Session: 19-02: Material Characterization by Ultrasonic waves

Paper Number: 98443

98443 - Polycrystalline Reconstruction Based on 2d Ultrasound Computed Tomography 

Microstructural mapping of the polycrystalline metallic alloy is a key component in predicting macroscopic material behavior. Non-destructive subsurface polycrystalline imaging is a valuable yet challenging field. This paper proposes a computational ultrasonic imaging method for high-resolution, subsurface polycrystalline reconstruction using signals measured on a sample's boundary and a full waveform inversion technique. For this 2D numerical study, the anisotropic elastic coefficient parameterization is introduced and connected to the corresponding polycrystalline orientation. The forward wave propagation simulation is performed using a spectral finite element method. The theoretical background and numerical tools are introduced for the parameterization of crystalline orientation and elastic coefficients, the wave propagation simulation software, and the proposed grain reconstruction framework. An inversion framework is developed for inverting the six elastic coefficients, and the crystalline orientations. To benchmark the performance of the proposed grain inversion methodology, we have designed two models containing rectangular granular regions using the structured mesh. Reconstruction performance benchmarking is systematically conducted for both rectangular regions and a representative polycrystal. The generation of polycrystalline samples, and discuss the inversion of spatial orientation maps, as well as the calculation of crystallographic texture has also been introduced. Overall, the reconstructions have broad correspondence to the scanned, unknown models. We further discuss artifact mitigation strategies and the potential to extend this work. 

Presenting Author: Jiaze He University of Alabama