Adhesive dynamic behavior in the clinch-bonding process of aluminum alloy A5052-H34 and advanced high-strength steel JSC780

Mechanical clinching is a commonly used method for joining dissimilar materials in the automotive industry. The clinch-bonding process was developed based on the clinching process to ensure the fixation of the adhesively bonded parts up to the curing process, where the adhesive gains its maximum strength. However, the fluid flow of the adhesive during clinch-bonding interferes with the interlock formation, thereby causing quality issues. The lack of a systematic understanding of the dynamic behavior of adhesives during the process poses optimization obstacles. This study aims to clarify, using numerical simulation, the dynamic flow behavior of the adhesive and its influence on clinch-bonding joint formation. Simulation models of the clinching and clinch-bonding processes of high-strength steel JSC780 and aluminum alloy A5052-H34 under different process conditions were established and validated experimentally. The modeling clarified the critical role of blank holding force on the adhesive flow direction and local hydraulic pressure evolution that led to adhesive pockets. The Cockcroft–Latham damage criterion was introduced to evaluate the local damage to the steel, based on which the root cause of neck cracking generated under insufficient adhesive outflow condition was revealed. The knowledge obtained from the modeling was subsequently experimentally proven.