抄録
The proposed modified crack arrester was intensively evaluated by the numerical analysis with thermal residual strain and the fracture toughness test. The crack arrester concept is to suppress the interfacial crack for foam core sandwich panels. However, the basic crack arrester has problem of the interfacial crack penetration due to the micro-crack occurred during the manufacturing process of a foam core sandwich panel with the crack arrester. The thermal shrinkage of the crack arrester owing to the difference of thermal expansion coefficient from that of the surface skin might cause the onset of the micro-crack, which led to the crack penetration. The basic crack arrester was directly attached to the surface skin. This configuration might cause the onset of the micro-crack. The modified crack arrester had been proposed to prevent this behavior by covering the crack arrester with the surface skin. In this study, the crack suppression effect of the modified crack arrester was evaluated by the FE analysis considering the thermal expansion coefficient and the fracture toughness test under the mode I type loading. In the fracture toughness test, interfacial crack propagated in the foam core just below the resin impregnated layer and completely stopped in front of the leading edge of the arrester. Based on these results, the modified crack arrester has comparable crack suppression effect to the basic crack arrester and no crack penetration. In the fracture toughness test, strain distribution was directly measured with the DIC (Digital Image Correlation) method. Visualization of the experimental strain distribution on the foam core material could be realized. This strain distribution shows that the load redistribution on the foam core due to the modified crack arrester, which led to the crack suppression, was confirmed.
