1、Lessons Learned Entry: 0204Lesson Info:a71 Lesson Number: 0204a71 Lesson Date: 1993-07-06a71 Submitting Organization: LERCa71 Submitted by: S. PapellSubject: Wind Tunnel Model - Analysis Failure Description of Driving Event: During a test run on a model in a wind tunnel, several components of a wood
2、en test rig could not withstand the loads on them with the tunnel at maximum speed. Stress calculations made prior to the mishap indicated an acceptable factor of safety. However, the assumptions in the calculations for stress neglected to consider the drag force on a flat plate which is a multiplie
3、r to the dynamic pressure, resulting in a force 80 percent higher than was used in the calculations.The stress calculations on the model also made certain assumptions that were not consistent with the quality of its material and construction. The investigating committee found that the failed parts w
4、ere fabricated from inferior wood with numerous knots and that glue was not used to help keep the parts together. The inferior strength of the wood was not noted initially because the model was painted over when delivered to the test site.Lesson(s) Learned: To prevent failure, stress calculations sh
5、ould include the action of all forces on a model in a wind tunnel, taking into consideration the material of the model and method of attachment.Recommendation(s): Evaluate wind tunnel model integrity and stability by including both dynamic pressure and drag forces in the stress calculations.Evidence
6、 of Recurrence Control Effectiveness: The recommendations from the mishap report were approved by the LERC executive safety board.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Documents Related to Lesson: N/AMission Directorate(s): a71 Exploration
7、Systemsa71 Aeronautics ResearchAdditional Key Phrase(s): a71 Test Articlea71 Test Facilitya71 Test & VerificationAdditional Info: Approval Info: a71 Approval Date: 1993-10-19a71 Approval Name: Evan E. Blancoa71 Approval Organization: LERC/501-4a71 Approval Phone Number: 216-433-8717Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
