Dynamic analysis of scarf adhesive joints in CFRP composites modified with Al2O3-nanoparticles under fatigue loading at different temperatures

Fatigue tests were conducted on scarf adhesive joints (SAJs) with composite substrates at room temperature (RT) and 50 degrees C. The adhesive layer was modified with Al2O3-nanoparticles. Dynamic parameters such as damping factor, storage modulus, dissipated energy and potential energy (U-p) were measured from the stress-strain hysteresis loops of the SAJs with the aim of knowing which ones are best for early prediction of joint collapse. Incorporation of Al2O3-nanoparticles into the adhesive layer improves the fatigue strength by about 4.8 and 24.5% at RT and 50 degrees C respectively. The glass transition temperature was improved by 8.3% and thus, at 50 degrees C the fatigue strength of the Al2O3-SAJs was decreased by 5.4% in return of 20.3% for the NE-SAJs. The variation of the U-p with fatigue life is more pronounced compared to the other dynamic parameters and thus, can be modeled to monitor the integrity of the joint and preventing their catastrophic failure.

Automated summary

Fatigue tests were conducted on scarf adhesive joints (SAJs) with composite substrates to investigate the effects of Al2O3 nanoparticles on fatigue strength at different temperatures. Incorporation of Al2O3 nanoparticles improved fatigue strength and influenced the glass transition temperature. The U-p parameter was found to be the most suitable for predicting joint collapse.