# Axial Tension Force

Last updated: August 28, 2020

## What Does Axial Tension Force Mean?

Axial tension force can be defined as the force acting on a body in its axial direction. It’s a pulling force that will cause the body to elongate linearly in the positive direction causing a change in its dimension.

The axial tension force is exactly opposite to the axial compression force where the body will experience a change in dimension due to compression in the negative direction.

The axial tensile force or stretching forces acting on the body has two components, namely: tensile stress and tensile strain. This means that the material experiencing the force is under tension and the forces are trying to stretch it.

When a tensile force is applied to a material, it develops a stress corresponding to the applied force, contracting the cross-section and elongating the length.

## Trenchlesspedia Explains Axial Tension Force

Buried pipes can be damaged due to a variety of factors such as corrosion, external loading, construction defects, and ground movement. Buried pipelines may also experience axial loads due to ground movement induced by slope instability.

Some pipes made of flexible material may even experience changes in the cross-sectional area due to axial loading. For calculating stress due to an axial load, the stress will be constant when the cross-sectional area remains the same, but if the area changes, stress will also change.

Stress is calculated as:

Stress (σ) = Force (F) / Area (A)

Tensile Force on an Axial Bar

When an axial bar is subjected to a tensile force, it elongates by a certain length. Assuming the bar is of length L and cross-sectional area A, and the change in length is ΔL, the strain (ε) is given by:

ε = ΔL / L (change in length divided by original length)

The strain in the direction of the load is called axial strain and is associated with an increase in length. The axial strain is positive in tension i.e. if ΔL is greater than zero, ε is less than zero. Since strain is very small or fractional, it has a non-dimensional length and is given as a percentage by multiplying by 100%.

### Poisson’s Ratio

Materials that experience strain in the direction of the applied load experience relative axial strain which is an important component of Poisson's ratio. Poisson’s ratio is the ratio of the relative lateral strain to the relative axial strain. Poisson's ratio varies with the material. The axial strain is positive in tension and negative in compression.

### Hooke’s Law

The tensile strain ε is expressed as ε = ΔL/L. If a compressive force is applied, the compressive strain is expressed as ε = -ΔL/L. Based on Hooke's law, the relation between stress and strain is expressed as σ = Eε, where σ - stress, E - Young's modulus and ε - strain. On receiving a tensile force, the material expands in the axial direction (longitudinal strain) while contracting in the transverse direction (transverse strain). 