Dean, G; Wright, L (2002) Comparison of the measured and predicted deformation of a circular plate of an ABS polymer used under centre loading. NPL Report. MATC(A)105

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Abstract

Apparatus is described for deforming plate specimens that are supported on their lower surface by a circular ring of diameter 100 mn. The plates are loaded by a rigid, hemispherical shape contacting the centre of the upper surface of the plate. The apparatus has been instrumented to enable simultaneous measurements of the applied force, the central deflection and the displacement of reference marks on the lower surface of the plate.
Predictions of strains and deformations have been using an elastic-plastic model in the Abaqus finite element system. The measurement of materials properties and parameters required by this model is described. The analysis of these data for an ABS polymer demonstrates limitations in the model for describing the non-linear deformation behaviour of rubber-toughened plastics. The cause of this is traceable to the nucleation of cavities in the rubber particles under certain stress states.
A new, elastic-plastic model is described that takes account of the influences of cavitation on yield and flow behaviour. Predictions of force against central deflection and surface strains using both models are compared with experimental values at a low test speed. Comparisons of force against central deflection measurements at higher test speeds are also made with predictions based on analyses that account for rate-dependent plasticity.

Item Type:	Report/Guide (NPL Report)
NPL Report No.:	MATC(A)105
Keywords:	cavitation, biaxial stress test
Subjects:	Advanced Materials Advanced Materials > Polymers
Last Modified:	02 Feb 2018 13:17
URI:	http://eprintspublications.npl.co.uk/id/eprint/2443

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