# Tensile Stress

## Definition - What does Tensile Stress mean?

Tensile stress is the resistance of an object to a force tending to tear it apart. It is calculated as the highest tension the object can endure without tearing, and is measured in Newtons/sq.mm, but was initially denoted as tons/sq. in.

Stress is defined as the force per unit area of a material (Stress = force / cross sectional area), and is a measurement of the strength of a material. Therefore, tensile stress refers to a force that attempts to pull apart or stretch a material.

Many of the mechanical properties of a material can be extracted from a tensile test. In a tensile test, a sample is strained at a constant rate and the stress needed to maintain this strain rate is measured. A tensile test can determine:

- Elastic modulus
- Ultimate tensile stress
- Fracture stress
- Modulus of toughness
- Modulus of resilience

Tensile stress is also known as normal stress or tension.

## Petropedia explains Tensile Stress

The strength of structures of equal cross-sectional area loaded in tension is independent of the shape of the cross section. Materials loaded in tension are susceptible to stress concentrations such as material defects or abrupt changes in geometry. However, materials exhibiting ductile behavior (most metals for example) can tolerate some defects, while brittle materials (such as ceramics) can fail well below their ultimate material strength.

Tensile stress is the stress state causing material to elongate, i.e., the tensile stress may be increased until the reach of tensile strength, namely the limit state of stress.

The formula for computing the tensile stress in a rod is: tensile stress = force / area.

Tensile stress causes stress corrosion cracking (SCC) in refinery equipment, which is the combined influence of tensile stress and a corrosive environment. The required tensile stress may be in the form of directly applied stress or in the form of residual stress. The problem itself can be quite complex. The situation with buried pipelines is a good example of such complexity.

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