Detection and Quantification of Damage in Metallic Structures by Laser-Generated Ultrasonics

According to the statistics on predecessors, the failures in metallic structures caused by fatigue cracks account for more than 90% [4]. According to the NNPE values calculated from each excitation point, the damage can be quantified successfully. [...]the changing of the laser beam spot caused by damage is helpful for the damage detection. The widths of the measuring points in Figure 16b are 380 (0.1 × (17.1 − 13.3)) um, 250 (0.1 × (25.1 − 22.6)) um, and 110 (0.1 × (28.4 − 27.3)) um, respectively, which match the actual measurements well. [...]the proposed technique was again able to detect and quantify the damage on the connection transverse plane of the twin-screw compressor body.