Measuring the grain structure of aerospace materials is very important to understand their mechanical properties and in-service performance. Spatially resolved acoustic spectroscopy is an acoustic technique utilizing surface acoustic waves to map the grain structure of a material. When combined with measurements in multiple acoustic propagation directions, the grain orientation can be obtained by fitting the velocity surface to a model. The new instrument presented here can take thousands of acoustic velocity measurements per second. The spatial and velocity resolution can be adjusted by simple modification to the system; this is discussed in detail by comparison of theoretical expectations with experimental data.
Smith, R. J., Li, W., Coulson, J., Clark, M., Somekh, M. G., & Sharples, S. D. (2014). Spatially resolved acoustic spectroscopy for rapid imaging of material microstructure and grain orientation. Measurement Science and Technology, 25(5), https://doi.org/10.1088/0957-0233/25/5/055902