2016 Mar

Distinguishing Plastic and Elastic Deformation

March 28, 2016

Plastic and Elastic Deformation

Deformation is the change of an object shape, brought about by temperature or force. Any solid material can breakdown under appropriate force. Even so, a couple materials, like aluminum and steel, at first respond by twisting when subjected to pressure. As pressure increases, this kind of objects breakdown at a certain point. Centrally to this, there are other materials like ceramics and glass which break directly without bending. This criterion employed in distinguishing these materials’ categories is referred to as deformation. Objects which can undergo deformation when subjected to pressure, recognized as ductile, and those that don’t are referred to as brittle. Even so, elastic and plastic deformations are the two techniques which can alter the dimensions of an object. Let’s comprehend their differences.

Shape Reversal

Plastic deformation leads to permanent change of an object’s size or shape on subjection to pressure, which can’t be reversed after the pressure is withdrawn. Elastic deformation entails a temporary in the object’s size or shape, which reverses after the pressure is withdrawn. Elastic deformation is related to Hooke’s Law which we have learnt during our Physics tuition classes.

Necessary Force

The plastic deformation takes place when the force applied on a given solid exceeds a certain limit, known as the solid’s ‘elastic limit’. Elastic deformation takes place when the force exerted on the object is less than the elastic limit of the object. By this reasoning, an object goes through elastic deformation prior to plastic deformation.

How Atomic Structure is affected

Plastic deformation takes place when bonds among atoms are destroyed, and then new bonds are formed, which makes it impossible to reverse to the initial shape. On the other hand, elastic deformation takes place due to the stretching of the atomic bonds upon pressure application, making it possible to regain their initial locations after the pressure is withdrawn.

Force Increase Effect

Change in the dimensions of an object, in plastic deformation, doesn’t correspond directly to the amount of force applied. There is much more change in size or shape of an object, in elastic deformation, if there is an increase in the applied force.

Strain Hardening

Before a specific boundary, plastic deformation makes atoms move and then occupy atomic defects inside the metal, which makes it tougher. Hence, this is known as ‘strain hardening’, and it’s used to strengthen polymers and metals in industries. As elastic deformation doesn’t lead to permanent atomic alterations, it doesn’t boost the metals’ strength.

Process Stages

Plastic deformation occurs in distinct phases. First, it causes strain hardening, which is followed by object narrowing, and lastly the object fractures at that narrow portion, that is, if the applied force is increased continuously. Elastic deformation is a simple process, where the deformation increases with a force increase, until object’s elastic limit is reached.

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