Prediction and detection of primary microcracks in carbon fiber reinforced polymer under load

Abstract

Carbon fiber reinforced polymers (CFRP) are widely used in the manufacturing of critical parts and structures in the aerospace industry due to the combination of low density, high strength, and stiffness. Production of parts and structures with pre-predicted properties is a difficult task provided significant anisotropy of physical properties and complex microstructure. The solution to this problem has to be based on the correct mathematical model describing the behavior of parts and structures made of CFRP under operational loads. Moreover, experimental data on physical, mechanical, and thermophysical properties and their change depending on the number of loading cycles has to be implemented. In view of the above, prediction of the occurrence and development of microcracks in the material becomes significant. The aim of this article is to develop algorithms for prediction and detection of primary microcracks in CFRP under loading using fiber Bragg grating (FBG) sensors and multiscale mathematical modeling. The results of measuring the primary residual deformations in the plates made of CFRP at the manufacturing stage by embedded FBG sensors and testing its performance under loading was presented. Multiscale mathematical modeling of a numerical experiment performed to evaluate the occurrence of areas of primary microcracks in CFRP under loads. It is demonstrated that splitting of peaks of resonant wavelengths of embedded FBG sensors indicates the occurrence of primary damage and microcracks.