Robotic NDT for turbine blades based on the transverse waves

The defects located on the curved surface are difficult to be distinguished by the traditional reflected echo waves, in this paper, the transverse wave is applied to test those micro-cracks, which near to the test surface. A high recurrence positional accurate robotic manipulator is used for manipulating the test object so that the positional accuracy of robotic scanning trajectory can be guaranteed, as well as the incident angle and ultrasonic propagation length. Signal to noise ratio of ultrasonic A-scan waves is improved when the constraint parameters are correct, moreover, ultrasonic C-scan image is offered to the inspector to gain the nondestructive evaluation conclusion. Experimental results indicate the crack with minimize width of 0.15 mm that can be identified by the proposed robotic NDT system, when the oblique incident test method is used, the transverse waves can be excited so that the characteristic of defects can be displayed in the C-scan image.