Accession Number : ADA322266

Title :   Evaluation of Innovative NDI Methods for Detection of Widespread Fatigue Damage.

Descriptive Note : Technical rept.,

Corporate Author : DEFENCE SCIENCE AND TECHNOLOGY ORGANIZATION CANBERRA (AUSTRALIA)

Personal Author(s) : Sharp, P. K. ; Rowlands, D. E. ; Clark, G.

PDF Url : ADA322266

Report Date : AUG 1996

Pagination or Media Count : 67

Abstract : High-performance high-strength aircraft components such as the F/A-18 FS488 bulkhead can experience catastrophic failure in fatigue tests from very small cracks. At the same time, the efficiency of design methods used for these components results in highly uniform stressing, and a large number of fatigue cracks all growing at approximately the same rate - multi-site cracking. These circumstances place extreme demands upon the use of Non-Destructive Inspection (NDI) methods for finding and characterising defects, and when surface treatments such as peening are also employed to extend service fatigue life, it becomes almost impossible to detect the small crack arrays which are of concern. This report examines and evaluates some novel Non-Destructive Inspection techniques, that may allow numerous small cracks (less than 1 mm) over a large area to be detected. Conventional NDI techniques are also used for comparative purposes. The novel techniques used are (1) Holographic Interferometry, (2) Structural Integrity Monitor, and (3) Laser Ultrasonics. This report examines the extent to which each technique can locate cracks on a large polished specimen representing part of a bulkhead. Techniques which perform well in this evaluation will be further evaluated on a large peened specimen.

Descriptors :   *AIRCRAFT EQUIPMENT, *FATIGUE TESTS(MECHANICS), DETECTION, NONDESTRUCTIVE TESTING, LIFE EXPECTANCY(SERVICE LIFE), AIRCRAFT MAINTENANCE, MONITORING, PERFORMANCE(ENGINEERING), GROWTH(GENERAL), SURFACE FINISHING, DAMAGE ASSESSMENT, ARRAYS, EFFICIENCY, LASERS, INTERFEROMETRY, CRACK PROPAGATION, HOLOGRAPHY, ULTRASONICS, HIGH STRENGTH, ALUMINUM, INSPECTION, ATTACK AIRCRAFT, JET FIGHTERS, CATASTROPHIC CONDITIONS, STRUCTURAL INTEGRITY.

Subject Categories : Aircraft
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE