The Testing and Analysis of Novel Top-Hat Stiffener Fabrication Methods for Use in GRP Ships

Abstract

Reinforced and unreinforced specimens representative of GRP ship hull/ frame structures have been tested by a slow pull-off method. Changes in bondline stress distribution and overall test system compliance produced by the three loading modes used affected bondline crack initiation loads and the crack propagation behaviour. The loading mode did not influence the ranking order of the various fabrication techniques. As a simulation of the behaviour of the structure under shock loading, the use of the most severe, centre clamp, loading method is recommended.

The beneficial effects of incorporating a low modulus acrylic matrix in the bondline stress concentration under the heel of the stiffener web are described. The crucial role of the stiffness of the stiffener frame web/flange corner in determining the failure pattern is discussed. It is suggested that local reductions in stiffness in the web/flange corner may have a beneficial effect in inhibiting damage to the frame/hull connection during overloads.