SETTING OF THE ANGLE OF INCIDENCE FOR GENERATING LAMB WAVES BY NON-CONTACT METHOD

Abstract

The article examined the problem of the experimental setting of incidence angles for the generation of Lamb waves in plate-type parts by the non-contact ultrasonic control method. This type of control is mainly done by the use of two types of waves: Rayleigh, which detects invisible defects on the surface of parts, and Lamb waves mode A0 and S0. Mostly used is the mode A0 due to the propagation over distances of interest in the tested materials. One of the primary aim during the testing process is to position the ultrasonic transducers (transmitter and receiver) at oblique angles of incidence on a surface. The transducers should be positioned on an access face of the plate, as is common in industrial practice, at a fixed distance from the measured plate, and leaving an air gap between transducers and the tested plate. The ultrasonic transducers are moved simultaneously linearly or in zigzag on the surface of the plate-type part to measure the hidden defects (cracks, pores, inclusions) that appear in the composite materials during the manufacturing process or during the operation. The presented work brings new insights into the setting of the angle of incidence for generating lamb waves by non-contact method.

Keywords

• non-contact ultrasonic control
• invisible defects measurement
• lamb waves
• ultrasonic transducers
• angle of incidence