Multifrequency Eddy Current Inspection for Cracks Under Fasteners

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Abstract:

The experimental evaluation was conducted on two typical wing splice joint configurations used in the C5-A aircraft consisting of two aluminum layers each 316 to 14 inches thick. Notches simulating cracks were machined in a radial direction extending from the fastener hole and the faying surface between sheets. A digital eddy-current system designed around a PDP-1140 minicomputer was utilized for the experimental evaluations. The digital system was programmed to generate the signal wave-forms that excite the test coil and perform the function of phase-sensitive detection of response signals that are received from the test coil. Special test coils were designed to induce eddy currents in the aluminum alloy that lies beneath the head of the fasteners. A series of measurements were taken on the wing-splice samples at various frequencies, excitation levels, and phase settings. These data were analyzed using the Automatic Interaction Detector, AID, computer code to indicate initial capabilities of crack detection, and to compare the various operating parameters such as excitation frequency and test coil design.

Author(s):
Flora, J. H. ; Gruber, H. T. ; Thomas, R. E. ; Meister, R. P.
Author Organization(s):
BATTELLE COLUMBUS DIV OH
Descriptive Note:
Final rept. Dec 1975 Oct 1976
Pagination:
0135

Security Markings

DOCUMENT & CONTEXTUAL SUMMARY

Distribution:
Approved For Public Release
Distribution Statement:
Approved For Public Release; Distribution Is Unlimited.

RECORD

Collection: TR
Identifying Numbers
Report Number(s):
AFML-TR-76-209
Contract/Grant Number(s):
F33615-76-C-5062
Task Number(s):
09
Project Number(s):
7351
Monitor Series:
TR-76-209, AFML
 Subject Terms
Joint Capability Areas:
JCA_5_Command and Control; JCA_5.3_Planning; JCA_1_Force Support; JCA_1.2_Force Preparation; JCA_5.4_Decide; JCA_5.3.3_Develop Strategy; JCA_5.3.4_Develop Courses of Action; JCA_5.3.5_Analyze Courses of Action; JCA_6.1.3_Switching and Routing; JCA_6_Net Centric; JCA_6.1.1_Wired Transmission; JCA_6.1_Information Transport; JCA_1.2.1_Training; JCA_1.3_Human Capital Management; JCA_1.2.3_Educating; JCA_1.2.7_Experimentation; JCA_1.3.2_Personnel Management; JCA_1.2.5_Lessons Learned; JCA_1.2.6_Concepts; JCA_4.3_Maintain; JCA_6.2.1_Information Sharing
Modernization Areas:
Microelectronics; Fully Networked C3
Communities of Interest:
C4I
Descriptor(s):
*CRACKS, *EDDY CURRENTS, *FASTENINGS, *NONDESTRUCTIVE TESTING, *WINGS, ALUMINUM ALLOYS, CONFIDENCE LEVEL, ELECTRIC COILS, FREQUENCY, HOLES(OPENINGS), MINICOMPUTERS, NOTCH SENSITIVITY, PANELS, SAMPLING, SIMULATION, SPLICES, TEST EQUIPMENT, TITANIUM, TRANSPORT AIRCRAFT
Field(s)/Group(s):
Transport Aircraft, Couplers, Fasteners and Joints, Test Facilities, Equipment and Methods, Mechanics
Keyword(s):
C 5A AIRCRAFT, PDP 11 40 COMPUTERS
Report Date:
1976 Dec 15