Integrally 3D Woven/3D Braided Composite Joining Elements For Ship Construction

During Phase I, 3TEX designed universal, one-piece, 3D woven fiber preforms which can be used as either a “Butt” (H) joint or as a “P” joint as needed. Composite joints were fabricated and tested, demonstrating the benefit of the integral nature of the 3D preforms. 3D stress/strain and crack propagation analysis of composite Π-joint was performed using 3D MOSAIC code. 3D displacement, strain and stress fields, and energy release rates in the joint with and without the “noodle” crack were computed and compared to the critical value. Applied displacements corresponding to failure initiation were predicted. Composite panels made with one ply of thick 3WEAVE™ preform were drilled and tapped for various bolt sizes and tested. 3D reinforcement provided thread strengths exceeding that of the steel bolts in the composite panel without inserts. Novel joining methods are proposed for the Phase II work for Navy ship construction with particular emphasis on application to DD (X). The joints are practical, more robust, and of a lower cost than current designs using 2D laminates. Phase II will elaborate on, document, and demonstrate practical application of the devised systems. The 3WEAVEÔ methods and machinery to produce the novel joining systems are available for immediate production.