Young's Modulus

Young’s modulus - also known as the modulus of elasticity or elastic modulus - defines how stiff a material is when a force is applied. It’s the ratio of stress (force per unit area) to strain (the relative change in length), and indicates how much a material will stretch or compress within its elastic limit.

The higher the Young’s modulus, the stiffer the material. For example, metals like steel have a high modulus and resist deformation, while elastomers and some plastics have a low modulus and are more flexible.

This fundamental property is essential in the design and quality assurance of materials across industries such as aerospace, automotive, medical, and packaging. It is measured using tensile or compression testing systems, in accordance with widely adopted test methods including:

• ISO 527-1 / ISO 527-2 – Plastics: Determination of tensile properties

• ASTM D638 – Standard test method for tensile properties of plastics

• ASTM E111 – Modulus of elasticity determination for metallic materials

• ISO 7500-1 – Verification of testing machines

Young’s modulus (E) is calculated from the linear portion of a stress-strain curve using this formula:

E = σ / ε

Where:

• E is the elastic modulus (Pa or N/m²)

• σ is stress = force ÷ cross-sectional area

• ε is strain = extension ÷ original length

This calculation is most relevant in the elastic (reversible) deformation region of the material. The slope of the linear stress-strain curve in this region represents the Young’s modulus - a direct measure of how much the material stretches under load.

Typical values of Young’s modulus:

• Steel: ~200 GPa

• Aluminium: ~70 GPa

• PET (Polymer): ~2–3 GPa

• Rubber: ~0.01–0.1 GPa

Mecmesin tensile and compression testers, coupled with VectorPro® software, automatically generate stress-strain curves and calculate modulus values with accuracy and repeatability - ideal for R&D and quality control environments.