A simplified predictive approach to assess the mechanical behavior of pinned hybrid composites aged in salt-fog environment

Aim of this paper is to assess the predictive capabilities of a simplified theoretical approach on the failure load of aged pinned hybrid composites. In particular, the mechanical performances of glass-flax hybrid epoxy laminates exposed to salt spray fog environment, were used as input data in order to address the analytical model. Preliminarily, the relationship among mechanical performances, failure mechanisms, joint geometry and ageing time, was evaluated by double-lap joint tests on pinned samples at varying joint geometry and ageing time. The bearing and shear out limit stress of samples aged for 60 days under the salt-fog environment underwent a reduction of about 20% compared to the unaged one. Instead, the net-tension limit stress evidenced a reduction slightly above 10%. Afterward, a simplified theoretical approach, based on failure mechanisms stress limits, was proposed to forecast both joint resistance and failure mechanism occurrence. The composite degradation in a salt-fog spray environment was also taken into account in the model. The results highlight a good reliability, with an average error of about 6–8% compared to experimenatal results, thus indicating the suitability of the proposed approach to support the long-term design of a specific pinned composite subject to critical aggressive environments.