Application of three-dimensional spline variational analysis for composite repair

The purpose of this research was 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, the scarf joint and the stepped-lap joint, subjected to static tensile loading. Test specimens with scarf and stepped-lap joints were fabricated using quasi-isotropic 16 ply panels made from IM6/3501-6 pregreg with a [+452/02/−452/902]S lay-up. Moiré interferometry, a high-resolution full-field optical technique used to measure displacements on a surface, was used to determine experimental strain data. Full-field strains along the free-edge were predicted and compared to experimental strain data. Line plots are generated from predicted and experimental data extracted at several points across the width of the repair to provide a quantitative comparison. Overall, both the full-field strain images and line plots show good agreement between the BSAM analysis and the experimental data.