抄録
Sandwich composites are widely used in load-carrying structures and there is a need for a testing method that will allow for qualitative and quantitative assessment of the bond between the face-sheets and the core. The sandwich single cantilever beam (SCB) test has attracted attention as one of the best candidates for evaluating the debond fracture toughness between face-sheet and core in sandwich panels under mode I type loading. In the sandwich SCB test, when the bending stiffness of the face sheet is low and the debond fracture toughness between the face-sheet and the core is high, the deflection of the face-sheet may become large to a degree that the assumption of small deformation does not hold. Regarding the theoretical analysis of sandwich SCB test, a beam on elastic foundation model has been proposed. However, the incorporation of large deformation effect into the theoretical analysis model has not yet been thoroughly investigated. In this study, sandwich SCB test by using specimens with thin face-sheets is conducted and the nonlinear load-deflection behavior which is possibly caused by the effect of large deflection of loaded upper face-sheet is confirmed. The finite element analysis (FEA) including geometric nonlinear effect is conducted and it is confirmed that the nonlinear behavior predicted by the numerical analysis generally agrees with the test result. Furthermore, to theoretically analyze the sandwich SCB test specimen including the large deflection effect, an analysis method which incorporates the ‘elastica’ solution into the beam on elastic foundation model is used. The result of the theoretical analysis agrees well with that of FEA. It is suggested that the theoretical analysis employed in this study has the potential for both qualitative and quantitative evaluation of the sandwich SCB test which includes the effect of large deflection of loaded upper face-sheet.
