Large Deformation Behaviour of Continuum Compliant Systems

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Author(s) Theddeus T. Akano | Omotayo A. Fakinlede
Pages 16-29
Volume 2
Issue 1
Date January, 2013
Keywords Compliant mechanisms, Hyperelasticity, Nonlinear Finite Element Method, Continuum mechanics, Geometric nonlinearity; Finite Deformation, AceGEN, AceFEM
Abstract

Continuum topology of continuous, monolithic compliant mechanisms is designed for finite elastic deformation such that an output port moves in a desired direction when a specified force is applied through an input port. The pseudo-rigid body equivalent of compliant mechanisms (CMs) has been the conventional approach used by earlier researchers to synthesize and analyze compliant mechanisms. Attempts at direct analysis from existing literature are predicted on such assumptions as static linearity or a few times geometric nonlinear conditions. These are justifiable in several situations where compliant systems have been successful in replacing materials with several moving parts. However, the application domain of compliant mechanisms is widening to dynamic environment where the deformations are relatively large. It is therefore necessary to consider nonlinearities resulting from geometry and hyperelasticity. In this paper, methods of continuum mechanics and nonlinear finite element method were deployed to develop model that could capture the behaviour of compliant mechanisms. A hybrid system of symbolic algebra (AceGEN) and a compiled back end (AceFEM) were employed, leveraging both ease of use and computational efficiency. Numerical results using published laboratory investigated compliant mechanisms reveal the deviation that exists with linear and only geometric nonlinear assumptions.

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