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Title: Fatigue characterisation of FRP structural tee joints
Author: Read, Paul John Charles Lewis
ISNI:       0000 0001 3510 3315
Awarding Body: University of Southampton
Current Institution: University of Southampton
Date of Award: 1997
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Joints are a necessity in the construction of large structures such as ships. In the context of Fibre Reinforced Plastics (FRP), joints present a site of potential weakness due to material and geometric discontinuities. This problem is most significant in out-of-plane joints were stresses can occur in the materials weaker through-thickness direction. It is important therefore that the behaviour of these type of joints is fully understood. A substantial body of literature exists concerning their static behaviour but very little exits concerned with their long term fatigue behaviour. The aim of this thesis is to present an understanding of the long term fatigue behaviour of a particular out-of-plane joint, the single skin tee joint. As a first step in understanding the fatigue behaviour of tee joints, further static experimentation of four different joint configurations is presented. This helps fill the gaps in the knowledge of static load transfer mechanisms using thermoelastic and photoelastic techniques to produce novel full field pictures of through-thickness stress and strain distributions. The static experimental results also provide a first point on the fatigue load-life curve for each joint configuration. Extensive fatigue experimentation is then presented for the same four tee joint configurations. Uniquely, load-life curves and stiffness degradation, residual strength degradation and energy dissipation through life results are presented for the tee joints subjected both to constant loading and two-step loading fatigue. Damage processes and failure mechanisms are also highlighted in detail, as never before. Theoretical analysis of the tee joints is presented in two parts as internal behaviour predictions and global behaviour predictions. Internal behaviour is modelled using Finite Element Analysis (FEA). The results are used in a novel manner of tee joints to provide a means of understanding and predicting the damage processes and failure mechanisms seen during experimentation. Global behaviour is modelled using a new method based on energy dissipation as a damage indicator. This method gives relatively good predictions of two step load fatigue lives compared to existing theoretical approaches. Furthermore a second new method of global fatigue behaviour prediction is proposed for use as a design tool.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Fibre reinforced plastics; Stress analysis