Stress-strain carves for ductile materials, Mechanical Engineering

Stress-strain carves for ductile materials:

A material is said to be ductile in nature, if it elongates before fracture. One this type of material is mild steel. Shape of stress strain diagram for mild steel is shown in the figure given below.

A mild steel specimen of circular cross section or rectangular section is pulled until it breaks. The extensions of bar can be measured at every load increments. The stresses can be calculated based on the original cross sectional area and strains by dividing extensions by gauge length. When specimen of a mild steel is loaded in tension gradually, increasing tensile load, in the tension testing machine. The initial portion from O to A is linear where the strain linearly varies with stress. The line is called as line of proportionality and is known as proportionality limit. The stress corresponding to point is known as Limit of Proportionality. Hook's law obeys in this, slope of line gives, modulus of elasticity.

Further any increase in load increases extension rapidly and the stress strain diagram becomes curved. At the point B, material reaches elastic limit of it indicating end of elastic zone and entry into plastic zone. In most cases A and B coincide. If load is removed material returns to original dimensions of it.

Beyond elastic limit, the material enters into plastic zone and removal of load does not return specimen to its original dimensions, therefore subjecting the specimen to permanent deformation. On loading further the curve reaches the point 'C' called as upper yield point at which sudden extension occurs which is called as ductile extension where strain increases at constant stress. This can be identified by horizontal portion of the diagram. Point C gives yield stress beyond which load decreases with increase in strain up to C called as lower yield point.

After lower yield point has been crossed, stress again begins increasing, till stress reaches the maximum value at the point 'D'. The increase in load causes non linear extension up to point D. The point D called as ultimate point or maximum point. This point gives ultimate strength or maximum load of bar. The stress corresponding to highest point 'D' of stress strain diagram is called as ultimate stress.


2365_Stress-strain carves for ductile materials.png

Posted Date: 10/20/2012 8:09:46 AM | Location : United States

Related Discussions:- Stress-strain carves for ductile materials, Assignment Help, Ask Question on Stress-strain carves for ductile materials, Get Answer, Expert's Help, Stress-strain carves for ductile materials Discussions

Write discussion on Stress-strain carves for ductile materials
Your posts are moderated
Related Questions
Difference between turbulentna laminar

Illustrates about the need for reinforcement? NEED FOR REINFORCEMENT Concrete is economical and durable and is currently universally utilized for footings. Plain concrete is

Explain Principal Process for Abrasive Jet Cutting Machines Abrasive particles are fed from the hopper in to the mixing chamber by regulating device as shown in figure.

what is the importance of stress analysis in steels

Axis Perpendicular to the Vertical Plane - square prism: Here a square prism, side of base 40 millimeter and axis 60 millimeter long is resting on the HP on its base along wit

The first laboratory report, covering the two-part exercise involving tension testing and stress concentrations is due in lab two weeks after the conclusion of fatigue testing.

matlab programme for carnot cycle

what is meant by thermal sress in tapered sections

a) Illustrate with the help of neat sketch any three straight line mechanism. b) Describe Degree of Freedom and prove the relation for Grumbler's equation.

what is physics ?