Thermal stress occurs when a material is subjected to temperature changes that cause it to expand or contract. If these dimensional changes are restricted, internal stresses are generated within the material. Understanding thermal stress is critical for designing structures and components exposed to varying temperatures.
Thermal stress (σt) is defined as the stress induced in a material due to changes in temperature when the material's expansion or contraction is constrained. It is mathematically expressed as:
σt = E * α * ΔT
Where:
Thermal stress can be compressive or tensile, depending on whether the material is cooling (contraction) or heating (expansion).
Thermal strain (εt) is the deformation caused by temperature change, given by:
εt = α * ΔT
If the material is constrained, thermal strain cannot occur freely, and instead, a stress develops according to Hooke’s Law for elastic deformation:
σt = E * εt
This relationship highlights that thermal stress depends on the material's elastic properties and its thermal expansion behaviour.
Thermal stress is assessed through controlled experiments that simulate temperature changes and measure the resulting stresses. These steps are typically involved:
Common Testing Equipment:
Calculating Thermal Stress in a Steel Rod
Problem: A steel rod with a Young’s modulus (E) of 200 GPa and a coefficient of thermal expansion (α) of 12 × 10-6 1/°C is heated by 50 °C while being constrained. Calculate the thermal stress.
Solution:
σt = E * α * ΔT
σt = (200 × 109) * (12 × 10-6) * 50
σt = 120 MPa
Thermal stress = 120 MPa.
Thermal Stress in a Constrained Aluminum Plate
Problem: An aluminum plate with E = 70 GPa and α = 23 × 10-6 1/°C undergoes a temperature drop of 30 °C. Calculate the thermal stress if the plate is fully constrained.
Solution:
σt = E * α * ΔT
σt = (70 × 109) * (23 × 10-6) * 30
σt = 48.3 MPa
Thermal stress = 48.3 MPa.
Thermal stress analysis is crucial in many engineering disciplines, including:
Thermal stress is a vital concept in engineering, ensuring the safety and performance of structures and components subjected to temperature variations. Understanding its principles and applications is essential for designing reliable systems in various industries.
Disclaimer:
The content on this website is intended solely for educational purposes. While every effort has been made to ensure the accuracy and reliability of the information provided, the website owner, authors, and contributors make no warranties or representations regarding the completeness, accuracy, or applicability of the content.
Engineering principles and concepts discussed here are based on established knowledge and research available at the time of writing. However, due to the rapidly evolving nature of the engineering field, some information may become outdated. It is strongly recommended to consult with a qualified professional engineer or academic institution for specific technical advice and up-to-date information.
The website owner and contributors are not responsible for any consequences arising from the use or application of the information contained on this website. Users assume full responsibility for verifying any information and for any actions taken based on this content.
By accessing and using this website, you acknowledge that the material provided is for general educational purposes only and should not be relied upon as a substitute for professional engineering advice or services.
