Session: CT-01-02 Design and Analysis of Bolted Flange Joints-2

Paper Number: 124331

124331 - Investigation and Modelling of Static O-Ring Sealing Performance After Ageing 

Monitoring and predicting the ageing of industrial systems equipped with sealing products implies the necessity to ensure tightness. This is not an easy task due to the combined effects of the viscoelastic nature of the materials of interest and the heterogeneous material evolution due to ageing.

The work aims to improve the lifetime prediction methodology in the case of static elastomer O-rings by understanding the link between material ageing, mechanical properties evolution and sealing performance.

The material studied is a peroxide crosslinked EPDM manufactured using a known standard industrial formula. These conditions favour the initial guess of material behaviour and facilitate the knowledge transfer to industrial partners.

To investigate the impact of ageing on sealing performance of O-rings, an experimental campaign is defined. Standard samples as well as O-ring were aged in thermo-oxidative and pure-thermal environments to better understand the role of oxygen during ageing. Local modifications of material behaviour are investigated throughout nanoindentation.  Leakage rate and stress relaxation measurements are controlled during ageing with a specific fixture integrating O-ring in a groove. The end-of-life criterion is based on maximum leak rate caused by interfacial leakage.

As interfacial leakage is linked to the local contact pressure changes on the sealing surfaces, which cannot be determined analytically, a numerical model was developed. It aims to evaluate the local stress state after aging in O-ring cross section by modelling the changes in mechanical properties measured on aged samples.

This paper will focus on the confrontation between early experimental results and numerical model performance.

Presenting Author: Oscar Péta Cetim

Presenting Author Biography: PhD Student (second year out of three / full time)

Working in the Sealing Technologies Lab of Cetim (Technical Center for Mechanical Industry) and the Dupuy de Lôme research Lab in the Material Behaviour & Durability departement in Brest, Brittany, France. Working on identifying the link between thermo-oxidative aging and leak tightness of rubber O-rings.

Authors:

Oscar Péta Cetim
Vincent Le Saux ENSTA Bretagne / IRDL UMR CNRS 6027
Yann Marco ENSTA Bretagne / IRDL UMR CNRS 6027
Benoît Omnès Cetim
Hubert Lejeune Cetim