Viscoelastic Matrial

[nsg]

Can any one give the details about Mooney-rivilian constants for HN750D2 rubber compound applied in seal ring, for an FEA analysis

Thanks

NSG

[Jorgen]

I suspect that your question is too specific :(

What material is HN750D2?
Have you talked to the raw material manufacturer?

- Jorgen

[nsg]

It is an type of "Hydrogenated Nitrile Rubber - HNBR", the same was indicated by my supplier as HN750D2.

We receiving the same material in form of O - Rings.

Material Hardness will be in the range of Shore Hardness A : 70 ~ 80

This much details only presently Im having.

For the above configuration of rubber, if u had Mooney rivilian constants please guide me...

This constant will help me for an analysis in ANSYS

Hope i explained my situations

Thank you in advance

By
NSG

[Jorgen]

OK, I see. If all you know is the Shore Hardness, then the best you can do with that is to estimate the Young's modulus, which would then allow you to use a neo-hookean material model.

Unfortunately I don't recall seeing a conversion equation between shore A hardness and the Young's modulus. If anyone know of a reference that has that info, please share that info.

In your case, I recommend that you ask the raw material manufacturer if they know what the Young's modulus is. If they don't know, then I recommend that you perform a few simple experiments.

- Jorgen

[Nimish]

Elastic modulus can approximately be calculated from the Shore A hardness using the below relation:

E = 11.427*A -0.4445*A^2 + 0.0071*A^3

A = durometer hardness (Shore A)
E = Elastic modulus (psi)

Once you have the young's modulus, you can use neo-Hookean material model. However, neo-Hookean model may not be suitable for modeling higher strain levels.

Nimish.

[nsg]

Thank u very much Nimish ,

However, Im more particularly interested in knowing the Mooney rivilian constant C10 & C01

Mr.Jorgen,

Thanks for your replu

I checked with rubber supplier, actualy they also doesnt aware of it. Since, its an FEA terms , they could not able to provide the datas

Can u suggest me an experiments to find out above constants.

Reg

NSG;)

[Jorgen]

You can determine the C10 and C01 parameters from any monotonic loading experiment, for example, uniaxial tension.

- Jorgen

[nsg]

Dear Mr.Jorgen,

Based on your suggetion, I had conducted an uniaxial tension test as per ASTM D 412 and following are observations in test slab of size : 150 x 150 x 2mm

(a) Tensile strength,
Specification : 101.95 Kgf / cm2
Observation : 213.33 Kgf/cm2

(b) Ultimate elongation,
Specification : 175% min
Observation : 250% min

Based on the above, can u guide me to derive the equivalent Mooney Rivilian constant of C10 & C01 for my FEA analysis of HNBR rubber O ring

Once again I greatfull u for your suggestions,

Reg

NSG

[Jorgen]

:arrow: I am not too fond of the unit "Kgf / cm2". I would convert that to Pascal (Pa)

:arrow: The ultimate elongation should not have a unit of min. What do you mean?

:arrow: It would have been better if you obtained the complete stress-strain curve from the experiment. Without that info, the best you can do is to estimate the secant modulus, which you can convert to an equivalent shear modulus which in turn can be converted to the C10 coefficient.

- Jorgen

[nsg]

Dear Mr.Jorgen,

(i) Tensile strength Equivalent value in pascal

Spec. : 101.95 Kgf/cm2 (9997880 Pascal)
Obs. : 213.33 Kgf/cm2 (20920526 Pascal)

(ii)The ultimate elongation should not have a unit of min. What do you mean?

Actually "min." indicates the short form of "minimum ultimate elongation", it doesnt indicating any units.

(iii)It would have been better if you obtained the complete stress-strain curve from the experiment. Without that info, the best you can do is to estimate the secant modulus, which you can convert to an equivalent shear modulus which in turn can be converted to the C10 coefficient.

Can you guide me to calculate (a) secant modulus, (b) how to convert it to equivalent shear modulus, (c) then how to convert same to has C10 & C01 coeffificent?

More over as per your guidance, herewith I attached the uniaxial test graph sheet for your refernce and further guidance.

Hope the above data is inline and expect favourable reply

Thanks & regards,

NSG

[manfred]

OK, I see. If all you know is the Shore Hardness, then the best you can do with that is to estimate the Young's modulus, which would then allow you to use a neo-hookean material model.

Unfortunately I don't recall seeing a conversion equation between shore A hardness and the Young's modulus. If anyone know of a reference that has that info, please share that info.

In your case, I recommend that you ask the raw material manufacturer if they know what the Young's modulus is. If they don't know, then I recommend that you perform a few simple experiments.

- Jorgen

I have a correlation function between shore hardness and neo hookean constant