A Review of Nondestructive Methods for the Detection of Concealed Cracks

摘要

The report is a discussion of NDI methods for detecting concealed cracks with emphasis on crack detection under fasteners and painted and plated surfaces. Many methods are considered. They are classified as: recommended, potentially applicable, and inapplicalbe. The recommended methods are ultrasonic and eddy current. They are now field applicable. An ultrasonic method can be immediately applied to detecting cracks under fasteners and plated and painted surfaces. Eddy currents can be used to detect cracks that have propagated beyond fastener heads, in fastener holes (after removal of fasteners) and under protective surfaces. Between the two they should allow inspection of most geometries of interest. (Author)