Publications Archives - ESRD https://www.esrd.com/category/news/publications/ Engineering Software Research and Development, Inc. Thu, 21 Dec 2023 17:51:59 +0000 en-US hourly 1 https://wordpress.org/?v=6.6.2 https://www.esrd.com/wp-content/uploads/cropped-SC_mark_LG72ppi-32x32.jpg Publications Archives - ESRD https://www.esrd.com/category/news/publications/ 32 32 Happy Holidays from ESRD (2023 Edition) https://www.esrd.com/happy-holidays-2023/ https://www.esrd.com/happy-holidays-2023/#respond Thu, 21 Dec 2023 17:51:55 +0000 https://www.esrd.com/?p=30592 From all of us at ESRD, we wish you a very happy holiday season! We truly feel that each and every one of our users are part of the ESRD family and we are incredibly grateful to get to work with all of you. There is much we are thankful for as we approach the end of the year, and we'd like to take a moment to acknowledge some of the reasons we're looking back fondly on 2023...]]>
Original geometry courtesy of user Charlie Dearman of GrabCAD.

From all of us at ESRD, we wish you a very happy holiday season! We truly feel that each and every one of our users are part of the ESRD family and we are incredibly grateful to get to work with all of you. We hope that you enjoy your year-end celebrations, quality time with friends and family, and wrap up 2023 with a big automesh-patterned bow 😉

There is much we are thankful for as we approach the end of the year. Our ESRD team has grown, we have had the opportunity to engage with our FEA community in new and important ways, and we’ve continued to strengthen our relationships with many of our beloved StressCheck users through conference visits and in-person trainings. We’d like to take a moment to acknowledge some of the reasons we’re looking back fondly on 2023…


ESRD’s New Account Manager

Patrick Goulding joined ESRD back in June as our new Account Manager. Many of you have had the chance to meet or speak with him this year, but if you have not yet been introduced feel free to reach out and say hi anytime, he would be thrilled to hear from you!

Patrick comes to us with several years of technical experience in the CAE industry, primarily with a background in multibody dynamics and mechatronics, and received his Master of Science in Mechanical Engineering from University of Illinois, Chicago. Patrick works remotely from his home office in Long Beach, CA, where he spends much of his time playing beach volleyball and repairing vintage turntables. If you’re looking for a turntable recommendation for your new stereo setup, he’s your guy.

Before Patrick was an engineer he devoted his career to the arts, co-founding a theatre company in Chicago and managing the day-to-day activities of a startup non-profit. From this experience, he learned the tremendous value of genuine and lasting business relationships. Patrick sees his role at ESRD as an opportunity to partner with talented engineers like yourself, help you to achieve your goals, and further his respect and admiration for those in the aerospace community.

Connect with Patrick on LinkedIn.


Blog Series Authored by ESRD Co-founder, Dr. Barna Szabó

Starting in October, Dr. Barna Szabó has authored weekly blog articles published to our ESRD Blog. These concise discussions address hot topics in engineering such as XAI, the misconceptions between Finite Element Modelling and Finite Element Analysis, and the importance of Simulation Governance for today’s engineering managers. We think that not only are these critical topics for our ESRD community to engage in, but that they are compelling insights into the fundamental values our software is built upon.

If you have not yet taken a look, we invite you to browse the currently published articles, choose your topic of interest, and share the discussion with others on your team. Dr. Szabó’s invites feedback and discussion, so feel free to reach out to us and to him with your thoughts and insights!


ASIP Conference 2023

We had a fantastic time attending the ASIP Conference this year and getting the chance to spend time with so many from our ESRD community! We look forward to it every year, because we get to catch up with so many of you and attend wonderful presentations demonstrating StressCheck in the ASIP industry.

Take a look at our recap of the 2023 ASIP Conference in Denver and we look forward to seeing many of you in Austin next year!


Looking Forward to 2024!

We’ve been working VERY hard on what we consider the most significant release of StressCheck in years, StressCheck v12.0! Our developers are in the very final stages of testing, making sure we deliver the highest quality analysis tool for you to use in 2024.

While we wait patiently for its debut, we want to make sure each of you know what to expect with the new functionalities, GUI updates, and overall improvements. Please schedule your demo of StressCheck v12.0 using the form below:

Please indicate an organization, such as the agency, company or academic institution to which you are affiliated.
For more details on the engineering applications supported by our software products, refer to our Applications page.
ESRD will work with you to schedule a 1 to 2-hour Teams meeting to review the selected engineering applications.

Original geometry courtesy of user Bryan Quille of GrabCAD.
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How Real-World Scenarios Can Make the Case for Simulation Governance https://www.esrd.com/simulation-governance-scenarios/ https://www.esrd.com/simulation-governance-scenarios/#respond Fri, 30 Apr 2021 00:56:48 +0000 https://www.esrd.com/?p=20853 All major engineering organizations use numerical simulation in support of decisions pertaining to design and design certification. The question of how well numerical simulation is managed is being addressed by the various stakeholders with increasing urgency. It is now generally recognized that numerical simulation, properly managed, can be a major corporate asset but poorly managed, or not managed at all, can become a major corporate liability. Find out why in the latest Safer Simulation article from ESRD.]]>

By Dr. Barna Szabó, ESRD Co-Founder & Chairman

All major engineering organizations use numerical simulation in support of decisions pertaining to design and design certification. The question of how well numerical simulation is managed is being addressed by the various stakeholders with increasing urgency. It is now generally recognized that numerical simulation, properly managed, can be a major corporate asset but poorly managed, or not managed at all, can become a major corporate liability.

What Is Simulation Governance?

By its definition in Wikipedia: “Simulation governance is a managerial function concerned with assurance of reliability of information generated by numerical simulation. The term was introduced in 2011 [1] and specific technical requirements were addressed from the perspective of mechanical design in 2012 [2]. Its strategic importance was addressed in 2017 [3] [4]. At the 2017 NAFEMS World Congress in Stockholm simulation governance was identified as the first of eight “big issues” in numerical simulation.

NAFEMS has named Simulation Governance a “Big Issue”. But what is it?

Simulation governance is concerned with (a) selection and adoption of the best available simulation technology, (b) formulation of mathematical models, (c) management of experimental data, (d) data and solution verification procedures, and (e) revision of mathematical models in the light of new information collected from physical experiments and field observations [5].”

Why Is Simulation Governance Important?

To appreciate the fundamental importance of simulation governance, please consider the following scenarios.

Scenario #1

A senior executive (SE) of a Fortune 500 corporation, in charge of a multi-billion dollar program, came to suspect that something was very wrong with the way finite element modeling was being done. There were large discrepancies between the outcomes of physical tests and the outcomes predicted by engineer-analysts. This made it necessary to do more testing than originally planned, resulting in substantial delays and cost overruns.

Getting reliable and timely correlation between predicted and realized test results was particularly important because new materials were being introduced for which design rules had to be developed, yet the discrepancies between predicted and realized outcomes were substantial, to say the least.

The SE invited outside consultants to address his concerns. He also invited five senior engineers to the first meeting. These engineers were responsible for finite element modeling in one way or another. Each of them had impeccable academic credentials and decades of experience.

The consultants explained the difference between finite element modeling and numerical simulation. They conveyed (in as diplomatic a way as they could) that the erroneous predictions were caused by the now obsolete practice of finite element modeling which can produce reasonable results in structural calculations but is not suited for strength calculations.

The engineers were visibly upset by the suggestion that the method they have been using for years is now obsolete. Their strong opposition to any substantive change in current practices became obvious. What do you think the SE should do?

Scenario #2

Your corporation grew over time by acquisition. Each acquisition brought with it a corporate culture, engineering manuals, software, Excel-based calculations and the like. Just to see what would happen, you gave a problem to three engineer-analysts and you got three different answers. What do you think you should do?

Scenario #3

You feel overwhelmed by the number of software products used by your engineering staff. You would like to streamline the workflows and initiate a vendor-reduction program. Your senior engineers agree with your goals but do not agree on what streamlining means and what criteria should be used in the vendor-reduction program. What will you do?

Scenario #4

A flight-critical component of a rotorcraft is to be tested in a fatigue experiment. A finite element model predicted that the probability is 90% that failure will occur between 100 and 250 thousand cycles. The failure occurred at 80 thousand cycles. If you were the engineer in charge of the design, what would you do?

Scenario #5

Your organization decided to introduce a new type of composite material for which design rules are not yet available. You were assigned to set up a program for the development of design rules. Your senior analysts proposed three different ideas on how the failure criteria should be formulated. How will you decide which one to use?

Scenario #6

The cost of unscheduled maintenance is much higher than the cost of scheduled maintenance. You would like to justify postponing maintenance actions relating to safety critical components to scheduled times. How would you go about establishing guidelines?

Scenario #7 – The JSF Story

In 2011 and 2012, two high-ranking US military officials commented on the (costly) lessons learned from the Joint Strike Fighter (JSF) project. From JSF program chief Vice Admiral David Venlet (AOL Defense, 2011):

JSF’s build and test was a miscalculation…. Fatigue testing and analysis are turning up so many potential cracks and hot spots in the Joint Strike Fighter’s airframe that the production rate of the F-35 should slowed further over the next few years… The cost burden sucks the wind out of your lungs.

And, from Gen. Norton Schwartz, Air Force Chief of Staff (Defense News, 2012):

There was a view that we had advanced to a stage of aircraft design where we could design an airplane that would be near perfect the first time it flew. I think we actually believed that. And I think we’ve demonstrated in a compelling way that that’s foolishness.

What do you think should have been done differently? What steps did your organization take to avoid similar problems in the future?

Scenario #8

You asked your principal vendor of finite element analysis software; what tools are provided to support solution verification? The response was that the software had been tested against all NAFEMS benchmark problems and the correct solutions were obtained. Should you be satisfied with this answer? Have you communicated your technical requirements to your software vendors? Is solution verification among your technical requirements? – Should it be?

Planning For Simulation Governance

The concept of simulation governance is easily grasped, however formulation of a plan for simulation governance for a particular organization is not simple at all.

Recognizing that technology advances and the available information increases over time, planning must incorporate data management and systematic updates of simulation practices so as to take advantage of new data and technology.

The preservation and maintenance of corporate know-how and institutional knowledge are important objectives of simulation governance. The productivity of newly hired engineers rapidly increases if routine simulation procedures are standardized so that applications consistently produce certifiable results.

A plan for simulation governance has to be tailored to fit the mission of each organization or department within an organization:

  • If the mission is application of existing design rules, then the goal should be:
    • Standardize recurring numerical simulation procedures through the creation of smart applications. Smart applications, also called “simulation apps” are expert-designed, in such a way that the use of those applications does not require expertise in numerical simulation.
    • Economic benefits: Improved productivity and improved reliability.
  • If the mission is formulation of design rules, then the plan should focus on:
    • Collection, maintenance and documentation of experimental data.
    • Management of solution and data verification procedures.
    • Revision and updating mathematical models in the light of new information collected from physical experiments and field observation.
    • Economic benefits: Substantial savings through optimization of design and certification procedures.
  • If the mission is to support condition-based maintenance (CBM), then the main activities are:
    • Collection, maintenance and documentation of field data.
    • Update calibration records based on unit-specific information.
    • Standardize recurring analysis tasks.
    • Economic benefits: Substantial savings through improved disposition decisions.

Implementation

The first and perhaps the most challenging problem is to overcome widespread misunderstanding of what numerical simulation is. Most managers and many individuals who present themselves as experts in numerical simulation confuse numerical simulation with “finite element modeling” or “numerical modeling “. Those are outdated concepts, responsible for much of the disappointing results.

Existing simulation and data management practices have to be reviewed and evaluated in terms of efficiency and reliability. When a need for change is identified, a business case and consensus among the stakeholders have to be developed.

Metrics that measure the economic value of numerical simulation have to be established.

References

[1] Szabó B. and Actis R. Simulation governance: New technical requirements for software tools in computational solid mechanics. International Workshop on Verification and Validation in Computational Science University of Notre Dame 17-19 October 2011.
[2] Szabó B. and Actis R. Simulation governance: Technical requirements for mechanical design. Comput. Methods Appl. Mech. Engrg. 249-252 158-168, 2012.
[3] Meintjes J. Simulation Governance: Managing Simulation as a Strategic Capability. NAFEMS Benchmark Magazine, January 2015.
[4] Imbert J-F. Simulation Governance – Building confidence, a key dimension of simulation strategy. NAFEMS World Congress NWC15 San Diego, June 2015.
[5] Oberkampf WL and Pilch M, Simulation Verification and Validation for Managers. NAFEMS, 2017. ISBN 978-1-910643-33-4.

Request a Simulation Governance Briefing

Would you like to request a Simulation Governance briefing with our team of experts? Complete the form below and we’ll be happy to reach out with more information:

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Happy Holidays from ESRD (2022 Edition) https://www.esrd.com/happy-holidays-2022/ https://www.esrd.com/happy-holidays-2022/#respond Wed, 21 Dec 2022 00:29:46 +0000 https://www.esrd.com/?p=26678 As we continue to adapt to a mix of remote and in-office work, we hope that this past year you found our software products, customer support, training options/courses, "StressCheck Tip of the Week" posts, and e-Learning resources to be helpful and accommodating. We certainly couldn't do it without your valuable feedback and contributions! We are committed to supporting your current and future engineering endeavors and look forward to what the future holds in 2023. Happy Holidays from all of us at ESRD, and we hope you'll check out our year-end summary!]]>
Original geometry courtesy user DC of GrabCAD

As we continue to adapt to a mix of remote and in-office work, we hope that this past year you found our software products, customer support, training options/courses, “StressCheck Tip of the Week” posts, and e-Learning resources to be helpful and accommodating. We certainly couldn’t do it without your valuable feedback and contributions! We are committed to supporting your current and future engineering endeavors and look forward to what the future holds in 2023.

In 2022, we re-designed StressCheck’s documentation to include online and offline versions, attended ASIP 2022 as exhibitors and presenters, released StressCheck v11.1 (our best release yet!), and made numerous additions to our resource library to aid in a more efficient and enjoyable StressCheck onboarding process. The following are a few highlights that we’d like to share from this past year.


ASIP Conference 2022 Impressions…

ESRD’s Exhibit Booth at ASIP 2022 in Phoenix, AZ.

In late November 2022, ESRD exhibited at the ASIP Conference and enjoyed re-connecting with StressCheck users, industry colleagues and our partners Hill Engineering (BAMpF 3D fatigue crack growth software developers) and LexTech (AFGROW developers). We also provided a training course and conference paper on the modeling and analysis of bonded doubler repairs.

Read more about our conference proceedings here.


StressCheck v11.1 Released…

We were pleased to release StressCheck v11.1 in late July 2022, made possible by the dedication and hard work of our development and QA teams. This release was packed with new features and enhancements in the areas of automatic meshing, fracture mechanics and global-local applications:

The new Thin Section automesh method supports meshing thin regions with penta- and hexa-dominant element layers for efficient solutions of lightweight aerospace structures
The enhanced Crack Front automesh method supports meshing 3D cracks with penta- and hexa-dominant element layers for significantly improved SIF extractions
New parametric TLAP scaling feature for linear and incremental nonlinear analyses supports load stepping/load reversals

For a quick recap of the highlights in StressCheck v11.1 view the following short video:

Does your organization have an active StressCheck SM&TS contract but hasn’t yet upgraded to StressCheck v11.1? Contact us to get started with the upgrade!


Live Webinar Coming Soon…

On February 7th, 2023, we are planning for a live webinar to review what’s new and improved with the release of StressCheck v11.1, as well as preview the new features and enhancements under development for StressCheck v11.2 (targeted for release in Summer 2023).

Some highlights of features under development include (but are not limited to):

  • Mesh seeding to guide the Automesh by automatically using pre-existing node locations.
  • Upgraded toolbar icons for a clear and improved user experience.
  • New option to select the toolbar icons between 16×16 (default), 20×20 and 24×24 pixels size.
  • Movable Min/Max labels for Results plotting and extractions.
  • A Dependencies button on the Parameter pane which lists all dependencies on the selected parameter.
  • Column sorting and filtering for Parameters pane table including “Go To” to search for parameters.
  • Predictive text on input fields has been implemented for parameter and formula names.
  • Enhanced Index controls for filtering and sorting Geometry and Mesh object lists. including “Go To ID…” to access a specific ID.
  • Improved visualization of Selected status on dropdown lists containing assignment/set records.
  • Overhauled the Display Objects pane to support selective number ranges and additional object types.
  • Re-designed color definitions pane.
  • A list of object IDs belonging to a set “Contents:” and a list of objects that reference the set “Used By:” are now displayed when selecting a record on the Sets page.
  • Improved consistency of DeLast/Undo functionality

Snapshot of the improved icons (20×20 pixels shown) and user experience in StressCheck v11.2

Pre-register for the “What’s New and Improved in StressCheck” webinar by completing the form below:


Wishing for Good Tidings and Good Health

Original geometry courtesy user Alex Petuhov of GrabCAD

Finally, we’d like to wish all of our customers, partners and friends Happy/Safe Holidays and a Happier/Healthier 2023!

Keep up with the latest from ESRD by subscribing to our newsletter:

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ESRD Poses FEA Puzzler in NAFEMS Benchmark Magazine October 2018 https://www.esrd.com/esrd-fea-puzzler-nafems-benchmark-magazine-october-2018/ https://www.esrd.com/esrd-fea-puzzler-nafems-benchmark-magazine-october-2018/#respond Wed, 31 Oct 2018 20:53:37 +0000 https://esrd.com/?p=8255 In the October 2018 issue of NAFEMS Benchmark magazine, ESRD Chairman Dr. Barna Szabó posed a new "FEA Puzzler": Can you determine the progression in spring rate as a 3D coil spring is deformed? And, can you verify the accuracy of your solution? Give it your best shot! ]]>

ESRD has posed a new FEA challenge problem in the October 2018 issue of NAFEMS Benchmark Magazine. Can you show that you solved it with sufficient accuracy?

In the October 2018 issue of NAFEMS Benchmark magazine, ESRD Chairman Dr. Barna Szabó posed a new “FEA Puzzler”: Can you determine the progression in spring rate as a 3D coil spring is deformed and can you verify the accuracy of your solution?

Dr. Szabó has produced a converged solution for the spring rates in our high-fidelity FEA software StressCheck Professional, and is requesting solutions from the engineering community on how they tackled the problem.  He will publish his solution after the submission deadline of February 1st, 2019.

The problem posed in NAFEMS Benchmark magazine is as follows:

FEA Puzzler from NAFEMS Benchmark Magazine October 2018

You can download the geometry (in Parasolid or STEP format) from nafe.ms/puzzler. Do you think you have the “FEA Puzzler” solved? Submit your reply to challenge@nafems.org by February 1st, 2019.

Are you an ESRD customer? If you’d like some tips on how to solve the model in StressCheck Professional, feel free to contact us below:

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ESRD Pens SimGov Article for July 2021 NAFEMS Benchmark Magazine https://www.esrd.com/esrd-pens-simgov-article-for-july-2021-nafems-benchmark-magazine/ https://www.esrd.com/esrd-pens-simgov-article-for-july-2021-nafems-benchmark-magazine/#respond Mon, 02 Aug 2021 14:41:26 +0000 https://www.esrd.com/?p=22065 A new Simulation Governance (SimGov)-oriented article by ESRD's Dr. Barna Szabo and Dr. Ricardo Actis, titled "Planning for Simulation Governance and Management - Ensuring Simulation is an Asset, not a Liability", is available to read in the July 2021 issue of NAFEMS Benchmark magazine.]]>
Image courtesy of July 2021 NAFEMS Benchmark magazine.

A new Simulation Governance (SimGov)-oriented article by ESRD’s Dr. Barna Szabo and Dr. Ricardo Actis, titled “Planning for Simulation Governance and Management – Ensuring Simulation is an Asset, not a Liability”, is available to read in the July 2021 issue of NAFEMS Benchmark magazine here (download is free for NAFEMS members). The article’s abstract is as follows:

Advances in predictive computational science make it possible to increase the reliability of numerical simulation, necessitating fewer physical experiments for substantial savings in time and cost of product development projects. To take advantage of those advances, industrial organizations will have to exercise simulation governance.


More SimGov Resources:

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Watch Teaser Video for the NAFEMS Coil Spring FEA Puzzler https://www.esrd.com/watch-teaser-video-nafems-coil-spring-fea-puzzler/ https://www.esrd.com/watch-teaser-video-nafems-coil-spring-fea-puzzler/#respond Tue, 12 Feb 2019 20:37:13 +0000 https://esrd.com/?p=9291 The deadline for the NAFEMS coil spring "FEA Puzzler" submissions has been extended through June 1st! View a teaser video of ESRD's StressCheck model and qualitative deformation results.]]>

 

Qualitative Deformation Contours for StressCheck’s Coil Spring Solution

In a recent S.A.F.E.R. Simulation post, we announced that ESRD Chairman Dr. Barna Szabó had posed a new “FEA Puzzler” in the October 2018 edition of NAFEMS Benchmark magazine. This challenge problem related to determining incremental spring rates for a coil spring under axial displacement AND demonstrating that the approximation errors are small via solution verification procedures.

As a refresher, the original NAFEMS FEA Puzzler description was as follows:

FEA Puzzler from NAFEMS Benchmark Magazine October 2018

As noted in a January 2019 LinkedIn post by Mr. David Quinn (Chief Marketing Officer at NAFEMS), the original deadline of February 1st, 2019 has been extended an additional four (4) months. From Mr. Quinn’s post:

Send your responses, in confidence, to Professor Szabó at challenge@nafems.org. Responses of sufficient merit will win an exclusive NAFEMS business card holder, and a summary of the responses will be published without attribution in a future issue of Benchmark.

The challenge will close on June 1st 2019 – best of luck!

So, there is still ample time to submit your solutions (along with proof of solution verification) to challenge@nafems.org. Feel free to use any FEA software tool, and make note of your modeling process and interpretation of results.

Need A Hint?

To help provide a nudge in the right direction, ESRD has recorded the following teaser video using its StressCheck Professional FEA software to show some of the model setup and results processing (no actual values, that would be cheating!):

Dr. Szabó and NAFEMS are very much looking forward to your submissions!

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Second Edition of ESRD Co-Founders’ Finite Element Analysis Book Published https://www.esrd.com/second-edition-of-finite-element-analysis-book-published/ https://www.esrd.com/second-edition-of-finite-element-analysis-book-published/#respond Wed, 23 Jun 2021 17:56:17 +0000 https://www.esrd.com/?p=21718 Recently, Wiley published the second edition of "Finite Element Analysis: Method, Verification and Validation" by ESRD Co-Founders Dr. Barna Szabo and Dr. Ivo Babuška as part of their "Wiley Series in Computational Mechanics". This edition provides an updated and comprehensive review of the theoretical foundation of the finite element method, and provides engineering students and professionals the tools, concepts, techniques, and procedures that help with an understanding of finite element analysis.]]>
2nd Edition of Finite Element Analysis: Method, Verification and Validation (courtesy Wiley)

Recently, Wiley published the second edition of “Finite Element Analysis: Method, Verification and Validation” by ESRD Co-Founders Dr. Barna Szabo and Dr. Ivo Babuška as part of their “Wiley Series in Computational Mechanics“. This edition provides an updated and comprehensive review of the theoretical foundation of the finite element method, and provides engineering students and professionals the tools, concepts, techniques, and procedures that help with an understanding of finite element analysis.

The following description from Wiley’s website provides additional details on the goals of the new book:

The revised and updated second edition of Finite Element Analysis: Method, Verification, and Validation offers a comprehensive review of the theoretical foundations of the finite element method and highlights the fundamentals of solution verification, validation, and uncertainty quantification. Written by noted experts on the topic, the book covers the theoretical fundamentals as well as the algorithmic structure of the finite element method. The text contains numerous examples and helpful exercises that clearly illustrate the techniques and procedures needed for accurate estimation of the quantities of interest. In addition, the authors describe the technical requirements for the formulation and application of design rules.

To learn more about the new edition of the book (including access to multiple excerpts), to request a digital evaluation copy, and/or to purchase an e-book or hardcopy of the book, visit the book’s official homepage on Wiley’s site:

Visit Book Homepage

For a full list of publications regarding ESRD’s simulation technology and theoretical background, as well as additional publications by ESRD staff, visit our Simulation Technology References page.

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Watch StressCheck Demos of Digital Engineering.com FEA Case Studies https://www.esrd.com/watch-stresscheck-demos-digital-engineering-fea-case-studies/ https://www.esrd.com/watch-stresscheck-demos-digital-engineering-fea-case-studies/#respond Tue, 14 Aug 2018 18:19:43 +0000 https://esrd.com/?p=7586 In recent years, Digital Engineering contributor, NAFEMS instructor and FETraining.net developer Tony Abbey has put together a list of practical engineering simulation case studies, walk-thrus and software overviews for a variety of FEA software tools. Watch as ESRD reproduces a selected set of his 3D detailed stress analysis case studies, and see how we compare with Digital Engineering's published results! ]]>

Extraction of minimum principal stresses for the aircraft keel section case study. Digital Engineering case study results (bottom right) compared well with StressCheck’s live dynamic extractions (bottom left, images courtesy of Digital Engineering/ESRD).

Introductory Remarks

In recent years, Digital Engineering began publishing articles on practical engineering simulation case studies, walk-thrus and software overviews for a variety of FEA software tools. In each article, FETraining developer and NAFEMS FEA training instructor Tony Abbey selected a commercially-available FEA software tool to analyze a mechanical component under various loads and constraints, and provided commentary, tips, tricks and process workflow of how he arrived at the results. His goal for each article was to focus on general instruction and best practices for FEA rather than in the particular FEA tool used for solving the problem.

With the consent of Mr. Abbey, ESRD selected four (4) case studies from his list of Digital Engineering simulation articles and were provided the geometric description, material properties and boundary conditions to solve these problems in StressCheck Professional.

For comparative and instructional purposes, ESRD then recorded and published video demonstrations of the modeling, solution and live dynamic results extractions of each case study to our Resource Library.

Note: while these were not “blind” case studies (the Digital Engineering case study results were known in advance), the video demonstrations show the unaltered, associated StressCheck process workflow, with solution verification provided for each result to ensure that the approximation error is sufficiently small.

Case Studies in Detailed Stress Analysis

Case Study #1: “Stress in Finite Element Analysis”, Digital Engineering May 2016

Cross brace structure showing constraint and loading set up (image courtesy of Digital Engineering).

In this particular case study, Mr. Abbey’s focus was to examine detailed cross-sectional stresses for a 3D solid cross brace geometry under off-axis loading. This involved defining multiple “zones” for extracting stresses, for a multitude of stress components and local system directions:

Zones of interest A through E and the SX stress distribution (image courtesy of Digital Engineering).

The following video demonstrates how StressCheck was used to reproduce the 3D detailed cross brace analysis and how cross-sectional lines were added after the solution for mesh-independent, curve-based stress gradient extractions. It is shown that StressCheck’s live, dynamic extractions compared favorably with Digital Engineering’s zone-based detailed stress results:

 

Case Study #2: “Dealing with Stress Concentrations and Singularities”, May 2017

Geometry and mesh of filleted model (image courtesy of Digital Engineering).

For this case study, Mr. Abbey discussed the influence of stress singularities on the FEA solution, and why it is important to model radii and fillets in regions of interest for more accurate stresses if a subsequent fatigue analysis is the goal. He studied the convergence of the stresses in a shoulder fillet geometry by increasing the mesh refinement until the difference in his results was small:

Stress distributions for the filleted model (image courtesy of Digital Engineering).

The following video demonstrates how the 3D shoulder fillet detailed stress analysis was performed in StressCheck, including the steps required to show convergence in the peak stresses. The results were nearly identical with Digital Engineering’s computed peak stress of 65.6 ksi:

 

Case Study #3: “Siemens FEMAP with NX NASTRAN Overview”, March 2018

Initial imported geometry and cut-out region (image courtesy of Digital Engineering).

For this case study, Mr. Abbey utilized Siemens FEMAP with NX NASTRAN to model and solve a 3D solid tie rod under axial loading. He also recorded videos for how to perform the pre-processing, solution and post-processing and deployed them on his website, FETraining.net.

Below are the von Mises stress contours from the NX NASTRAN results, with an unaveraged peak von Mises stress of ~43.6 ksi:

von Mises stresses (image courtesy of Digital Engineering).

The following video demonstrates how the full 3D tie rod geometry is imported into StressCheck, modified to remove all solid material outside of the cut-out region, automeshed with curved tetra elements, assigned the appropriate boundary conditions and solved with a p-extension process to increase degrees of freedom (DOF) on the fixed mesh.

Then, the converged peak von Mises stress was computed from the hierarchic sequence of linear solutions via a live dynamic extraction request and was observed to compare closely to Digital Engineering’s refined mesh NX NASTRAN result:

 

Case Study #4: “SOLIDWORKS Simulation Overview”, July 2018

Applied loads and boundary conditions (image courtesy of Tony Abbey/Digital Engineering).

For this case study, Mr. Abbey utilized SOLIDWORKS from Dassault Systèmes to analyze a 3D solid aircraft keel section, in which several load cases (vertical and lateral loads) were applied to the structure’s attachment points via sinusoidal bearing distributions. From Mr. Abbey about the origin of this aircraft keel section structure:

The keel section is on the lower centerline of a combat aircraft fuselage. It transmits undercarriage loads into the fuselage. It also provides a load path through the lower fuselage section in overall bending and torsion loading due to maneuvers. The geometry has been created in SOLIDWORKS. Many of the smaller fillet radii have been defeatured in preparation.

Of interest were the peak von Mises stresses and minimum principal stresses in the left-hand end upper fillet radii (38.46 ksi and ~-37.5 ksi, respectively):

Von Mises stress distribution in the left-hand end upper fillet regions (image courtesy of Digital Engineering).

Minimum principal stress, P3, plotted around the left-hand end upper fillet (image courtesy of Digital Engineering).

The following video demonstrates how the 3D solid aircraft keel section was imported in StressCheck as a Parasolid and analyzed for detailed stresses in the left-hand end upper fillet regions for the vertical/lateral load cases and end abuttment/bolt radial constraints. The end abuttments were represented by symmetry constraints, and the bolt radial by stiff normal springs. The vertical and lateral load cases would be represented by sinusoidal bearing load distributions applied to the lug holes.

Again, the solution was obtained by increasing the polynomial order of the approximation functions on the fixed mesh, and the solutions for each load case were available for live dynamic processing.

It can be observed that the peak von Mises stress in the left-hand end upper fillet radii converges tightly to a value similar to that produced in Digital Engineering’s results, and the live dynamic principal stress gradient extractions were also quite similar in nature to those produced by Mr. Abbey in SOLIDWORKS probes:

 

Case Study Summary and a Note on Benchmarking

Many thanks to Mr. Abbey, FETraining.net and Digital Engineering for providing the model files to ESRD. The outcome of these case studies reinforce that only with careful engineering analysis methodologies, appropriate modeling assumptions, and tight control of approximation errors is meaningful to perform comparisons of stress results produced by different analysts using different FEA software tools.

Also, as we highlighted in the above case studies, the practice of solution verification is especially important for any benchmarking, round-robin or other comparisons involving the computation of the results of interest by numerical means for a well-defined mathematical problem. Reporting results without objective measures of the size of the approximation errors does not meet the technical requirements of Simulation Governance.

Finally, if you are interested in results of published benchmark problems solved with StressCheck, check out our solutions to the Standard NAFEMS Benchmarks:

The Standard NAFEMS Benchmarks: Linear Elastic Tests

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Happy Holidays from ESRD (2021 Edition) https://www.esrd.com/happy-holidays-2021/ https://www.esrd.com/happy-holidays-2021/#respond Wed, 22 Dec 2021 18:55:40 +0000 https://www.esrd.com/?p=23559 While 2021 continued to present unique challenges and unprecedented disturbances, we hope that you found our customer support, on-demand webinars, web-based training services and overall experience with our team to be refreshingly positive. Happy Holidays from all of us at ESRD, and we hope you'll check out our year-end summary!]]>
Geometry courtesy Radu Octavian, GrabCAD.

While this past year continued to present unique challenges and unprecedented disturbances, we hope that you found our customer support, on-demand webinars, web-based training services and overall experience with our team to be refreshingly positive. It is our pleasure to serve you, and we look forward to what the next year brings!

The following are a few highlights we’d like to share:

ASIP Conference 2021 Impressions…

In late November 2021, ESRD exhibited at the ASIP Conference and had a blast re-connecting with StressCheck users, DaDT colleagues and our partners Hill Engineering (BAMpF 3D fatigue crack growth software developers) and LexTech (AFGROW developers). We also provided a training course on standardization and automation of DaDT solutions via StressCheck-based Sim Apps.

Read more about our conference proceedings here.

New Edition of Wiley’s Finite Element Analysis Released…

In June 2021,  Wiley published the second edition of “Finite Element Analysis: Method, Verification and Validation” by ESRD Co-Founders Dr. Barna Szabo and Dr. Ivo Babuška as part of their “Wiley Series in Computational Mechanics“. This edition provides an updated and comprehensive review of the theoretical foundation of the finite element method, and provides engineering students and professionals the tools, concepts, techniques, and procedures that help with an understanding of finite element analysis.

For more information on the new edition, click here.

Live Web-Based Training Options Expanded…

With engineers continuing to work mostly from home or in limited-capacity office settings, we expanded and refined our web-based StressCheck training options to provide more clarity on our supported DaDT features. In addition to revising our successful web-based Intro to StressCheck course, we also developed and deployed a web-based version of our Advanced Training in Fracture Mechanics course. This advanced StressCheck training course focuses on DaDT applications for which StressCheck is well-suited, as well as modeling, analysis and extraction best practices for 2D and 3D crack modeling.

Even though we could not be face-to-face, it was a pleasure connecting with our users via webcam/audio and helping them achieve proficiency with StressCheck’s features.

For more information on scheduling a live web-based training, click here.

Enhanced DaDT Analysis Features In Development…

Since the release of StressCheck v11 Update 1 in June 2021, we have been hard at work in preparing for the release of StressCheck v11.1. With this forthcoming release (expected in mid-2022), we are focusing on significant improvements to 3D crack front automeshes and SIF extractions (mixed tetra/penta/hexa meshes are now supported!!) as well as scaling features for imported global loads (TLAPs can now be scaled via parameters in linear or nonlinear analysis!!).

Live Webinar Coming Soon

In Q1 2022, we are planning for a live webinar to preview StressCheck’s new DaDT and TLAP scaling enhancements, and answer questions about the upcoming release of StressCheck v11.1.

Pre-register for the “New and Improved Features for 3D Fracture Mechanics Analysis in StressCheck” webinar:

Once a date/time is announced, you will be notified with more details about the webinar. Stay tuned!

Preview: Mixed Boundary Layer Automesh and SIF Extraction Improvements

The following is a brief demo of the mixed boundary layer automeshing feature (with SIF comparisons) coming soon in StressCheck v11.1:

  • 0:00-1:20 mark – Two all-tetrahedral element boundary layers are automeshed around the crack front of a 180 degree embedded ellipse using the original Crack Front method available in v11.0.
    • The model is then solved at p=4 (for demonstration purposes) and the SIF distribution along the crack front is extracted using Radius = AUTO.
  • 1:21-2:44 mark – Four pentahedral/hexahedral element boundary layers are automeshed around the crack front of a 180 degree embedded ellipse using the new Crack Front method available in v11.1 (and StressCheck v11 Update 1 for beta testing).
    • The model is re-solved solved at p=4 (for demonstration purposes) and the SIF distribution along the crack front is re-extracted using Radius = AUTO.
  • 2:45-3:43 mark – The two SIF distributions are compared, with the new Crack Front automeshing method demonstrating clear improvements in efficiency and quality.


Wishing for Good Tidings and Good Health

Finally, we’d like to wish all of our customers, partners and friends Happy/Safe Holidays and a Happier/Healthier 2022!

Keep up with the latest from ESRD by subscribing to our newsletter:

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NAFEMS Coil Spring FEA Puzzler Solution Revealed https://www.esrd.com/nafems-coil-spring-fea-puzzler-solution-revealed/ https://www.esrd.com/nafems-coil-spring-fea-puzzler-solution-revealed/#respond Tue, 03 Sep 2019 19:54:04 +0000 https://esrd.com/?p=11414 In NAFEMS' July 2019 edition of Benchmark Magazine, ESRD Chairman Dr. Barna Szabó reveals the converged StressCheck solution for the incremental spring rates, provides a summary of the FEA Puzzler respondent submissions, and documents the various approaches taken by the respondents.]]>

The finite element mesh used in the reference solution for the NAFEMS FEA Puzzler (courtesy NAFEMS).

In a February 2019 S.A.F.E.R. Simulation post, ESRD provided a teaser video of the October 2018 NAFEMS FEA Puzzler solution, in which the incremental spring rates for a 3D coil spring were numerically investigated. In NAFEMS’ July 2019 edition of Benchmark Magazine, ESRD Chairman Dr. Barna Szabó reveals the converged Numerical Simulation solution for the incremental spring rates, provides a summary of the FEA Puzzler respondent submissions, and documents the various approaches taken by the respondents.

As a refresher, the original October 2018 NAFEMS FEA Puzzler description was as follows:

FEA Puzzler from NAFEMS Benchmark Magazine October 2018

Reference Solution

Below is a short summary of Dr. Szabó’s reference solution results, computed with ESRD’s StressCheck and verified by numerical convergence studies (all images courtesy NAFEMS):

The finite element mesh chosen for the reference solution is shown in Figure 1. The mesh is comprised of 9,691 tetrahedral isoparametric (10-node) elements, and solved by p-extension from p=2 to 5.

Table 2 summarizes the computed values of strain energy, U, associated with each polynomial level, p, and degrees of freedom, N:

The spring rate, k, may be computed from the strain energy, U, and imposed spring displacement, Δ, using the following equation:

k = 2*U/Δ2

Using the extrapolated value of U, in which N→∞, we compute k = 20.83 N/mm for an imposed spring displacement Δ=-25 mm.

From the NAFEMS FEA Puzzler solution article:

The estimated relative error in k is less than 0.05%. Note that this error does not account for the curved surfaces being approximated by piecewise quadratic polynomials. However, given the large number of 10-node tetrahedra (see Figure 1), the errors of approximation in the surface representation can be neglected.

More generally, the stiffness of the spring can be computed by energy methods. These methods are superconvergent.

Download the Full NAFEMS Article

The entire NAFEMS FEA Puzzler article, complete with the computation of the spring rate via linear and geometric nonlinear force resultants (also shown to be k=20.8 N/mm), comparison with classical methods (k=19.33 N/mm), a summary of respondent submissions, and additional commentary, may be downloaded at the following link:

Download Article

 

Note: There is a typo in Equation 1 on page 28 of the NAFEMS article. The value of k in Equation 1 should be 20.83 N/mm and not 25.83 N/mm.

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