In Situ Damage Monitoring of CFRPs by Electromagnetic Tomography With the Compatible Multitemplate Supervised Descent Method

In this article, an in situ damage detection framework for carbon fiber-reinforced plastics (CFRPs) is proposed. The methodology involves the design of an electromagnetic tomography (EMT) sensor and develops an absolute image reconstruction method for EMT. A linear EMT sensor is designed for in situ structural health monitoring of CFRP tensile load test specimens. A compatible multitemplate supervised descent method (cmt-SDM) based on a normal mixture distribution model of pixels is proposed for EMT image reconstruction. The cmt-SDM was developed to overcome the ill-posed problem in absolute image reconstruction. Simulation and experimental results show that the method proposed in this article can be employed to monitor and evaluate the local damage degree of CFRP specimens under quasistatic tensile loading. In addition, when the local fiber-breaking ratio reaches 40%, the damage location can be accurately reflected by the imaging results. Compared with the traditional SDM method, the method proposed in this article shows smaller estimation errors and delivers more accurate reconstructed images.