A 2nd Generation Crack-Growth Prediction Methodology for Cold-Worked Fastener Holes

Award Information
Agency:
Department of Defense
Branch
Air Force
Amount:
$99,999.00
Award Year:
2002
Program:
SBIR
Phase:
Phase I
Contract:
F33615-02-M-3237
Award Id:
57735
Agency Tracking Number:
021VA-1302
Solicitation Year:
n/a
Solicitation Topic Code:
n/a
Solicitation Number:
n/a
Small Business Information
455 N. Jackson Ave., University City, MO, 63130
Hubzone Owned:
N
Minority Owned:
N
Woman Owned:
N
Duns:
085252240
Principal Investigator:
WilliamFujimoto
President
(203) 878-8327
wfujimoto@compuserve.com
Business Contact:
WilliamFujimoto
President
(203) 878-8327
wfujimoto@compuserve.com
Research Institute:
n/a
Abstract
"The objective of this project is to develop and validate a 2nd generation crack-growth prediction methodology for cold-worked fastener holes. The methodology will be based on a three-dimensional weight function, and will handle cracks growing from theedge of the hole, as well as cracks initiating in the residual tension zone away from the hole. A predictive capability, based on probabilistic fatigue analysis, will be used to determine the most probable failure mode for the hole. For cracks initiatingin the residual tension zone, the methodology will account for the multi-stage crack growth. It will track the relaxation of the residual stresses as the crack grows through the residual stress in Stage I. In Stage II, the methodology will predict theinitiation and the growth of a secondary crack at the hole edge, resulting from the relaxation of the compressive residual stresses. The methodology will track the coalescence of this secondary crack and the primary crack into a single macro-crack inStage III. To predict the net section stress contour for the probabilistic fatigue analysis, the methodology will be combined with a CAD-based multi-layer joint analysis program to enable the cold-worked hole to be treated as part of a complex structuralsystem, rather than as an isolated hole. the 2nd generation crack-growth prediction methodology will lead to an improved ability to predict the fatigue and crack growth lives for multi-layer

* information listed above is at the time of submission.

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