Innovative Helicopter Hangar Door Seals
Navy SBIR 2019.2 - Topic N192-106
NAVSEA - Mr. Dean Putnam - [email protected]
Opens: May 31, 2019 - Closes: July 1, 2019 (8:00 PM ET)
TECHNOLOGY AREA(S): Materials/Processes
ACQUISITION PROGRAM: PMS 400D, DDG 51 New Construction Program
OBJECTIVE: Develop an advanced wear-resistant water seal for DDG-51 FLT IIA/III Helicopter Hangar Doors.
DESCRIPTION: The U.S. Navy’s DDG-51 Class Destroyer helicopter hangar door water seals are designed to prevent seawater and aviation fuels from entering the hangar when the door is closed. The seals serve a critical function on the ship, as seawater can corrode and damage important ship components, and uncontained aviation fuel spills are a grave fire hazard. In order to function as an effective seal, the elastomer must meet competing requirements to withstand the harsh environment on a Navy vessel and maintain the mechanical properties to endure frequent use. The current design of the destroyer hangar door drags the water seal across the non-skid surface on the deck. Thus, the elastomer-based seals have a high failure rate due to abrasion, which increases required maintenance and compromises the safety of the ship.
Previous attempts to solve this issue involving different physical configurations (i.e., cross sections) have failed. The conclusion is that the Navy requires innovation in the current elastomer seal material. The Navy is seeking an elastomer that will allow the hangar door seal to resist the abrasive characteristics of the non-skid surface in accordance with Per MIL-PRF-24667C, maintain integrity when exposed to fuels and chemicals such as JP-4, JP-5, lubricants, hydraulic fluids, solvents, and Aqueous Film-Forming Foam (AFFF), and withstand the harsh maritime environment. The goal of this SBIR topic is to develop an advanced, wear-resistant water seal for DDG-51 FLT IIA/III Helicopter hangar doors capable of lasting a minimum of 4800 open-close cycles.
Elastomers are resistant to many environmental factors, but different elastomers possess varying levels of immunity and weakness. Elastomer product designs that fail to account for environmental factors will experience premature failure. Compounded elastomers must be tuned to possess the desired mix of mechanical properties, while resisting harsh environmental hazards on a Destroyer such as sunlight, seawater, aviation fuel, and a wide ambient temperature range of -40 to 120 degrees Fahrenheit. This trade-off in properties is illustrated by considering that compounding increasing amounts of carbon black into nitrile rubber increases abrasion resistance, which is desirable, but also increases hysteresis loss, which may cause premature seal failure.
The latest commercial research focuses on advanced nanocomposite innovation in elastomers. Advanced nanocomposites are compounds of nanomaterials such as Multiwalled Carbon Nanotubes, Nano Carbon Black, Nano Silica, and Graphene with various elastomers to improve their mechanical properties. The addition of nano-
fillers to elastomers show marked improvements in many mechanical properties including abrasion resistance; however, the addition of nano-fillers still negatively affects some of the elastomer’s dynamic mechanical properties, including hysteresis loss.
Several potential avenues of innovation exist that could improve nanocomposite elastomers and meet the Navy’s need for an improved seal. Possible solutions include reducing the amount of filler required and developing a novel nanocomposite. Reducing the amount of nano-filler needed to achieve the required abrasion resistance of leakage after 4800 door open and close cycles, which entails compressing and decompressing on ships deck surface could preserve the elastomer’s dynamic mechanical properties. This may be achieved through innovative developments such as improving nanomaterial fabrication and advancing compounding techniques, among other possibilities that increase the efficiency of the nano-filler. Novel nanocomposite development includes the development of a new nanomaterial, or the less ambitious but still innovative development of a new nanocomposite that combines multiple fillers, including nano-fillers, to obtain the desired mechanical properties. Feasibility will be established by coupon development and laboratory testing/demonstration of materials in the areas of wear and physical deformation (crush) resistance and accelerated environmental effects testing (salt water, UV, and various fuels and oils). Mechanical testing is required to take place in a simulated shipboard environment. A successful project will result in production of a full-scale prototype to be installed and tested at sea for an extended period.
PHASE I: Develop a concept for an Innovative Helicopter Hangar Door Seal that meets the requirements described above. Demonstrate the feasibility of the concept in meeting Navy needs and establish that the concept can be developed into a useful product for the Navy. Establish feasibility by coupon development and laboratory testing/demonstration of materials. Develop a Phase II plan. The Phase I Option, if exercised, will include the initial design specifications and capabilities description to build a prototype solution in Phase II.
PHASE II: Develop prototype seals for evaluation. Evaluate the prototype seals to determine capability in meeting the performance goals defined in the Phase II SOW. Demonstrate product performance through prototype evaluation, modeling, analytical methods, and demonstration over the required range of parameters, including 4800 cycles. Use shipboard evaluations to refine the prototype seal into a design that will meet Navy requirements.
Prepare a Phase III manufacturing and development plan to transition the innovative seal to Navy use.
PHASE III DUAL USE APPLICATIONS: Support the Navy in transitioning the Innovative Helicopter Hangar Door Seal to Navy use on FLT IIA/III class ships. Develop installation and maintenance manuals for the seals to support the transition to the fleet.
Rubber gaskets are used to make doors, hatches, and various other machinery interfaces water- or weather-tight. Due to the remote operating areas, harsh environments, and limited space available onboard ships, oil rigs, and other marine platforms, reliable sealing mechanisms are extremely important. Additional commercial applications include improved abrasion resistant elastomer products and sports equipment.
1. Boonbumrung, Atip. “Reinforcement of Multiwalled Carbon Nanotube in Nitrile Rubber: In Comparison with Carbon Black, Conductive Carbon Black, and Precipitated Silica.” Hindawi, Volume 2016 Journal of Nanomaterials, 9 November 2017. https://www.hindawi.com/journals/jnm/2016/6391572/
2. Ponnamma, Deepalekshmi. “Rubber Nanocomposites: Latest Trends and Developments.” ResearchGate, (2013) https://www.researchgate.net/publication/256426533_Rubber_Nanocomposites_Latest_Trends_and_Concepts
3. Walker, James. “Elastomer Engineering Guide.” www.jameswalker.biz, 9 November 2017. https://www.jameswalker.biz/de/pdf_docs/148-elastomer-engineering-guide
KEYWORDS: Multiwalled Carbon Nanotubes; Elastomer; Advanced Nanocomposites; Abrasion Resistance; Helicopter Hanger Door Seals; Nanofiller