Comparative study of failure analysis in glass fiber reinforced laminated pin joints under cyclic and static loading conditions

Abstract

Glass Fiber Reinforce Polymer (GFRP) composite Joints were studied under monotonic loads for aerospace and marine applications, but cyclic loading is also a common and serious concern in these applications. In this current study, GFRP composite pin joints were analyzed under cyclic loading, at various geometric factors experimentally and numerically using finite element analysis (FEA) and also compared with monotonic loading. Fatigue tests were carried out using sinusoidal tension-tension loading and covering a range of stress levels from 50% to 90% of effective failure strength (EFS). Weibull distribution was utilized to predict the reliable fatigue life of joints at various joint configurations. Under cyclic loading rapid degradation of dynamic modulus indicated catastrophic failure with shorter fatigue life, while gradual degradation implied slow micro-crack growth and extended fatigue life with progressive failure while in monotonic loading, a sudden fall in the stress-strain curve represented catastrophic failure, and a zigzag curve indicated bearing failure mode before fracture. The damage rate was also determined from the hysteresis loop cycles which indicate greater loop expansion due to the stiffness degradation and higher energy dissipation shows rapid damage accumulation and shorter fatigue life at higher stress level. On the other hand at lower stress level, moderate enlargement of the hysteresis loop demonstrates extended fatigue life with slower damage propagation.