Mode-converted diffuse ultrasonic backscatter.
Diffuse ultrasonic backscatter describes the scattering of elastic waves from interfaces within heterogeneous materials. Previously, theoretical models have been developed for the diffuse backscatter of longitudinal-to-longitudinal (L-L) wave scattering within polycrystalline materials. Following a similar formalism, a mode-conversion scattering model is presented here to quantify the component of an incident longitudinal wave that scatters and is converted to a transverse (shear) wave within a polycrystalline sample. The model is then used to fit experimental measurements associated with a pitch-catch transducer configuration performed using a sample of 1040 steel. From these measurements, an average material correlation length is determined. This value is found to be in agreement with results from L-L scattering measurements and is on the order of the grain size as determined from optical micrographs. Mode-converted ultrasonic backscatter is influenced much less by the front-wall reflection than an L-L measurement and it provides additional microstructural information that is not accessible in any other manner.
Mechanical and Materials Engineering, W342 Nebraska Hall, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0526, USA.
Ping
P
Hu
Christopher M
CM
Kube
Lucas W
LW
Koester
Joseph A
JA
Turner
D003198:Computer Simulation; D003460:Crystallization; D004058:Diffusion; D004548:Elasticity; D004867:Equipment Design; D008962:Models, Theoretical; D009038:Motion; D009716:Numerical Analysis, Computer-Assisted; D012542:Scattering, Radiation; D013016:Sound; D013232:Steel / Q000737:chemistry; D013997:Time Factors; D014159:Transducers; D014465:Ultrasonics / Q000295:instrumentation / Q000379:methods*
D013232:Steel