Experimental investigation of nanoparticles effects on cohesive model and bridging laws of mode I fracture in the adhesive joints

In this paper, an experimental study is conducted on bridging and cohesive mechanism of adhesive bonded joints including Nano-composite and Nano-adhesive for mode I fracture. Nano-composite adherents with glass fibers and alumina nanoparticle have been fabricated and underwent DCB test. The concentration of this study is on the comparison of three different types (ECM, CBT, and MCC methods) of traction-separation laws and the effect of adding nanoparticles on them. A modified trapezoidal model (P1) is presented. The obtained bridging laws and cohesive mechanism (traction-separation laws) for different nanoparticles wt% (in adhesive and adherent) can be used in the finite element method for numerical simulation. Values obtained for critical displacement by different methods have a good consistency with each other with a relatively similar value, except for the sample by 0.5% wt Nano-particle in adhesive. In addition, critical displacement increases with increasing nanoparticle content in the adhesive, and then decreases. In that, the greatest critical displacement was observed in adhesive samples with nanoparticle content of 0.5%. Although, critical stress obtained from CBT to MCC methods were consistent, they were different from ECM results. The critical stress decreased with further addition of nanoparticles to the adhesive, and then started increasing. In that, the lowest critical stress was observed in sample adhesives with nanoparticle content of 0.5%.