A Novel Technique With a Magnetostrictive Transducer for In Situ Length Monitoring of a Distant Specimen

A Magnetostrictive sensor was used to generate sound waves in a specimen through thirty feet of wire. Many hardware aspects are discussed such as boundaries, materials, acoustic horn design, and sound propagation characteristics which facilitated the generation of sound energy in the specimen. Temperature effects on velocity and length were calculated and a model was developed to determine length from a time of flight measurement. The specimen was heated in an oven to various temperatures and times of flight were measured and compared to the model. Results show agreement between the measured values and the model as well as the ability for a high precision length measurement.