Relaxation of Stress Concentration in FRP Plate with a Circular or Square Hole

Abstract

Numerical analysis by the Finite Element Method has been carried out on the relaxation of stress concentration in FRP plates with a circular or square hole under uniaxial tension. As one of the successful ways to relax stress concentrations, it is conceivable to make two additional holes along the direction of tensile load.
This paper deals with glass/epoxy and carbon/epoxy plates containing one original and two additional holes. The fibers were oriented parallel to the load direction. The relation between the pitch of hole and the hole size to optimize the relaxation of stress concentration was obtained. The result of FRP plate was compared with that of isotropic plate.
It was found that the fiber reinforced composite plate showed a larger effect of relaxation than the isotropic plate. In FRP plate, the higher the fiber reinforcement, the more the effect of the relaxation of stress concentration. Also, the relaxation of stress concentration at a circular hole due to additional holes was more than that at a square hole having round corners.