Damage detection of C/C composites using ESPI and SQUID techniques

Nondestructive Testing of Polymers and Polymer–Matrix Composites

“…A combination of techniques can be used either as a validation method for one or the other, as a benchmark, or the increased evidence of indications can be explored for a more detailed description of damage, for example by data fusion (327,328). Combinations reported include, among others, DSPI, X-ray CT and TSA (317); ultrasonic C-scan and shearography (318); ultrasound, thermography, vibration testing and embedded sensors (319); IRT and AE (329); IRT and DSPI (330); AE, ESPI and Superconducting Quantum Interference Device (SQUID) current mapping (331), and Electrical Potential Change method, AE and Lock-in Thermography applied to debonding monitoring of composite repairs (332). Combinations of NDT or NDE methods and their application raise two important issues.…”

A Survey of Scrutinizing Delaminated Composites via Various Categories of Sensing Apparatus

“…The basic concept of phase shifting interferometry is inserting a device (e.g., a PZT transducer) into the optical path to incorporate known phase shifts. As depicted in Figure 5, the techniques may classified into camera-based interferometry [65][66][67][68][69][70][71] and detector-based interferometry , out of which the former is limited in temporal domain resolution, whereas the latter limited in spatial domain resolution [11]. In second classification, when coupling a broadband light into the fiber, local FBG sensors using Bragg gratings as sensing elements placed within an optical fiber reflect back a narrowband signal whose peak wavelength (Bragg wavelength) depends on the grating's period and effective refractive index.…”

“…Data of largely deformed areas located within bulge borders processed through genetic algorithm along with FE data predicted a thorough identification of delamination. Moreover, electronic SPI displacements measured at in-plane and out-of-plane directions have successfully been applied to inspect composite laminates containing damage mechanisms of splitting, microcrack, and delamination under laser illumination [67].…”

In situ damage sensing in the glass fabric reinforced epoxy composites containing CNT–Al2O3 hybrids

“…However, the composites usually exhibit gradual degradation of mechanical properties during service, then resulting in catastrophic failure, due to the initiation and propagation of different levels of damage, such as, the microcracking, interfacial debonding, delamination and fiber breakage [2,3]. As a result, it is required to develop methods for predicting the damage in advance.…”