Uncertainty evaluation for bearing fatigue property of CFRP double-lap,single-bolt joints

The considerable uncertainty in mechanical properties of composite bolted joints not only prevents advanced composite materials from efficient applications, but also threatens the safety and reliability of the aircraft structures. In this paper, the uncertainty in bearing fatigue properties of a CFRP double-lap, single-bolt joint was evaluated by combing a Progressive Fatigue Damage Model (PFDM) with the interval analysis method. In the PFDM, a residual-strain-based gradual material degradation model and a strain-based fatigue failure criterion were combined with a micromechanics-based sudden material degradation model to predict fatigue properties of the joint. Based on the interval analysis, the key uncertain parameters, which were firstly picked out from eighteen structural parameters of the joint, were described by estimated intervals, and the envelope cases were determined to estimate the lower and upper bounds of fatigue properties of the joint. The predicted results have the same tendency with the experimental results in literatures, which indicates that the PFDM combined with the interval analysis shows potential in efficiently evaluating the fatigue reliability of the complex bolted joints with an adequate accuracy.