Calculation of thermal stress.

In summary: Residual stresses are created when the structure is not restrained from deforming. They can be a problem if they become too large.Thank you for your input.
  • #1
chetanladha
59
0
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)]
 

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  • #2
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.
 
  • #3
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.
 
  • #4
Unless there is some restraint thermal strain is stress free.

So I repeat my comment.
Define your restraints.
 
  • #5
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?
 
  • #6
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?
 
  • #7
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..
 
  • #8
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?
 
  • #9
what is creap?
 

1. What is thermal stress?

Thermal stress is a type of stress that occurs in materials when they are exposed to changes in temperature. It is caused by the expansion and contraction of the material due to the temperature change, which can lead to strain and potential damage.

2. How is thermal stress calculated?

Thermal stress can be calculated using the formula: stress = E * α * ΔT, where E is the material's Young's modulus, α is the coefficient of thermal expansion, and ΔT is the temperature difference.

3. What factors can affect thermal stress?

The main factors that can affect thermal stress include the material's thermal properties, such as its thermal conductivity and coefficient of thermal expansion, as well as the temperature difference and the geometry of the material. Other factors, such as external forces and constraints, can also play a role.

4. Why is the calculation of thermal stress important?

The calculation of thermal stress is important in engineering and materials science because it helps determine the potential for material failure or damage due to temperature changes. It can also aid in the design and selection of materials for specific applications to ensure their durability and reliability.

5. How can thermal stress be managed or reduced?

Thermal stress can be managed or reduced by using materials with lower coefficients of thermal expansion, providing thermal insulation or barriers, and controlling the temperature difference to minimize thermal gradients. Design modifications, such as adding joints or relief areas, can also help reduce stress concentrations and prevent damage.

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