TECHNOLOGY AREAS: Air Platform, Materials/Processes

ACQUISITION PROGRAM: F35 - Joint Strike Fighter, ACAT I

OBJECTIVE: Develop and demonstrate interlaminar tension test methods for CMCs at high temperatures.

DESCRIPTION: The JSF and other military platforms are targeting CMCs for aero-engine applications in order to increase power. Concerns still exist regarding the degradation of CMCs at elevated temperatures due to life limiting phenomena. Currently, there are quite a few military handbook and American Society for Testing and Materials (ASTM) test standards for CMCs at both room and elevated temperatures, including interlaminar shear strength test methods [1-3]. However, there are no test methods in interlaminar tension for CMCs at high temperatures, primarily because it is extremely difficulty to develop appropriate high-temperature (up to 2300oF) adhesives between test coupons and push rods. Epoxy-type polymeric adhesives can be conveniently used in room-temperature interlaminar tension testing [4]; however, this is not the case for high temperatures. A new test method is required to evaluate material properties/affordability in interlaminar tension at elevated temperatures and establish design data. Development of this test is especially important because CMCs exhibit more inferior properties in interlaminar than in-plane directions due to their unique woven architectures. In many cases (e.g., airfoils) CMCs' interlaminar properties can be a design criterion/limit rather than a 'superior' in-plane property.

PHASE I: Determine the feasibility of developing high-temperature test methods in interlaminar tension. Demonstrate the feasibility by analytical method (e.g., finite element analysis) and by fabricating and testing preliminary test fixtures and test coupons at temperatures up to 2300oF in air.

PHASE II: Provide practical implementation of a pertinent test method to implement the approaches developed in Phase I. Evaluate the approach by conducting interlaminar tension testing utilizing a sufficient number of test coupons with different architectures of CMCs at temperatures up to 2300 oF in air. Also, show long-term (life limiting) test capability.

PHASE III: Transition the approach to JSF and additional propulsion applications.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: CMC propulsion components have a great potential to transition to civilian aero-engine applications. Development of the proposed test method would allow the complete evaluation of high-temperature interlaminar properties. The development also will provide national consensus on a test method for the military, ASTM, and/or ISO communities.

REFERENCES:
1. ASTM C 1292, "Test Method for Shear Strength of Continuous Fiber-Reinforced Advanced Ceramics at Ambient Temperatures," Annual Book of ASTM Standards, Volume 15.01, ASTM, West Conshohocken, PA, 2007.

2. ASTM C 1425, "Test Method for Interlaminar Shear Strength of 1-D and 2-D Continuous Fiber-Reinforced Advanced Ceramics at Elevated Temperatures," Annual Book of ASTM Standards, Volume 15.01, ASTM, West Conshohocken, PA, 2007.

3. MIL-HDBK-17-5, Ceramic Matrix Composites, 2002.

4. ASTM C 1468, "Test Method for Transthickness Tensile Strength of Continuous Fiber-Reinforced Advanced Ceramics at Ambient Temperature," Annual Book of ASTM Standards, Volume 15.01, ASTM, West Conshohocken, PA, 2007.

KEYWORDS: Ceramic matrix composites (CMCs); interlaminar; tension test methods;elevated temperatures; test coupons; propulsion.

** TOPIC AUTHOR (TPOC) **

DoD Notice:   Between April 21 and May 18, 2008, you may talk directly with the Topic Author(s) to ask technical questions about the topics. Their contact information is listed above. For reasons of competitive fairness, direct communication between proposers and topic authors is not allowed starting May 19, 2008, when DoD begins accepting proposals for this solicitation.

However, proposers may still submit written questions about solicitation topics through the DoD's SBIR/STTR Interactive Topic Information System (SITIS), in which the questioner and respondent remain anonymous and all questions and answers are posted electronically for general viewing until the solicitation closes. All proposers are advised to monitor SITIS (08.2 Q&A) during the solicitation period for questions and answers, and other significant information, relevant to the SBIR 08.1 topic under which they are proposing.

If you have general questions about DoD SBIR program, please contact the DoD SBIR Help Desk at (866) 724-7457 or email weblink.