Amendment in observation of cracklike defects in metal plates with new instrumentation by utilizing holographic interferometry as NDT method

摘要

In holographic interferometry an object must be irritated in order to make material defects or displacements of the object visible. In solids an elastic wave is a reliable source of this irritation for holographic interferometry purposes. The nature of the elastic wave is quite essential when studying crack-like defects in metal plates. A high quality CO$-2$/-pistol can establish an impact velocity of over 100 m/s and adequate stability in a long series of impacts can be generated by the pistol's bullet. In this paper a new instrumentation for external impact on the object in holographic interferometry is described. Interferograms are recorded by a double-pulsed ruby laser synchronized with the external impact. Some interferograms of a 10 mm thick iron plate are studied. In these interferograms the crack-like defects are clearly observable.