Plastic Strain Formula |
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\( \epsilon_e \;=\; \epsilon - \epsilon_e \) (Plastic Strain) \( \sigma \;=\; \epsilon_e \cdot E \) \( E \;=\; \dfrac{ \sigma }{ \epsilon_e }\) |
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| Symbol | English | Metric |
| \( \epsilon_p \) (Greek symbol epsilon) = Plastic Strain | \(in \;/\; in\) | \(mm \;/\; mm\) |
| \( \epsilon \) (Greek symbol epsilon) = Strain | \( dimensionless \) | \( dimensionless \) |
| \( \epsilon_e \) (Greek symbol epsilon) = Elastic Strain | \(in \;/\; in\) | \(mm \;/\; mm\) |
Plastic strain is the permanent deformation that remains in a material after the applied stress is removed and occurs when the stress exceeds the material’s elastic limit. In this regime, the material no longer follows a linear stress–strain relationship, and atomic planes begin to slip or dislocations move within the crystal structure. As a result, the material does not return to its original shape, even after unloading. Plastic strain is characteristic of ductile materials such as metals during forming processes like bending, rolling, or forging, and it is associated with permanent shape change and energy dissipation.
