Verification of Cold Working and Interference Levels at Fastener Holes

Award Information
Agency: Department of Defense
Branch: Air Force
Contract: FA8650-08-M-3842
Agency Tracking Number: F081-088-0945
Amount: $98,141.00
Phase: Phase I
Program: SBIR
Awards Year: 2008
Solicitation Year: 2008
Solicitation Topic Code: AF081-088
Solicitation Number: 2008.1
Small Business Information
6669 Fyler Ave., St. Louis, MO, 63139
DUNS: 018571666
HUBZone Owned: N
Woman Owned: N
Socially and Economically Disadvantaged: N
Principal Investigator
 Thomas Mills
 Consulting Engineer
 (314) 644-6040
Business Contact
 Craig Brooks
Title: President
Phone: (314) 644-6040
Research Institution
The USAF recognizes that benefits to cold working fastener holes include significantly increased life of a structure subjected to fatigue loading. However, full realization of this potential from a maintenance and engineering standpoint is hindered by the fact that there is currently no adequate field technique for determining how well the material structure immediately surrounding the hole has responded to the cold working process. Thus, there is a distinct need be able to: 1. Determine the success of a cold working treatment at a fastener hole, 2. Quantify the results of the treatment in a robust crack growth and residual life analysis, 3. Monitor the evolution or relaxation of the residual stress state as usage on the component accumulates, and 4. Understand the effectiveness of the residual stress field in the presence of a crack. Our team’s approach strives to provide depot-supportable measurement of cold work residual stresses using NDI techniques currently in the USAF maintenance infrastructure. We also aim to provide the ASIP community with the life assessment tools (based on AFGROW) and criteria needed to capture the benefits of cold working in life extension and to guard against stress relaxation, the influence of cracks, and inadequate processing.

* Information listed above is at the time of submission. *

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