Study on Mechanical Bearing Strength and Failure Modes of Composite Materials for Marine Structures

With the gradual application of composite materials to ships and offshore structures, the structural strength of composites that can replace steel should be explored. In this study, the mechanical bearing strength and failure modes of a composite-to-metal joining structure connected by mechanically fastened joints were experimentally analyzed. The effects of the fiber tensile strength and stress concentration on the static bearing strength and failure modes of the composite structures were investigated. For the experiment, quasi-isotropic [45°/0°/–45°/90°]2S carbon fiber-reinforced plastic (CFRP) and glass fiber-reinforced plastic (GFRP) specimens were prepared with hole diameters of 5, 6, 8, and 10 mm. The experimental results showed that the average static bearing strength of the CFRP specimen was 30% or higher than that of the GFRP specimen. In terms of the failure mode of the mechanically fastened joint, a cleavage failure mode was observed in the GFRP specimen for hole diameters of 5 mm and 6 mm, whereas a net-tension failure mode was observed for hole diameters of 8 mm and 10 mm. Bearing failure occurred in the CFRP specimens.

A review on composite patch repairs and the most important parameters affecting its efficiency and durability

In many industries, when replacement of a part is not possible or economic, the repair is done. One of the best methods for repairing metal and composite parts is using composite patches. Repairing with a composite patch is a widespread field to extend the service life of the cracked components. This technique is more structurally efficient with fewer damages on the structure than others. The bonded patch offers many advantages over a mechanically fastened doubler, which include improved fatigue behavior, reduced corrosion, and easy conformance to complex aerodynamic contours. In this article, advantages of the composite patch and its efficiency and durability are discussed, and the most important parameters (patch and adhesive thickness, patch separation, residual stress, patch length and width, etc.) affecting its performance are studied based on the latest available references.