Comparsion of Stiffness
Comparsion of Stiffness
(OP)
I need to find a material that is as stiff as possible (bending stiffness). For the calculation in my application I want to find out how much stiffer a material is compared to steel.
Tungsten carbide, silicon carbide or Al2O3 for example have a higer young's modulus. 3.6 x, 2.5 x and 1.8 x higher than the steel. Tungsten carbide is very expensive, whilst the stiffness of SiC and Al2O3 might not be enough according to young's modulus.
My question is: Are there other properties affecting the stiffness than the young's modulus, as someone mentioned in thread 367-114094? Which property defines the bending stiffness?
Thanks for any help.
Tungsten carbide, silicon carbide or Al2O3 for example have a higer young's modulus. 3.6 x, 2.5 x and 1.8 x higher than the steel. Tungsten carbide is very expensive, whilst the stiffness of SiC and Al2O3 might not be enough according to young's modulus.
My question is: Are there other properties affecting the stiffness than the young's modulus, as someone mentioned in thread 367-114094? Which property defines the bending stiffness?
Thanks for any help.





RE: Comparsion of Stiffness
E = 80 million psi
RE: Comparsion of Stiffness
RE: Comparsion of Stiffness
Don't forget Mo, it is 47msi, and it can be worked with. The drawback is its density.
If you need light, how about Be. Not freindly, but light and stiff.
Of course you can build composites that are in the 40-50 million range, in a specified direction. Graphite fiber/epoxy can get you some great results.
SiC is, for most purposes, the stiffest engineering material available.
Look at the periodic table. Re, Os, Ir and Ru are the stiffest by a large margin. It is all down from there for pure materials and metals.
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RE: Comparsion of Stiffness
RE: Comparsion of Stiffness
I'm still wondering, why there are certain materials with a high "flexural rigidity" referred to stiffness, despite a low "young's modulus". Look at the following example:
Zirconia: flexural rigidity 980 MPa, young's modulus 210 GPa
SiC: flexural rigidity 500 MPa, young's modulus 410 GPa
(http://www.asuzac.com.vn/ceramics_products.html)
If rigidity is directly related to the YM how come that Zirconia has a much higher flexural rigidity than SiC, although SiC has a higher YM? The provider confirmes that the Zirconia has a higher stiffness than the SiC.
I would be lucky if that is true... What do you think about this "flexural rigidity" vs. "young's modulus"-relation?
RE: Comparsion of Stiffness
You might also note that ceramics have widely varying poisson ratios.
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Rust never sleeps
Neither should your protection
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RE: Comparsion of Stiffness
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Comparsion of Stiffness
Relating to the material, regardless the geometry, SiC having the higher YM - would it be stiffer than zirconia then?
CoryPad, as you mentioned the "flexural strength" would be independent of YM - is this a material or geometrical property? If it is the former can it be used to derive the stiffness rather than with YM?
RE: Comparsion of Stiffness
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Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.