Fatigue failure investigation of pultruded GFRP pre-tightened single-tooth connector (PTSTC)

Abstract

The clamping force perpendicular to the fiber has a significant and complex effect on the fatigue behavior of the composite mechanical joint. In this paper, the pultrusion glass fiber reinforced polymer (GFRP) plate was selected, and the fatigue test (R = 0.1) was conducted to study the effect of clamping stress on the fatigue failure mode of the pre-tightening single tooth connector (PTSTC).The fatigue-test results show that reducing the maximum cyclic stress could increase the life under the same pre-tightening stress. Numerical analysis shown that under the same maximum cyclic stress, the shear stress concentration along the tooth-root plane decreased with the increase of pre-tightening stress. Therefore, the fatigue life corresponding to the interlaminar shear failure also increased. However, above a certain pre-tightening stress level, the life improvement discontinued because the failure mode changed from interlaminar shear failure on the tooth-root plane to fiber failure on the tooth groove. This phenomenon was verified using the Puck's fiber failure criterion. In addition, the numerical analysis results show that the tensile and transverse shear stress concentrations on the cross section in the tooth groove were more severe as the pre-tightening stress increased. Therefore, the fatigue life corresponding to the fiber failure also decreased. In summary, choosing an appropriate pre-tightening stress is critical to the fatigue design of GFRP PTSTCs.