ABSTRACT
One viable solution to the inherent problem of the insensitivity of a particular velocity measurement to a particular elastic modulus is to oversample and take more measurements than minimally required for property reconstruction. Many of the recent papers in elastic modulus reconstruction employ descent approach, and may be expected to have greater accuracy in modulus determination than techniques that are minimally sampled. A further area of considerable interest is that of the sensitivity of ultrasonic velocity measurements to all pertinent elastic moduli, particularly the in-plane moduli. For orthotropic plates, for example, instead of taking measurements along the two symmetry axes in the plane of the plate to isolate the contributions from the various moduli totally arbitrary directions may be employed. R. Mignogna and co-workershave achieved good success in materials with symmetry through the use of twenty-seven measurements in nonsymmetry directions to solve for the nine unknowns using a least squares minimization procedure.
