Novel High Performance and Multifunctional Sandwich Composite Structures

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Advanced Materials OBJECTIVE: Develop advanced sandwich composite structures with improved bond strength and multifunctionality via performance driven design customization. DESCRIPTION: Sandwich composites are high-performance structures due to their lightweight, high strength-to-weight ratio, impact resistance, and high specific energy absorption capabilities. Honeycomb sandwich composite materials are specifically utilized in both aerospace engineering and marine engineering applications. The performance of the sandwich composite structure is dependent on the type and material selection of the core and face-sheets. In conventional sandwich structures, the core provides compressive and shear strength, and the face-sheets provide bending strength and energy absorption capacity. Core and face-sheet interface debonding is a common failure observed in sandwich composite structures. Current fabrication methods are operating within a limited design space that cannot provide a rational load path for complex geometries subjected to multiaxial loading. The Navy seeks development of advanced sandwich composite structures with improved bond strength and multifunctionality via performance driven design customization. Innovative core and joining method designs are essential to increase the load-carrying capability without penalizing weight, cost, and fabrication time. Existing 3D printing technology can produce complex core topologies but increasing bonding strength between the face-sheets and core is still an obstacle. The design of the core with improved interface bonding provides a unique challenge and opportunity to develop novel sandwich composites structures. PHASE I: Develop high-performance sandwich composite structures that have improved bond strength. and additively manufacture different cellular cores with optimized designs. Demonstrate at least one multifunctional capability of the developed structure. The core materials to be used should have comparable properties to aluminum or Nomex cores. Conduct numerical modeling for the optimization of process parameters such as laser power, laser scan speed, and powder feed rate. Perform mechanical tests like edge wise compression, flat wise tension, climbing drum peel, impact, open-hole compression, and compression after impact to demonstrate the desired performance reliability of the sandwich structure. Also, evaluate the structural performance using unit-cell based modeling and simulation. Incorporate a digital technique like machine learning to develop a model to optimize structural performance and process parameters. The Phase I effort will include prototype plans to be developed under Phase II. PHASE II: Optimize the structural performance, design, and process parameters. Manufacture curved and complex sandwich composites based on the optimized cellular configuration. Conduct mechanical tests for performance evaluation. Expand the unit-cell modeling and the developed machine learning model. Compare the functionality and durability of the multifunctional prototype with a conventional baseline part. PHASE III DUAL USE APPLICATIONS: Develop and manufacture a representative sandwich composite for naval aircraft and conduct testing to demonstrate its multifunctional capability and that the mechanical performance of the component meets or exceeds that of a conventional sandwich structure. Coordinate with industry partners that are manufacturing sandwich composites to facilitate the utilization and transition of the proposed technology. The proposed technology can be integrated into rotorcraft and fixed wing aircraft with sandwich structures as direct replacements. These sandwich composites will not only have increased performance compared to conventional sandwich structures but will supplement their known benefits with additional multifunctional capabilities. This technology will allow aircraft manufacturers to utilize and apply the benefits of this developed additive manufacturing process to critical and complex aircraft sandwich composites. REFERENCES: 1. Singh, A. K.; Davidson, B. D.; Hasseldine, B. P. and Zehnder, A. T. Damage Resistance of Aluminum Core Honeycomb Sandwich Panels with Carbon/epoxy Face Sheets. Journal of Composite Materials, Vol. 49, 2015, pp. 2859-2876. https://journals.sagepub.com/doi/abs/10.1177/0021998314557297 2. Du Plessis, A.; Razavi, N.; Benedetti, M.; Murchio, S.;, Leary, M.; Watson, M.; Bhate, D. and Berto, F. "Properties and Applications of Additively Manufactured Metallic Cellular Materials: A Review." Progress in Materials Science, Vol. 125, 2022, pp. 1-28. https://www.sciencedirect.com/science/article/pii/S0079642521001420 3. Sahu, S. K.; Sreekanth, P. R. and Reddy, S. K. A Brief Review on Advanced Sandwich Structures with Customized Design Core and Composite Face Sheet. Polymers, Vol. 14, 2022, pp. 1-34. https://www.mdpi.com/2073-4360/14/20/4267 4. Kausar, A.; Ahmad, I.; Rakha, S. A.; Eisa, M. H. and Diallo, A. "State-of-the-art of Sandwich Composite Structures: Manufacturing - to - High Performance Applications." Journal of Composites Science, Vol. 7, 2023, pp. 1-28. https://www.mdpi.com/2504-477X/7/3/102 KEYWORDS: Multifunctional sandwich composites; Cellular composite core; Composite core bonding; Additive manufacturing; Numerical modeling; Mechanical testing