Material thickness?

Question

I have a steel grade of material thickness 0.62 mm. I want to know how to calculate equivalent thickness of Aluminium which will have the same strength as that of the steel. Can I do that by using Ultimate Tensile Strength of both the materials. Please clarify.

Thanks
Harshad

Answer 1

You can do this for a construction with only tensile load(pulling or compressing). If the material is subjected to bending, you will can not so easily translate between materials.

For example, if the steel has double the tensile strength of the aluminum.
In tensile load, you will have to use twice as much Al as steel.
In bending you will have to use less then twice as much. How much is depending on the shape.

Answer 2

Only if your loading is purely tensile can you just match tensile strength and be done. Though you might want to match yield strength, not UTS. For most material substitutions, you have to account for the difference in modulus of elasticity and the effect that has on the bending moments in the structure. For soft steel, you can easily find an aluminum alloy with equivalent strength, but the aluminum will only have about one third the rigidity of the steel.

Answer 3

For bending you need to know the elastic modulus of Aluminum for steel the number is 29 E +6 lbs/in^2. Aluminum is less. That will determine the amount of deflection.

You need to be concerned with not only the stress limits but also the total allowable deflection.