Compressive stress

Compressive Stress

Compressive stress is a type of mechanical stress that occurs when an object is subjected to a force that pushes or squeezes it, causing it to become shorter or more compact. It is the opposite of tensile stress, which occurs when an object is pulled or stretched.

Definition

Compressive stress is defined as the force per unit area that acts on a material in a direction perpendicular to the surface. It is denoted by the symbol σc and is measured in units of pressure, such as pascals (Pa) or pounds per square inch (psi).

Causes

Compressive stress can be caused by various factors, including:

1. External forces: When an external force is applied to an object, such as when a weight is placed on top of it, the object experiences compressive stress.

2. Confinement: When a material is confined or surrounded by other objects, it can experience compressive stress due to the pressure exerted by the surrounding objects.

3. Thermal expansion: When a material expands due to an increase in temperature, it can exert compressive stress on its surroundings.

Effects

Compressive stress can have several effects on materials, including:

1. Deformation: When a material is subjected to compressive stress, it tends to deform by becoming shorter or more compact. This deformation can be temporary or permanent, depending on the material's properties.

2. Buckling: In some cases, compressive stress can cause a slender object, such as a column or beam, to buckle or collapse under the applied load. This is a critical failure mode that engineers need to consider when designing structures.

3. Strength reduction: Excessive compressive stress can weaken a material and reduce its strength. This can lead to structural failure if the material is unable to withstand the applied load.

Examples

Compressive stress can be observed in various everyday situations, such as:

1. Building construction: The weight of a building exerts compressive stress on its foundation and supporting columns.

2. Car tires: The weight of a car compresses the air inside the tires, resulting in compressive stress on the tire walls.

3. Crushing objects: When a heavy object is placed on top of a smaller object, the smaller object experiences compressive stress, which can cause it to deform or break.

See Also

• Tensile stress - The opposite of compressive stress.
• Stress-strain curve - A graphical representation of the relationship between stress and strain in a material.
• Structural engineering - The field of engineering that deals with the design and construction of structures to withstand various types of stress.