Compression set ratio of an o-ring

Dear Jorgen,

Ive read some articles showing that either the material, compression set ratio also depends on the cross section of the o-ring,

(please correct me if Im wrong) so my questions are :

1. Does it mean we have to do compression set testing for specified dimension we want to observe?

2. Do we have to set the CSR testing in the same specific media where theyll be applicated on (lets say they will be applicated in

hydraulic oil shell tellus 46) in order to get CSR curve & its activation energy more accurate?

3. What kind of input data (beside hyperelastic & viscoelastic data) in abaqus if I would like to make a squeezed simulation of an o-ring

(showing decay of radial stress) after thousand hours used?

Hope you can help me

Many thanks

best regards,

mick johansen

Good questions. Here are my comments:

1) The compression set depends on the material, the o-ring geometry, the applied load, and the environment. One way to handle this is to perform experiments of each conditions, but that of course is ineffective. In many cases a more useful approach is to characterize the response of the material, and then use finite element (FE) simulations to predict the long term response of different o-rings in different environments. So the answer to your question is no.

2) It is usually a good idea to use the same or similar media, unless you know that the response is the same in another (perhaps more convenient media).

3) That is all you need. Note, however, that you need to be very careful when you select and calibrate your material model. I have done a lot of work in this area and will write case study (some time this spring) demonstrating how it can done accurately.

-Jorgen