Thermal expansion of solid rod with blind hole

spotfriends · 2009-06-15T20:09:15+00:00

Friends, I have a 20mm dia.,30mm height, solid rod of stainless steel with a hole of dia.5mm, depth of 15mm at the center of the rod.(solid rod with a blind hole). Means wall thickness is 7.5mm radially and 15mm thick at the bottom. When I #-Link-Snipped-# the solid rod to a temperature, we are sure the hole dia. will also increase(expand) in size; say to dia.5.05mm. My question is, does the amount of material (radial thickness 7.5mm) influence the amount of hole expansion. Will the amount of material control the expansion-contraction ? my ideas is to play on the wall thickness to control the radial expansion........... SPOT

Thermal expansion of solid rod with blind hole

spotfriends

Member

Updated: Oct 26, 2024

Views: 1.0K

Friends,

I have a 20mm dia.,30mm height, solid rod of stainless steel with a hole of dia.5mm, depth of 15mm at the center of the rod.(solid rod with a blind hole). Means wall thickness is 7.5mm radially and 15mm thick at the bottom. When I #-Link-Snipped-# the solid rod to a temperature, we are sure the hole dia. will also increase(expand) in size; say to dia.5.05mm. My question is, does the amount of material (radial thickness 7.5mm) influence the amount of hole expansion. Will the amount of material control the expansion-contraction ? my ideas is to play on the wall thickness to control the radial expansion...........

SPOT

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Rohan_sK

Member • Jun 22, 2009

I dont think that the amount of the material will influence the Thermal Expansion or Contraction if the Tempreature doesnt vary.

The Coefficient Of Thermal Expansion is the controlling factor for the expansion or contraction of any metal under influence of any Heat source.

This Coefficient of thermal expansion varies from material to material. Its value is different for different metals.

Secondly, the degree of exapnsion or contraction depends upon the TEMPREATURE of the material and not the amount of Heat Flux alone.

Thus if you keep the Amount Of Heat supplied the SAME and simply INCREASE the amount of material around the hole, then definetely the degree of expansion will be LESSER as compared to the expansion with same amount of heat supplied but with lesser material around the hole.

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pramod.pal007

Member • Jun 28, 2009

sir.....
i think the hole dia. will contract.............
because when you heat up the the rod with blind hole then the material tendency is to expand in every possible direction...........

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Rohan_sK

Member • Jun 28, 2009

You are right Pramod, the blind hole will tend to contract on heating.

I would like to go one step ahead, and say that due to the confined area of the hole and the material expanding from all the sides ( radially inwards) there will be considerable THERMAL STRESSES developed around the reducing circumference of the hole due to CONSTRAINT to expansion. This will lead to DISTORTION in the material in the immediate vicinity of the hole.

The comment in my earlier post was strictly on the possibility of influence of material addition on the resulting expansion of the object.

Please correct me if Im wrong.

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