Constitutive Equations Of Rubber Under Large Tensile Strain And High Strain Rates

Download or read book Constitutive Equations of Rubber Under Large Tensile Strain and High Strain Rates written by Xin Ouyang and published by . This book was released on 2006 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Based on a detailed experimental investigation, new hyper-viscoelastic constitutive models for describing the high strain rate behavior of the elastomers have been developed. Uniaxial tensile tests and sheet tension tests were performed at strain rates ranging from 0.1 s-1 to 450 s-1 by use of an Instron electro-mechanical machine and a Charpy tensile test apparatus. The constitutive models were based on a phenomenonlogical Zener model: a hyperelastic equilibrium spring, which describes the steady-state, long-term response, in parallel with a Maxwell element, which captures the rate-dependency. The rate-dependence of the Maxwell element is controlled by a nonlinear viscous damper connected in series to a hyperelastic intermediate spring. A fractional power-law strain energy potential function was proposed for the hyperelastic springs in order to describe the steep initial gradient of the stress-extension ratio curves that result under high strain rate. Two kinds of constitutive equations were proposed using a history integral and differential approach. The history integral constitutive law was developed based on Kaye-BKZ theory. Multiplicative decomposition of the deformation gradient and the second law of thermodynamics were used to develop the differential constitutive equations. All material constants were obtained from the uniaxial tensile tests. The constitutive equations were implemented into ABAQUS via user-defined material subroutines. The history integral constitutive equation was difficult to implement in FEA because numerical integration had to be performed at every time step. Numerical predictions of the tensile strip and sheet force-deformation response were at best within 14% of experimental values. The differential constitutive equations based on thermodynamics principle was not only easier to implement, but gave solutions that were within 5% of test results."--abstract.