Effects of Interlaminar Failure on the Scratch Damage of Automotive Coatings: Cohesive Zone Modeling

Interlaminar failure caused by scratches is a common damage mode in automotive coatings and is considered the potential trigger for irreversible destruction, i.e., plowing. This work strives to numerically investigate the mechanisms responsible for the complex scratch behavior of an automotive coating system, considering the interfacial failure. A finite element model is developed by incorporating a large deformation cohesive zone model for scratch-induced debonding simulation, where the mass scaling technique is utilized to minimize computational burden while ensuring accuracy. The delamination phenomenon of the automotive coating is reproduced, and its effects on scratch damage behavior are analyzed. Accordingly, it is revealed that the interlaminar delamination would produce significant stress redistribution, which leads to brittle and ductile damage of the coating and consequently affects the formation of plowing. Eventually, parametric studies on the effects of interfacial properties are performed. They demonstrate that the shear strength and shear fracture energy dominate scratch-induced delamination.

Automated summary

Interlaminar failure caused by scratches is a common damage mode in automotive coatings and is considered a potential trigger for irreversible destruction. This study aims to numerically investigate the mechanisms responsible for the complex scratch behavior of an automotive coating system, considering interfacial failure. A finite element model incorporating a large deformation cohesive zone model is developed to simulate scratch-induced debonding, and the effects of interfacial properties on the delamination phenomenon and scratch damage behavior are analyzed. The research reveals that interlaminar delamination results in significant stress redistribution, affecting the brittle and ductile damage of the coating and the formation of plowing. Parametric studies on interfacial properties demonstrate the dominance of shear strength and shear fracture energy in scratch-induced delamination.