Thermal Expansion

By BYJU'S Exam Prep

Updated on: September 25th, 2023

Thermal expansion is the tendency of a material to expand in its longitudinal or transverse direction when subjected to temperature variations. The expansion of a material will depend on the material properties and the amount of temperature change. Thermal expansion is one of the important parameters among the designing parameters of the structural elements.

Thermal Expansion PDF [GATE Notes]

Thermal expansion is the ability of a material to change its shape and size. Hence, due to thermal expansion, the volume and area of the material can change. It may decrease or increase based on the temperature change. In this article, we will understand the effect of thermal expansion on a material.

What is Thermal Expansion?

Thermal expansion is the phenomenon of expanding or shortening a material when it undergoes a temperature change. In the thermal expansion process shape and size of a structural member may change. Hence it affects the total volume or area of the structural member. Thermal expansion meaning can be understood properly by understanding the thermal expansion phenomena.

Thermal expansion means a material may expand or shorten when it is supposed to change temperature. If the working temperature exceeds the standard temperature, the expansion will occur in this case. But if the working temperature is less than the standard temperature, then shortening of the material will occur in such a case. These expansions or shortening amounts will depend on the coefficient of thermal expansion.

Coefficient of Thermal Expansion

The coefficient of thermal expansion is a coefficient that describes the effect of temperature on a material. It describes how the material dimension will change when the temperature of the material changes with the standard temperature. It can be defined as the fractional change in dimension with respect to its original dimension when it goes to a unit change in temperature.

The coefficient of thermal expansion also depends on the material properties of the structural element. The coefficient of thermal expansion of steel is 9 × 10-6 per degree celsius change in temperature. More value of the thermal expansion coefficient indicates more change in the structural element when it undergoes temperature change. The unit of thermal expansion coefficient is per degree celsius of temperature change.

Thermal Expansion Formula

The thermal expansion formula can be derived from its definition itself. The coefficient of thermal expansion shows the amount of change in dimensions when it is subjected to temperature change. The formula for thermal expansion can be described as follows:

ΔL = α L ΔT

Where ΔL is the change in length of the structural member

α is the coefficient of thermal expansion

L is the length of the structural member

ΔT is the change in the temperature.

Application of Thermal Expansion

The concept of thermal expansion is used in the civil engineering design of structures and in mechanical engineering, chemical engineering, aeronautical engineering, etc. In the real world of designing structural elements, thermal expansion plays an important role. It has various uses and advantages in the design sector. For example, a structural member with less coefficient of thermal expansion is preferred when designed for an environment more prone to temperature change. Here a few applications of thermal expansion are listed below.

  • Increase in the length of railway tracks during summer.
  • Expansion of metallic joints in concrete bridges.
  • Rise of mercury level in thermometer.
  • Wings design in the jet plane.
  • Cracking of glass when it is subjected to heat.

Thermal Expansion Examples

The concept of thermal expansion will be more clear by understanding it with the help of a few real-life examples. Thermal expansion applications can be seen in various domains like railway structures, highway structures, designing of airplanes, etc. Here are a few examples.


Other Important GATE Notes
Steel Zero Force Member In A Truss
Functions Of The Network Layer Transverse Loading
Geometric Design Of Highways Moment Area Method
Macaulays Method Impact Load
Impulse An Momentum Uniformly Varying Load
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