Patent ID: 7089795

Claim:
A system for detecting changes in the properties of a polymeric material, the system comprising: a frame held against the outside surface of a curved polymeric test specimen; a transmitting probe attached to said frame, wherein the transmitting probe emits critically refracted longitudinal ultrasonic waves that travel across the chord of said curved test specimen; at least one receiving probe having a frequency lower than the transmitting probe and attached to said frame, wherein said receiving probe detects said critically refracted ultrasonic waves; and a data processing system that measures the travel time of said critically refracted ultrasonic waves from the transmitting probe to the receiving probe and compares said measured travel time to an expected travel time, wherein the speed of said ultrasonic waves is affected by variations in material properties along the penetration path of the ultrasonic waves; wherein said transmitting probe and said receiving probe contain silicone cores through which the critically refracted ultrasonic waves travel.