Carbon composite drivetrain components and torsion testing apparatus

Glen Hogan

Abstract


The following text outlines the work completed during a final year project as part of a mechanical engineering degree. The goal of the project was to develop supporting data, testing capabilities and lightweight carbon drivetrain component designs for the Academy Racing FSAE vehicle. The project began by conducting a literature review into lightweight, carbon drivetrain components and their manufacture. Following this a torsional testing apparatus was designed and manufactured for integration into a linear Universal Testing Machine for later use in testing adhesively bonded carbon/aluminum single lap joints in torsion. A high-performance 3M acrylic adhesive was selected to conduct single lap shear testing against ASTM D3165 to develop a reliable bond specification for torsional bonding with variation occurring in bond thickness and surface preparation methods. The most consistent bonding method from single lap shear testing was selected for varied profile, single lap torsion testing of +/- 45o carbon fibre tube with 2011-T6 aluminum. Various bond lengths and outer/inner, inner/outer surface bonding configurations were selected to validate preliminary FEA testing, previous single lap shear test data and to develop sufficient information to select a final bonding specification suitable for integration with a once-piece tripod CV joint adherend for later testing on an FSAE vehicle. The manufactured torsion testing apparatus performed its function with no failure and applied reliable loading to all test specimens. The modified ASTM D3165 single lap shear testing returned adhesive shear strengths significantly lower than that specified by 3M across all 24 test specimens due to peel effects however the results obtained were consistent and allowed for key trends to be identified across changing variables. The torsion testing of the final set of aluminum/carbon shafts using 3M DP8405NS adhesive demonstrated varied trends across bond length, aluminum adherend wall thickness and between outer and inner surface bonding to the carbon tube. The analysis of results suggested additional emphasis and design is required within the adhesive application stages of joint construction to achieve reliable coverage of the complete bond area on both adherends.

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