A cohesive model with a multi-stage softening behavior to predict fracture in nano composite joints

The scope of this research is presenting a new traction-separation law for composite adhesive joints in the presence of nanoparticles in mode I and II fracture. The experimental work involved evaluation of nanoparticles effects on bridging laws, cohesive mechanism, and traction-separation laws in mode I and II fracture. Nanocomposite samples have been undergone double cantilever beam, and end notched flexure tests. The experimental bridging laws were converted into traction-separation models applicable to user-defined interface/cohesive finite elements, and a new modified model was presented to simulate and predict fracture in mode I and mode II. The obtained traction-separation laws for various nanoparticles contents can be utilized in the finite element methods for numerical simulation. A damage evolution formulation was presented, and contributing parameters were modified. Numerical modeling in Abaqus software was implemented to compare experimental results of single lap joint strength and predicted mechanism within the new proposed model.