2D VOLUMETRIC STRAIN IMAGING THROUGH THZ TIME-DOMAIN SPECTROSCOPY OF STRONTIUM TITANATE FLEXIBLE COMPOSITE ACTING AS REMOTE PASSIVE SENSOR

Strain field imaging can have important applications in the fields of material characterization and structural health monitoring. Terahertz Time-Domain Spectroscopy (THz TDS) is a relatively new technique capable of measuring the amplitude and phase of an electromagnetic pulse (EMP) in the THz band, which is characterized by very low absorbance in most dielectric materials and allows to study small variations in a material’s electromagnetic properties The work studies how applying a composite of Strontium Titanate (STO) particles dispersed in a low dielectric matrix to a structural component, a material that changes its dielectric constant when loaded, and sensing the change in dielectric properties with strain, a new non-destructive and remote sensing method of strain field mapping can be achieved. This method has made possible to correlate strain to changes in the time of arrival (TOA) of the EMP, and then use this correlation to measure the localized strain field around different geometries through previous material-specific calibration, which is reported in this document together with a theoretical modeling of the physics involved in the sensing process.