In-Plane Testing Behavior of Adhesive-Bonded Steel Sheets: Influence of Sheet Surface Roughness, Adhesive Thickness, and Bonding Width

Abstract

Abstract There are various parameters such as bonding width, bond and adhesive thickness, blank surface roughness, adherend thickness, bond length, the geometry of the joint, surface treatment, curing and working temperature, bonding pressure, curing conditions, type of loading, etc. that affect the forming of adhesive bonded blanks in a synergistic manner. The main aim of the present work is to investigate the influence of bonding width, adhesive thickness, and blank surface roughness on the tensile behavior of adhesive bonded blanks. Interstitial free steel grade sheet is used as a base material and the two part epoxy adhesive is used for bonding the base materials. It is found that the engineering stress attained in forming the bonded blank for the same amount of strain is greater if the surface roughness is greater. The extension of the bonded blank at the break point is less for higher surface roughness base materials. With an increase in the adhesive thickness, the engineering stress decreased for a particular strain and there was no effect due to adhesive thickness on the elongation at the break point of the bonded blank. The engineering stress required decreases with the bonding width and the extension at the breaking point of the bonded blank is greater in the case of the bonded blank with a higher bonding width. A sudden fall in engineering stress has occurred in the case of adhesive bonded blanks with higher (2.4 mm) and medium adhesive thickness (1.3 mm), base material surface roughness, and bonding width, while this is not observed in 0.5 mm bonding thickness. The different stages of the forming of adhesive bonded blanks are proposed. Initially, adhesive failure occurs and then base material failure occurs depending on its ductility. Both cohesive failure and interface (adhesive) failure is seen during the forming of adhesive bonded blanks in this work.