An evaluation model of bearing capacity for CFRP connection structure with lightning thermal damage

Abstract

Connection structure of carbon fiber reinforced plastic (CFRP) is fragile to lightning and its damage form is complex. Its bearing capacity is affected, which should be evaluated to ensure safety after lightning strike. Thus, a model of bearing capacity prediction (BCP) is proposed for CFRP connection structure. Its lightning damage is evaluated from thermal perspective combining joule heat and dynamics failure, which is caused by lightning ablation and the Blow-Off Impulse (BOI) effect, respectively. Electrical thermal coupling and high explosive models are utilized for calculation. Subsequently, lightning thermal damage is inherited by full restart method. The computing efficiency and convergence is improved caused by structural local distortion. Tensile bearing capacity of structure is assessed by employing the strain-based 3D Hashin criterion. A tensile experiment is carried out to verify BCP model. The results show that lightning thermal damage is the worst around current injection region. Tensile-shear and extrusion-shear failures concentrate at CFRP fastener holes under tensile load. Tensile failure load of structure is further reduced by 8.03% due to the BOI effect. The bearing capacity of CFRP connection structure can be accurately predicted by BCP model after lightning strike and deviation is 9.8% from experiment.