NON-DESTRUCTIVE EVALUATION OF DEFECTS IN COMPOSITE BI-MATERIAL STRUCTURES AND ESTIMATION OF FRACTURE FRONT USING DATA DRIVEN TERAHERTZ TIME DOMAIN ANALYSIS
The high luminosity Large Hadron Collider (HL-LHC) will collide particles at unprecedented rates to search for new physics and make high precision measurements to challenge the standard model with emerging technologies that pose high demands for the materials of charged particle tracking detector support structures. Tracking detectors at current (and future) colliders are encounter high-radiation environment where polymeric and carbon fiber composite materials are used in the mechanical support structures of the detectors. The accumulated radiation dose for these materials and thermal loads lead to defects like voids and cracks due to de-gassing and thermal cycling. Terahertz time domain spectroscopy is used to map these strains in a bi-material strip and trace the locations of fractures in a thermal interface material (TIM) layer or an adhesive layer. Statistical data driven terahertz scan image processing analysis is used for predicting the fracture propogation behavior to validate the cohesive FEA model for the fracture observed.