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jp4294
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Homework Statement
This is one of the questions in my materials engineering assignment.
1. Thermal shock is the focus of this problem. Note that the resistance to thermal shock of a material, “R”, is defined here as the temperature change required causing fracture: (σc*λ*(1-v))/(α*E)
Where:
σc is the compressive strength
v is Poison’s ratio
α is the thermal expansion coefficient
E is the Young’s modulus
λ is the thermal conductivity
The Poison’s ratio term is necessary because thermal shock often results in a biaxial stress.
a) If the surface of a material is under compression, is it hot or cold relative to the body of the same piece of material? Explain why?
Homework Equations
The Attempt at a Solution
I have a few ways of thinking of this problem.
A) If a material's surface is to be under compression, it must be colder on the inside and as the warmer inside tries to expand, the outside will go under compression in an attempt to hold itself together.
B) The outside will be hotter than the inside and as the outside begins to cool due to the colder inside and the diffusion of heat, it will begin to contract and therefore come under compression.
I'm not sure which one is right if any at all and the question seems a bit vague to me...?
Any help would be great anyway.
Cheers,
JP