Durability of steel/CFRP double strap joints exposed to sea water, cyclic temperature and humidity

This paper discusses the mechanical performance of steel/CFRP double strap joints subjected to harsh environments. Seventy-five joint specimens were exposed to various conditions, including (1) simulated sea-water at 20 °C and 50 °C up to 1 year in a temperature-controlled sea-water tank, (2) constant and (3) cyclic temperatures with a high level of relative humidity (RH) up to 1000 h in an environmental chamber. Tensile tests were undertaken to determine the mechanical properties of the unexposed and exposed specimens. Significant reductions in joint strength and stiffness were found for the specimens exposed to simulated sea-water after 1 year of exposure, while the specimens exposed to combinations of temperature and humidity in the environmental chamber showed little decrease in joint strength and stiffness after 1000 h of exposure. A model was developed to predict the strength and stiffness degradation of the joints in sea-water and the results compared well with the experimental results.