Endurica unveils updated software to help part makers predict durability

FINDLAY, Ohio—When, precisely, will a rubber bushing crack? How will the boot on a CV joint fail, and where on the boot will the fracture occur? How large will the crack become over time? What are the road conditions that could cause such fatigue?

These are questions that now can be answered thanks to software developed and updated by Endurica L.L.C., a six-employee company in Findlay that is making a difference in the bottom line for suppliers of OEM products in the transportation, defense, medical technology and offshore industries.

"It is going to change how suppliers develop rubber parts for the automotive sector, and it's going to change how they compete for business from OEMs," said Will Mars, founder and president of Endurica. "Instead of leaving proving ground tests until the very end of a development program, suppliers will be able to show OEMs how their part endures under actual loads during the initial proposal stage of a prospective program.

"It really is a game-changer if there ever was one."

While Endurica produces the patented CL, DT and EIE software dedicated to making precise end-of-life part predictions that can "get durability right the first time," as the company's motto states, it is the speed with which the 2020 EIE software now functions that can save a customer time and money, Mars said.

With improved full-load prediction times for fatigue failure for a particular elastomer product now possible in a single workday, a customer can now troubleshoot fatigue performance on the front end, not before "design and break" occurs.

And this can save tens of thousands to hundreds of thousands of dollars for a supplier, as fatigue testing can be one of the most exhaustive parts of the development process, Mars said.

"What is new is the improvement in how long it takes to compute the durability prediction," he said. "Although we demonstrated feasibility several years ago, it still was not practical to get the job done fast enough for analyzing full load histories recorded from a test track. But we've been working hard at it, and we have now achieved speeds that make this very doable in a single workday."

According to Mars, many times suppliers are forced to begin with general assumptions about the loads that will be forced on a particular part, and they attempt to refine that model to ensure that it matches predictions—sometimes using only a theoretical model, and sometimes based on a previous version of a part.

"We can do it completely virtually, although sometimes there is a real part," Mars said. "Before this, people had to guess and there were a lot of what-ifs. This lets suppliers see a part's durability for an OEM use without an actual part."

Because many times the engineering package that is issued to a supplier by an OEM for a particular elastomeric part contains only the largest load recordings, it "ignores a whole bunch of stuff that should not be ignored," Mars said.

"It's a low resolution way of doing things," he said. "There are all sorts of new things in the (EIE) code. Sometimes people have no part, and they can't test it. They just kind of look for the file that has the largest load, and this misses huge chunks of information. It's fine if every car is like the next one, but now with EV cars coming on the market, this is a big change and experience doesn't help as much. You need accurate predictions."

The new 2020 software releases provide licensed users with updates to all of Endurica's software products (CL, DT, and EIE). Besides the execution speed enhancements from EIE, estimated at 10,000 times faster than finite element analysis, the DT and CL platforms offer new analysis and visualization capabilities, according to Endurica.

The Endurica Viewer now is provided with the Endurica CL license, providing a graphical, interactive visualization of analysis results. Endurica CL also features new tools for dealing with lengthy load signals, including a tool that removes "non-damaging load history segments from further analysis," and a new binary file format that reduces file size and read time.

The Endurica DT solver now features new damage extrapolation abilities, calculating the number of repeats of the "entire schedule," or full range of stresses and motions, that can be endured by a part, according to Endurica.

How does it work?
The software, used in conjunction with finite element analysis, begins its coding journey with the input of general characteristics, or governing behaviors, of the raw materials in an elastomer product—durometer, stress-strain response, fatigue crack growth rate, crack precursor size and strain crystallization.

FEA then is used to construct "a nonlinear mapping between loads and strain components within each element," according to a 2016 abstract (using a rubber bushing) written by Mars and an engineer from General Motors.

Various strain histories—including multi-axial strain histories of varying amplitudes—then are computed from road loads, and cracks occur in this reckoning, Mars said. Crack growth then is calculated via a rate law contained in the software.

But whereas finite element analysis is a way to simulate how a product will change and deform with the stresses and strains placed on it, such a model does not foretell durability.

"The software can tell a customer when, where and how a part will fail—after 'x' number of cycles or rotations, and in what direction the crack will occur and how large it gets. Our tool in the work flow is as a post-process to the finite element analysis."

Mars said Endurica's programs also are useful for diagnostics, such as determining what road conditions will cause the most damage.

"Which bump in the road does the most damage? It's not always obvious what does the most damage. If I need to strengthen a part, where do I add material? Or with lightweighting, where do I take material away without giving up durability?"

Endurica's software can work in conjunction with other optimization codes, which can predict an optimum shape for a product, one that minimizes weight under a certain strain threshold.

"Another is sustainability," Mars said. "Sometimes people are looking for friendlier chemicals to make a material more sustainable. But the problem here is that usually those sustainable materials are weaker."

Cost of the software depends on whether the license is shared over a network or locked in to a specific user, and upon the software option a supplier chooses—CT, DT or EIE, Mars said.

"It pays for itself the first time you avoid buying the mold for a design that wouldn't have passed the durability spec, or the first time you win a new contract because your bid made the best case for part durability," Mars said.

Development history
Endurica began developing the software about four years ago, and the abstract written by Mars and GM in 2016 marked the first public announcement of it.

"It took us about two years to develop, but as soon as we offered it to OEMs, they said it was too slow," Mars said. "We had the right idea, but it just needed to run faster. We spent another year going through the code, optimizing it to make it run faster."

And Endurica saw its vision validated with a job it was given late last year, involving Endurica's DT software and a "really short timeline."

"We had a product that was really close to production, and we were looking at two alternatives on the mounting," Mars said. "The customer needed to decide which was the most durable, and they gave us two weeks to come up with an answer, which would have been completely impossible (without the software)."

But via its DT software, Endurica was able to "parallelize" the workload, and split the massive amount of information over multiple platforms. In this case, Endurica rented cloud space through Amazon for $500.

"The program can be as fast as you make the computer big," Mars said. "They were super impressed we got the job done."

Mars, an industry leader in the failure mechanics of rubber, began Endurica in 2008 during the Great Recession. He said that tough times, like the coronavirus pandemic of today, can force companies "to think about the right things to spend money on."

"Obviously this is a very weird time, and we are waiting to see the impact on us. I could see it cutting either way," he said. "I am just really excited about this. Suppliers will be able to find out quickly how each design decision along the path from winning the contract to production is impacting durability.

"It's going to help them make better material selections. It's going to help them make better part geometry. It's going to help with industry efforts toward lightweighting and with sustainability. We can bring value to help people win new business. If you are trying to position yourself for the future, you want to buy this software."

Solutions provided by Endurica include software, characterization services, testing instruments, and training for engineers and analysts. Endurica's testing instruments are produced by Coesfeld GmbH & Co. K.G., and Endurica can work with customers so they can use those instruments in their own labs, with Endurica's codes and processes.

"We are continuing to invest strongly in the Endurica tools," Mars said. "Our user base has been expanding to include a wider range of user background and experience, so our work flows have evolved toward greater simplicity, greater interactivity and greater flexibility. At the same time, our most experienced users are running jobs with growing scope and complexity."