The detection of tightly closed flaws by nondestructive testing (NDT) methods

Liquid penetrant, ultrasonic, eddy current and X-radiographic techniques were optimized and applied to the evaluation of 2219-T87 aluminum alloy test specimens in integrally stiffened panel, and weld panel configurations. Fatigue cracks in integrally stiffened panels, lack-of-fusion in weld panels, and fatigue cracks in weld panels were the flaw types used for evaluation. A 2319 aluminum alloy weld filler rod was used for all welding to produce the test specimens. Forty seven integrally stiffened panels containing a total of 146 fatigue cracks, ninety three lack-of-penetration (LOP) specimens containing a total of 239 LOP flaws, and one-hundred seventeen welded specimens containing a total of 293 fatigue cracks were evaluated. Nondestructive test detection reliability enhancement was evaluated during separate inspection sequences in the specimens in the 'as-machined or as-welded', post etched and post proof loaded conditions. Results of the nondestructive test evaluations were compared to the actual flaw size obtained by measurement of the fracture specimens after completing all inspection sequences. Inspection data were then analyzed to provide a statistical basis for determining the flaw detection reliability

Development of a laser based inspection system for surface defect detection

The objective of this project was to design and develop a laser based inspection system for the detection of surface defects and to assess its potentiality for high-speed online applications. The basic components of this inspection system are a laser diode module as illumination source, a random access CMOS camera as detector unit, and an XYZ translation stage. Algorithms were developed to analyze the data obtained from the scanning of different sample surfaces. The inspection system was based on optical triangulation principle. The laser beam was incident obliquely to the sample surface. Differences in surface height were then detected as a horizontal shift of the laser spot on the sample surface. This enabled height measurements to be taken, as per the triangulation method. The developed inspection system was first calibrated in order to obtain a conversion factor that would render a relationship between the measured spot shift on the sensor and the vertical displacement of the surface. Experiments were carried out on different sample material surfaces: brass, aluminum <ind stainless steel. The developed system is able to accurately generate three-dimensional topographic maps of the defects presented to it in this work. A spatial resolution of approximately 70 pm and a depth resolution of 60 pm were achieved. Characterization o f the inspection system was also performed by measuring the accuracy of distance measurements

Index to 1981 NASA Tech Briefs, volume 6, numbers 1-4

Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1981 Tech Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

Index to 1984 NASA Tech Briefs, volume 9, numbers 1-4

Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1984 Tech B Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

Development of nondestructive testing techniques for honeycomb heat shields Annual report, 1 Jul. 1965 - 31 May 1966

Nondestructive testing techniques for Saturn honeycomb heat shield