Cryogenic interfacial performance and failure mechanism of Al-CFRP single-lap adhesive joint

Adhesive bonding is widely used in aerospace applications because it can effectively join carbon fiber-reinforced polymer (CFRP) components with metallic structures. However, the reliability of bonded joints in low-temperature environments remains a major concern because cryogenic interfacial behavior is not fully understood, and thermal expansion mismatch can produce severe local stresses. This study investigated the cryogenic mechanical behavior of CFRP-based dissimilar adhesive joints through experiments, theoretical analysis and numerical simulation. Tensile tests were conducted on Al–Al, CFRP-CFRP and Al-CFRP joints at 293 K, 193 K and 93 K. Failure morphologies were examined using scanning electron microscopy (SEM) to clarify the cryogenic interfacial failure mechanisms. Thermal stresses were incorporated into an existing theoretical model based on first-order shear deformation theory (FSDT) to predict interfacial stress distributions. The results showed that the interfacial strength of Al–Al joints increased as the temperature decreased. In contrast, CFRP-CFRP joints showed a 65% strength reduction from 293 K to 93 K, mainly because thermal mismatch at the fiber-matrix interface intensified microcracking. This degradation substantially reduced the load-bearing capacity of Al-CFRP adhesive joints, whose two single-lap configurations showed tensile strength reductions of 76% and 79% from 293 K to 93 K, respectively. The developed model captured the temperature-dependent interfacial stress distribution and showed that thermal expansion mismatch increases local stresses near adhesive edges under cryogenic conditions. Overall, the proposed method provides an effective approach for analyzing cryogenic interfacial behavior in dissimilar adhesive joints.