechanical Analyzer as a frequency–dependant complex function. To account for the pre-deformed state of elastomers, the Yeoh material constants are modified which includes frequency–dependant material characteristics and damping in the range of interest using multiplicative non-separable variable law based on the methodology provided for Mooney–Rivlin model. The Finite Element formulation and experimental validation provided for frequency domain response in the previous work is modified to study the isolators for rectangular and trapezium pulse loads and sinusoidally varying loads. Numerical results are validated with experimental observations for rectangular pulse load.