Application of Spline Variational Analysis Method in the Modeling of Composite Repairs

摘要

The purpose of this thesis is to apply a non-commercialized spline- based (B-Spline Analysis Method or BSAM) computer program to model and predict strain fields in two composite repairs, a scarf joint and a stepped-lap joint, subjected to static tensile loading. Test specimens with straight scarf and stepped-lap joints are fabricated using quasi-isotropic sixteen ply panels made from IM6/3501-6 prepreg. The panels were bonded together with FM-300M (0.05psf), a 176oC cure film adhesive. A total of five coupons of each joint type are made. Two of the stepped-lap and scarf coupons are instrumented with acoustic emission sensors and loaded in tension to determine loading for experimentation. Moire inteferometry, a high resolution full-field optical technique used to measure displacements on a surface, is used to acquire experimental strain data. Diffraction grating is applied to the polished edge of two stepped-lap and two scarf coupons, while one coupon of each was selected for experimentation under a static tensile load of 450lbf. Using measurements from the actual coupon specimens, idealized models of the stepped-lap and scarf joints are developed for the BSAM computer program. Overall, both the fullfield strain images and line plots show a good agreement between the BSAM analysis and the experiment.