What is stiffness and it's importance in mechanical properties?

What is stiffness and it's importance in mechanical properties? Stiffnessis the ability of materials to resist deformations under the action of loads. So this is stiffness that it will be the ability of any given material to resist deformation that is a material should not change its shape, when the load is applied and when we go on increasing the value of load then the deformation should be very very small. It should not increase with the increase in load.

Like for example if I can say that if the load is 10 Newton then the deflection is around 1 mm if it is 20 Newton then the deflection becomes 10 mm. So it should not be like this the deformation should be slow that is the meaning of stiffness, you go on increasing the load value but the deflection is less so here.

It is load to produce per unit deflection that is in order to produce a deflection of 1 mm. How much load should be applied that is in terms of Newton or if it is in terms of kilo Newton, then again to produce a deflection of 1 mm how much load in kilo Newton should be applied so that is the meaning of stiffness and it is mostly considered in the design of Springs.

So a very important property that while we are designing the Springs we will be considering the property of stiffness and here I can say that stiffness is given by the formula your stiffness. I'll denote it by K and that is equal to load which is W upon deflection as Delta.

What makes a material stiff? 

A stiff material requires high loads to elastically deform it - not to be confused with a strong material, which requires high loads to permanently deform (or break) it. The stiffness of a component means how much it deflects under a given load.

What is the unit of bending stiffness?

The S.I. unit of stiffness is newtons per meter, N/m. However, the deformation (or, displacement, or, deflection) experienced by the above member is axial deformation. For structural members, such as a beam, rod, bar or plate, we have another scenario of bending deformation due to applied bending moment.

What is the difference between stiffness and rigidity?

Rigidity Inability of a material to be to bent or be forced out of shape. Stiffness is the rigidity of an object — the extent to which it resists deformation in response to an applied force.

What is axial stiffness?

Axial stiffness is the ratio of axial load to axial displacement or ratio of axial stress to axial strain. Bending stiffness is the ratio of bending moment to rotation. Or moment required to cause unit rotation.

How do you calculate relative stiffness?

If at any joint, many members are meeting, the stiffness of a particular member can be found out by the relative stiffness concept. Relative stiffness can also be defined as ratio of second moment of area and member length.