Damage Detection of CFRP Laminates under Compression Using an Embedded FBG Sensor

摘要

In CFRP laminates under compression, the local buckling of the laminate occurs due to the existing interlaminar delamination. The local buckling reduces the compressive strength of the laminates. Recently, the health monitoring technique with an embedded FBG sensor is shown to be efficient to detect the non-uniform strain distribution in the laminates. In this research, we examine the possibility of detecting the local buckling of the laminate using an embedded FBG sensor. First, we examine the deformation behavior of CFRP laminates with a circular interlaminar delamination by the buckling analysis based on nonlinear extended FEM. We confirm that the local buckling occurs at the delaminated sublaminate of the laminates under a remarkably small compressive load. Then, we analyze the reflection spectra of FBG sensors embedded at the delaminated region in the laminate, by combining the post-buckling analysis with the optical analysis based on the coupled-mode theory. The analytical results show that the shapes of the reflection spectra from FBG sensors change significantly with the occurrence of the local buckling. This indicates that we can detect the local buckling of the delaminated sublaminate by the reflection spectra from the embedded FBG sensor.