1. Concepts about the science of "Strength of Materials" tasks, consistency, uniformity, priority, brief history

34.
Stresses generated by temperature changes ( temperature stress, coefficient of linear expansion)
When a material is subjected to temperature changes, it experiences thermal stresses due to the differential expansion or contraction of its components. These stresses are known as temperature stresses or thermal stresses. The coefficient of linear expansion plays a significant role in understanding and calculating these stresses. Let's delve into these concepts further:

1. 
   Temperature Stress: Temperature stress, also referred to as thermal stress, is the stress induced in a material when it is exposed to temperature changes. Temperature stress occurs because different parts of a material expand or contract at different rates when subjected to temperature variations.
   
2. 
   Coefficient of Linear Expansion: The coefficient of linear expansion (α) is a material property that quantifies the extent of expansion or contraction a material undergoes per unit change in temperature. It is expressed in terms of the fractional change in length (or dimension) per unit change in temperature (typically in units of 1/°C or 1/°F). The coefficient of linear expansion is an inherent characteristic of each material and can vary significantly between different materials.
   
3. 
   Calculation of Temperature Stress: To calculate temperature stress, the coefficient of linear expansion and the temperature change are considered. The temperature stress can be determined using the equation:
   

Δσ = α × ΔT × E,
where Δσ is the temperature stress, α is the coefficient of linear expansion, ΔT is the temperature change, and E is the modulus of elasticity or Young's modulus of the material.
This equation assumes that the material is constrained, meaning it is unable to freely expand or contract. If the material is free to expand or contract, the resulting stresses will be reduced.

4. 
   Effect of Temperature Stress: Temperature stresses can lead to dimensional changes, warping, or distortion in a material or structure. The magnitude of the stress depends on the coefficient of linear expansion, the temperature change, and the material's mechanical properties. If the temperature stress exceeds the material's strength or if it is repeatedly cycled, it can lead to cracking, buckling, or failure of the material or structure.
   
5. 
   Compensation Techniques: To mitigate the adverse effects of temperature stresses, compensation techniques are employed. These techniques aim to reduce the differential expansion or contraction between different components of a system, ensuring minimal thermal stresses. Examples of compensation techniques include the use of expansion joints, selecting materials with similar coefficients of linear expansion, and incorporating structural design features to accommodate thermal expansion and contraction.