| ||STATEMENT OF INTENT: Life cycle monitoring of polymer matrix composite components.
|| Objective: ||Develop a service life monitoring system for high-temperature polymer matrix composites used in jet engine and exhaust wash structural applications.
|| Description: ||Integrated vehicle health monitoring (IVHM) or health management approaches that have been applied to polymer matrix composites have typically been limited to composites with maximum use temperatures of approximately 250ºF. High-temperature polymer matrix composites (HTPMCs) with use temperature of 550ºF and above are known to experience physical and chemical aging due to the in service environments. Two of the primary life-limiting mechanisms in HTPMCs are hygrothermal degradation and oxidative degradation.
Hygrothermal and oxidative degradation in HTPMCs can lead to chemical changes in the resin system causing cracking and embrittlement in the surface layers of the composites. Within the oxidized layer of the composite, it is typical that the tensile strength, strain to failure, flexural strength, density, and toughness decrease while the modulus increases. Surface cracks provide pathways for the transport of moisture and oxidants to the fiber/matrix interfaces that act as high diffusion paths thereby increasing the degradation rate.
Concepts are needed to monitor the degradation of HTPMCs that are used in jet engine applications and exhaust wash structures. Examples of these new concepts may include surface or embedded sensors, active or passive sensors, etc.
|| ||PHASE I: Demonstrate the scientific, technical and commercial feasibility of the HTPMC health management ideas submitted. This includes demonstration of concept by monitoring oxidative degradation for a neat resin specimens aged in high-temperature oxidizing environments.
|| || ||PHASE II: Extend the proposed system to demonstrate performance for composites in high-temperature environments including hygrothermal and oxidative degradation and thermal cycling. Correlate measured high-temperature degradation and aging from the developed health management system to mechanical performance and expected remaining life of HTPMC components and develop a deliverable prototype system.
|| ||DUAL USE COMMERCIALIZATION: Military application: Technology can be applied to military aircraft for both engine applications and exhaust wash structures for monitoring high-temperature polymer matrix composites. Commercial application: Technology can be applied to civilian and military aircraft as well as non-aerospace applications in which high-temperature polymer matrix composites are used.
|| References: ||1. Bowles, K.J., ”Durability of Graphite-Fiber-Reinforced PMR-15 Composites Agaed at Elevated Temperatures,” Journal of Composites Technology and Research, 21(3) (1999) 127-132.
2. Meadors, M.A., Lowell, C.E., Cavano, P.J., and Herrera-Fierro, P.,”On the Oxidative Degradation of Nadic Endcapped Polyimides: I. Effect of Thermocycling on Weight Loss and Crack Formation,” High Performance Polymers, 8 (1996) 363-379
3. Schoeppner, G.A. and Curliss, D.B.,"Model-Based Design for Composite Materials Life Management," Proceedings of the 9th AIAA/ISSMO Symposium on Multidisciplinary Analysis and Optimization Conference, 4-6 September 2002, Atlanta, GA, Paper number AIAA-2002-5516.
|Keywords: ||polymer composite structures, thermal oxidative stability, health monitoring|