Improving low cycle fatigue performance of cracked aluminum plate with carbon fiber composite patches reinforced with B4C nanoparticles

Abstract

Composite patch over the cracked metal surface plays a vital role in repairing the damaged part of the lightweight structures, as it is one of the most efficient and could be done with the reduced cost. This manuscript documents the repair efficacy of pre-cracked aluminum alloy AA6061 under low cycle fatigue (LCF). As a novel attempt, the alloy is patched using carbon fiber composite, with and without nano ceramic boron carbide (B₄C) particles infused. In this regard, B₄C nanoparticles are added in 0.2%, 0.4%, and 0.6% wt. composition, referred herein as 2BCF, 4BCF, and 6BCF, respectively. Each sample, either patched and non-patched, are tested for LCF loading at two strain ratios, 0.1 and 0.3. LCF-test outcomes reveal that adding B₄C nanoparticles effectively reduces the plastic strain amplitude (PSA) and energy dissipation. As a result, the fatigue life of the patched AA6061 alloys is significantly improved. Notably, the sample 6BCF exhibits higher fatigue resistance at strain ratio of 0.1, resulting in 6.5-fold improvement in fatigue life compared to other patched specimens indicating a strong adhesion between the patch and the aluminum surface. Therefore, more stable response to fatigue loading is observed due to less dissipated energy.