Young's Modulus

[mengchuan]

Hi,

When I check for material properties, they usually give me yield strength, tensile strength and elongation.
How do I convert into Young's Modulus? Is it just divide yield strength by elongation?

Thank you

mengchuan

 

[welding1]

Young's modulus is stress divided by strain within the elastic limit (or stress divided by elongation). Some tensile testing machines will actually plot this value for you.

If you have the accurate yield stress and divide it by the elongation at the point when the yield stress was recorded, this will give you Young Modulus.

Note This may not be true if you are using proof stress, because you are outside the elastic limit.

It's an unusual property that is mainly encountered in calculations involving buckling

http://www.gowelding.com

 

[brad]

'It's an unusual property . . ' ????

I would view it as one of the most fundamental properties. It most directly determines stiffness of a structure, and generally has a huge play in loadpaths for most engineering structures.

Mengchuan, wherever you are getting your other values, I would expect somewhere in that same text there is a table of standard values of Young's modulus. Otherwise, any standard introductory mechanics of solids book should give a good value (or Mark's Handbook or similar text).
Brad

 

[AlanD]

My observation, so it may not be correct.

You may not find the Young's modulus listed for each alloy. This is potentially because the Young's modulu is related the phase of the metal present rather than the actual alloy. By this I mean that all austenic steels will have the same Young's modulus. It certainly holds true for aluminium alloys.

 

[Ant101]

Dear Mengchuan

As a very general rule the youngs modulus is reasonably constant for groups of materials. For the purposes of most engineering work if you are dealing with any steel, stainless steel or cast iron you can use a value of 200GPa or 30,000,000psi this value varies with alloying between 197 to 210 GPa for all these alloys. It is more dependant on the bulk element property than any other thing such as alloying (if less than 15 to 20%) and also is relatively independant of the heat treatment for any steel no matter what the alloying or heat treatment you will not get values outside the above range.

Somebody mentioned aluminium the value for this is around 10,000,000psi.

Hope this helps

Ant101

 

[AJohnson]

Brad and Ant make a number of good points that I agree with. However, to be accurate, 200 GPa is equivalent to 29 Million psi, not 30. Andy

 

Try

http://www.matweb.com.

They have the Young's Modulus available for virtually all materials along with a comprehensive list of other physical and chemical properties.