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Title: Temperature profiles and thermal strain analysis in multi-fastener carbon fibre reinforced plastic-aluminium lap joints
Author: Miller, Jodi R.
ISNI:       0000 0001 3402 0120
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2004
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Temperature profiles of and combined thermal-mechanical induced strains for Carbon Fibre Reinforced Plastic (CFRP)-Aluminium multi-fastener double lap joints in a wingbox structure are examined. Two dimensional (2D) FE analyses for cases of full, empty, and half-full fuel tank scenarios are used to develop temperature profiles. The influence of conduction, convection, and radiation on temperature profiles is examined. Results show that the empty tank scenario produces the highest temperatures, with the joint region having the peak temperatures, and that convection and radiation must both be modelled in order to accurately estimate wingbox temperatures for the empty, and halffull tank scenarios. Analytical temperature prediction models, both at and away from the joint region, are developed for combined convection and radiation boundary conditions at both external surfaces of this unique finite geometry. For transient analyses, single and multiple layer models are designed using integral transforms and separation of variables, respectively. To show the joint region is critical in terms of induced strains, sequentially coupled thermal-stress analysis is performed using the resulting temperature profiles. Based on these results, and on the results of the temperature profiling, an experimental model is designed to study the effects of thermal and mechanical 1 oading on a threefastener double lap joint with CFRP'skin and aluminium laps. To fully explore the joint region, three dimensional (3D) FE results are compared with experimental data. Mechanical tensile stress in the elastic range is applied at room temperature (295K) and at an elevated temperature (373K). Increasing temperature alters the strain patterns among the fasteners and generally decreases' the peak radial strains at individual fasteners, but increases tangential strains. The effect of torque on the strain distribution in these multi-fastener double lap joints is examined by comparing finger-tight and operationally-tight (35Nm) torques at both temperatures. Increasing torque significantly reduces peak strains on individual fasteners and evens the strain distribution across the joint
Supervisor: Weaver, Paul Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available