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Suppose a brick is kept on a floor and we apply a constant perpendicular pressure on it for an indefinite period, will it cause the brick to deform in any way? Assume the pressure is small enough to not to break it immediately. Brick is brittle and pressure is applied by any material which can withstand the reaction by the floor. The floor is made up of concrete or the iron like in trains. Pressure is applied on the upper surface of the brick. Assume pressure can be applied indefinitely (assume forever). Deformation can be of any kind.

If yes then how small but non-zero , pressure can be applied for indefinite period without causing any deformation in the brick. (I guess we can assume we can measure the deformation up to quantum scale.)

Qmechanic
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SacrificialEquation
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3 Answers3

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The long term effect of applying a load to a material is called 'creep' and it is irreversible (unlike elastic compression, say, which relaxes when the load is removed). As far as I know, there is no theoretical model to allow you to calculate the long term effects of creep in bricks. However, tests have been performed to quantify creep in masonry (where the creep is partly in the brick and partly in the mortar), so you could google that if you are interested.

You will see creep in many old buildings, where their timbers, brickwork and stonework have become permanently deformed over the centuries.

Professor Sushing
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In addition to the existing answers, if you are interested in the long long term effects, Freeman Dyson discusses the behaviour of solids over astronomical time scales, in "Time without end: Physics and biology in an open universe".

As an example, consider the behavior of a lump of matter, a rock or a planet, after it has cooled to zero temperature. Its atoms are frozen into an apparently fixed arrangement by the forces of cohesion and chemical bonding. But from time to time the atoms will move and rearrange themselves, crossing energy barriers by quantum-mechanical tunneling.

He concludes that due to quantum tunneling, even at minimum temperature, solids will continue to deform under pressure, and calculates the speed of this effect (detailed calculations can be found in the paper):

On a time scale of 1065 yr, every piece of rock behaves like a liquid, flowing into a spherical shape under the influence of gravity. Its atoms and molecules will be ceaselessly diffusing around like the molecules in a drop of water.

HugoRune
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The brick will deform a small amount, according to its Young's modulus, immediately when the force is applied then it will stay at that deformation for as long as the force is applied. It will not deform any further as time goes on.

Jagerber48
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