Abstract
A peristaltically actuated device, PADeMIS, composed of silicone rubber (SR) is under development for use in minimally invasive surgery. During locomotion, the device will be subject to a few thousand load changes involving varying, sometimes high, strains. The design is being optimised by finite element analysis, for which a constitutive law for the mechanical behaviour of silicone rubber is required. Uniaxial and biaxial tension tests have been performed on specimens of used silicon rubber. Synchronous fitting of uniaxial and biaxial tensile data gives significantly better results than using uniaxial or biaxial results alone to derive constitutive laws. The mechanical properties of SR were found to change from loading to loading up to few thousand cycles. Hence, simulating the deformation of SR structures is problematic. Furthermore, variability was observed between batches of SR.
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