長ゲージひずみ測定によるCFRP層間破壊靭性試験の精密化および安定化

概要

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Mode I Double Cantilever Beam (DCB) and mode II End Notched Flexure (ENF) tests for Interlaminar fracture toughness were carried out on unidirectional carbon fiber reinforced plastics (CFRP) using a long and a short strain gages glued on the specimen surface. For the DCB test a new analysis method has been developed to calculate the fracture toughness, G_<IC>, based on the strain output. The results were compared with the G_<IC> calculated by an usual analysis method based on a load-displacement curve. For the ENF test, a new control method to stabilize the fracture propagation has been developed. Here the test is conducted so as to increase at a constant rate the difference of the strain of the long and the short gages. This method makes it possible to obtain a continuous R-curve of the mode II interlaminar fracture toughness, G_<IC>. Further an analysis method to calculate crack length and G_<IC>, based on the strain data is also established. Because the strain output is significantly sensitive to the crack propagation, fracture initiation is detected more precisely and accurate determination of crack initiation becomes possible by these method.
一般社団法人日本機械学会の論文
1999-06-25