In-situ AM-2 Aluminum Mat Repair

Navy STTR 24.A - Topic N24A-T002
NAVAIR - Naval Air Systems Command
Pre-release 11/29/23   Opens to accept proposals 1/03/24   Now Closes 2/21/24 12:00pm ET    [ View Q&A ]

N24A-T002 TITLE: In-situ AM-2 Aluminum Mat Repair

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Sustainment

OBJECTIVE: Evaluate the implementation of a novel repair technique for AM-2 aluminum matting repair in-situ. The idea is to analyze the repair effectiveness by comparing virgin AM-2 specimens to specimens artificially damaged and repaired, in terms of mechanical performance.

DESCRIPTION: Rapid deployment of Expeditionary Airfields (EAF) is critical to expedited military transportation and sustained presence across multiple military theaters around the world. At the core of EAF, utilization of aluminum matting, referred to as EAF AM-2 matting, is essential to lay down for air vehicles to successfully land in a variety of soil environments. Maintenance of such a system ensures prevention of premature structural failure, thereby preventing in-service landing failures and loss of life. However, AM-2 matting is often shipped back to a refurbishment facility for various reasons, one of which includes significant structural damage.

The decision to repair is influenced by the type of damage and the defect size encountered when the matting is damaged. Guidance will be provided to awardees. Damage due to forklift tines are also taken into account, where the maximum allowable hole dimensions for repair are 1.5 in. (3.81 cm) wide by 10 in. (25.4 cm) long. If the matting is damaged, the EAF Marines have to pull up and remove all of the surrounding mat to be able to remove and replace the affected piece. Depending on where the damaged mat is in the airfield the current process of removal and replacement can take a substantial amount of time and labor to complete both while downing that portion of the airfield. With the ability to rapidly repair in situ, the mean time to repair (MTTR) will be greatly decreased, thus improving the Operational Availability.

The EAF Marines are an expeditionary force, therefore a premium is placed on weight, size, and maneuverability of materials, which imposes constraints on any solution. The EAF Marines must be prepared to operate in any feasible climate, a requirement that extends to their equipment as well. AM-2 matting is manufactured in either 6 ft (1.83 m) or 12 ft (3.66 m) by 1.5 in. (3.81 cm) by 2 ft (.61 m) pieces of aluminum and weigh 75 lbs (34.02 kg) or 150 lbs (68.04 kg) respectively. AM2 mats are additionally treated with nonskid coating.

The aim of this STTR topic is to enhance the repair and refurbishment capability of EAF AM-2 aluminum matting. Ultimately, an ideal application would involve on-site repair of holes and cracks that form on AM-2 matting while installed on an airfield. Areas of consideration for a potential solution should include fuel/power consumption (if needed), time to repair, and comparable mechanical properties to undamaged AM-2. The threshold for this effort is to repair the damaged aluminum AM-2 matting utilizing a preferred repair technique or method. The objective is to repair the damaged matting and provide some semblance of a friction surface for the repaired surface area.

PHASE I: Provide a conceptual design for a process for the repair and refurbishment of EAF AM-2 aluminum matting. Prove the engineering and economic feasibility of meeting the stated requirements through analysis and lab demonstrations. Identify specific strategies for meeting performance and reliability goals. Optimize the processing parameters for application to various hole and crack sizes on AM-2 matting specimens. Assess representative macrostructural matting specimens under flexure loading is recommended in this phase. Sustainment or improvement of mechanical properties is to be evaluated with use of the chosen repair method/technique. The Phase I effort will include prototype plans to be developed under Phase II.

PHASE II: Demonstrate prototype performance with AM-2 matting. Provide an estimate of costs including manufacturing. Provide a failure analysis, service life estimate, and assessment of meeting requirements. Using optimized parameters evaluated in Phase I, repairs would ideally be conducted on full-scale AM-2 matting structures (6 ft–12 ft) (1.83 m–3.66 m), and full-scale mechanical testing is to be conducted. Data sets are to be obtained and compared to existing data on AM-2 mechanical analyses.

PHASE III DUAL USE APPLICATIONS: In partnership with the PMA and the Arresting Gear IPT, new repair/refurbishment cost and logistics estimates are to be assessed given the optimal materials and parameters established in the previous phases. This will ultimately prepare the repair method for fielding.

Any aluminum paneling or matting that is utilized in commercial systems (e.g., stiffener walls for a train, aircraft fuselage paneling and floorboard repair, building materials and building structures) can be repaired with relative ease without having to replace or even remove the part from the rest of the structure or system.

REFERENCES:

  1. Widener, C. A.; Ozdemir, O. C. and Carter, M. "Structural repair using cold spray technology for enhanced sustainability of high value assets." Procedia Manufacturing, 21, 2018, pp. 361-368. https://doi.org/10.1016/j.promfg.2018.02.132
  2. Chaudhary, B.;, Jain, N. K. and Murugesan, J. "Development of friction stir powder deposition process for repairing of aerospace-grade aluminum alloys." CIRP Journal of Manufacturing Science and Technology, 38, 2022, pp. 252-267. https://doi.org/10.1016/j.cirpj.2022.04.016

KEYWORDS: aluminum; matting; in-situ; repair; expeditionary; airfield

** TOPIC NOTICE **

The Navy Topic above is an "unofficial" copy from the Navy Topics in the DoD 24.A STTR BAA. Please see the official DoD Topic website at www.defensesbirsttr.mil/SBIR-STTR/Opportunities/#announcements for any updates.

The DoD issued its Navy 24.A STTR Topics pre-release on November 28, 2023 which opens to receive proposals on January 3, 2024, and now closes February 21, (12:00pm ET).

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Topic Q & A

12/18/23  Q. This posting represents Frequently Asked Questions to DoN STTR topic N24A-T002 during the Pre-release period.
  1. What are the current damage scenarios that have happened, or, are expected, besides the forklift tine damage? Ballistic damage? Aircraft triggered damage?
  2. What are the current repair methods for the AM-2 panels? In this topic summary it appears that the panels are disassembled and the damaged panel is sent to a repair depot to make weld repairs. Are the welded patches doubler plates or flush welded repairs?
  3. The patch that we developed for the CG 47 TYCOM is 100 mils thick with gently tapering edges. Can the repair have a 100 mil ‘bump’?
  4. "Optimize the processing parameters for application to various hole and crack sizes on AM-2 matting specimens." Tine damage of 1-1/2 x 10 was mentioned. However, what could be the maximum hole size?
  5. What is the alloy of the aluminum so that we may know the material mechanical properties?
  6. What are the Impact loads from landing directly on the patch?
  7. What is the shear load from braking on the patch?
  8. ".. analyze the repair effectiveness by comparing virgin AM-2 specimens to specimens artificially damaged and repaired, in terms of mechanical performance"
    Is objective to have the patched area have the same strength, and stiffness as an unpatched area?
  9. Is this a permanent or temporary repair?
  10. Is there a target time for MTTR; between start of repair and ready to use?
  11. What is a good model of the damaged and repaired panel to demonstrate the technology – remove YY x ZZ inch of skin plus underlying stiffener, then show patched version area meets requirements of undamaged area?
   A. Below are responses to the FAQ posted on 12/18/2023 above:
  1. Ballistic damage is not very common, despite the varying factors in multiple theaters. Aircraft triggered damage may be due to repeated cycling with landings and jet plume heat exposure. There may be others, but we can discuss more in details with the Expeditionary Airfield team as needed. Damage from installation is common, such as hammer dings and dents. For long term installations, water freezing inside the mat causes mat bulging which in some cases can cause cracks in the top surface of the mat. Forklift tine holes come from the staging of AM2 Mat packages.
  2. For field repairs we have a procedure for using epoxy repair to repair holes. For refurbishment, we utilize flush weld repair.
  3. This could be tricky for packaging purposes. If all the mats have the 100 mil bump, it could adversely affect how the mats are packaged in a mat package. If only a few mats in a package have the bump, it should not be a problem. There is no problem with this bump in the mat when it is installed in an airfield.
  4. Maximum hole side is 3 inches in any dimension.
  5. The aluminum is 6061-T6, extruded
  6. I do not believe we have this information. (AM2 can withstand 330 psi load, if that helps for 6 & 7.)
  7. I do not believe we have this information.
  8. The objective is to ensure that the patched area results in a repaired matting system that can perform comparable to a virgin mat. Localized strength may not necessarily result in a higher performing mat; therefore it behooves us to obtain data on the full-scale matting system to gain insight into performance.
  9. The idea is to avoid mat replacement as often as possible in order to reduce logistics cost. (Would like it to be a permanent repair!)
  10. Not specified, a good guide is this: for the epoxy repair, the wait time is 24 hours before placing back in service.
  11. If the rib of the mat is damaged, the mat is considered NRFI in most cases. The proposed repairs should only apply to the top skin of the mat. If the patched & repair area meets the requirements of the undamaged area, that would be acceptable.
12/06/23  Q. Q-1) Assuming a company receives and satisfactorily completes the Phase I award how extensive is the expectation to " Provide a failure analysis, service life estimate, and assessment of meeting requirements. Using optimized parameters evaluated in Phase I" ? (i.e. load drop; vs. load support; or load concentrated psi strength)?
Q-2) The objective is unclear as to whether there is one or two focuses. [One focus on repairing in place the flat damaged upper surface to prevent in-service landing failures and loss of life or from the landing mat and damage from forklift tines to that surface (like as if mat was rammed into by forklift tines into the flat surface while mat was standing on its edge) or if damage from forklift tines is done to the double interlocking edges from the handling of a stack of the mats on the fork i.e. trying to get under a stack and gouging the interlock is part of the focus, (preventing the mat piece from being suitable for use in the runway construction process).] ?
Q-3) Is it anticipated that all of the repairs will still be suitable for the next runway built or if the fix is just to get the runway by in place for continued use?
   A. A-1) The expectation is to assess the mechanism of enhancement in mechanical performance of the optimized "patch" (powder formulation, patch method, etc.). One suggestion: We can look into load cycling of the AM-2 matting under flexure (the most common loading configuration), and either compare it to previous tests performed , or conduct cycling on an unbroken/virgin mat for comparison. We can proceed further with suggestions and guidance from our expeditionary airfield team.
A-2) For this STTR, since there is an established Statement of Work for AM-2 refurbishment that delineates crack/flaw damage on the flat upper surface and subsequent instructions, it may be best to focus on that, instead of the interlocking edges.
A-3) The repair is intended to improve logistics and reduce airfield downtime. Much like refurbishment, it would be ideal to have the repair done in order to provide continued use of the matting asset on the current airfield, as well as other airfields to be established that will used the repaired matting panel. The intent is to restore the mat to an RFI condition (not new) for use in the expeditionary airfield. This is the intent of our repair & refurbishment contracts. The mat will not be "new" when repaired, but it will be RFI.

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