Failure behavior of single-strap lap (SSL) and double-strap lap (DSL) composites-with adhesive joints and different fiber reinforcement angles under hydrothermal conditions

The behavior of single-strap lap (SSL) and double-strap lap (DSL) composites-with adhesive joints and different fiber reinforcement angles were experimentally studied under hydrothermal environment. Glass fiber reinforced epoxy composite plates with fiber reinforcement angles of [0 degrees]8 and [45 degrees/ -45 degrees/0 degrees/90 degrees]s were used with different patches. Three different constant water temperatures and three different time periods were used to determine the failure behavior of composites. In addition, failure loads, moisture absorption rates and failure modes were obtained from experimental data. The effects of absorption rates on failure morphology were also observed through scanning electron microscope (SEM) images. From experimental results, failure loads of specimens were found higher in SSL and DSL joints with plate-patch fiber orientation of [0 degrees]8 and in a dry state compared to those of SSL and DSL joints with plate-patch fiber orientation of [45 degrees/ -45 degrees/0 degrees/90 degrees]s. While a combined failure mode was generally observed in the specimens of both SSL and DSL joints, stock-break failure mode was also detected in the specimens of DSL joints. In all groups, it was determined that the highest moisture absorption rate and the lowest failure load values were obtained from those specimens kept in hot water at 80 degrees C for 45 days. [Graphics] .