What happens to a body's stress if the temperature goes up or down?

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Discussion Overview

The discussion centers around the effects of temperature changes on a body's stress, particularly in the context of materials like rods under thermal conditions. Participants explore the theoretical and mathematical aspects of temperature-induced stress, including relevant equations.

Discussion Character

  • Technical explanation, Mathematical reasoning

Main Points Raised

  • One participant inquires about the relationship between temperature changes and a body's stress, asking for equations related to this phenomenon.
  • Another participant requests clarification on the initial question, suggesting that temperature changes typically affect size, which may be the intended focus.
  • A participant references a university professor's explanation regarding temperature stress in a constrained rod, indicating that thermal expansion leads to stress when the rod cannot expand due to fixed ends.
  • A later reply confirms the previous point, providing a mathematical expression for axial strain and incorporating thermal strain into the equation for stress under constraints.

Areas of Agreement / Disagreement

Participants appear to agree on the existence of temperature stress in constrained materials, but the discussion includes varying levels of detail and understanding regarding the equations and concepts involved.

Contextual Notes

Some assumptions about material behavior under temperature changes and the definitions of stress and strain may not be fully articulated, leading to potential gaps in understanding the complete scenario.

armin11
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What happens to a body's stress if the temperature goes up or down?What are the equations?
 
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Can you be a little more specific? What makes you think anything happens to a body's stress?

(A temperature change generally leads to a change in size; is this what you mean?)
 
Our university professor told us that there are some equations for temperature stress that apply to a body.for example if we restrict 2 ends of a rod and heat it up,rod grows in size but there isn't any room for it to grow so there is temperature stress.What are the equations for these kinds of temperature stress?
 
This is correct. When a bar is loaded uniaxially, the axial strain is [itex]\epsilon=\sigma/E[/itex]. Add thermal strain and you have [itex]\epsilon=\sigma/E+\alpha\Delta T[/itex]. Take into account that [itex]\epsilon=0[/itex] when the bar is fixed, and you can calculate the stress due to the constraint.
 

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