Moment analysis methods of ultrasonic waveforms to characterize the internal temperature and melt transition boundary for materials with irregular porosity.
The utilization of acoustic measurements occurs frequently in a multitude of industries. Monitoring the internal thermal and phase states of materials is of particular interest to the petro-chemical, food, and polymer processing industries, and ultrasound has found limited investigation within the literature for such applications. In this thesis, ultrasound is shown to be useful for monitoring spatial thermal variations through the thickness of a material system without the need to access the interior of the medium in question. The research presented within this thesis will show how the characterization of the internal thermal state of a structure containing random and irregularly shaped internal voids is possible using the internal moments of the captured acoustic waveform. Studies are presented to demonstrate the sensitivity of the resulting analysis to variations in the experimental configuration. The results of this research demonstrate how the proposed methodology is capable of quantifying the internal thermal and phase states of porous mediums with thermal gradients and approximating the two-dimensional variation of the temperature from ultrasonic waveforms.