The buckling state was reproduced in a compression test of a glass fiber reinforced plastic (GFRP) specimen. Furthermore, an effect of stiffness improvement by applying the adhesive was verified by the compression test. The load test was performed on the warmed thick plate of GFRP composites, and the state in which delamination due to buckling was produced. Compared to the non-damaged material, the stiffness of the two specimens was reduced to 16% and 22%, respectively. It was clarified in the test that the stiffness was improved by 2.5 times when the adhesive was applied to the vicinity of the buckling part, and the stiffness was restored to 66% of the initial value. Strain measurement by image correlation method (DIC) revealed that the strain in the buckling part was effectively reduced by applying the adhesive. In addition, the residual strain caused by buckling behavior can be quantitatively grasped, and the DIC can be effectively used to estimate the penetration range of adhesives.
