Study of Adhesive Deformation at Bonding Interface between CFRP and AHSS by Micro Digital Image Correlation Technique

The integration of carbon fiber-reinforced polymer (CFRP) with advanced high-strength steel (AHSS) offers significant promise for lightweight, multi-material vehicle applications. While adhesive bonding is a commonly used joining method, the understanding of its effectiveness in bonding metal to CFRP remains limited. The traditional traction-separation law does not accurately represent the non-linear behavior observed during lap shear tensile testing of adhesive bonded metal-composite joints. For this reason, an in-house micro digital image correlation technique was developed to investigate localized adhesive deformation and failure at the adhesive-adherend interface using miniature lap shear tensile testing. Structural adhesives with different moduli were utilized to assess the effectiveness of joining CFRP and AHSS. The constitutive behavior of these adhesives was characterized using the micro digital image correlation technique. Initial numerical modeling of the adhesive bond was conducted, and the results were compared with experimental findings.