Development of a Non-contacting Stress Measurement System during Tensile Testing Using the Electromagnetic Acoustic Transducer for a Lamb Wave

Abstract: In recent years, investigations into the changes in the microstructure during the processing of functional metal materials have been carried out by many researchers. Therefore, it is required that the change in the material characteristic during processing by a nondestructive evaluation method be evaluated. However, conventional technology has been restricted to a static material characteristic evaluation. For example, a strain gauge has the problem that it can influence the measurement conditions of the tensile test and can only evaluate the position at which the strain gauge is attached. We then tried to develop a non-contact stress measurement system for tensile testing using an EMAT with a Lamb wave. The EMAT measures the propagation time of a Lamb wave between the receiver and a transmitter during the tensile testing. The actual measurement system consists of 2 sets of EMATs. The interval between the transmitter and the receiver of the first set is 100mm and the interval between the lead lines of the meander sensor coil is 5mm. Another one is installed between the transmitter and the receiver of the former EMAT, and the interval between the transmitter and the receiver is 10mm, while the interval between the leads lines is 0.5mm, and can move in the direction of the load. The average stress of the entire piece can be measured by the former EMAT and the partial stress distribution can be measured by the latter one. In this presentation, the specifications of the measurement system and the evaluation results are reported.