Predicting Seal Life with FEA

Simulating aging and chemical effects can help determine how long seals will last. Finite-element modeling is an attractive alternative to physical testing for predicting seal life, particularly when aging poses major concerns and seal replacement is expensive. For years, seal manufacturers and users alike have been searching for their industrial Holy Grail — a method for predicting how long seals will last in service. Traditional methods for evaluating an elastomer's potential as a static or dynamic seal use ASTM or other standard immersion tests. These tests involve immersing the material in a test fluid for a specific time. Technicians then compare physical properties such as hardness and ultimate tensile strength, before and after immersion, and make a judgement as to the material's suitability as a seal. Immersion testing certainly plays a role in screening potential materials. A good engineer, obviously, would not choose a material that severely deteriorated in the immersion test. However, some physical degradation and volume swell can generally be tolerated, so results are often ambiguous. The problem is, elastomers are not tested in their final form — compressed and with little surface exposed to the fluid or environment. Thus, immersion tests do not predict how long