Using Standing Lamb waves and the Finite Element Method to Detect Hard Inclusions in Silicone Rubber Disks
(English)Manuscript (preprint) (Other academic)
The presence of an inclusion in a cylindrical silicone rubber disk is determined using FEM, standing Lamb waves, and an algorithm using multiple frequency footprints. Radial elastic waves are emitted into the disk by a cylindrical piezoelectric sensor placed in the center of the disk. The visco-elastic properties of the silicone rubber disk is modeled by a fractional derivative model and the hyperelastic effect at the radial resonance frequency was compensated for. Using the finite element model, the Lamb wave transition frequencies in the impedance frequency response of the sensor was calculated for a specified position of the inclusion. The set of frequencies was named the footprint for that position. The position of the inclusion was varied between 0.05 to 0.95, with a step of 0.01, of the radial length of the silicone rubber disk. For each position, a footprint was calculated. The footprints,s, with corresponding positions, were stored in a database. A positioning algorithm was developed that could match an unknown footprint to a footprint in the database. A self-test of the algorithm showed that the correct position was found for 94% of the tested positions. The results of the positioning algorithm was that the presence of the inclusions were detected, and that the positions of the inclusions at 0.38 and 0.63 were estimated by the positioning algorithm as: 0.45 and 0.74, with relative errors +18% and +17% respectively. The positions are given as the ratio of the radius of the inclusion to the silicone rubber disk radius.
Piezoelectric, Silicone rubber, Impedance, Resonance, Lamb waves, Phantom, footprint
Medical Laboratory and Measurements Technologies
Research subject Electronics
IdentifiersURN: urn:nbn:se:umu:diva-88217OAI: oai:DiVA.org:umu-88217DiVA: diva2:714404