This document discusses the stress-strain curve for textile fibers. It defines stress as the force per unit area applied to a material, and strain as the increase in length from an applied stress. A typical stress-strain curve shows four regions: the elastic region where deformation is recoverable, yielding where permanent deformation begins, strain hardening where the curve rises continuously, and necking and failure where the material fractures.

2. Submitted by: Asif Ahmed Tonmoy
ID: 131-23-3505 ; Sec: D (L3T1)
Assignment topic: Stress-Strain Curve
Submitted to:
Lecturer
Daffodil International University
Mousumi Rahman Hashi

3. For Example

4. 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

5. 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

6. Stress-Strain Curve for Textile Fibre

7. 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

8. Elastic Behavior
• If the specimen returns
to its original length
when the load acting on
it is removed, it is said
to response elastically

9. 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

10. 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

11. 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.