Elasticity and Plasticity

Elasticity:

       External loads tend to deform materials from their original shape and size. Elasticity is the ability of a material to return to its original shape and size after removing the load applied. Elastic deformation (change of shape or size) lasts only as long as a deforming force is applied to the object, and disappears once the force is removed.This is so because the atoms in the metal change their position due to external stress but can't take new positions because the change of position is too small (or in acceptable range)

     Steels and other such materials are elastic over good range.

Plasticity:

     External loads tend to deform materials from their original shape and size. Plasticity is the ability of a material to retain the deformation even after external load is removed.In plastic deformation, the atoms in the material due to external force are displaced and take up new positions. They cannot come back to their natural positions once force is removed.

     This is very desirable property in machine tools. Lead has good plasticity at room temperature. Cast Iron has no plasticity even at very high temperature.    

PS: Some of the info here is taken from science.jrank.org & from Wikipedia. Please do refer to them for further info

with warm regards

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What are Mechanical Properties of Materials??

Hello Everyone,

From what I studied, I can come to conclusion that:

External loads are always applied on Materials during their service. The properties which describe the re-action of a material to those external loads are all classified as Mechanical Properties of materials.

It is important to ascertain the mechanical properties of material with standard laboratory tests in which the loads on the materials in real environment  are applied. This lets us determine behavior of materials and ensure we choose the right materials

 The important Mechanical Properties include:

• Ductility
• Hardness
• Elasticity and Plasticity
• Poission's ratio
• Creep
• Stress and Strain W.R.T Tensile stress, Shear Stress

with warm regards

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Mechanical Properties of Materials

Hello Everyone,

  Well I am a little tensed. Exam dates have been released. My preparation till now amounts to almost nothing and the pressure is huge. So started serious study from today morning itself.

  So stated with chapter called as Mechanical Properties of Materials. So the important topics to be studied here include:

• Tensile strength
• Poission's Ratio
• Yield strength
• Elastic and viscoelastic properties
• Creep, stress relaxation and impact.
• Fracture behaviour.
• Ductile fracture
• Griffith theory
• effect of heat treatment and temperature on properties of metals.

Well I stated at-last. Will see what is gonna happen at the D-Day

with warm regards

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