Multiscale Modeling for Numerical Prediction of Bonded CFRP Structural Strength
In transportation equipment such as aircraft, further weight reduction of airframe structures is required to improve fuel efficiency and reduce carbon dioxide emissions. In next-generation aircraft in particular, there are high expectations for “bonded structures” that join CFRP (Carbon Fiber Reinforced Plastics) with adhesives, reducing the use of mechanical fasteners such as bolts. While epoxy resin is widely used in aviation adhesives due to its excellent heat resistance and mechanical properties, it is naturally brittle. Therefore, modifiers such as rubber particles are added to enhance toughness (resistance to cracking). However, predicting in advance how property changes will occur depending on the amount of modifier added has been difficult, requiring conventional development to rely on iterative trial-and-error experiments.
In this study, a research group led by Assistant Professor Yamato Hoshikawa at the Research Center for Green X-Tech, Organization for Promoting Innovation, Tohoku University, developed a “multiscale analysis model” that couples a microscopic damage model around the modifier with a fracture model for the entire CFRP bonded structure. By focusing not only on strength but also on “toughness,” this achievement clarified the mechanism behind the improvement of bonding strength caused by modifier addition from both experimental and numerical analysis approaches. This is expected to significantly reduce trial and error in adhesive development and contribute to the design of highly reliable bonded structures in the future.
These research results were published in the academic journal International Journal of Solids and Structures (IJSS) on June 20, 2026.
Figure 1. Adhesive strength test conducted in this study. Traces of CSR particles are visible on the fractured adhesive surface.
【Publication Information】
Title: Multiscale Modeling of Toughening in Thermosetting Resins Based on a Microscopic Damage Model: Application to Bonded CFRP Structures
Authors: Yamato Hoshikawa*, Sera Koo, Yoshiaki Kawagoe, Shoko Mishima, Kazuki Ryuzono and Tomonaga Okabe
*Corresponding Author: Yamato Hoshikawa, Assistant Professor, the Research Center for Green X-Tech, Green Goals Initiative, Tohoku University
Journal: International Journal of Solids and Structures