SITIS Archives - Topic Details
Program:  SBIR
Topic Num:  N07-032 (Navy)
Title:  Innovative Material for Enhancing Landing Gear Life
Research & Technical Areas:  Materials/Processes

Acquisition Program:  PMA 274; Presidential Helicopters Program
 RESTRICTION ON PERFORMANCE BY FOREIGN CITIZENS (i.e., those holding non-U.S. Passports): This topic is “ITAR Restricted”. The information and materials provided pursuant to or resulting from this topic are restricted under the International Traffic in Arms Regulations (ITAR), 22 CFR Parts 120 - 130, which control the export of defense-related material and services, including the export of sensitive technical data. Foreign Citizens may perform work under an award resulting from this topic only if they hold the “Permanent Resident Card”, or are designated as “Protected Individuals” as defined by 8 U.S.C. 1324b(a)(3). If a proposal for this topic contains participation by a foreign citizen who is not in one of the above two categories, the proposal will be rejected.
  Objective:  Develop and demonstrate innovative low-cost, high-strength, high-fracture-tough, corrosion-resistant metal alloys.
  Description:  Aircraft landing gear components are subjected to some of the highest stresses on an air vehicle. Common materials used today by the United States Navy (USN) are 4340 steel, 300M, and AerMet 100. AerMet 100 has superior material properties to 4340 and 300M. These landing gear materials are chosen because of their material properties and the austere environment in which USN aircraft operate. The USN air vehicle environment facilitates this need for a high-strength, high fracture toughness, corrosion-resistant metal alloys. Landing gear components made from AerMet 100 has had success within the USN. However this is an expensive, limited supply material. The USN is interested in pursuing an alternative to AerMet 100 with the development of a high-strength, fracture-tough, corrosion resistant, lower cost metal alloy. The nominal material property values for AerMet 100 are 250-ksi 0.2 percent yield strength, 285-ksi ultimate strength, and 100 ksivin. Modeling and simulation (M & S) technology could be used to develop this material for the USN. Traditional methods of trial and error to develop new materials are very costly and time consuming. M & S techniques would allow for the creation of a material to fit the specific needs of the USN. Previous projects along these lines have been unsuccessful in providing the corrosion resistance necessary for the USN aircraft. Once the material composition has been refined, a coupon could be produced and tested to verify the M& S conclusions. An alternative landing gear material would reduce life-cycle maintenance and cost for USN aircraft. Landing gear components produced from these innovative metal alloys could have increased capabilities. With corrosion resistance, plating of the components would not be necessary. Plating involves coating components with expensive toxic materials to prevent damage and/or failure due to corrosion. Corrosion causes rust, cracks, and breaks that can cause failure of landing gear components. Thinner dimensions and lower weight components could be fabricated with these materials. With the increased fracture toughness and strength, fatigue cracks that occurred would have a slower growth rate, thus lengthening the period for detection before critical crack length is reached. In addition, the inspection interval would be decreased.

  PHASE I: Develop low-cost, corrosion-resistant, high-strength, high-fracture toughness materials suitable for USN landing gear components. Design the selected alloy using modeling and simulation. Establish feasibility through limited coupon testing.
  PHASE II: Optimize the properties of the alloy through an iterative approach that includes modeling, fabrication, and testing. Initiate the development of the material design allowable database for the optimized design,through a coupon fabrication and testing program.. Mechanical property testing should include fracture toughness, ultimate strength, yield strength, and elongation at room temperature. Corrosion resistance testing should include resistance to general corrosion, stress corrosion cracking, and corrosion fatigue in 3.5% NaCl solution.

  PHASE III: Fully develop the design allowable database for the material. Demonstrate and validate the performance of the new material through component testing in a service environment. PRIVATE SECTOR COMMERCIAL POTENTIAL/

  DUAL-USE APPLICATIONS: A high-strength, high-fracture toughness, corrosion-resistant metal alloy has the potential for transition to the commercial aircraft market for cost reduction and enhanced landing gear life expectancy.

  References:  1. Metallic Materials Properties Development and Standardization (MMPDS),http://www.cartech.com/products/wr_products_strength_am100.html

Keywords:  Landing Gear Components; High Strength; High Fracture Toughness; Corrosion Resistance; Cost Reduction; Modeling & Simulation

Questions and Answers:
Q: The description gives as a goal a replacement for AERMET 100 and list nominal mechanical values for that alloy. Should those values be considered minimums for the new material or as targets? e.g. Would a 250ksi ultimate tensile strength material be acceptable?

A: The required mechanical properties are as follows:
Yield Strength: Not Less than 250 ksi
Ultimate Tensile Strength: Not Less than 285 ksi Plane Strain Fracture Toughness, Kic: Not Less than 100 ksi sr in Threshold Stress Intensity for Stress Corrosion Cracking, Kiscc: Not Less than 50 ksi sr in

The nominal mechanical values should be met or exceeded. 250 ksi would be an acceptable 0.2% yield strength, 285 is the acceptable ultimate strength.
Q: 1. Can we get a ranking for the following:
Cost/lb
Corrosion Resistance
Fracture toughness (room temp)
Cold temperature fracture toughness
Tensile/Yield Strength
Weldability

2. Should we shoot for tube or forged bar as final form?

3. Cold temperature fracture toughness: Are we looking for -40F or -65F K1c values?
A: 1. Tensile/Yield Strength, Fracture Toughness and Corrosion Resistance (These three are equally important.) 2. Cost/lb 3. Weld ability 4. Cold Temperature Fracture Toughness

2. Forged bar. (Current landing gear materials, e. g., AerMet 100 steel, are forged bar.)

3. Currently, we are looking for the room temperature fracture toughness, not the cold temperature one.
Q: The description gives as a goal a replacement for AERMET 100 and list nominal mechanical values for that alloy. Should those values be considered minimums for the new material or as targets? e.g. Would a 250ksi ultimate tensile strength material be acceptable?

A: The required mechanical properties are as follows:
Yield Strength: Not Less than 250 ksi
Ultimate Tensile Strength: Not Less than 285 ksi Plane Strain Fracture Toughness, Kic: Not Less than 100 ksi sr in Threshold Stress Intensity for Stress Corrosion Cracking, Kiscc: Not Less than 50 ksi sr in

The nominal mechanical values should be met or exceeded. 250 ksi would be an acceptable 0.2% yield strength, 285 is the acceptable ultimate strength.
Q: 1. Can we get a ranking for the following:
Cost/lb
Corrosion Resistance
Fracture toughness (room temp)
Cold temperature fracture toughness
Tensile/Yield Strength
Weldability

2. Should we shoot for tube or forged bar as final form?

3. Cold temperature fracture toughness: Are we looking for -40F or -65F K1c values?
A: 1. Tensile/Yield Strength, Fracture Toughness and Corrosion Resistance (These three are equally important.) 2. Cost/lb 3. Weld ability 4. Cold Temperature Fracture Toughness

2. Forged bar. (Current landing gear materials, e. g., AerMet 100 steel, are forged bar.)

3. Currently, we are looking for the room temperature fracture toughness, not the cold temperature one.

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