FINDLAY, Ohio—About four years ago, an OEM came to Endurica L.L.C., a pre-prototype solutions company that focuses on the predictive durability of elastomers, seeking a more accurate fatigue life estimate for a rubber component.
The customer had complained that its previous testing firm had missed the mark by a wide margin in its end-of-life predictions for the part, which was attached to a hot engine at one end and a cold frame at the other.
Such a drastic temperature range takes a toll on such parts, so Will Mars, Endurica founder and president, and his team set out to create algorithms that accounted for the influence of time and temperature on a rubber part—ultimately creating pioneering software that combines aging and crack growth predictions in the same simulation.
"This is one of our most significant developments to date because aging impacts so many applications," Mars said. "If there is a big temperature difference, or if there is significant self-heating, and if your part is expected to have long-term endurance, this feature is a real game-changer in terms of your ability to predict durability performance."
In essence, the software helps solve a root problem for OEMs: How does one perfect the chemistry of a tire, seal or gasket if one does not know how a part will react over time in a harsh environment?
"This is a feature that was developed and validated over the last few years in partnership with one of our Tier 1 automotive OEM users for an application where long-term exposure to high temperatures was leading to early part failures," Mars said. "The impetus for the software was that what they were doing was not working. It became obvious pretty quickly that aging was the missing part of the simulation."
When something goes wrong with a part, Mars said, it is usually due to poor decision-making in raw material selection.
Should an engine hose be made of silicone, which exhibits excellent aging but is susceptible to cracking? Should it be made of natural rubber, which is strong and crack-resistant, but ages poorly?
"Do they use natural rubber? Silicone? A TPE? I run into many poor decisions in the selection of materials," he said. "And testing is time consuming and expensive, offering no visibility into what happens if this is changed or that is changed. This could make a huge impact on material selection decisions, all of which depend completely on the conditions of the application—what the part is intended to do, and the loads and temperatures to which it will be subjected."
And numerical simulation provides a tried and true method for evaluating design features before making a larger investment in physical simulation, or before getting to the "build and break" stage, Mars said.
After the years-long project, Endurica was able to offer a customized version of the new simulation software to the OEM, and the official release of the predictive aging software came just last month, complete with a well-attended training webinar led by Endurica on its use.
"We've had a very good response to it so far," Mars said. "There has been a lot of interest. Aging is everywhere—look at Ford and Firestone and the aftermath there. Other studies have been on the shelf life of tires, and in oil and gas it's the same thing. When there is high pressure and high temperature, the rubber chemistry is crucial—and can save a company in downtime and its bottom line."
How it works
New data points offered in Endurica's software include age-equivalent time and age-influenced stiffness analytics, which, combined with crack growth simulation, make the new software unique, Mars said.
For years, Endurica has offered software that addresses crack growth simulation, another predictive measurement, but has never combined it with these two parameters.
"There is no other commercial software that does this," he said. "For a long time only academic papers were addressing the aging side. We have combined aging and crack growth in one simulation."