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Comparison of the measured and predicted performance of adhesive joints under impact.

Dean, G; Lord, G; Duncan, B C (1999) Comparison of the measured and predicted performance of adhesive joints under impact. NPL Report. CMMT(A)198

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The work reported here is concerned with predicting the performance of an adhesive joint under impact loading. Analyses of stress and strain distributions in a joint specimen were made using finite element methods for a range of speeds at which the specimen was loaded. Predictions of force against extension of the joint are compared with experimental data obtained up to failure of the specimen. The adhesive used was a toughened epoxy which was able to sustain large strains before failure. Elastic-plastic models have therefore been used in the FE analysis with materials parameters obtained from a variety of tests carried out in an earlier phase of the project. A wide range of deformation speeds has been employed in these tests to determine the strain rate dependence of mechanical properties.
Predictions of force against extension were made on a lap joint specimen whose dimensions were chosen with the intention of minimising plastic deformation of the adherends during a test. Solutions were obtained over a range of loading speeds using static and dynamic analyses with both standard and explicit solver codes. Predictions were compared with experimental data obtained under controlled deformation at slow speeds and under falling weight impact at higher speeds. Under impact loading, attempts have been made to interpret and model the transient forces that dominate the force/extension record at high speeds.
Calculations have also been made of strain components in the region of strain concentration in the adhesive where specimen failure is expected to initiate. Strain levels are compared with a failure criterion developed in a earlier part of the project, and attempts are made to interpret the force/extension measurements in terms of partial failure of the adhesive prior to complete rupture of the joint.

Item Type: Report/Guide (NPL Report)
NPL Report No.: CMMT(A)198
Subjects: Advanced Materials
Advanced Materials > Adhesives
Last Modified: 02 Feb 2018 13:18
URI: http://eprintspublications.npl.co.uk/id/eprint/1235

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