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Title: Damage mechanisms arising from advanced fasteners for aerospace
Author: Shariatpanahi, Sepideh Vali
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2013
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This thesis presents a study of a new composite joint method for use in aircraft structural components. Traditional bolted/bonded joints for composite "T joints" requires the addition of feet to attach the vertical members to the horizontal members. The addition of feet will, in most cases, lead to an increase in weight resulting in loss of the weight-saving advantage of composite over metallic materials. To overcome this problem a new generation of fastening methods is being investigated. One of the most promising is the barrel nut concept which is suitable for thick laminate joints. Once the laminate thickness increases, membrane stresses cannot be used to estimate and predict joint failure. Particularly in 3-D joints and complex geometry, through-thickness stresses play a dominate role in determining the failure and failure mode of the joints. The aim of this PhD work is to study and analyse barrel nut joints and to predict their failure mode and failure point. The two approaches presented in this work are: empirical testing and the finite element method (FEM). The experimental programs determine failure mechanisms and crack paths and observe the real joint failure under tension, transverse shear and longitudinal shear of loaded lap joints and barrel nut joints with selected layups. In this modelling work I first analysed a simple joint failure (filled hole) and then gradually built up to analysis of a specific type of joint, taking into account the thickness effect of composite laminate and the complex geometry of the barrel nut joint. The results were then used to predict the failure and failure mechanisms of this type of joint. Comparison of the experimental result and the FEM prediction of failure showed a good correlation . The failure loads were considered to be where the major load drop occurred . The force-time graph from the FE model predicts the failure load by less than 10% of the experimental data for lap joint and to within 13% of the experimental data for barrel nut joint.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available