Nondestructive Testing, 1. General

Nondestructive testing (NDT) of materials has become an indispensable part of modern industry. Beginning with the oil and whiting method, a forerunner of the penetrant testing method used for crack detection, a variety of tests - based on numerous physical principles - have been developed. At the start, the primary task was to find flaws and discontinuities. With the advent of fracture mechanics, the measurement of flaw dimensions became more urgent. Increasing use of fiber-reinforced plastics since the 1980s has posed new challenges in material characterization