axial stress-strain curve & modulus of elasticity

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