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A further evaluation of the cavitation model for rubber-toughened plastics.

Dean, G; Read, B E; Wright, L (2002) A further evaluation of the cavitation model for rubber-toughened plastics. NPL Report. MATC(A)75

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The version of the cavitation model described in earlier reports predicts that, contrary to experimental observation, rubber particles will cavitate under shear and compressive stresses. This arises because the cavity nucleation is expressed in terms of the total volumetric strain in the polymer, and the volumetric strain during plastic deformation is relatively large for associated flow in shear and compression. This report investigates the assumption of associated flow and explores alternative relationships for the cavity nucleation criterion based on the total and the elastic volumetric strain on the rubber particles.
Measurement of volumetric strain in uniaxial tension and compression tests reveal that plastic flow is non-associated and imply that the flow parameter depends on the stress state. Expressions for the volumetric strain on rubber particles have been derived that take account of the predicted reduction in elastic properties with cavity nucleation. Cavity nucleation criteria based on these expressions give satisfactory predictions of stress/strain curves and Poisson's ratio under uniaxial tension and compression but a poor fit to stress strain behaviour in a butt-tension test. Based on these observations, a preferred version of the model is identified for future FE analyses.

Item Type: Report/Guide (NPL Report)
NPL Report No.: MATC(A)75
Keywords: elastic-plastic models, rubber-toughened plastics, cavitation, non-associated flow
Subjects: Advanced Materials
Advanced Materials > Powder Route Materials
Last Modified: 02 Feb 2018 13:17
URI: http://eprintspublications.npl.co.uk/id/eprint/2303

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