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.
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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.

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My SAE WCX 2022 Top Takeaway

 

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 with 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!

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.

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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.

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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.

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

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.

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.

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Tire Society Takeaways 2021

The Tire Society held its 40th annual meeting last month with the theme The Virtual Tire.  It has always been the place to see up and coming ideas, to see who is pushing into the frontiers of the field, and to renew professional connections across the industry.  Endurica was very proud to sponsor this year.

Here’s a brief recap of our favorite talks…

GM’s Mike Anderson, Executive Director of Global Virtual Design, Development and Validation, kicked off the meeting with his keynote lecture, titled “The Move To Virtual”.  He spoke of GM’s target to achieve 100% virtual design by 2025.  Anderson explained that this doesn’t mean that physical testing will go away, but rather that GM is dead serious about getting to a “right the first time” scenario rather than a “discover and recover” mode.  “It’s a measure twice, cut once” culture, he said.  He noted that upstart competitors are sprinting ahead in areas like EVs through the use of simulation and that the speed of discovery has increased significantly in the current competitive environment.  Simulation drives learning speed, not only because of the opportunity to get engineering answers at the pre-build phase but also because it enables exploration of more of the design space and more of the performance outcomes.  He told the conference that “we need to go beyond just replicating physical tests with simulation, we need to leverage the strength of simulation to go beyond test”.  In the Q&A, Anderson was asked whether suppliers will also be expected to be virtual.  “That’s gonna be tough to play together” for rubber part suppliers that can’t engage via simulation.

There were three talks given by Endurica users at this year’s Tire Society meeting.

Pooya Behroozinia of Maxxis Tires spoke on “Tire Durability Prediction Using Three-Element Layered Mesh for Cord-Rubber Composites”.  Behroozinia shared a tire meshing technique for improving representation of interlaminar shearing in their tire model.  They used Endurica DT to simulate the damage accruing across all of the 6 steps in a stepped-up load durability test, and they were able to predict correctly the lower sidewall failure mode, the life (45 hours observed, 38 hours predicted), and the crack orientation.  They also had a 2nd validation case in which the loads were increased by 10% in all steps of the test.  The simulation again predicted correct failure, and the comparison of experimental life (41000 km) to simulated life (36330 km) was in good agreement.

Vidit Bansal of CEAT spoke on “Incremental, Critical Plane Analysis and Experimental Verification for TBR Tyre Bead Endurance Applications”.  Similar to the Maxxis paper, CEAT used Endurica DT to simulate a multi-step durability test with loads ranging from 80% to 250%.  In this paper, two different truck tire sizes were modeled and tested, a 10.00R20 and an 11.00R20.  The analysis correctly predicted the ply turnup as the critical location.  The predicted lives of the two tire sizes were predicted at 90-93% of the actual tested life in both cases.

Tom Ebbott and Gobi Gobinath of Goodyear spoke on “A Model for Predicting Residual Casing Life of a Tire Following an Impact Event”.  This work demonstrated the consequences on tire damage development of a range of impact event scenarios (3 speeds, 4 impact angles, 3 different wear states) early in the life of the tire.  It used Endurica DT to accrue damage from both the impact event (computed with explicit FEA) and subsequent tire runout under steady state rolling conditions (computed with implicit FEA).  The crack growth rate curve during the impact was based upon experimental measurements of the critical tearing energy at impact rates.  When asked about experimental validation of the simulation results during the Q&A, Ebbott noted that “the modeling work stands on its own – it is based on sound physics”.

We at Endurica were delighted with the significance and innovation on display in all of these talks.  We have often been challenged to show validation for tire durability predictions, but such measurements are difficult to obtain without significant tire testing resources. So, the fact that the Maxxis and CEAT papers showed multiple direct comparisons of tire durability tests with simulations, and the fact that excellent predictions of both failure mode and tire life were achieved was a very significant moment for us and for the industry.

The Goodyear paper was significant for a different reason.  Their paper showed an application that would have been difficult or impossible to evaluate with physical testing.  They showed how getting the right physics into the model builds the trust necessary to leverage simulation to increase the speed and scope of discovery and to go beyond the limits of physical testing.  It was the perfect illustration of keynoter Mike Anderson’s point that simulation opens significant opportunities for competitive advantage and ‘right the first time’ engineering.

Click here to download a .pdf summary of this blog post: Endurica Spotlight on The Tire Society 2021 Annual Meeting The Virtual Tire

 

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Virtual vs. Physical in 2021 and Beyond

These days everybody’s talking about whether to meet in person or online.  There are great tools available for online meetings, and these have helped us navigate Covid-19. Like everyone else, Endurica teammates regularly use online meeting technology.  But if there is one thing we learned over the last year, it is that sometimes physical presence really matters. Living and working in isolation is just not healthy in the long run.

The new normal during the pandemic had some benefits that were enabled by the virtual world. Time and energy that used to be consumed by travel were rechanneled into improving our software, testing services, and marketing materials. In our personal lives, we had more opportunities to spend quality time with our immediate families and found more time for fitness activities. We previously talked about our pandemic pivots to bring our training courses online and offer webinars to stay in touch with our existing and potential customers.

But virtual meetings can’t replace the full experience of being together in person.  The face-to-face engagement at a trade show, the serendipitous bumping into a client, the spontaneous discussion of ideas with fellow conference-goers with a shared interest, the rapport building that comes from shared experiences.  We fundamentally need physical connection. A hug, delivered via Zoom, will never feel the same.

The world of 2021 and beyond is hybrid: part virtual, part in-person.  The benefits of the virtual are too great to set aside, and the necessity of the physical is too compelling to neglect.  Both are critical to our future, at home and at work.

So, too, with Endurica’s simulation workflows. It was NEVER Simulation OR Build-and-Break. Even the best simulations are not enough to completely skip physical testing. The virtual approach saves significant time and money in product development and design refinement. It allows you to explore a huge space of compound options and of design features before investment in building and testing prototypes. Our simulations enable you to balance difficult trade-offs. Still, before you head into production, you must complete actual physical testing on your rubber part – the physical world is what counts in the end. It is simulation AND build-and-break that are both needed in concert to #GetDurabilityRight.

Just as a Zoom hug will never replace the real thing, software will never replace the role of physical testing.  But just as online meetings are creating new opportunities and efficiencies, Endurica’s tools position you for unprecedented success when it’s time to test.

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Use This One Simple Trick to Ensure Rubber Part Durability

We’ve just added a new output to the Endurica fatigue solver: Safety Factor.  This feature makes it simple to focus your analysis on whether cracks have the minimum energy required to grow. Safety Factor is a quick and inexpensive way to identity potential failure locations.  It minimizes the number of assumptions you need to defend, and it is backed by hard science.  You don’t need to measure or explain the many influences that together determine how fast cracks grow.  You don’t need lengthy materials characterization experiments that take days or weeks.  You do need to know your material’s Intrinsic Strength T0 (ie Fatigue Threshold) and its crack precursor size c0. The test takes about an hour using the Coesfeld Intrinsic Strength Analyser.

The Safety Factor S is computed as the ratio of T0 to the driving force T on a potential crack precursor.  If the value of the Safety Factor S = T0/T is greater than 1, it indicates the margin by which crack growth is avoided.  If S is less than 1, it indicates that crack growth is inevitable. The calculation of the Safety Factor includes a search for the most critical plane, as we do for our full fatigue life computations.

Although the Safety Factor can’t tell you how long a part will endure, it nevertheless does offer great utility.  You can make a contour plot showing the locations in your part where the Safety Factor is the lowest.  This is a quick and inexpensive way to identity potential failure locations.  You can make statements about the reserve capacity of your design that are easy to communicate and understand with a wide audience.

The images above show a vibration isolation grommet operating under small (Safety Factor 2.6) and large displacements (Safety Factor 0.83).  Color contours indicate the Endurica-computed Safety Factor, and use the same scale for both images.  Large Safety Factors are shown in blue.  Safety Factors approaching 1 are shown in red.  Safety Factors smaller than 1 are indicated in black.  These results show that the grommet can be expected to operate indefinitely under the small displacements, but that large displacements will produce cracks at some point, in the regions colored black.

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Durability by Design on Any Budget

Durability by Design

So, you’ve got a tricky durability problem to solve, a budget, and a deadline.  Let’s look at a helpful framework for sorting which Endurica workflows you need.  In the grid below, each row represents a potential approach you can take.  The approaches are, in order of increasing complexity and cost, the Infinite Life approach, the Safe Life approach, the Damage Tolerant approach, and the Fail Safe approach.

Endurica Durability Workflows

The Infinite Life approach is by far the simplest approach.  Here, we say that damage will not be allowed at all.  All locations in the part must operate, at all times, below the fatigue limit (ie intrinsic strength) of the rubber.  The required material testing is minimal: we need only know the fatigue limit T0 and the crack precursor size c0.  We avoid the question of how long the part may last, and we focus on whether or not we can expect indefinite life.  We report a safety factor S indicating the relative margin (ie S = T0 / T) by which each potential failure location avoids crack development.  When S>1, we predict infinite life.  For S<=1, failure occurs in finite time and we must then go on to the next approach…

In the Safe Life approach, the chief concern is whether or not the part’s estimated finite life is adequate relative to the target life.  The material characterization now becomes more sophisticated.  We must quantify the various “special effects” that govern the crack growth rate law (strain crystallization, temperature, frequency, etc.).  We consider the specific load case(s), then compute and report the number of repeats that the part can endure.  If the estimated worst-case life is greater than the target life then we may say that the design is safe under the assumptions considered.  If not, then we may need to increase the part’s load capacity, or alternatively to decrease the applied loading to a safe level.  In critical situations, we may also consider implementing the next level…

The Damage Tolerant approach acknowledges that, whatever the reasons for damage, the risk of failure always exists and therefore should be actively monitored.  This approach monitors damage development via inspection and via tracking of accrued damage under actual loading history.  A standard nominal load case may be assumed for the purpose of computing a remaining residual life, given the actual loading history to date.  Changes in material properties due to cyclic softening or ageing may also be tracked and considered in computing forecasts of remaining life.

The Fail Safe approach takes for granted that failure is going to occur, and obliges the designer to implement measures that allow for this to happen safely.  This can take the form of a secondary / redundant load path that carries the load once the primary load path has failed.  It can take the form of a sacrificial weak link / “mechanical fuse” that prevents operation beyond safe limits.  It can take the form of a Digital Twin that monitors structural health, senses damage, and requests maintenance when critical damage occurs.

The last three columns of the grid show which Endurica fatigue solver workflows align with each design approach.  The Endurica solvers give you complete coverage of all approaches.  Whether you need a quick Infinite Life analysis of safety factors for a simple part, or deep analysis of Damage Tolerance or Fail Safety, or anything in-between, our solvers have just what you need to get durability right.

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