Features

4-in-1

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Wow – this year has really been one of many firsts for Endurica.  We had our first ever Community Conference in April, we started our first sister company – in Europe, and from September 9 – 13, 2024, we presented 4 technical papers – a new Endurica record for one week!  The other impressive aspect of this latter feat was that the four presentations were on vastly different topics! I’ll just list the venues and titles and then discuss each one.

International Elastomer Conference 2024, Pittsburgh, PA, USA:

  1. “Heat Build-Up and Thermal Runaway in a Rotating Bending Experiment”

44th Annual Meeting and Conference of The Tire Society, Akron OH, USA:

  1. “Coupled Multiphysics Strategy to Monitor the Health of Rubbery Structures Using Endurica Tools”
  2. “Critical Plane Analysis of Surface-proximal Fields for the Simulation of Mechanochemical Wear”
  3. “Models, Materials and the Move Towards Virtual Product Development”

Let’s start with the first presentation on heat build-up. Will Mars presented this paper at the IEC in Pittsburgh on Tuesday the 10th of September. The presentation highlighted a new machine that has been developed by Coesfeld to evaluate the heat build-up behavior of rubber compounds. It uses a hollow rubber tube that is bent to a 60-90 degree arc and then rotated at about 600 rpm to create a tension-compression cycle throughout the tube due to the pre-bending as shown below.

This test offers many advantages over the historical Goodrich Flexometer self-heating test originally developed in 1937.  The Heat Build-Up Analyzer is instrumented to measure internal temperature as well as forces and deformations while the test is progressing.  The recent advances in the Endurica software and workflows are also equipped to predict the transient behavior in this test.  When the rubber reaches a certain high temperature, the rubber starts to break down, often due to the volatilization of low molecular weight additives creating an exothermic reaction, and also due to the reversion of the cross-links.  The exothermic reaction and thermal “runaway” condition can also be predicted by Endurica software.  The animation below shows the elevated temperatures and the internal pressure rise due to the exothermic reactions. The combination of the HBA test and the Endurica FEA-based analysis will add understanding to the heat-rise behavior of compounds for any company.  As with some other Coesfeld machines, Endurica is the sole distributor in the Americas.

The second presentation listed was presented by Mahmoud Assaad, co-authored by others at Endurica and also by Ed Terrill at ARDL.  This work aims to provide the combination of a full oxygen diffusion and oxidation reaction simulation and experimental characterization capability.   The plot here shows the distribution of reacted oxygen in the crown area of a commercial truck tire.  As the oxygen diffuses into the carcass it also reacts with the rubber compounds creating a phenomenon known as Diffusion Limited Oxidation.  Mahmoud, Ed Terrill and I worked on rubber oxidation with Sandia National Laboratories when the three of us worked together at Goodyear. Now we have developed a characterization and simulation capability that should be ready for customers to try in 2025!

For the third presentation listed, Will Mars quickly travelled from the IEC in Pittsburgh to the Tire Society in Akron to give a talk on an evolving capability for wear prediction. This work was co-authored by Lewis Tunnicliff and James Kollar at Birla Carbon as well as others from Endurica. For many years, researchers have been trying to link rubber fracture and tearing behavior to surface wear. One of the early works on this topic is shown in the drawing below from Southern and Thomas in 1979.

This work attempted to explain observations from blade abrader experiments. The Endurica/Birla work broadens this concept to different asperity shapes and a cumulative fatigue process that depends on the depth into the surface.  Temperature distribution near the surface was also calculated and included in the analysis.  Initial results gave similar trends for wear rates as work done by Gent and Pulford in 1983.  This new approach also makes it easy to also incorporate any aging effects that may occur on the surface of a rubber product. Development work on this new capability will continue well into 2025. In the meantime, Endurica does have a more basic FEA-based offering for wear prediction that has been used for multiple customers.

Lastly, on Friday the 13th of September, I had the honor of giving the Plenary Lecture for the Tire Society conference.  Thanks go to Jim McIntyre and the conference organizers for giving me this unique opportunity to address the society.

In April, we conducted the first ever Endurica Community Conference, and we tied in the Solar Eclipse that passed over Findlay, Ohio on April 8th, to produce a very successful event.  I wanted to include the solar eclipse in my Plenary talk and somehow relate it to topics concerning the development of tires.  The two concepts I used to make the connection were:

  • All models are approximations, but some can be very useful, and
  • Some very good physics theories predict singularities. The singularities reveal our ignorance on the topic and show the area where further work and insights are needed.

The first concept comes from the late George E. P. Box, a statistics professor at the University of Wisconsin. The quote is usually stated as: “All models are wrong, but some are useful”. The second concept makes a tie between fracture mechanics and Einstein’s General Theory of Relativity, which was validated by data taken during a solar eclipse in 1919. Both of these theories predict non-physical singularities but remain extremely useful.

The bulk of my talk was on Virtual Tire Development using tire durability as one of the performances to evaluate without building and testing prototypes. It largely followed my experience and contributions to the topic over the 3+ decades I worked on this at Goodyear with many excellent colleagues and partner organizations like Sandia.

All four of these presentations are available on our website at this location: Fatigue Ninja Frontier – Resources from Endurica’s First Annual Meeting.

Please contact us if you have any questions about these presentations or if you would like to chat with us about anything, including possible work together.

One final note: we are working on a revised website. Our Marketing Director, Pauline Glaza, is heading up a project to develop a new website for us that should make navigating our material and interacting with us much easier.  Expect to see our new site in early 2025!

 

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Combine Multiple Load Cases into a Block Cycle Schedule that Executes as a Single Endurica Job

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Our most recent Users Survey garnered two surprising requests:

  • “Very interested in ability to run a single model with increasing load and combine with “Duty cycle” definition to predict/calculate expected lifetime.”
  • “Would like to see more on how to use duty cycles (loads) within one analysis rather than running at one load.”

Endurica already does this! Allow me to break down the process and show how easy it is.

Multiple loading cases for a specific duty cycle is often part of Fatigue analysis. You can piece together a schedule of varying Loads, Displacements, Temperatures, Ozone Exposure, and more with Endurica DT.

I focus on load variability in this example. This duty cycle contains three unique loading conditions for a Simple Tension Strip: (A) 10mm displacement, (B) 20mm displacement, and (C) 35mm displacement.

Each load case is a separate FEA simulation. The strains are all exported separately for use with Endurica DT. Each FEA job is a single cycle of the desired loading.

Figure 1.  Contours of maximum principal engineering strain for each of load cases A, B and C. 

Here is a breakdown of the Duty Cycle for this analysis. One Cycle or “Life” is equivalent to 300 repeats of 10mm, 200 repeats of 20mm, and 100 repeats of 35mm.

Figure 2.  Block cycle schedule consisting of 300 repeats of load case A (displaced of 10mm), followed by 200 repeats of load case B (displaced of 20mm), and by 100 repeats of load case C (displaced of 30mm). 

When setting up the Endurica input file we specify the “schedule” under the “history” header in the input file. The number of “block_repeats” is then specified for each of the loading conditions. Once they are specified you submit the Endurica DT job like you would a single load Endurica CL job. The resulting life you receive will be the total number of cycles till failure.

Figure 3.  Endurica input file json syntax defining the block cycle schedule. 

Once submitted, Endurica provides a minimum life prediction of 2,944 Cycles of the full schedule. That is 883,200 cycles of 10mm, 588,800 cycles of 20mm, and 103,040 cycles of 35mm.

Figure 4.  Contours of fatigue life, reported as repeats of the total block cycle schedule. 

Want more information? Check out more details of Endurica DT’s capabilities.

For tutorials visit Endurica Academy:

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The New Endurica Architecture – It’s Time to Migrate

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Our transition to a new software architecture is a vital move in navigating the dynamic technological landscape. In a recent webinar, we discussed the aspects of this transition, providing insights into the why and how of adopting a new architectural approach despite having a functional existing one. This post will highlight the motivations behind the shift, the present status of feature migration, alterations in the latest software release, and an overview of projects within this new framework.

The Rationale and Benefits

Why Overhaul?

The complete rewrite of our software’s architecture was not a decision made lightly. The reasoning extends beyond merely wanting a refresh; it was driven by pivotal motivations, primarily surrounding the necessity for speed and efficiency in executing computing processes. Speed is invariably tied to productivity and operational fluency in software and technology. The plot below illustrates a compelling story: the old architecture (represented by the blue line), exhibited a static runtime, regardless of the number of threads engaged, revealing its inability to utilize parallel processing. Contrastingly, the new architecture demonstrates a significant speed-up, even with just a single thread, and scales to allow an increase in speed by many multiples, contingent on thread capacity.

Solving Larger Problems

The pursuit of faster execution isn’t arbitrary; it is intrinsically linked to our objective of solving larger problems. With larger tasks and projects on the horizon, scaling up and utilizing more CPU threads became essential. Exemplified through a job run on a virtual machine with 96 available CPU threads, the linear decrease in runtime with increasing threads (until certain hardware limitations are met) exhibits the new architecture’s adept handling of larger jobs (see plot below). The capability to scale and manage tasks of escalating complexity and size was a crucial driver for our transition.

Enhancing Integrations and Streamlining Workflows

Then, we turned our attention toward improving the user experience in interfacing with our software. Our prior use of the HFI and HFO file formats, while functional, presented numerous challenges regarding modification and integration, particularly when scripted modifications were necessary. The new architecture employs the JSON file format, widely recognized for its robustness and versatility across various industries and applications. With JSON, modifying job inputs and managing data become significantly simplified, as illustrated by a Python script example, wherein the entirety of job modifications, inputs, and submissions can be seamlessly handled with a handful of lines of code.

Improved Usability and Real-Time Error Checking

In an effort to enhance usability and mitigate the common issue of erroneous entries and syntax use, the new architecture, especially when utilized with a text editor like VS Code, offers real-time checking and syntax suggestions. This not only makes job submission more precise but also substantially reduces the trial-and-error cycle, saving valuable time. Additionally, upon job submission, the new architecture performs rigorous error and syntax checks, ensuring smooth execution and user experience.

Comprehensive Feature Migration: A Successful Transition

Reflecting on the past two years, we have accomplished a near-complete feature migration to the new software architecture, with 99% of features now successfully transitioned. This includes all outlined output requests, material models, history types, and various procedures.
Our commitment to supporting multiple interfaces remains, with support for Abaqus, Ansys, and Marc using the new architecture. Furthermore, Endurica Viewer is fully compatible, providing enhanced visualization capabilities under the new system.
The comprehensive migration and the incorporation of new functionalities marks the new architecture as fully operational and ready for use across all undertakings.

Implementation of Directory and Execution Changes in Endurica Software

Refined Directory Structure

In efforts to provide a seamless transition and user experience with the upgraded Endurica software, modifications have been made to the directory structure. The new architecture, once labeled “Katana” during its development phase, has now been ubiquitously integrated into the top-level Endurica directory. With the most recent software installation, users will observe the top-level CL and DT directories contain the new architecture, and the Katana directory has been removed.

Consequently, when we refer to Endurica CL and Endurica DT moving forward, it denotes reference to the new architecture.

Accommodating Transition: The Legacy Folder

Acknowledging that the transition to the new architecture may not be instantaneous for all users, the old architecture will still be available and designated within a “Legacy” folder. Though it requires navigation into subfolders, we ensure its accessibility for users who need more time to transition fully into the new structure.

Executable Naming Conventions

In tandem with the directory adjustments, executable naming conventions have been revised to be more intuitive. Previously, “endurica” was employed to submit fatigue analyses in the old architecture, while “katana” pertained to the new. To streamline, “katana” has been rebranded as “endurica” for submitting the JSON input file, with the legacy version adopting the name “endurica-legacy.” It is crucial to note that users accustomed to utilizing “katana” may continue to do so — “endurica” and “katana” will run the same executable. However, usage of the old architecture requires invoking a new “endurica-legacy” command.

Delivering the Unattainable with Endurica’s New Software Architecture

Embarking upon two recent projects with our new computational architecture, we explored the realms of virtual simulation and data management in tire durability and elastomeric mount durability performance.

Project 1: Tire Durability with Dassault Systems

In collaboration with Dassault Systems, a multi-body dynamic simulation was conducted to compute tire durability at the Nurburgring circuit. Utilizing SIMPACK for generating virtual road load data and employing Endurica EIE and Abaqus to establish a workspace map of driving conditions, the endeavor yielded significant data, processed through 176,000 time steps to evaluate the tire’s fatigue life. After a meticulous analysis, the results spotlighted the fatigue life to be 214 laps, pinpointing the most critical point around the tire bead edge.

Project 2: Durability of an Elastomeric Mount with Ford

Undertaken with Ford, the second project navigated through the durability performance of an elastomeric mount, involving a behemoth of data from 144 load history files, each load file containing tens or hundreds of thousands of time points, accumulating to over 15 million total time points. Utilizing a similar approach as the Nurburgring project, Endurica EIE and Abaqus were used together to generate the strain history data. The analysis focused on membrane elements on the mount’s free surfaces to precisely gauge surface strains. Culminating the analysis, the project succeeded in qualifying the part with a fatigue life of 9.4 repeats of the entire schedule, wherein the requisite was just one repeat.

These projects underscored the capabilities of our new architecture, navigating through large data sets and providing tangible insights in significantly reduced timeframes compared to the old architecture. In essence, the implementation of the new architecture has not only streamlined our processes but also expanded our horizons in handling large data and achieving nuanced analyses in our projects.

Summary

The new Endurica CL and Endurica DT architectures have now fully replaced our old system, maintaining the accuracy our users expect while introducing an easier, more powerful, and scalable solution. Everything has been successfully migrated over to this complete solution. With its enhanced capabilities, it addresses problems that were previously too large or took too long to solve, enabling our customers to tackle challenges they might not have considered before. The ability to solve unprecedented problems is just one more example of our steadfast commitment to providing accurate, complete, and scalable solutions.

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License Queueing

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Design optimization studies are driving a need to support the efficient management and execution of many jobs.  This is why we are announcing that Endurica’s software license manager now supports queueing for licenses. This allows a submitted job to automatically wait to start until enough licenses are available, instead of the prior behavior of exiting with a license error. Now you can submit many jobs without worrying about license availability.

License queueing is only available for network licenses (not node-locked). It is currently supported for Katana CL/DT jobs and EIE jobs submitted from a command prompt.

To enable queueing, set the environment variable RLM_QUEUE to any value. This environment variable must be set on the client machine (not the license server).

To learn more about license queueing, search for “How to Queue for Licenses” in the RLM License Administration documentation here: https://www.reprisesoftware.com/RLM_License_Administration.pdf

 

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

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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.

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Keeping Your Secrets

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Keeping your Secrets

The old saying “loose lips sink ships” is as true in product development as it is in war.  Maybe more so – while warships are heavily armored, intellectual property is never more secure than the least ethical person’s willingness and ability to misappropriate.  And the stakes have never been higher. Simulation software makes it easier than ever to document material properties, geometry, physics and functions of your next product.  So, collaborators can communicate design intentions more easily and more fully than ever before.  The downside?  It’s easier than ever for an adversary (or the next disgruntled employee) to walk out with your crown jewels!

This is why we’ve just implemented an encryption feature in the Endurica fatigue solvers.  Now you can password-protect sensitive information.  You control which information gets encrypted, and which stays as plain text.  You can share material property or load case definitions for use by collaborators without revealing private details in which you are heavily invested.

Here is a quick demo of how the new feature works.  Check it out.

One more way we are helping you to win on durability.

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