Modeling Dual Material Seal

**JFpoly?** · 2010-03-25, 13:33

Dr. Jorgen and all,

I am a metallurgical engineer that has been tasked with getting data for an elastomeric seal so that an accurate abaqus model can be run. The seals shell is made of polyurethane and it has a groove in it where an NBR energizer ring is compressed into it.

Needless to say I have some questions. I have reviewed 18.5.1 of the user's manual and spent a great deal of time at this site trying to make sure I did not post anything that was already covered. Anyway, I would appreciate your advice on a few things.

1) It seems that you like the NH model. This model requires K and G which are expensive tests for me to have done. I am already having the shell ground up and injection molded to make tensile bars (not the case for the NBR) for uniaxial tension tests. What is your opinion of the Marlow model? It seems that I could input my uniaxial tension data and this model would be accurate. Would there be a large benefit for me to perform poisson's ratio as well so that i have a value for material compressibility and can determine K and G?

2) Lets say that it is best to determine poisson's ratio...that will work for the PUR shell, but it worries me with NBR as it is not linearly elastic...would I just use E and v at some predetermined elongation?

Anway, in a nutshell, I have a dual material seal that i need to model, I would like to hear your opinion on what tests I should perform and what model I should try to use? Thank you so much for your help...it is greatly appreciated.

-JF

**manfred** · 2010-04-02, 13:04

Originally Posted by JFpoly?

Dr. Jorgen and all,

I am a metallurgical engineer that has been tasked with getting data for an elastomeric seal so that an accurate abaqus model can be run. The seals shell is made of polyurethane and it has a groove in it where an NBR energizer ring is compressed into it.

Needless to say I have some questions. I have reviewed 18.5.1 of the user's manual and spent a great deal of time at this site trying to make sure I did not post anything that was already covered. Anyway, I would appreciate your advice on a few things.

1) It seems that you like the NH model. This model requires K and G which are expensive tests for me to have done. I am already having the shell ground up and injection molded to make tensile bars (not the case for the NBR) for uniaxial tension tests. What is your opinion of the Marlow model? It seems that I could input my uniaxial tension data and this model would be accurate. Would there be a large benefit for me to perform poisson's ratio as well so that i have a value for material compressibility and can determine K and G?

2) Lets say that it is best to determine poisson's ratio...that will work for the PUR shell, but it worries me with NBR as it is not linearly elastic...would I just use E and v at some predetermined elongation?

Anway, in a nutshell, I have a dual material seal that i need to model, I would like to hear your opinion on what tests I should perform and what model I should try to use? Thank you so much for your help...it is greatly appreciated.

-JF

. . . as a first approximation I would consider both of the sealing components as NH and start with appropriate C10 values which may be obtained just from a correlation between C10 and elastomer hardness (applicable for rubber as well thermoplastic materials).