ARMY SBIR 17.1 Topic Descriptions

TECHNOLOGY AREA(S): Air Platform

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 Announcement.

OBJECTIVE: Develop and demonstrate lightweight, durable, low cost recuperators for 5 Kilowatt turbo-generators to power DoD Group 2/small Group 3 unmanned aerial systems (UASs) for increased reliability and operational capability.

PHASE I: Key components/geometry features of the proposed recuperator concepts should be studied by the company with design work, analysis, computational studies, and key idea tests to substantiate the ability to provide a lightweight, low cost, and durable/reliable recuperator that can be effectively integrated into a current or future 5-8 kilowatt turbo-generator system.

PHASE II: Phase II will fully develop and fabricate the recuperator, integrate it with a 5-8 kilowatt turbo-generator (that will operate on heavy-fuel (JP-8, diesel) and provide power to electrical payloads in additional to motor driven propulsors), and demonstrate the fully recuperated turbo-generator system in a ground test environment.

PHASE III DUAL USE APPLICATIONS: Phase III options would include further design enhancements, endurance/reliability testing of the recuperated micro-turbine engine, and potential integration into a representative UAS system and demonstration of the performance of the system with flight testing in a UAS mission environment.

REFERENCES:

1. McDonald, C.F., 1996, “Heat Recovery Exchanger Technology for Very Small Gas Turbines,” International Journal of Turbo and Jet Engines, 13, pp.239-261.

2. McDonald, C.F., 2000, “Low Cost Recuperator Concept for Microturbine Applications,” 2000, ASME paper 2000-GT-0167, Am. Soc. Mech. Engin., New York, NY.

3. Ward, M.E., 1995, “Primary Surface Recuperator Durability and Applications,” Turbomachinery Technology Seminar paper TTS006/395, Solar Turbines, Inc., San Diego, CA.

4. Oswald, J.I., Dawson, D.A., and Clawley, L.A., 1999, “A New Durable Gas Turbine Recuperator,” ASME paper 99-GT-369, Am. Soc. Mech. Engin., New York, NY.

KEYWORDS: unmanned aerial system, recuperated small turbo-generator, heavy fuel engine, power to weight ratio, fuel efficiency, low noise, low-cost manufacturing

TECHNOLOGY AREA(S): Air Platform

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 Announcement.

OBJECTIVE: Develop and demonstrate lightweight, durable, high power density electric motor technologies for main/auxiliary propulsors to enable future turbo-generators to power DoD Group 2/small Group 3 unmanned aerial systems (UASs) for increased reliability and operational capability.

DESCRIPTION: Tactical requirements for unmanned aerial systems are exceeding current capabilities for performance (payload, range), reliability, maintainability, detectability, and supportability. Mission requirements such as increased power, extended endurance, low altitude maneuverability in urban environments without detection, increased tactical capability, and high reliability are becoming paramount. These combined requirements are currently not fully realized with conventional rotary, internal combustion, or turbine-based propulsion architectures. Improved engine reliability is a critical need area. Electrical power requirements for advanced payloads is also increasing, which adds weight to the air vehicle. Micro-Turbine based hybrid more-electric architectures offer the potential for a new paradigm for increased UAS system level flexibility, efficiency, readiness level, weight reduction, reliability, mission capability, and survivability. A weak link in this type of hybrid architecture is the electric motor drive. Improvements in electric motor performance at lower power settings while addressing thermal issues are needed. The following goals/metrics will be followed: motor input voltage will be 270VDC; nominal output RPM will be 3200-3500 rpm; Continuous Shaft Power at Nominal RPM will be 20HP; weight goal is less than or equal to 6lbs; motor efficiency goal is greater than or equal to 95% at 50-100% power and 90-95% at 25-50% power. The electric motor will be air cooled and operate up a pressure altitude of 18,000 feet without detrimental effects to its operation. Additionally, the motor will be required to pass MIL-STD-810G testing for altitude, high and low temperatures, rain, sand and dust, and salt fog at a minimum.

The resulting advanced electric motor propulsion system would need to be able to meet different operational requirements of a Group 2/small Group 3 UASs, which include full power takeoff capability, high part-power efficiency for improved cruise endurance, and quiet operation capability.

PHASE I: During the Phase I effort, the electric motor should be designed, fabricated and validated to substantiate the ability to provide a lightweight, low cost, and durable/reliable system that can be integrated into a current and future 5-20 HP micro-turbine/more electric hybrid UAS systems.

PHASE II: Phase II will fully develop, fabricate, and demonstrate the electric motor, in a bread-board simulated UAS environment. Various realistic mission profiles will be used during testing. Environmental tests will be executed. Additional validation to be performed at an Army facility to corroborate evidence of performance goals.

PHASE III DUAL USE APPLICATIONS: Phase III options should include endurance testing and integration of the enhanced hybrid propulsion system into an appropriate UAS airframe and demonstrate the performance of the advanced electric motor/system with flight testing in a UAS mission environment.

DUAL USE COMMERCIALIZATION: Military Application: UAS performing Intelligence, Surveillance and Reconnaissance (ISR), targeting and target acquisition missions. Commercial Application: Law enforcement, Homeland Security, and emergency service Unmanned Air Systems performing intelligence, surveillance, search and rescue, and disaster relief missions.

REFERENCES:

1. Petro, John, 2011, "Achieving High Electric Motor Efficiency", EEMODS 2011Energy Efficiency in Motor Driven Systems, Paper 060, European Commission, Luxenbourg, EU

2. Macheret, J., Teichman, J., and Kraig, R., 2011, “Conceptual Design of Low-Signature High-Endurance Hybrid-Electric UAV”, Institute for Defense Analysis (IDA), IDA Doc NS D-4496, Washington D.C.

3. Harrop, P., Harrop, J., 2015, “Electric Drones: Unmanned Aerial Vehicles (UAVs) 2015-2025”, ID Tech Exchange, Automotive & Electric Vehicles Report, Cambridge, MA

4. Bullis, Kevin. 2015, “Hybrid Power Could Help Drone Delivery Take Off”, MIT Technology Review, Cambridge, MA

KEYWORDS: unmanned aerial system, electric motor, micro-turbine engine, electric hybrid propulsion, heavy fuel engine, electric UAS

TECHNOLOGY AREA(S): Air Platform

OBJECTIVE: Develop and demonstrate in-process monitoring and closed-loop feedback methods that can be utilized in metallic additive manufacturing processes to improve repeatability for geometric dimensions, material properties, and quality.

DESCRIPTION: Army rotorcraft components require structural integrity to be flight safe. Traditional manufacturing methods have been refined over time to achieve high reliability such as casting processes used for gearbox housings or machining used for mounts, fittings, and pitch-link horns. Recent progress with use of Additive Manufacturing (AM), especially powder bed fusion processes, has demonstrated manufacture of complex components as a single part, which may save manufacturing labor, cost, and reduce production time. The application of optimized topology in design of parts can have the added benefit of weight savings unfeasible using traditional manufacturing processes. In order for additive manufacturing to transition to widespread use in aerospace, the AM processes must be repeatable and reliable to meet aerospace qualification standards. There are several challenges with AM processes that limit the use for manufacturing. Some of the common challenges/limitations for metal are:

1. Residual stresses can be high in AM parts, which limit the loading of parts. Optimization strategies must be developed as part of the effort.

2. Density of the material throughout the part can be inconsistent. Density can be influenced by un-melted entrapped powders. Overcoming this challenge needs to be addressed as part of the effort.

3. The rapid cooling rates associated with AM processes can affect the microstructure of the base material resulting in variations in desired strength, ductility, toughness, and modulus. The new AM process control system must mitigate the effects to material properties.

4. Geometry and surface finish of parts can be inconsistent from part to part.

The relationship between AM process parameters and part quality have been studied and reported [1]. Porosity/density is affected by laser power, laser speed, and layer thickness. Temperature can affect residual stresses, material microstructure, and geometry. Many of the process parameters such as temperature and laser speed, can be controlled. In-situ sensors can provide information such as melt pool temperatures, layer thickness, laser power, and laser track. Methods are needed for in-process monitoring and closed-loop feedback for AM processes to improve repeatability for geometric dimensions, material properties, and quality. The methods need to monitor and control the AM process parameters, identify flaw areas, and provide feedback to AM equipment during the build of each layer. It is also desired that any flaws, such as un-melted powder or voids, be corrected by the AM equipment prior to building the subsequent layers. The closed-loop feedback methods must integrate with AM equipment computer controls. Technologies should enable determination of the boundaries of the molten pool within 0.001” (in order to define the size and shape), measurement of temperature over the range from 700 °F to 3000 °F (representative of the molten pool and surrounding regions) to within 25 °F, measurement of geometric features to within +0.005”, detect flaws in the range of 0.010 - 0.001”, and determine chemical composition within 1 weight percent.

For Phase I and Phase II, the technology shall concentrate on aluminum alloy applications to achieve equivalent or superior mechanical properties of Aluminum A357 (AMS 4219). The demonstration of the technology should be the manufacturing of an Army helicopter gearbox (e.g., intermediate or tail rotor gearbox). Offerors are encouraged to team with a helicopter Original Equipment Manufacturer (OEM).

PHASE I: Demonstrate the feasibility of sensors for use as an in-process monitoring and feedback system for additive manufacturing. Efforts should show that the sensors can meet the demands of the AM process environment and provide feedback to the computer control system.

PHASE II: Create a closed loop feedback system to optimize the AM processes for flaw density control, thermal stresses, surface finish and material properties. Demonstrate the improved AM processes by manufacturing several sets of coupons and testing them for yield strength, ultimate strength, fatigue strength, hardness testing, etc. Test the system on AM metallic powders. Compare coupon performance to baseline properties using other AM and traditional processes. Manufacture at least two full-size gearboxes for testing to demonstrate the technology in a relevant part.

PHASE III DUAL USE APPLICATIONS: Transition the new or optimized AM process closed loop feedback system via aerospace Original Equipment Manufacturers (OEM) and/or qualified suppliers for Army rotorcraft. Demonstrate the AM process for actual aircraft components. Potential commercial / dual-use applications include aviation, medical, automotive, marine and industrial applications.

REFERENCES:

1. 
   Mani, Mahesh, et al. “Measurement Science Needs for Real-time Control of Additive Manufacturing Powder Bed Fusion Processes,” NISTIR 8036. National Institute of Standards and Technology. http://dx.doi.org/10.6028/NIST.IR.8036
   

2. 
   Manfredi, D. et al. “Additive Manufacturing of Al Alloys and Aluminum Matrix Composites (AMCs),” Contract FP7-2012-NMP-ICT-FoF-313781. European Space Agency. http://dx.doi.org/10.5772/58534
   

3. 
   “Measurement Science Roadmap for Metal-Based Additive Manufacturing,” NIST, May 2013 http://www.nist.gov/el/isd/upload/NISTAdd_Mfg_Report_FINAL-2.pdf
   

4. 
   McLellan, D., "Tensile Properties of A357-T6 Aluminum Castings," Journal of Testing and Evaluation, Vol. 8, No. 4, 1980, pp. 170-176, http://dx.doi.org/10.1520/JTE11609J
   

5. 
   AMS 4219. “Aluminum Alloy Castings 7.0Si - 0.55Mg - 0.12Ti - 0.06Be (A357.0 T6) Solution and Precipitation Heat Treated,” SAE International. October 2015. http://standards.sae.org/ams4219/
   

6. 
   Hu, Dongming, Radovan Kovacevic. “Sensing, modeling and control for laser-based additive manufacturing,” International Journal of Machine Tools and Manufacture. Volume 43, Issue 1, January 2003, Pages 51-60.
   

7. 
   http://dx.doi.org/10.1016/S0890-6955(02)00163-3
   

8. 
   ASTM E1479 – 99 (2011), “Standard Practice for Describing and Specifying Inductively-Coupled Plasma Atomic Emission Spectrometers,” ASTM International. http://dx.doi.org/10.1520/E1479-99R11
   

9. 
   ASTM B822-10, “Standard Test Method for Particle Size Distribution of Metal Powders and Related Compounds by Light Scattering,” ASTM International. http://dx.doi.org/10.1520/B0822-10
   

10. 
    ASTM B311-13, “Standard Test Method for Density of Powder Metallurgy (PM) Materials Containing Less Than Two Percent Porosity,” ASTM International. http://dx.doi.org/10.1520/B0311
    
    
    

TECHNOLOGY AREA(S): Air Platform

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 Announcement.

OBJECTIVE: Develop a non-destructive bondline inspection technique suitable for assessing structural integrity of high-efficiency composite structures.

DESCRIPTION: Trends indicate aircraft structural components are increasingly being designed using composite materials. Because continuous-fiber composites allow a material to have great strength in the fiber direction, designers are able to tailor plies to create laminates that have strength in the direction where it is needed. The resulting composite systems, with fiber supported in polymer matrix, have high strength-to-weight efficiency.

Current aerospace composite components are often joined using mechanical fasteners, which add weight, increase stress, and essentially damage the component. The drilled fastener holes act as static stress raisers. Structural composites are known to be static notch sensitive due to drilled holes, as opposed to the fatigue notch sensitivity of aluminum. Holes in composite can lead to additional ply build-up to ensure a slow crack growth failure mechanism by greatly surpassing static loads requirements. Minimizing mechanical fasteners in composite structures can reduce weight, manufacturing complexity, and assembly labor.

Advancement in composite joining methods is needed. Adhesive bonds are already inherent to composite materials at the laminate level where plies are bonded. Joining composite structure through bonding could minimize or completely replace mechanical fastening methods; however, there currently exists no way to validate the integrity of the bond. To realize aircraft design of primary structure using adhesive bonding, the structural integrity must be ensured throughout the service life.

The Army desires an inspection technique capable of detecting any degradation of bondline strength due to combined loading and environmental effects such as temperature and moisture. Previous efforts of Hennige and Cribbs (2008) have explored ultrasonic inspection methods which generate pulse amplitudes that produce strains just below the accepted bond strength. A drawback of this approach is the destructive effect on strength degraded bonds. A truly non-destructive solution is sought which will not degrade the load carrying ability of structure. Possible directions for solutions that can achieve the desired state may include in-situ monitoring methods which have potential for manufacturability, light weight, and reliability. Another avenue for a solution may be a rapid inspection technique to be used with existing maintenance inspections, while remaining cognizant of life-cycle cost associated with the tradeoffs in maintenance and benefits from bondline design. Solutions should be consistent with the Army’s desired maintenance free operating period concept and have enough fidelity to ensure bond integrity, and ultimately structural integrity, between inspections.

PHASE I: Develop an inspection method for bondlines of aerospace composite material systems. This phase should determine limitations of material system, limitations to joint types, limitations for size resolution, limitations to geometric configuration, and precision tolerances of fracture energy for proposed bondline inspection method. At the end of Phase I the Offeror shall perform proof-of-concept testing to show that system can non-destructively inspect a bondline for meeting the minimum threshold for strength.

PHASE II: Further refine and mature the developed bondline inspection method. This phase should test a variety of materials and joint configurations with good and poor quality bonding to build confidence in the inspection method as a universal solution. Verify detection of any degradation of bondline strength due to environmental effects. Provide analytical and experimental verification that inspection technique has sufficient fidelity (probability of detection and confidence) to ensure structural integrity of bondline between inspection periods. This phase should develop a prototype device as a deliverable.

PHASE III DUAL USE APPLICATIONS: Refine the design for commercialization for aerospace applications. A successful Phase II will provide evidence that the technology is promising for both use in field applications and in manufacturing quality assurance. A business case analysis should be conducted. Single or multiple product development will include design of user-interface and software verification and validation. Fully characterize the inspection reliability, including probability of detection and confidence interval.

REFERENCES: