What is Tensile Stress? – How to Calculate Tensile Stress


Tensile stress refers to the internal stress induced in a material when it is pulled or stretched. It is the opposite of compressive stress.

What Can Be Calculated When Tensile Stress Acts on a Material

When a tensile stress is applied, you can calculate the resulting elongation, strains, strength limits, stiffness, and factor of safety for the material based on its mechanical properties. This helps determine if the material will yield, deform, or fracture under the given loading conditions.

The increase in length of the material due to the applied tensile force. This depends on the elastic modulus of the material.

The ratio of elongation to the original length. This is a dimensionless quantity.

The ratio of transverse contraction strain to longitudinal extension strain in the direction of stretching force.

The stress at which material starts deforming plastically.

The maximum stress the material can withstand before fracture.

Ratio of the stress to strain in the elastic deformation region. Indicates stiffness of the material.

The stress level at which fracture occurs.

Ratio of fracture stress to working stress. Indicates how much stronger the material is than the expected load.

How To Calculate Tensile Stress

Measure the applied force, find the perpendicular cross-sectional area, and divide the force by the area to obtain the tensile stress value. Check this value against material limits to ensure it does not fail.

σ  = F /A

σ – Tensile stress (Pa or N/m2)

F – Applied force (N)

A – Cross-sectional area (m2)

What Are the Examplesof Tensile Stress?

When you hang an object from a rope, the suspended weight puts the rope under tensile stress. The rope elongates slightly under the applied tensile force.

Stretching a rubber band causes tensile stress. The molecular chains in the rubber experience forces trying to separate them lengthwise.

 Tightening nuts and bolts induces axial tensile stress in the bolt shank. This clamping force holds the parts together.

 Reeling in a big fish applies large tensile forces on the fishing line. This can cause the line to snap if the tensile strength is exceeded.

Suspension cables in bridges carry the deck’s weight through axial tension forces. The cables are under constant tensile stress.

Gears, pulley belts, and other machine parts undergo tension when transmitting torque or power. The tensile stress must be below the yield strength.

 The coil of a stretched spring experiences tensile stress proportional to the displacement from its relaxed length.

Pulling metal wire through a die reduces its diameter and subjects it to tensile stresses. This strengthens the wire.

Fabrics experience tensile stresses when stretched or pulled. Clothing needs to withstand such stresses during wear.

How Does Tensile Stress Relate to Die Casting

Controlling tensile stress through die design and process parameters is important in die casting to avoid hot tearing defects and achieve high-quality castings. Understanding how tensile stress develops guides the design.