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

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

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

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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Things that went right in 2020 at Endurica

Things that went right in 2020 at Endurica

2020 is burned in all our minds as a chaotic and tough year.  Just like the rest of the world, Endurica staff experienced times of isolation and loss due to the pandemic.  On a positive note, we invested heavily in making our tools and workflows better than ever so that we’re ready to come back strong in 2021.  Here is a list of our top new developments in 2020:

Endurica Software Enhancements

  • Endurica DT’s new Ageing Feature now enables you to simulate how ageing affects your rubber product. Your compound’s stiffness, strength, and fatigue properties can all evolve with time.
  • Our new Linux distribution takes our solutions beyond the Windows world.
  • We’ve added an encryption feature to safeguard your trade secrets.
  • Viewer Improvements make it easier than ever to visualize your fatigue simulation results.
  • EIE Enhancements give you blazing-fast compute speed for full road-load signals.
  • We’ve also planned an aggressive development agenda for 2021. Stay tuned for a new Endurica-based smartphone app for materials engineers, for a new feature that computes fatigue threshold safety margins, for a new block cycle schedule extraction algorithm, and more!

Training

  • The new Fatigue Ninja Friday webinar series provides step-by-step application training for key the workflows that you need to get durability right. All of the recorded episodes are now available in the online Endurica academy.
  • The new Winning on Durability webinar series provides high-level overviews of both technical and business topics so you can connect Endurica tools to your strategic imperatives. All of these recorded webinars are available gratis on our website.
  • We’ve recast our in-person training events as LIVE, ONLINE workshops accessible safely around the world.

Testing Instruments

Fatigue Property Mapping Testing Service

  • We added the Reliability Module to our Fatigue Property Mapping testing service. Use it to quantify crack precursor size statistics when you need to estimate probability of failure.
  • We also reorganized the Thermal Module and the Ageing Module into Basic and Advanced levels, to offer a lower price-point when a basic option will suffice.

Want to leverage any of these new capabilities in your next durability project?  Give us a call and let’s talk!

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Endurica 2019 Updates Released

Endurica CL

Endurica CL received many improvements over the past year.  These improvements cover a wide variety of different aspects of the software:

Reducing Run-time

Our investments in code benchmarking and performance are paying off! We’ve been able to make internal optimizations to the code that reduce analysis run-times by approximately 30%. 

HFM and HFO Formatting

To make our output cleaner and more meaningful, small changes have been made to the number formatting in the HFM and HFO files.

All results reported in scientific notation are now formatted in standard form where the leading digit before the decimal point is non-zero (previously the leading digit was always zero).  This gives one more significant figure to all the results without increasing the output file size.

Signal compression

The shortest fatigue life for the analysis is now printed to the console and HFM file with six significant figures.  Previously, the life was reported with only two significant figures.  This change makes it easier to quickly compare two different analyses, especially when the analyses have similar fatigue lives.

New features have been added to Endurica CL to make it easier to process and analyze histories.  Using the new COMPRESS_HISTORY output request, you can generate new HFI files containing compressed versions of your original history.  The generated history is composed of the rainflow counted cycles from your original history.  An optional output parameter allows you to further compress the signal by specifying the minimum percentage of the original damage that should be retained in the new history.  When keeping a percentage of the damage, the cycles are sorted from most to least damaging so that the generated history always contains the most damaging cycles and discards the least damaging cycles.

This output request is useful when you want to reduce a long complex history while keeping the important damaging cycles.  This can reduce file sizes and simplify experimental testing setups as well as give you a deeper insight into your duty cycle. 

Endurica DT

Endurica DT is our incremental fatigue solver.  With Endurica CL, your analysis starts at time zero and integrates the given strain history until end-of-life.  With Endurica DT, you can start and end at a series of times that you specify.  This lets you accumulate many different histories and loading conditions repeatedly until end-of-life.

With Endurica DT, it allows you to start and end at a series of times, when specified.

Endurica DT gives you new ways to control your analyses, and we have been using it over the past year in many applications.  For example, fatigue results for laboratory test procedures that involve multiple loading stages (such as FMVSS No. 139 for light vehicle tires, or block cycle schedules for automotive component applications) can be fully simulated using Endurica DT. You can also compute residual life following some scheduled set of load cases. 

Endurica DT can also be used to accumulate the actual loads measured on a part in situ.  This allows you to create a digital twin that keeps a near real-time record of the part’s current simulated damage state and the part’s remaining fatigue life. 

Stiffness Loss Co-Simulation

Endurica DT now includes a stiffness loss co-simulation workflow that allows you to iteratively update the stiffness of your part over a series of time steps, based on the amount of damage occurring in the part.  The stiffness loss is computed per element so you will have a gradient where the more damaged regions become softer.  Endurica DT computes the current fraction h of stiffness loss based on the stress and strain, and the finite element solver computes the stress and strain based on the current fractions of stiffness loss. The capability accurately predicts the effects of changing mode of control during a fatigue test.  For example, stress controlled fatigue tests show shorter life than strain controlled fatigue tests. 

Endurica DT now includes a stiffness loss co-simulation workflow

Endurica EIE

Endurica EIE, our efficient interpolation engine, quickly generates long, complex histories using a set of precomputed finite element results (i.e. the ‘nonlinear map’).  We first launched EIE last year with the ability to interpolate 1-channel and 2-channel problems.  We have recently added the ability to interpolate 3-channel problems. 

In the example below, EIE was benchmarked with three-channels.  Three separate road load signals were computed from a single nonlinear map.  With EIE, you don’t need to rerun the finite element model for each history.  Instead, EIE interpolates from the nonlinear map, providing the equivalent results with a 60x speed-up in compute time. 

Endurica EIE interpolates from the nonlinear map, providing the equivalent results
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