Hooke’s law
Hooke’s law applies only up to the limit of proportionality Ru. In this linear region, the slope of the curve is Young’s modulus E and stress is calculated as σ = E · ε. Above Ru, the relationship may begin to deviate from a straight line; above Re/Rp0.2, plastic and therefore permanent deformation occurs.
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Hooke’s law applies only up to the limit of proportionality Ru. In this linear region, the slope of the curve is Young’s modulus E and stress is calculated as σ = E · ε. Above Ru, the relationship may begin to deviate from a straight line; above Re/Rp0.2, plastic and therefore permanent deformation occurs.
Up to Ru, the curve is a straight line and σ = E · ε applies. Deformation is reversible and the slope is Young’s modulus E. Beyond Ru, the relationship need no longer remain ideally proportional.
Ru marks the end of linear proportionality, whereas Re/Rp0.2 is the boundary beyond which plastic deformation occurs. For materials without a distinct yield point, proof strength Rp0.2 is used.
In the plastic region, stress may continue to increase up to Rm, the maximum engineering stress reached in the tensile test.
What the module covers
- Hooke’s law — interactive engineering diagram
- Core principle
- How to read the diagram step by step
- 1. Ru — limit of proportionality
- 2. Yield strength Re/Rp0.2
- 3. Strain hardening and Rm
- 4. Necking and fracture
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