Presented byMd. Nafizul Haque
ID: 10.01.03.095
AHSANULLAH UNIVERSITY OF SCIENCE & TECHNOLOGY
Department of Civil Engineering
Presentation OnAxial Stress-Strain Curve
&Modulus of Elasticity
What Is Axial Stress?A tension or compression
stress created in a structural member by the application of a lengthwise axial load.
Axial stress is defined as the force per unit area of a material.
i.e. Axial stress = axial force / cross sectional area:
What Is Axial Strain?Increase (or decrease)
in length resulting from a stress acting parallel to the longitudinal axis of the specimen.
Axial strain is defined as extension per unit length.
Axial Strain = extension / original length
Universal Testing Machine
Axial Stress-Strain Curve for Brittle Material
Axial Stress-Strain Curve for Ductile Material
Typical regions that can be observed in a stress-strain curve are:Elastic region, Yielding, Strain Hardening, Necking and Failure
Elastic behavior
If the specimen returns to its original length when the load acting on it is removed, it is said to response elastically
YieldingA slight increase in stress
above the elastic limit will result in permanent deformation. This behavior is called yielding for ductile materials.
The stress that causes yielding is called yield stress sy.
The deformation that occurs is called plastic deformation
Strain HardeningWhen 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 & FractureAfter 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.
Modulus of ElasticityThe modulus of a material describes how well it
resists deformation. A material with a higher modulus is stiffer and has better resistance to deformation. The modulus is defined as the force per unit area required to produce a deformation or in other words the ratio of stress to strain.
Modulus of elasticity=Stress/Strain