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# The static and dynamic behaviour of carbon fibre composites used in golf club shafts

Slater, Carl (2012)
Ph.D. thesis, University of Birmingham.

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## Abstract

The static and dynamic properties of carbon fibre composites of varying orientation, stacking sequence and geometry has been analysed in terms of modulus and material loss factor up to strain rates applicable to golf club shafts. No noticeable change in modulus or damping was seen at strain rate applicable to golf club shafts. All panels tested strain rate sensitivity onset occurred at around 0.4 s$$^{-1}$$, which is above the maximum observed during a golf swing (0.1 s$$^{-1}$$). The strain rate sensitivity was found to be sensitive to aspect ratio (for strain rates above 0.4 s$$^{-1}$$). Two 20° panels of the same fibre interfacial area, but with different aspect ratios (length/width) showed different strain rate sensitivities. The short wide panel (aspect ratio 1.5) showed a higher stiffness and lower strain rate sensitivity when compared to a panel with an aspect ratio of 2.6. A model was created to predict the modulus and damping of lay-ups for laminates and golf club shafts. The model was validated against three composite systems at varying orientations and stacking sequences. The software agreed well with laminate experimental data (data sets showed a RMSD of less than 5 %). From this an optimising software was developed to provide the user with a stacking sequence that will optimise modulus, damping or the product of both. This thesis also evaluated commercial shafts in order to determine the models applicability to this application. Commercial shafts were tested for both stiffness and damping, where a number of aspects such as inter-ply resin rich regions and seam were observed as possible areas for discrepancy with the models prediction. Shafts were fabricated in order to analyse these aspects in greater deal, and to determine the models limits for this application. The model accurately predicted the stiffness of the shafts however the model failed to predict the damping of the shafts when comparing to the average values taken. When damping was compared to the areas where no seams were present, the model agreed well except for in two cases, which have been attributed to shafts flaws (cracks or excess inter ply resin). The model presented in this research consistently characterised the stiffness of fabricated shafts, however the seams proved too dominant a feature to be neglected in the prediction of damping.

Type of Work: Ph.D. thesis. Strangwood, Martin and Davis, Claire Colleges (2008 onwards) > College of Engineering & Physical Sciences School of Metallurgy and Materials T Technology (General)TN Mining engineering. MetallurgyTS Manufactures University of Birmingham 3476
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