SBIR-STTR Award

A significant barrier to the insertion of ceramic matrix composite (CMC) materials into advanced aircraft engines is their inherent lack of toughness under foreign object Damage (FOD) as well as post FOD. Our team will develop and demonstrate a physics-based model for FOD/post FOD in CMCs. The model will incorporate physical mechanisms associated with impact for two different CMC systems: a) matrix-dominated system and b) fiber-dominated system. Our methodology will address impact and post-impact of both as-built 0x9D and as-is 0x9D CMCs. It will account for architecture (2D/3D-nano) and CMC manufacturing (layered thickness, void shape/size, interfacial strength, micro-crack formation) taking advantage of the strength and toughness enhancing effect of different length scales of CMC structure. The model will be incorporated into our commercial progressive failure analysis software GENOA, that integrates commercial FEA and enhances their accuracy limitation. It will be validated using available CMC impact test data from NAVAIR SiC/SiC and Oxide/Oxide for a range of FOD tests. We will determine the feasibility for performing impact tests with Acoustic Emission/Electrical Resistance monitoring as damage assessment and health monitoring techniques that relates to damage model and life prediction. In Phase II high temperature impact testing will be conducted to further validate our model.

Benefit:
The application of CMC engine parts in advanced aircraft allows engines to operate at higher temperatures and significantly reduces engine weights. The analytical modeling strategy in CMC gas turbine engine development, as proposed herein, is a significant advantage in terms of reducing concept-to-commercialization time. This approach will result in the development of a verifiable analytical/design tool for optimization of CMC architecture and manufacturing processes. A novel approach to significantly enhance impact toughness of both SiC fiber-based, as well as Oxide fiber-based CMCs will bring these technologies closer to reality and enable the transition of these advanced material technologies to various military aircraft propulsion systems. Future use of these technologies can include hypersonic, space Thermal Protection System, and DOD aircraft parts as well as various DOE/NASA sponsored industrial power generation and aerospace related engine development programs. It has been demonstrated through a number of prior studies that ceramic matrix composite based material technologies will offer large economic and social benefits. With successful broad-based implementation, it can result in billions of dollars of cost savings and billions of tons of pollution reduction over the next couple of decades. FOD resistant CMC will allow life/durability to increase, enhancing time-on-wing and increased affordability.

Keywords:
1. Foreign Object Damage (FOD) , 1. Foreign Object Damage (FOD) , 8. Impact mechanics, 5. Ceramic Matrix Composite , 7. Compression after Impact , 4. Impact , 3. Ballistic impact , 2. Toughness , 6. FOD modeling

The Phase II STTR technical objective will update, expand, and validate the excellent results achieved in the Phase I Analysis and Modeling of Foreign Object Damage (FOD) in Ceramic Matrix Composites (CMCs) 0x9D program. The program will evaluate CMC component life capability before and after impact in a realistic operating environment. Predictions will be validated using new experimental impact results at elevated temperatures and NDE measurements of CMC specimens before and after impact. Multi-scale Progressive Failure Analysis (MS-PFA) will use the GENOA commercial software coupled with LS-DYNA/ABAQUS to assess the micromechanical multisite damage evolution process. Updated models will include triangulation, adaptive meshing, microstructure and damage visualization, interface influences, etc. Damage and stress are fully visualized down to the micromechanical level, and show fiber/matrix/ply stress redistribution after damage. Delamination initiation/propagation and damage size versus impact velocity between specific plies will be compared to test results. A high temperature impact test facility and advanced NDE measurement capability will be developed at the University of Akron. Example materials under evaluation are MI SCi/SCi, NASA N24A and S200. Life prediction in an engine environment will be demonstrated before and after impact in a Phase II Option. Close coordination will be maintained with the NAVAIR TPOC.

Benefit:
The proposed development of the micromechanical modeling technique and structural analytical tool will enable its transition to future commercial aircraft engines, both sub-sonic and supersonic. Future use may involve hypersonic aircraft propulsion systems for weight reduction and enhanced life expectancy. Analytical modeling strategy in CMC gas turbine engine design and application is an important complement to test investigation, which reduces test costs and shortens the design-to-production cycle of CMC engine components. Ceramic matrix composites also leverage large economic and social benefits in other commercial application. Commercial benefits include incorporation of advanced CMC materials in commercial land-based turbines. Catalytic converters alone in the power generation industry enable a $38 billion pollution control business each year and have reduced air pollution by 1.5 billion tons since 1975. Cutting tool and wear part manufacturers and energy generation plants will benefit from the CMC analyzing technique in development of CMC materials and components.

Keywords:
ceramic matrix composite, Impact tests, Damage evolution process, NDE of CMCs, Multi-scale progressive failure, FOD impact/post impact, Delamination size/length, CMC Lifing and Life prediction