The Student Room Group

Stress Strain

If Y. M (Young Modulus) of a material is less, then the Stress' value of that material is going to be less too, right?
Because Y.M= Stress/ Strain
Y.M is directly proportional to Stress

(Just want to quickly make sure if that's really right)
(edited 2 years ago)
Original post by Aleksander Krol
If Y. M (Young Modulus) of a material is less, then the Stress' value of that material is going to be less too, right?
Because Y.M= Stress/ Strain
Y.M is directly proportional to Stress

(Just want to quickly make sure if that's really right)

No. (please note this answer too @ukii )
The Y.M of a material is defined as stress/strain - that much is true.
You are looking at this from the wrong point of view.
The amount of strain a material undergoes when you apply a stretching force is directly proportional the the stress
stress = Y.M x strain (YM is the constant.)
the amount of stress a material is under is directly proportional to the amount of strain it has experienced
Strain = (1/YM) x Stress
the constant is 1/YM

But
YM = stress/strain - but stress and strain are related
YM could only be directly proportional to stress if the strain remained constant - but it doesn't.
When the apply stress you get strain. Strain is not constant under changing stress.

The Young Modulus is not really proportional to anything (at this level) it's a constant. It depends on both stress and strain.
In terms of the reason why the YM value for a material is what it is, you have to look at the interatomic or intermolecular forces with it.
!! i learned something new


i didn't know that strain cannot remain constant, sorry about that
OP please check out the post above ^^
:smile:
(edited 2 years ago)

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