Hygrothermally stable laminated compositeswith optimal coupling

Composite laminates;Hygrothermal stability;Extension-twist coupling;Bending-twist coupling;Optimization

Haynes, Robert Andrew ; Aerospace Engineering

University:Georgia Institute of Technology

Department:Aerospace Engineering

关键词: Composite laminates;    Hygrothermal stability;    Extension-twist coupling;    Bending-twist coupling;    Optimization;   

Others  :  https://smartech.gatech.edu/bitstream/1853/34671/1/haynes_robert_a_201008_phd.pdf

美国|英语

来源: SMARTech Repository

【 摘 要 】

This work begins by establishing the necessary and sufficient conditions for hygrothermal stability of composite laminates.An investigation is performed into the range of coupling achievable from within all hygrothermally stable families.The minimum number of plies required to create an asymmetric hygrothermally stable stacking sequence is found to be five.Next, a rigorous and general approach for determining designs corresponding to optimal levels of coupling is established through the use of a constrained optimization procedure.Couplings investigated include extension-twist, bend-twist, extension-bend, shear-twist, and anticlastic.For extension-twist and bend-twist coupling, specimens from five- through ten-ply laminates are manufactured and tested to demonstrate hygrothermal stability and achievable levels of coupling.Nonlinear models and finite element analysis are developed, and predictions are verified through comparison with test results.Sensitivity analyses are performed to demonstrate the robustness of the hygrothermal stability and couplings to deviations in ply angle, typical of manufacturing tolerances.Comparisons are made with current state-of-the-art suboptimal layups, and significant increases in coupling over previously known levels are demonstrated.