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Material Thermal Expansion Coefficient Formula

Posted Jun 28, 2022, 9:42 p.m. EDT Heat Transfer, Materials 1 Reply

鹏栋 钱
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How to interpret the formula for thermal expansion coefficient of materials in comsol：

(alpha_solid_polycrystalline_1(T)+(Tempref-293[K])*if(abs(T-Tempref)>1e-3,(alpha_solid_polycrystalline_1(T)-alpha_solid_polycrystalline_1(Tempref))/(T-Tempref),d(alpha_solid_polycrystalline_1(T),T)))/(1+alpha_solid_polycrystalline_1(Tempref)*(Tempref-293[K]))

1 Reply Last Post Jun 29, 2022, 2:08 a.m. EDT
Henrik Sönnerlind COMSOL Employee

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Posted: 2 years ago Jun 29, 2022, 2:08 a.m. EDT

The background is discussed in https://www.comsol.com/forum/thread/34508/Inaccuracies-in-the-formulas-of-the-Materials-Browser and the details are also given in the documentation for the Structural Mechanics module.

The 'if' part of the expression is necessary to avoid a potential 0/0 problem. It then makes use of L'Hôpital's rule to resolve that case.

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Henrik Sönnerlind
COMSOL
The background is discussed in and the details are also given in the documentation for the Structural Mechanics module. The 'if' part of the expression is necessary to avoid a potential 0/0 problem. It then makes use of L'Hôpital's rule to resolve that case.

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