The online ultrasonic testing system for composite strips

Abstract

Composite strips are often used as elastic elements, for example, springs. Beside stiffness, one of the most important characteristics is durability of such strips when they operate under cyclic load. This depends upon the quality of the composite, particularly on existence of the delaminations. Such qualitative properties of composites may be best evaluated using ultrasonic testing techniques.
The developed ultrasonic testing system allows on-line testing of composite strips when they moves with speeds up to 1 m/s. The operation principle of this system is based on evaluation of the ultrasonic signal propagating through the strip. The background for development of such system was development of the rotating excitation transducers (transmitters) investigation of acoustic fields, excited by these transducers, and development of the wideband ultrasonic microphones. The pulse excitation was chosen to avoid multiple reflections and propagation though the air influence.
Testing results are presented in a graphical format, showing position and size of defects in a strip.