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Submitted by: Asif Ahmed TonmoyID: 131-23-3505 ; Sec: D (L3T1)
Assignment topic: Stress-Strain Curve
Submitted to: Lecturer
Daffodil International University
Mousumi Rahman Hashi
For Example
What Is Stress?• A tension or
compression stress created in a structural member by the application of a lengthwise load.
• stress is defined as the force per unit area of a material.
• i.e. stress = force / cross sectional area
What Is Strain?• Increase (or decrease) in
length resulting from a stress acting parallel to the longitudinal axis of the specimen.
• strain is defined as extension per unit length.
• Strain = extension / original length
Stress-Strain Curve for Textile Fibre
Typical regions that can be observed in a stress-strain curve are:
• Elastic region,
• Yielding,
• Strain Hardening,
• Necking and Failure
Stress-Strain Curve for Textile Fibre
Elastic Behavior
• If the specimen returns to its original length when the load acting on it is removed, it is said to response elastically
Yielding
• A slight increase in stress above the elastic limit will result in permanent deformation. This behavior is called yielding
• The stress that causes yielding is called yield stress sy.
• The deformation that occurs is called plastic deformation
Strain Hardening
• When yielding has ended, a further load can be applied to the specimen, resulting in a cure that rises continuously but becomes flatter until it reaches a maximum stress referred to as ultimate stress, su.
• The rise in the curve is called Strain Hardening
Necking & Fracture• After the ultimate
stress, the cross-sectional area begins to decrease in a localized region of the specimen, instead of over its entire length. The load (and stress) keeps dropping until the specimen reaches the fracture point.