Ultrasonic NDE for Property Estimation and Process Characterization of Industrial Rubbers

Abstract

Ultrasonic testing is primarily used as one of the popular methods for testing in a non-destructive manner. Of late, an ultrasonic non-destructive methodology is also being used as an effective tool for process characterization and property detection purposes for rubbers. Various additives are combined with pure rubber to enhance mechanical properties such as hardness and tensile strength. These property changes directly affect ultrasonic wave parameters. The current study concentrates on examining the interaction between ultrasonic wave velocity and various types of additives in rubbers. Additionally, the research also focuses on real-time monitoring of the vulcanization process in nitrile rubber with various additives. Two in-house-developed ultrasonic setups, comprising both an ultrasonic transducer and a heater arrangement, have been established for observing the behaviour of ultrasonic pulses from the sample across a range of temperatures (30°C to 160°C). The current experimental configurations primarily function as ultrasonic data acquisition systems, enabling the storage of digitized ultrasonic data either manually at specific times or automatically in real-time. Automatic data acquisition is accomplished by interfacing the Automatic Mouse Clicking Software together with the data acquisition software, which in turn, seamlessly interfaces with the multi-layered pulsar, receiver and digitizer board installed in the PCI bus slot of the controlling PC. A-scan data, digitized at a sampling rate of 40 MHz, is captured through a high bandwidth 18 mm diameter transducer of central frequency 1 MHz and a delay-line made of plexiglass, ensuring its protection from high temperature. The heater is powered by pencil-type sources to make uniform heating, and the temperature for oil and rubber is monitored and controlled by a Digital Temperature Controller (DTC). A-scan data to determine the ultrasonic velocity in longitudinal mode for the rubber sample. Measurements indicate that the ultrasonic wave velocity and