# calculating force from strain

Discussion in 'General Electronics Chat' started by Vindhyachal Takniki, Nov 5, 2014.

1. ### Vindhyachal Takniki Thread Starter Member

Nov 3, 2014
358
6
Is it right way to calculate force from known strain & young modulus :

1. E = stress / strain
from where stress is calculated

2. Then stress = Force/area
From here force can be calculated

3. How to convert this force (in newton) into Kg.

2. ### studiot AAC Fanatic!

Nov 9, 2007
5,005
515
1) Correct, but be clear here whether mean shear stress or direct stress and do not mix them up.
Strain for electrical engineers is usually measured in millistrain units.

2) Correct, but again make sure you have the correct area.

3) You can't convert N into kg, since the first is a measure of force and the other a measure of mass.
This is a unit of force the kg-force which you obtain by dividing Newtons by g, but you should not be using this as is is non standard.

Last edited: Nov 6, 2014
3. ### Vindhyachal Takniki Thread Starter Member

Nov 3, 2014
358
6
1. I have square metal plate of .15m.
2. I was looking at formula , let say how much Kg-force for 1 microstrain
3. material is glass fibre. From below link young modulus of glass fibre is 17Gpa
http://www.engineeringtoolbox.com/young-modulus-d_417.html

Stress = E x strain = 17 * 10^9 * 1 * 10^-6 = 17000
Force = Stress * area = 17000 * .15 * .15 = 382.5

So kg-force = 382.5 / 9.8 = 39.03

1. One microstrain produces 39.03Kg force. Such small strain with such high Kg-f Is there any mistake in calculation I am doing?
2. My material is glass fibre. Or I have selected wrong young modulus??

4. ### studiot AAC Fanatic!

Nov 9, 2007
5,005
515
You took note of my comment 3, but do not seem to have bothered with 1 and 2.

I think you have the wrong area and have mixed up shear and direct force.