Croker, L E; Gower, M R L; Broughton, W R (2003) Finite element assessment of geometric and material property effects on the strength and stiffness of bonded and bolted T-joints. NPL Report. MATC(A)124

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Abstract

Finite element analysis (FEA) studies have been carried out on both bonded and bolted T-joints of similar geometry in order to determine the effects of key geometric parameters and material properties on the predicted mechanical performance of the joint. A series of simulated experiments have been conducted on aluminium and glass fibre-reinforced plastic (GRP) T-joint configurations for this purpose. FEA was used to establish the effects of changes in adhesive layer thickness, web and base plate thickness and separation distance, flange radius and thickness, and taper angle on the stiffness and load capacity of bonded joints. The effects of these parameters were assessed under direct tension, lateral tension and 45° (to horizontal) tension loads. The exponent Drucker-Prager materials model was used to characterise deformation behaviour of the rubber-toughened epoxy adhesives used for bonding the T-joints. A similar parametric exercise was carried out for bolted T-joints in which the previously mentioned geometric features were studied along with the effect of bolt position on joint performance.
The FEA results produce some simple empirical relationships that estimate the effects of the geometric parameters on joint stiffness and strength for this complex geometry. The effects of these parameters depend on the loading conditions. A fully bonded joint was shown to be far superior to a joint where the adhesive is restricted to only metal-metal interfaces. The presence of thermal residual stresses only had a small effect on joint strength. The performance of both bonded and bolted T-joints is far superior under direct tension compared with loading conditions containing a lateral tensile component. The FEA predicts that joint stiffness and strength (for all three loading modes) will generally increase as the dimensions of key geometric features are increased or when the bolt position is moved towards the central vertical axis. Base plate thickness had the largest influence on the component performance but increasing this adds to the component mass. Failure location is also dependent on loading mode, failure criteria selected and the joint geometry. In future work, predicted performance will be compared with experimental data.

Item Type:	Report/Guide (NPL Report)
NPL Report No.:	MATC(A)124
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/2563

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