Real-time monitoring of crack propagation in fiber-reinforced composite plates using iFEM methodology

Inverse finite element method (iFEM) is an efficient and robust approach to obtain displace- ment/strain/stress state of the structure by monitoring strain values obtained from discrete locations in the structure. Therefore, the iFEM methodology can precisely detect any variation in strain field of the structure due to presence of damages inside the material. In this study, the advantage of using iFEM methodology for monitoring crack propagation in a laminated composite is shown for the first time in the literature. To this end, a pre-cracked composite plate is loaded under tensile loading condition and crack growth is monitored using digital image correlation (DIC) system. The discrete strain data obtained from DIC are used as an input for the iFEM algorithm, and full field displacements/strains are reconstructed using an inverse-plane element formulation. This full field information is leveraged to predict an exact crack length and monitor its dynamic propagation until the global failure of the material. The iFEM methodology demonstrates an unprecedented precision in crack growth monitoring inside the composite laminate without necessity of previous knowledge about material properties and the position of the initial damages/cracks.