REG NASA-LLIS-0509-1994 Lessons Learned - Velocities of Acoustic Emission Signals in a Thin-Walled Graphite Epoxy Tube in Agreement with Classical Plate Theory.pdf

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1、Lessons Learned Entry: 0509Lesson Info:a71 Lesson Number: 0509a71 Lesson Date: 1994-07-25a71 Submitting Organization: LARCa71 Submitted by: Bernard LewisSubject: Velocities of Acoustic Emission Signals in a Thin-Walled Graphite/Epoxy Tube in Agreement with Classical Plate Theory Description of Drivi

2、ng Event: Simulated acoustic emission signals were induced in a thin-walled graphite/epoxy tube by means of lead breaks (Hsu-Nielson Source). The tube is of similar material and layup to be used by NASA in fabricating the struts of space station freedom.The resulting waveforms were detected by broad

3、 band ultrasonic transducers and digitized. Measurements of the velocities of the extensional and flexural modes were made for propagation directions along the tube axis (0 degrees), around the tube circumference (90 degrees) and at an angle or 45 degrees. These velocities were found to be in agreem

4、ent with classical plate theory.Lesson(s) Learned: Velocities of acoustic emission signals induced by means of lead breaks in a thin-walled graphite/epoxy tube were found to be in agreement with classical plate theory.Recommendation(s): For a detailed presentation of this work, see the paper, “Exten

5、sional and Flexural Waves in a Thin-Walled Graphite/Epoxy Tube“, by John Dorighi (Mechanical Engineering Student, University of Colorado, Boulder, Colorado 80309-0424) and William H. Prosser, NASA Langley Research Center, Hampton, Virginia 23665; and, Michael R. Gorman, Aeronautics and Astronautics,

6、 Naval Postgraduate School, Monterey, California 93943. The paper appeared in Vol. 226, No. 14/1992, Journal of Composite Materials.Evidence of Recurrence Control Effectiveness: Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-N/ADocuments Related to

7、Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Research & DevelopmentAdditional Info: Approval Info: a71 Approval Date: 1997-04-02a71 Approval Name: Elijah C. Kenta71 Approval Organization: 421a71 Approval Phone Number: 757-864-3345Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-