Abstract：To investigate the influence of adhesive layer thickness and adhesion strength on the scratch damage of polymethylmethacrylate (PMMA) coating, scratch experiments were systematically conducted to PMMA coatings with different adhesive layer thicknesses and adhesion strengths. A constitutive model considering the competition between shear yielding and brittle fracture was employed to describe the mechanical behavior of PMMA coating, the scratch behavior of PMMA coating was simulated by finite element method. The physical mechanisms of complex scratch damage modes were revealed. The results show that: Different from the coating structures with zero-thickness adhesive layer, the deformation of the finite-thickness adhesive layer leads to local bending of the PMMA coating, resulting in the formation of internal cracks in the bottom region of the coating beneath the scratch tip. Adhesive layer with strong adhesion strength restricts the deformation of the coating during scratching, preventing severe buckling of coating in front of the scratch tip and avoiding the formation of longitudinal crack that penetrate through the coating along the thickness direction. Increasing the coating thickness can enhance the resistance of the coating to bending and buckling during scratching, thereby delaying the formation of the internal crack and longitudinal crack. These findings contribute to the understanding of the scratch mechanism and further improvement of the scratch resistance and functional integrity of PMMA coatings.
2024, Vol. 45 
