Fatigue Life and Residual Strength Analysis of Steel-Composite Joints

Abstract

There are many instances where the use of weight saving composite materials for an entire structure is either; too complex, too expensive or unfeasible. In these circumstances the use of a hybrid structure can incorporate the benefits of traditional construction materials, for example steel, coupled with the advantages of composite materials in weight critical areas. In the present study, an investigation was undertaken into the fatigue life characterisation of a hybrid joint for marine application. In addition the residual strength of the joint, after a fixed number of fatigue cycles, was assessed under axial compression and bending loads. A progressive damage model was developed to predict the location of major stress concentrations, the path of damage and subsequent loss in stiffness of the joint under axial compression.

Testing and Analysis of Hybrid Composite/Metal Connections and Hull Section for the MACH Project

“…For instance, a study by Aim [1983] estimated that a 50-m composite naval ship was 2.4 times less stiff than its steel counterpart. Similarly, an article by Boyd [2004a] states that an all composite ship structure greater than 150 meters is currently unfeasible, and that the application of hybrid composite/metal construction needs to be explored further.…”

“…They concluded that placement of the steel has a significant effect on the strength and should be moved away from the point of stress concentrations. Boyd et al [2004aBoyd et al [ , 2004b describe an embedded metal joint connecting a composite sandwich panel to a steel deck for a helicopter hangar. In this application, a steel plate was embedded at the end of a tapered composite sandwich section panel made from FRP skins and a balsa core.…”