Description:
TECHNOLOGY AREA(S): Materials/Processes
The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), which controls the export and import of defense-related material and services. Offerors must disclose any proposed use of foreign nationals, their country of origin, and what tasks each would accomplish in the statement of work in accordance with section 5.4.c.(8) of the solicitation.
OBJECTIVE: Develop a general-purpose matrix approach using domestic, commercially available components, to provide matrix solutions for rocket motor structures fabricated using filament winding, resin infusion/transfer, and pultrusion-winding operations.
DESCRIPTION: Next-generation tactical propulsion systems require significantly more performance at the material level to support extended duration and multi-mission flexibility. In addition, the performance enhancements to current systems are accompanied by the need for lower cost material and processing technologies. Fiber reinforced polymer composites are extremely advantageous for many weight-critical structural applications, such as solid rocket motor cases and missile airframes, due to their high specific tensile strength and stiffness. In addition to weight savings over metals, composite rocket motor cases also offer higher operating pressures and improved Insensitive Munitions (IM) performance.
The many material-related benefits and advancements in composite fabrication technologies have facilitated the integration of composites into Army structures; however, many traditional matrix systems that are currently in use were originally derived for strategic and space-launch applications. These matrix systems, while well-suited for larger structures produced at lower volumes, have seen widespread use in the tactical propulsion community despite the fact that production quantities and rates are higher and operational and environmental requirements are more extreme. Furthermore, the focus on low-cost solutions for higher volume tactical propulsion applications has resulted in the move toward bonded end-fittings and other innovative joining techniques which impart interlaminar stresses within the composite. When confronted with multiple stressors and the increasingly severe demands of nextgeneration systems, traditional matrix systems have struggled to meet the challenge in a cost-effective manner.
Modern technology offers the opportunity to develop matrix formulations that achieve a better balance between processing, mechanical properties, and elevated temperature performance. Matrix solutions to mitigate stress-related delamination failure in tactical composite rocket motor cases and missile airframes are critical for the development of low-cost, high performance structures that meet the demands of next-generation systems.
Matrix solutions with glass transition temperatures above 400°F (and cure temperatures at or below 370°F) are desired. Due to cost constraints for tactical rocket motor case applications, solutions for this effort are limited to epoxy-based (single and multi-functionality) systems derived from domestic, commercially available components. Resin unit costs for the solution should not exceed that of commercially available 350°F glass transition temperature filament winding epoxy resin systems, and a cost analysis of a material and process developments should be included.
PHASE I: Offerors shall identify and investigate material and processing solutions that provide good processing, delivered fiber-direction tensile strength, and glass transition performance along with enhanced shear and flat-wise tensile laminate properties over state-of-the-art matrix systems. The material solution should also exhibit enhancements to Mode I and Mode II fracture toughness behavior. Material solutions should be processable using traditional wet filament winding processes at resin bath temperatures of <110°F. Material solutions should be capable of producing composite parts with fiber volume fractions of 60-65% and void contents less than 1.5%. Capability for high throughput in typical production environments must be considered (e.g., extended cure holds in excess of 6 hours should be eliminated). Offerors shall conduct formulation activities with strong consideration of potential material obsolescence issues. Resin rheological analysis and laminate mechanical property investigations shall be performed in order to substantiate the validity of the proposed formulations for the application. Offerors should develop methods to gain insight into fiber-matrix interaction with commercial high-strength, intermediatemodulus carbon fibers produced domestically within the United States. Offerors should include a cost analysis of the material and process development.
PHASE II: Offerors shall fabricate representative tactical rocket motorcase structures utilizing down-selected formulation(s) from Phase 1 and develop material allowables and supporting analysis for the intended application. Offerors shall explore tailoring of the proposed baseline matrix system for fabrication processes and applications and develop property-performance relationships. Modifiers/fillers to improve mechanical properties such as compressive strength, adhesion, modulus and glass transition will be investigated.
PHASE III DUAL USE APPLICATIONS: Demonstrate the matrix system’s performance in a relevant environment. As this technology is pervasive, a Phase III application for integration into Army missile systems would include replacement of legacy matrix systems which are currently being used in composite missile structures across the Capability Areas. Programs that would benefit from this innovation are not limited to Army systems, but extend throughout the Department of Defense and to the National Aeronautics and Space Administration. In addition to composite missile structure applications, this technology could be utilized in commercial applications in the private sector of the aerospace industry.
KEYWORDS: Fiber reinforced polymer composites, solid rocket motor cases, missile airframes, stress-related delamination failure, epoxy-based systems
