Dean, G D; Mera, R D (2004) Modelling creep in toughened epoxy adhesives for finite element analysis. NPL Report. DEPC-MPR 003

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Abstract

A model is introduced for describing the creep behaviour of glassy adhesives. Its application is illustrated using measurements on two rubber-toughened epoxy adhesives. The dependence of creep compliance on applied stress (non-linear creep behaviour) is explained by making the creep relaxation time dependent on the stress level. Creep behaviour under uniaxial tension and uniaxial compression is observed to be different, and this is explained through a dependence of creep relaxation time on an effective stress which is a function of the multiaxial stress state.
Attempts have been made to implement the model in the finite element system ABAQUS so that changes can be investigated in the stress and strain distributions in a bonded joint with time under load. None of the available models can be used for this purpose, but the adhesives creep model can be represented by a generalised model in ABAQUS for time-dependent plasticity. This has enabled changes in distributions of stress and strain in the adhesive in a lap joint to be calculated with approximate values calculated using long-term, isochronous data with an elastic-plastic materials model.

Item Type:	Report/Guide (NPL Report)
NPL Report No.:	DEPC-MPR 003
Keywords:	nonlinear, relaxation time, rubber-toughened adhesives
Subjects:	Advanced Materials Advanced Materials > Adhesives Advanced Materials > Materials Modelling
Last Modified:	02 Feb 2018 13:16
URI:	http://eprintspublications.npl.co.uk/id/eprint/3016

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