NASA NDE Working Group (NNWG)
In April 1993, a group of more than 20 NDE specialists representing all the NASA Centers have met at the Johnson Space Center (JSC) in Huston Texas and formed the NSAS NDE Working Group(NNWG).
QWNNWG↗
Engineering topics
Bar-Cohen, Y.
Publications and source records attributed to Bar-Cohen, Y..
Characterization of the Elastic Constants of Unidirectional Laminates by Oblique-Incidence Pulsed Data
Explore the source record for details and available documents.
composites composite components ultrasonic testing↗
Characterization of the Elastic Constants of Unidirectional Laminates Using Oblique-Incidence Pulsed Data
From Intro: In this paper, wer apply the LLW (leaky Lamb Wave) technique to determine the stiffness constants of unnidirectional graphite/epoxy materials...In this paper, we describe a new technique which can be used to determine all five stiffness constants by analyzing the times-of-flight of the recorded reflected acoustic waves in a pulsed LLW experiment.
composites composite components ultrasonics ultras↗
NDE Activity at Jet Propulsion Laboratory
None, This is a viewgraph outline from an oral presentation. From Intro.: Our speaker will review the NDE technology under development at the Jet Propulsion Laboratory (JPL). Emphasis will be given to Ultrasonics and application of sensors to space technology. Further, the efforts of JPL in technology transfer to the industry in the area of NDE will be covered.
NDE NDE technology defects detection Yoseph Bar-Co↗
Nondestructive Characterization of the Elastic Constants of Fiber Reinforced Composites
Composite structural components may be subjected to a variety of defects resulting in a sharp reduction in their load carrying capacity or even catastrophic failure...A nondestructive method based on ultrasonics has recently been developed for the quantitative evaluation of composite structural components during service...In this paper the method is applied to determine the stiffness constants of unidirectional graphite/epoxy materials.
composites↗
Nondestructive Characterization of Composite Materials
Increasingly, composite materials are applied to fracture-critical structures of aircraft and spacecraft...Ultrasonics offer the most capable inspection technology and recently developed techniques appear to improve this technology significantly... Recent progress in ultrasonic NDE of composites will be reviewed.
composites composite materials ultrasonics fractur↗
Wave attenuation in thick graphite/epoxy composites
The mechanics of wave attenuation in thick graphite/epoxy composites is examined in order to facilitate interpretation of the wave amplitudes recorded in ultrasonic experiments. The values of a small number of parameters are determined through comparison between calculated and measured waveforms for four specimens. The agreement between the measured and calculated waveforms are shown to be excellent in all four cases.
Mal, A. K.↗