Evaluation of the Crack Growth Gage Concept as an Individual Aircraft Tracking Device
Evaluation of the Crack Growth Gage Concept as an Individual Aircraft Tracking Device

Author: F. J. Giessler

Publisher:

Published: 1983

Total Pages: 168

ISBN-13:

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An analytical and experimental program was conducted to evaluate the crack growth gage concept for application as an individual aircraft tracking device. Three gage designs were evaluated. Volume I discusses the evaluation of two versions of a stepped thickness gage and a stepped width gage. Volume II discusses the evaluation of a side-grooved constant thickness gage. An analytical evaluation of the change in transfer function corresponding to gage design parameter changes was performed to determine the configuration of the gages to be tested. Initial spectrum tests were conducted on the first stepped gage design to determine the ranking ability of the gage. Then constant amplitude tests were conducted on the second stepped gage design. A modification of the gage was made to improve spectrum test response. The modified gage was subjected to both constant amplitude testing and spectrum testing. The analytically derived crack growth rates were compared to the test data. In general, the analysis predicted slightly higher growth rates than observed.

Evaluation of the Crack Growth Gage Concept as an Individual Aircraft Tracking Device
Evaluation of the Crack Growth Gage Concept as an Individual Aircraft Tracking Device

Author: F. J. Giessler

Publisher:

Published: 1983

Total Pages: 151

ISBN-13:

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An analytical and experimental program was conducted to evaluate the crack growth gage concept for application as an individual aircraft tracking device. Three gage designs were evaluated. Volume I discusses the evaluation of two versions of a stepped thickness gage and a stepped width gage. Volume II discusses the evaluation of a side-grooved constant thickness gage. An analytical evaluation of the change in transfer function corresponding to gage design parameter changes was performed to determine the configuration of the gages to be tested. Initial spectrum tests were conducted on the first stepped gage design to determine the ranking ability of the gage. Then constant amplitude tests were conducted on the second stepped gage design. A modification of the gage was made to improve spectrum test response. The modified gage was subjected to both constant amplitude testing and spectrum testing. The analytically derived crack growth rates were compared to the test data. In general, the analysis predicted slightly higher growth rates than observed.

Evaluation of the Crack Growth Gage Concept as an Individual Aircraft Tracking Device
Evaluation of the Crack Growth Gage Concept as an Individual Aircraft Tracking Device

Author: A. F. Grandt

Publisher:

Published: 1983

Total Pages: 0

ISBN-13:

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This report summarizes research conducted to develop the crack growth gage technique for individual aircraft tracking. The crack growth gage concept consists of mounting precracked coupons on a structural component so that service loads cause measurable crack extension in the coupon (or gage). Fracture mechanics techniques are then used to relate the gage crack growth with extension of an assumed structural flaw. Thus, the precracked coupon serves as a sensor which records service loads and responds with an output which may be related to the service life of the parent structural member. The effort described here involved two primary goals: development of a thin crack gage coupon which simulates thick section flaw growth, and development of an improved analysis method for relating gage and assumed structural crack growth. The approach employed for the first task was to design a crack gage which contained side-grooves along the crack plane. The side-grooves forced plane strain conditions in the thin coupon, and provided fatigue crack retardation behavior which more nearly matched that seen in the thicker structural member. A series of experiments conducted with the side-grooved gage geometry compared favorably with numerical predictions for the gage response.

Evaluation of the Crack Growth Gage Concept as an Individual Aircraft Tracking Device
Evaluation of the Crack Growth Gage Concept as an Individual Aircraft Tracking Device

Author: A. F. Grandt

Publisher:

Published: 1983

Total Pages: 129

ISBN-13:

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This report summarizes research conducted to develop the crack growth gage technique for individual aircraft tracking. The crack growth gage concept consists of mounting precracked coupons on a structural component so that service loads cause measurable crack extension in the coupon (or gage). Fracture mechanics techniques are then used to relate the gage crack growth with extension of an assumed structural flaw. Thus, the precracked coupon serves as a sensor which records service loads and responds with an output which may be related to the service life of the parent structural member. The effort described here involved two primary goals: development of a thin crack gage coupon which simulates thick section flaw growth, and development of an improved analysis method for relating gage and assumed structural crack growth. The approach employed for the first task was to design a crack gage which contained side-grooves along the crack plane. The side-grooves forced plane strain conditions in the thin coupon, and provided fatigue crack retardation behavior which more nearly matched that seen in the thicker structural member. A series of experiments conducted with the side-grooved gage geometry compared favorably with numerical predictions for the gage response.

Evaluation of the Crack Growth Gage Concept as an Individual Aircraft Tracking Device
Evaluation of the Crack Growth Gage Concept as an Individual Aircraft Tracking Device

Author: F. J. Giessler

Publisher:

Published: 1983

Total Pages:

ISBN-13:

DOWNLOAD EBOOK

An analytical and experimental program was conducted to evaluate the crack growth gage concept for application as an individual aircraft tracking device. Three gage designs were evaluated. Volume I discusses the evaluation of two versions of a stepped thickness gage and a stepped width gage. Volume II discusses the evaluation of a side-grooved constant thickness gage. An analytical evaluation of the change in transfer function corresponding to gage design parameter changes was performed to determine the configuration of the gages to be tested. Initial spectrum tests were conducted on the first stepped gage design to determine the ranking ability of the gage. Then constant amplitude tests were conducted on the second stepped gage design. A modification of the gage was made to improve spectrum test response. The modified gage was subjected to both constant amplitude testing and spectrum testing. The analytically derived crack growth rates were compared to the test data. In general, the analysis predicted slightly higher growth rates than observed.

Experimental Investigation of the Crack Growth Gage
Experimental Investigation of the Crack Growth Gage

Author: Donald R. Holloway

Publisher:

Published: 1980

Total Pages: 104

ISBN-13:

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The objective of this program was to determine the feasibility of the crack growth gage as a more direct method for monitoring potential crack growth damage in fatigue critical areas of F-4 aircraft structure. The major task consisted on mounting crack growth gages on a full-scale F-4C/D fatigue test article and collecting crack growth data from the gages at specified intervals. Two additional tasks were comprised of (1) conducting a gage qualification test program in accordance with MIL-STD-810C (Environmental Test Method) requirements, and (2) determining an appropriate method for collecting data from the gage. Inconsistencies in constant amplitude test results and bonding problems encountered on the F-4C/D full-scale fatigue test article prevented the MIL-STD-810C qualification tests from being started. Results of this investigation indicated that further research and development of the crack growth gage concept is required before the gage can be recommended as a fleetwide tracking device.