Landing Gear Alloy and Composite Analysis

By David Cobler

Problem

• The landing gear for the Lunar Lander Satcube must take up the minimum amount of space required and be as light as possible.

Solution

• Analyze various Alloys and Composites for a material that is very strong and light weight.– Aircraft grade Aluminum– Aluminum-Lithium Alloy 8090– Beryllium-Aluminum Alloy 363– Titanium Ti-6-2-4-2– Carbon-Epoxy

Comparison Criteria

• Material Properties– Focusing mainly on Yield Strength and Density

• Availability and Cost

Aircraft Aluminum

• Somewhat light weight• Low strength• Many suppliers• Cheap

Yield Strength

Modulus Of Elongation Density

11.0 ksi 10600 ksi 0.100 lb/in³

%Elongation @ Break

Poisson's Ratio

Shear Strength

20.00% 0.33 18000 psi

Aluminum-Lithium Alloy 8090

• Lighter than Aircraft Aluminum• Much stronger than Aircraft

Aluminum• Not Readily Available• Very Expensive

Yield Strength

Modulus Of Elongation Density

53.7 ksi 11200 ksi 0.0918 lb/in³

%Elongation @ Break

Poisson's Ratio

Shear Strength

7.00% 0.305 39200 psi

Beryllium-Aluminum Alloy 363

• Lightest Aluminum Alloy• Not as strong as Al-Li• Not Readily Available• Expensive• Permanent and or fatal

respiratory hazards when machining

Yield Strength

Modulus Of Elongation Density

30.990 ksi 29300 ksi 0.0780 lb/in³

%Elongation @ Break

Poisson's Ratio

Shear Strength

3.00% 0.2 35900 psi

Titanium Ti-6-2-4-2

• Not very light weight• Very strong• Specialty Suppliers• Somewhat Pricy

Yield Strength

Modulus Of Elongation Density

144.0 ksi 17,400 ksi 0.164 lb/in³

%Elongation @ Break

Poisson's Ratio

Shear Strength

3.00% 0.32 100,000 psi

Carbon-Epoxy Sheet

• Extremely light weight• Very strong• Specialty suppliers• Relatively Cheap

Yield Strength

Modulus Of Elongation Density

87.0 ksi 10200 ksi 0.0578 lb/in³

%Elongation @ Break

Poisson's Ratio

Shear Strength

0.80% None Found 13100 psi

Overall Comparison

Yield Strength11.0 ksi144000 psi87000 psi53700 psi30990 psi

Density0.100 lb/in³0.164 lb/in³0.0578 lb/in³0.0918 lb/in³0.0780 lb/in³

Yield Strength/Density110 ksi/(lb/in³)878 ksi/(lb/in³)1505 ksi/(lb/in³)584 ksi/(lb/in³)397 ksi/(lb/in³)

Aircraft AluminumTitanium Ti-6-2-4-2Carbon Fiber EpoxyAluminum Lithium alloy 8090Beryllium-aluminum

The Beryllium and Lithium Alloys are to expensive, unavailable, or warrant health risks that do not make them appropriate.

Aircraft Aluminum is the Cheapest material at about 15$ per ft^2Carbon-Epoxy was found around 65$ per ft^2Titanium was found to be much higher and ranging in prices.

Questions?