Introducing Tom Ebbott, the new Vice President at Endurica!

Thomas G. Ebbott, Ph.D. Vice President Endurica LLC

Hello everyone. I am really excited to be writing this as the newest member to Team Endurica! I am really enjoying my on-boarding with Will and the team thus far. I continue to learn all the capabilities that the Endurica software has to offer, along with all the services that Endurica the company offers. I’m looking forward to using my knowledge and experience with modeling and simulation combined with expertise in fatigue and fracture in polymers to bring value to Endurica’s customers.

Endurica’s software and services enable customers to monitor, predict and improve the endurance of products. This has a positive impact on many of today’s contemporary questions. For example, for sustainability, customers need to evaluate the durability impact of using a material with a more sustainable source, or one with better recyclability or re-useability in place of an existing material. Even re-designing a component to use less material, or to last longer is more sustainable. For electric vehicles, many of the elastomeric components are called on to carry higher loads and higher torques in the case of tires. And, for fleet operations, Endurica can be used to monitor the health of elastomeric systems and predict when maintenance will be needed.

I feel I have a good background to help both Will and the team at Endurica as well as Endurca’s many and wide-ranging customers. As many of you know, I recently retired from Goodyear after nearly 36 years with that great company. While I was at Goodyear, I worked with many wonderful and capable people, and I was fortunate to have many fulfilling experiences and roles. Some include developing fundamental technology, developing products–specifically Aviation Tires and Retreads, various people leadership roles, and finally a high-level technical leader role responsible for technical strategy. While at Goodyear, I was able to publish several papers on topics such as fracture mechanics of rubber in tires, temperature distribution and rolling resistance prediction for tires, crack growth in twisted rubber disks, and continuum damage analysis of cord-rubber structures. I served on The Tire Society Executive Committee for 8 years as Treasurer. One of my long-term contributions at Goodyear was to the 30-year partnership with Sandia National Laboratories.

For my formal training, I spent 10 years at the University of Wisconsin-Madison that culminated in a PhD in Engineering Mechanics. My masters work focused on structural dynamics while my PhD research was on crack growth in polyethylene. The application of my PhD work was for the durability evaluation of natural gas distribution pipelines. The crack growth evaluation in (high density, high molecular weight) polyethylene required development of viscoelastic material laws and characterization as well as crack growth measurement systems, means to measure strain distributions, and use of viscoelastic crack growth theories.

On a personal note, my wife Sheri and I have two adult children. Amanda is teaching 2nd grade at a school near Columbus, OH, and Zachary is a junior pursuing a Finance degree at Regis University in Denver. One of my passions is flying, and I’ve had my private pilot’s license for many years. One of my most memorable flying trips was to New Mexico and Colorado. The photo shows my plane with the sun rising over the Sandia mountains in Albuquerque, NM.

I’m looking forward meeting and talking with Endurica’s customers in the coming months and learning about their needs and challenges concerning the use of elastomers and polymers for component design.

 

 

twitterlinkedinmail

The View on ‘22 – The Top 10 Happenings for Endurica in 2022

  1. Expanded our team! We welcomed 35-year Goodyear veteran Tom Ebbott to our team as Vice President, and at one point we had 3 interns working with us this year.  It wasn’t all hard work – we enjoyed our first company canoe trip / picnic in July.
  2. Solved much bigger problems. We set a record this summer for the largest rubber fatigue analysis ever. Ford Motor Company gave us multi-channel recorded road load histories from the full schedule of 144 distinct test track events that they use to qualify a motor mount for durability. We used Endurica EIE to map the load space and generate 3.2 Terabytes of stress-strain history for fatigue analysis. The new Katana multi-threading architecture of our Endurica CL fatigue solver enabled us to process 152k elements through all 15,693,824 timesteps of the schedule.  Check out our presentation at RubberCon 23 in Edinborough UK.
  3. Made analysis of block cycles easier. The Endurica CL and DT solvers’ Katana architecture now enables multiple blocks of load history to be specified in a single analysis.WoD 6 - Strain Crystallization
  4. Added a Haigh diagram visualization to the Endurica Viewer. Use it to quickly understand your material’s dependence of fatigue life on mean strain and strain amplitude.
  5. Implemented a channel reduction algorithm to Endurica EIE. It will analyze your multi-channel loading history to check for opportunities to reduce the dimensionality of your analysis through a change of coordinate basis.  Often, a 6-channel signal can be reduced to 3, 4 or 5 channels, greatly reducing computational requirements for building the map for EIE’s interpolation process.
  6. Expanded our licensing model to offer local, regional and global options. If your organization uses Endurica at multiple sites around the world, ask us about the advantage of regional or global licenses. These licenses allow any number of users to share a pool of solver threads for maximum flexibility and compute power.
  7. Added an experimental characterization for ozone cracking. Ozone is a trace gas that strongly reacts with some rubbers to produce surface cracking. It limits useful product life, even for loads below the fatigue threshold.Ozone Module. quantify ozone attack critical energy and rate Our testing method gives you the parameters you need to set up the ozone attack model in your Endurica CL / DT analyses. Perfect for analysis of tire sidewall endurance.
  8. Were honored when our founder and president, Will Mars, received the Herzlich Medal – the highest award in the tire industry – at the International Tire Exhibition and Conference. This honor is bestowed every other year to recognize an individual whose career and accomplishments have changed the tire industry for the better and left a lasting impact on tire design, development and manufacturing.
  9. Strengthened our documentation. New and experienced users alike will find it easier than ever to find the theory, procedures and examples that will yield rapid success in applying our software workflows. Check out the new sections on Mullins Effect, Ageing, Safety Factor, and Block Cycle analysis.
  10. Celebrated our client’s success. Technetics Group (Pierrelatte, France Maestral® R&D Sealing Laboratory) and Delkor Rail (New South Wales, Australia) shared their Winning on Durability success in case studies.
twitterlinkedinmail

Necessity and Invention: Getting Durability Right and Winning

Will Mars Delivering Keynote Presentation as Herzlich Medal Winner 2022

William V. Mars, Ph.D., P.E.
2022 Harold Herzlich Award Winner
Acceptance Speech
at ITEC 2022, Akron, Ohio on 15 September 2022

Three key takeaways from our founder’s acceptance speech of the tire industry’s highest award.

  1.  There is a point at which commercial simulation code outcompetes internally developed simulation code. Will talks about how this played out in the early days of finite element technology in the tire industry, and how the lessons learned apply to durability simulation today.
  2. Traditional is not the same as conservative. Will talks about the tension between the tire industry’s conservatism and the necessities that drive its progress, and how Endurica navigated its entry to the industry with its disruptive technology.
  3. The industry is going through a transition from scientific discovery and invention towards the empowerment of product developers to leverage advances in durability simulation. Will talks about the integration of testing and simulation workflows, and some of the capabilities that open new channels for gaining competitive advantage.

Check out the full talk here to enjoy some fun insights about Will’s personal journey through the years.

 

twitterlinkedinmail

The 5-50-500 Rule

The 5, 50, 500 Rule with dice showing Chance to Change

2 Minute Read | 400 Words

I ran a marketing consulting business for 30 years before joining Endurica and tried to save clients from learning the hard way. When brochures were the only way to convey a company’s message (pre-internet), it was critical that people understood the $5, $50, $500 rule.

  • $5 = cost for changes during the earliest design phase. This is the point where everything is on the table as you develop the look, feel, message, and content of the brochure.
  • $50 = cost to make changes at the first mock-up of the brochure. No big deal. At this stage, changes take a bit of work and may impact multiple pages or sections – but it’s a LOT better to make changes now than later and I encouraged people to speak up about anything/everything because change was still pretty easy. Approval at this stage sends us into production.
  • $500 = cost to make changes after we sent the brochure to the printer. That’s the cost to change even one LETTER, let alone a photo or – heaven forbid – an entire page. It was at this point that one client said “ok, now I’ll read it” and I had to stop myself from throwing a file at him.

All of this came up as we talked about the value of our software in rubber product development. The concept’s the same but the numbers are SO MUCH BIGGER. “Add about 3 zeroes to each of those steps,” remarked Tom Ebbott, Endurica’s VP and newest team member. “It’s the same concept in tire development but the impact is just so much bigger.

From a technical side, one of our client’s says it best: “In optimizing a geometry to extend the fatigue life of a product I ran a few iterations of inner-cavity geometries, and found one specific geometry with Endurica that achieved 500,000 cycles to failure in contrast to the 30,000 I had before. It’s more than a 10-time improvement and that’s really significant. These concrete numbers are really powerful in helping us and our customers to make good decisions.” Francois Rouillard, R&D Mechanical Engineer, Maestral Sealing Laboratory, Technetics, Pierrelatte, France.

WHY IT MATTERS: Endurica’s users find THE BEST solution to their client’s problem early — at the $5,000 stage of design. They can skip the multiple iterations that easily run $50,000 each and go right into the $500,000 production testing cycle with complete trust in the product’s success.

twitterlinkedinmail

Tension / Compression Cycles, R ratio and a Discussion of Wohler Curve for Rubber

Fatigue Life of Rubber with different strain constraints

In fatigue testing, R is the ratio of the minimum to the maximum occurring during one period of a cycle.  If the mean value is zero (ie the cycle is centered on zero), then the minimum is equal and opposite in sign to the maximum.  In this case, we say that R=-1.  The cycle can be defined by various parameters.  If we define R in terms of the stress or the strain, then R may take either positive or negative values.  We might hear, for example, that R=-1 uniaxial loading is a symmetric tension / compression cycle.

Be careful about definitions, however! The Endurica material models define R in terms of the tearing energy (ie T = – dU/dA, where T is the tearing energy, U is the elastic potential energy and A is the crack area).  The tearing energy is the driving force responsible for crack growth.  It is always greater than or equal to zero.  When R is defined in terms of tearing energy, its range is 0 ≤ R ≤ 1.

This leads to the following question that we often hear:  how can Endurica compute fatigue in compression if it does not admit a negative R ratio?

Let’s look at a series of signals, all having the same strain amplitude, and each with a different mean strain.  We will set the mean strain so that it is at most equal to the amplitude (corresponding to fully relaxing R=0 tension), and at least equal to the negative of the amplitude (corresponding to fully relaxing R=0 compression).  In the middle of the range, we have fully reversed tension/compression (what some call “R=-1” loading when defining R in terms of strain).  The principal engineering strains are plotted below for each case.  This gives a smooth progression from a cycle that is only compression to a mixed cycle with both tension and compression and finally to a cycle that is only tension.

Series of signals with same strain amplitude but different Tension/Compression levels

Even for these simple uniaxial cases, the critical plane for simple compression is not the same as the critical plane for simple tension.  In simple compression, due to crack closure, the critical plane is the plane that maximizes shearing.  These planes make a 45-degree angle with the axis of loading (x direction).  In simple tension, however, the critical plane is perpendicular to the load (x direction).  In the figure below, the change in the critical plane as the mean strain increases from compression to tension is evident.  On each sphere, the arrows indicate the perpendicular of a critical plane.

Mean strain increase as compression to tension is evident with change in the critical plane

The next figure shows the cracking energy density (units of mJ/mm3, and proportional to tearing energy) as a function of time on the critical plane for each case.  The symbols on each line indicate the times at which the identified crack plane is open or closed.  Now we can see clearly that fully reversed tension/compression (ie “R=-1” loading in terms of strain) is really R=0 when viewed in terms of tearing energy on the critical plane.

Graphs showing the cracking energy density as a function of time on the critical plane. Fully reversed tension/compression is really R=0 when viewed in terms of tearing energy.

The computed fatigue life is given in the last figure for each case using this material definition:

MAT=RUBBER
ELASTICITY_TYPE=ARRUDABOYCE
SHEAR_MODULUS=1 ! MPa
LIMIT_STRETCH=4
BULK_MODULUS=3000 ! MPa
FATIGUE_TYPE=THOMAS
FLAWSIZE=0.025 ! mm
FLAWCRIT=1 ! mm
TCRITICAL=10 ! kJ/m^2
RC=3.42E-2 ! mm/cyc
F0=2
X(R)=LINDLEY73

The computed fatigue life depending on different percentages of tension/compression

The moral of the story:

  1. Fully reversed tension/compression cycles (“R=-1” in stress or strain terms) are really fully relaxing cycles (R=0 in tearing energy terms) from the perspective of the crack precursor on the critical plane.
  2. The critical plane depends on whether you have tension or compression. Wohler curve analysis completely misses the fact that the failure plane is not always perpendicular to the loading direction!
  3. A simple sinusoidal history that crosses through zero results in separate tension and compression events, each of which has its own peak and valley, and each of which influences the critical plane selection. Wohler curve analysis based on max principal stress or strain amplitude completely misses these physics.
twitterlinkedinmail

Busting Myths About Endurica

Myths vs Facts on Endurica, Test your knowledge about Endurica

True or False? Test your knowledge about Endurica

Endurica is only a software company.
False. While Endurica is perhaps best known for its game-changing fatigue solver software, we also deliver industry-leading testing services, testing instruments, and training.  If you need durability for elastomers, we are uniquely positioned to bring you winning capabilities.

Endurica is used by the majority of top rubber product makers.
True.  As of the 2021 Rubber News global rankings report, 6 of the top 9 global rubber product makers are using Endurica solutions to characterize and simulate durability.

Endurica invented Critical Plane Analysis.
False, but...  Critical Plane Analysis – the technology that gives best accuracy fatigue life predictions under complex multiaxial loading – was originally pioneered by the metals fatigue community.  But Endurica does hold the patent on the first Critical Plane Analysis algorithm suitable for elastomers, and we are the world leaders in making the technology available to product developers.

Wohler curve based methods are just as accurate and competitive as Endurica’s Critical Plane / Fracture Mechanics-based method.
False. Wohler curve based methods suffer from many problems that are solved by the Critical Plane Method.  1) they often assume a wrong crack orientation rather than searching for the most damaging scenario, 2) they do not account properly for mode of deformation effects, 3) the testing program required to populate a Wohler curve scales poorly and has poor repeatability.

I don’t need Endurica software if I already have a metal fatigue code (nCode DesignLife, FEMFAT, MSC Fatigue, and fe-safe).
False. Metals and elastomers have completely distinct molecular structures and behaviors.  While metals operate at small strain, elastomers tend to operate at large strain.  Where metals exhibit linear elasticity, elastomers exhibit nonlinear behavior.  Using a metal fatigue code for analyzing elastomer fatigue is like trying to use a car as a boat: you can certainly drive the car into the water, but you end up on the bottom of the lake.

Endurica solvers work with Ansys, Simulia, and Hexagon simulation platforms
True. We maintain software development partnerships with the major finite element software vendors so that we can offer easy to use pre-and post- integrations with Ansys, Abaqus, and MSC/Marc.  You can use the Endurica workflows with the finite element code that works for you.  We also develop the fe-safe/Rubber plugin.

Everyone knows you can simulate durability.
False. We’re always surprised by the number of people at conferences and trade shows who don’t know that simulating the durability of rubber is even possible.  Our tools simulate everything from basic constant amplitude cyclic loading, to variable amplitude, multiaxial loading (up to 6 input channels!), ageing, strain crystallization, ozone attack, cyclic softening, creep crack growth, self-heating, block cycle schedules, residual life.  Our multi-threading capabilities mean that large jobs can execute quickly.  Our solvers are fast enough to compute damage in real-time for a full finite element model!

Endurica solutions have had significant commercial impact.
True.  Endurica was founded in 2008 to reduce rubber product launch cost and risk and we have saved our clients millions of dollars.  Endurica’s impact was recognized with the prestigious U.S. Small Business Administration Tibbetts award.

twitterlinkedinmail

My SAE WCX 2022 Top Takeaway

 

SAE WCX | Detroit, Michigan | April 5-7, 2022

There were several papers on fatigue life prediction for elastomers at SAE WCX 2022, but the highlight for us was this one from Automotive OEM Stellantis: “Fatigue Life Prediction and Correlation for Powertrain Torque Strut Mount Elastomeric Bushing Application” by Dr. Touhid Zarrin-Ghalami, Durability Technical Specialist at FCA US LLC Fiat Chrysler Automobiles logowith coauthors C Elango, Sathish Kumar Pandi, and Roshan N. Mahadule from FCA Engineering India Pvt, Ltd.  Check out the abstract or buy the paper here…

The study shows that very accurate fatigue life prediction results are possible for elastomeric components under block cycle loading using Critical Plane Analysis.  A key feature of the analysis is the characterization and modeling of rubber’s hyperelastic properties, fatigue crack growth properties, crack precursor size, and strain crystallization behavior.  Careful measurement of these analysis ingredients led to a nearly perfect correlation of the predicted life (520 blocks) with the tested life (523 blocks, average of 4 replicate tests), and of predicted failure mode with observed failure mode.

Endurica users like Stellantis are developing a solid track record of routine and successful fatigue life prediction.  We soon expect to see the day when CAE fatigue life prediction for rubber components is regarded as obligatory, given the risk and cost avoided with “right the first time” engineering.

Congratulations to the Stellantis team on this impressive success!

 Fatigue Life (block) demonstrating the accuracy of the CAE Virtual Simulation compared to a physical test

Citation: Elango, C., Pandi, S.K., Mahadule, R.N., and Zarrin-Ghalami, T., “Fatigue Life Prediction and Correlation of Engine Mount Elastomeric Bushing using A Crack Growth Approach,” SAE Technical Paper 2022-01-0760, 2022, doi:10.4271/2022-01-0760.

twitterlinkedinmail

Get Durability AND Sustainability Right with Endurica

Sustainability is all about Precycling with Endurica

How do you respond to the call for sustainable solutions in the rubber industry?  Is it via bio-sourced polymers or fillers? elimination of carcinogenic additives from the compound? Inclusion of recycled content in the material?  light-weighting aimed at reducing material use or at fuel economy improvements?  supply of critical components to EVs?

There are many paths to sustainability, but they are all constrained by these three filters:

  1. Most alternatives risk a reduction in durability (despite the optimistic claims of suppliers).
  2. Your product still must pass its durability qualification requirements.
  3. The number of development iterations is severely limited by the time and cost of durability testing.

Endurica workflows have been driving a “right the first time” engineering culture for the last 14 years.  Putting durability characterization and simulation upfront in your development programs means that you find and resolve issues earlier and cheaper than if you depended only on your qualification to discover issues. 

With Endurica, you can rapidly evaluate the durability of a series of alternative materials under realistic conditions before you build the first physical prototype.  The impacts of polymer alternatives, filler alternatives, additives, recycled content alternatives, etc. can be characterized with a minimal sample of the material and represented accurately with Endurica’s material modeling capabilities.  You can see how material property changes play out in your actual part geometry, under actual part loading histories.  All without building a single prototype part.  The modeling process is simple to automate, enabling much richer explorations of the available design space.  Where a purely prototype-based development program may be able to compare two or three alternatives over a six-month period, a simulation-based program can compare several hundred alternatives in the space of a week! 

Just because it can be hard to find a sustainable alternative doesn’t mean that they aren’t out there.  It is their relative rarity that makes them so valuable.  The next crop of winning products will come from those who can quickly and reliably navigate durability.

twitterlinkedinmail

User Requests and New Features: You Asked For It, You Got It

You asked for it, Endurica gives you new features!Once a year, we ask our users to weigh in on what we can do to further improve your experiences with the Endurica fatigue solvers.  The feedback helps us aim our development at bringing you winning capabilities.  It is also a marker we can use to gauge progress.

Here are the survey results from 2020:

Results from consumer survey stating which products they are most likely to use. Results from consumer survey stating which products they are most likely to use.

How did we do this year?  Check it out:

Support for additional channels in Endurica’s Efficient Interpolation Engine (EIE).  EIE makes it possible to compute strain histories and fatigue life from lengthy road load signals. To date, EIE has supported up to 3 independent load channels.  But we’ve had several of our best users tell us they need 6 channels.  The expanded capability was a big focus for development this year, and now it is complete and nearly ready for launch.  Stay tuned for more details to come out in early 2022.

Safety Factor.  The Safety Factor calculation is a feature of Endurica’s new Katana CL that launched this year.  It avoids the need for full characterization of the crack growth rate law but gives you the benefits of critical plane analysis. Given only the intrinsic strength (fatigue threshold) and precursor size, it calculates the margin by which the most critical loads remain below your material’s fatigue limit.  It tells you whether you may expect indefinite life (or not). Use it with the Intrinsic Strength Analyser experiment.  Perfect for analysis projects where you need to demonstrate capacity for long life with limited timeline or budget.

UHYPER.  Abaqus users can now define their own hyperelastic law in Endurica.  The Endurica UHYPER interface matches the UHYPER Abaqus interface so that you can use the same subroutine with both codes.

Linux Support.  Did you know that the Endurica solvers are available on both Windows and Linux?  Our Linux users can now run the entire Endurica suite of software (CL, DT, and EIE) on their systems.

Execution Speed.  The recently launched Katana solver (for CL and DT licenses) offers unprecedented speed.  Our benchmarks show that on a single thread, users will cut run times by more than ½.  And the Katana solver also offers multithreading.  Our benchmarks showed excellent scaling behavior up to >40 parallel threads.  These capabilities means that users will be able to run much larger jobs, and to complete their existing jobs with much shorter run times.

Improved hfi syntax / error checking.  Another feature of the Katana solver is its adoption of the json format for the input file.  The switch to the widely adopted json standard means that our solutions are now much easier to script via python or matlab and that there are file editors which automatically do the syntax / error checking.

Cosimulation Interface for Ansys.  The cosimulation capability of Endurica DT updates the finite element solution so that material property evolution can be simulated.  It has previously only been available to Abaqus users, but has now been developed for Ansys.  It is currently being beta tested.  We expect to launch this addition in Q1 2022. This means that Ansys users will very soon be able to make full use of Endurica DT’s Cyclic Softening modules and Ageing Workflow.

Materials database expansion.  The next Endurica release will have an addition to the materials database: a series of six HNBRs. We are also preparing to release the database in several common unit systems, rather than the prior single unit system.

With 2021 behind us now, its time to look forward to 2022 (and beyond!).  Look for the client survey and let us know how to best serve your upcoming needs.

twitterlinkedinmail

Towards better rubber compound selection: Introducing Endurica’s new Companion (TM) App

Endurica Companion App | Fatigue Property Comparator

Rubber can be formulated in a very wide range of properties.  For materials developers, this cuts two ways. On one hand, it means that there are almost always excellent options for a given application.  On the other, it means that those options are usually hidden among lots of bad options.  This is job security for rubber compounders, but it unfortunately also underlies the fact that there are so many instances of sub-optimal materials selection decisions when it comes to rubber.  One study found that more than 40% of rubber product failures could have been avoided with better materials selection.

One cause of this statistic is poor visibility into how material properties map into application performance.  Too often, the material options are judged based on an over-simplified lab test, or an incomplete specification of application conditions. We made the CompanionTM app to address this gap.  Companion makes it easier to find the rubber properties that ensure durability in your application.  Companion can compare materials for strain-, stress- and energy control.  It can compare applications with different modes of deformation (tension, compression, shear).  It can account for fully relaxing and nonrelaxing loading. It can account for temperature effects.

Another cause of too-high rates of poor materials selection is that sometimes different parts of an organization use incompatible approaches to specify, characterize and analyze the material and the application.  Gaps between the materials, product and testing silos sometimes create unnecessary confusion, conflict and wasted effort, leading to poor durability.  Companion was built with the aim of getting materials engineers and product engineers using a common, validated framework.  The material properties and analysis principles in the Companion App are the same as those used in our product simulation software, but the user experience in the app is centered around the materials selection decision.  No special knowledge of fatigue theory or simulation technology is needed to start using the app.

 With the Companion App you can choose different variables to see how they affect the performance of the rubber

You can use the basic version of Companion for free.  Go to companion.endurica.com to set up your account and try it out.  The free version lets you define one material and one loading condition.  A subscription-based professional version is also available for about $1 USD / day.  The subscription version lets you compare 2 materials and 2 load cases side-by-side, it lets you save your material definitions to a local database for future use, and it includes several outputs that give deeper insight into the fatigue behavior of your materials.  The workflow is simple: 1) define your material(s), 2) define your load case(s), 3) run the calculation, and 4) review the results and compare performance of the materials for the given load cases.

Give it a try and let us know what you think.

twitterlinkedinmail
close
Trial License RequestTrial License RequestTrial License RequestTrial License RequestTrial License Request

Our website uses cookies. By agreeing, you accept the use of cookies in accordance with our cookie policy.  Continued use of our website automatically accepts our terms. Privacy Center