Bearing strength of interference-fit pin joined glass fiber reinforced plastic composites

Glass fiber reinforced plastic structures are mostly used in mid-sized marine vessels due to high strength and stiffness to weight ratio, corrosion resistance, and total life cost reductions. Mechanical joints using metallic bolts, screws, and pins are commonly used for joining thick glass fiber reinforced plastic laminates. Interference-fit pin connections provide beneficial effects such as fatigue enhancement and/or prevention of moisture intrusion to the fiber reinforced composites. This numerical and experimental study aims to investigate the effect of interference-fit on the bearing stiffness and strength of pin joined glass fiber reinforced plastic. The stress and strain distributions have been investigated for bearing loading through experiments as well as a nonlinear three dimensional finite element analysis. The quasi-static properties of the pin-loaded composites with interference-fit (0.6% and 1%) are compared with the samples with transition-fit (0% of interference-fit). The radial and the tangential strains on the vicinity of the hole obtained from the FE simulation were verified with the experimental results. The radial strains on the interference-fit pin joined glass fiber reinforced plastic coupons are lower than those on the transition-fit pin joined glass fiber reinforced plastic coupons at the consistent pin displacement, resulting in enhancement of the joint stiffness per unit bearing area by interference-fit.