Molecular dynamics simulation of weak bonds in carbon fiber reinforced plastic adhesive joints

Abstract

In carbon fiber-reinforced plastic (CFRP) adhesive joints, poor adhesion because of weak bonds may occur due to contamination at the bond line. We reproduced weak bonds by using a molecular dynamics simulation (MD) approach to investigate the mechanisms of weak bonds. Weak-bond models were created by inserting water (H₂O), xylene (C₈H₁₀), and silicone molecules as contaminants in the two epoxy models. Tensile analysis was performed to evaluate the mechanical properties of the weak-bond models. The results revealed that the insertion of contaminants reduced the strength of these models. Stress concentration occurred due to the concentration of inserted molecules at the bond line. In addition, the yielding behavior was slower in the H₂O model than in the C₈H₁₀ and silicone models, and the strength of the H₂O model decreased significantly even at a small insertion rate compared with the C₈H₁₀ and silicone models. The reason for the difference in yielding behavior may be due to the high diffusion of H₂O molecules into the whole epoxy resin. The weak-bond model was reproduced using MD, and the mechanisms of weak bonds were clarified by an analysis of van der Waals potential energy.

Keywords:

• CFRP
• weak bond
• molecular dynamics
• water
• xylene
• silicone

Disclosure statement

No potential conflict of interest was reported by the authors.