Calculation of thermal stress.

[chetanladha]

Hi.
I am trying to calculate thermal stress in a simple structure (cube) exposed to two different mediums at different temperatures.
I have come across 4 formulaes, can anyone please advice on which one would be most appropriate.
Please see the attached file as the fourth formulae is too big to write here..

thermal stress,
1. σ1= -EαT
2. σ1= -EαT/(1-v)
3. σ1=[-EαT/(1-v)]+ [E(ex + v*ey)/(1 – v2)]

 

[Studiot]

Good morning chetanladha,

Thermal stresses are developed as a result of reactions/shears between your cube and its environment. These need to be specified before your question can be answered.

 

[chetanladha]

Hey! Very good morning.
Thank you for your response.

the structure (cube) can deform. So the temperature gradient will first result in strain (till the time it can) and thereafter stress. Although i don't know how to find out how much will the structure deform before stresses could develop.
Mathematically i am planning to use some assumptions for the values of thermal strain.

 

[Studiot]

Unless there is some restraint thermal strain is stress free.

So I repeat my comment.
Define your restraints.

 

[chetanladha]

Ohh.. Yes i understand now, and i hve got my answer.

Another question:-
A metallic structure (e.g. a steel table) has got certain temperature gradient. This will result in thermal strain until restrains, followed by thermal stresses induced in it.

How can i find the thermal restrains in such a case?

 

[Studiot]

Another question:-
A metallic structure (e.g. a steel table) has got certain temperature gradient. This will result in thermal strain until restrains, followed by thermal stresses induced in it.

How can i find the thermal restrains in such a case?

I'm completely puzzled by this: what on Earth do you mean?

 

[chetanladha]

Temperature gradient in a body can either result in thermal stress, thermal strain or a combination of both.

Mathematically (not by measuring expansion/ contraction) how can one calculate how much is the stress and strain?

Thanks..

 

[Studiot]

Temperature gradient in a body can either result in thermal stress, thermal strain or a combination of both.

What makes you say that?

Are you sure you are not referring to residual stresses?

 

[mohdjavedmech]

what is creap?