Abstract
The intent of this research is to determine if changes in the macromechanical material properties of Polydimethylsfloxane (PDMS) produce appreciable changes in the phase or group velocity of waves in a 3 layered plate. The material properties of PDMS, such as elongation and shear moduli, can be varied through temperature. The application of this research is polymer composite curing and extrusion. Using the Lamb formulation for elastic waves in steel plates, a theory for a 3 layered plate is developed. Following Viktorov's method for excitation and reception of Lamb/Rayleigh waves, both an experimental device and acquisition method are developed. The materials chosen for this study are steel, which has elastic properties, and PDMS, which has viscoelastic properties. The material properties of steel remain constant in the temperature range being examined-- 20 to 1000C. The material properties of PDMS undergo significant changes for the same temperature range. Surface wave experiments are conducted at various temperatures, 25, 55, and 950C. The voltage time histories of antisymmetric and symmetric Lamb waves are digitally acquired and stored for analysis. The signals are analyzed using two methods: time analysis and frequency analysis. The time analysis, specifically "rough" group velocity calculations, reveal minimal information concerning changes in the signals. The frequency analysis of the data reveal meaningful changes in the phase velocity.
Sherman, Marcell (1993). An experimental study concerning the effect of temperature on phase velocity in a 3 layered, steel-Polydimethylsiloxane-steel, plate. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1993 -THESIS -S553.