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
Compute the velocity of a bar: A bar AB as shown in Figure slides so that its bottom point A has a velocity of 4 m/sec to the left along the horizontal plane. compute the velo

prove that 0 is an integer

difference between coplanar and noncoplanar force system

Determine number of coils and length of the spring: A close coiled helical spring ought to extend by 120 mm under an axial force of 1200 N. If mean coil radius is equal to 40

temperature lapse rate differentiation integration...

A shaft is supported on bearings A and B, 800 mm between centres. A 20° straight tooth spur gear having 600 mm pitch diameter, is located 200 mm to the right of the left hand beari

Q. Factors in the design of high temperature materials? There is typically little correlation between room temperature strength and high temperature strength of creep-resistant

How does the maximum the 10'''' flange horizontal offset allowable.

Physical meaning of gradient of 2 nd order tensor?

An amount of air contained in a rigid container is at  T1 = 300 K.  After adding 450 kJ of heat, the air temperature increases to  T2 = 430 K.  Determine the mass of air,  m [kg],