Ageing of corrosion resistant steel/rubber/composite hybrid structures

One of the major challenges when preparing reliable hybrid structures is the adhesion between different components. Besides enduring the specific stress state, hybrid structures should maintain the required properties in the service environment without degradation. In this study, the environmental resistance of stainless steel/rubber/GFRP (glass fibre reinforced plastic) hybrid structures were tested by exposure to hot, moist and hot/moist environments and after the ageing by peel testing. Two different stainless steel surface finishes and two different rubber grades were investigated. The results were compared with the properties of a mild steel/rubber/GFRP structure. Both mild steel/rubber and composite/rubber structures are used in industrial applications, such as in vibration damping devices and in automotive components.The peel tests showed that with right rubber compounds, stainless steel/rubber and GFRP/rubber interfaces can maintain their properties even in harsh hot/moist environments to such an extent that the interfacial strength of the joint is higher than the cohesive strength of the rubber. This enables the use of rubber's cohesive fracture properties instead of the substrate/rubber interfacial properties when estimating the strength of the steel/rubber/GFRP hybrid structure. In addition, based on the current study, time-consuming stainless steel pre-treatments are not needed but the stainless steel can be in the as-received stage. According to the chemical analysis even before and after the harsh hot/moist exposure used, none of the studied rubber grades had degraded. Thus, we conclude that it is possible to manufacture environmental resistant stainless steel/GFRP hybrid structures with the aid of EPDM rubbers.