Material Approaches to Mitigate Gap Filler Cracking

Award Information
Agency: Department of Defense
Branch: Air Force
Contract: FA8650-11-C-5115
Agency Tracking Number: F093-116-1069
Amount: $749,999.00
Phase: Phase II
Program: SBIR
Awards Year: 2011
Solicitation Year: 2009
Solicitation Topic Code: AF093-116
Solicitation Number: 2009.3
Small Business Information
9063 Bee Caves Road, Austin, TX, -
DUNS: 625120902
HUBZone Owned: N
Woman Owned: N
Socially and Economically Disadvantaged: N
Principal Investigator
 Rock Rushing
 Principal Investigator
 (512) 263-2101
Business Contact
 Monte Fellingham
Title: Contracts Administrator
Phone: (512) 263-2101
Research Institution
Development of crack resistant conductive gap-fillers fits within the Air Force"s goal of investing in low observable maintenance improvements to reduce sustainment costs and aircraft downtime. Commercially available gap-fillers are initially effective, but performance degrades under thermal and mechanical fatigue resulting in micro- and macrocracks within the matrix. Phase I showed the feasibility of formulating more durable elastomeric matrix resins capable of delivering the required conductivity and fatigue resistance. A 50-fold increase in fatigue crack resistance at 73oF was obtained with the materials developed compared to the commercial gap-fillers tested. The same gap-filler material tested a -65 degrees F showed improvement of 75 percent in crack resistance. The combination of mechanical and thermal fatigue generates the most aggressive stresses for gap-fillers on aircraft, where temperatures within the range of -65 degrees F to 250 degrees F are experienced. These stresses occur because of differential thermal expansion and modulus changes in the gap-filler material. Additional testing will be conducted in Phase II to replicate these stresses in the laboratory to determine durability over a range of temperature-stress profiles. The elastomeric gap-filler matrix developed during Phase I will be further refined and fully tested for qualification. The project team assembled includes a major gap-filler producer and airframe manufacturers. BENEFIT: Mitigation of cracking within gap-fillers will benefit many modern fighter/bomber platforms by reducing maintenance costs and downtimes. Commercial aircraft could potentially benefit as well from the development of high endurance sealant matrix materials.

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

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