Tensile Behavior of Double-Hole CFRP Composite with Different Holes Position

Multiple holes presented in composite structures due to design requirements or accidental impacts can reduce the structural strength, thus posing potential safety risks for aircraft structures. For the random hole damages caused by the impacts, hole numbers, hole-to-hole distance and position angles are part of the parameters that affect the structural strength. Effects of the position angle on tensile behavior, including stress concentration factors, stress distributions, damage initiation and propagation, and tensile strength of CFRP laminates are investigated experimentally and numerically based on progressive damage analysis. The stress concentration factor reaches its lowest and highest value when the angle is 0° and 60°, respectively. The tensile strength shows an opposite trend. Interferences of the stresses around the holes lead to a slight offset of the damage initiation point and a change of tangential stress pattern at the hole boundary. For the case of 60°, the matrix, fiber and delamination damages appear mostly in between the holes, causing a large reduction of its loading-carrying capacity.