ANSYS Discovery Live: Simulations for ALL

This article introduces you to a new, revolutionary technology called ANSYS Discovery Live. This technology provides instantaneous simulation results through an interactive design exploration experience for fluids, structural, and thermal studies.

With the inception of 4th industrial revolution, also called Industry 4.0, every industry is changing rapidly with groundbreaking innovations. In turn, this has placed a severe strain on the product development cycle. Innovative products need to be brought faster to market to reduce opportunity cost. This context has only reinforced my belief to expand the Simulation-Driven Product Development approach like never before.

Engineering simulation, though utilized for industrial applications for several years, is still underused and used by experts. A decade ago, it was difficult to learn and master such a technology. Often executing a simulation task end-to-end took time to set up and run.  In 2007, ANSYS, Inc. launched ANSYS Workbench as, what I believe was, the first step to democratize simulation adoption. Since then, and along with rapid advancements and easy availability of computer hardware, simulation adoption has grown leaps and bounds.

Greater Power to Design Engineers?

However, until late last year, I felt that there is a stronger need to foster a greater collaboration between the design and simulation engineers. From my experience, I have seen simulation engineers complain about “geometry cleanup for simulation of each design” on one end and design engineers complaining about “huge time taken by an analyst for each design validation” on the other end. With such a to and fro between both teams, there is such a huge market need that needed to be filled. Though there are many engineering simulation software products in the market, no one could democratize the simulation to potentially elevate the role of designers in product development. Although the design engineers have a very important role to play in the product development cycle, they have largely been restricted to developing CAD models at best.

In Fall 2017, ANSYS, Inc. conducted a webinar on a new, revolutionary technology that was going to “change how the simulation was done”. My colleagues from CADFEM Germany called it Das ist der Hammer (translation: it’s awesome). Rarely does a product match its hype, but several of us were blown away while watching the webinar on ANSYS Discovery Live (ANSYS DL). In a whole lot of ways, ANSYS DL is disruptive and it made me rethink how I have been doing simulations.

What is ANSYS Discovery Live?

ANSYS Discovery Live is the newest technology from ANSYS, Inc. HQ at Canonsburg, PA. With this technology, every engineer can use to perform instantaneous multiple physics simulation of virtual prototypes to understand the behavior of the product design.

The development team has leveraged on the advancements in Graphical Processor Units (GPUs), developed new discretization techniques along with their knowledge of advanced parallel solver technology. ANSYS DL is built on Direct Modeler tool called SpaceClaim platform to import and modify the solid geometry with ease. Once you define the physics and boundary conditions, you’ll get results in no time. This is instantaneous, real-time simulation! The technology in ANSYS DL has automated the steps of meshing, building the finite element model, solving and extracting the results in few seconds to give you an insight into your design.

ANSYS Discovery Live
Instantaneous Simulation for Every Engineer
Why is ANSYS Discovery Live Unique?
  • Instantaneous results show up for any change in geometry. No need to setup the simulation again. [VIDEO: 50 Simulations in 15 Minutes]
  • It combines GPU-based solvers for multiple physics.
  • You can easily integrate ANSYS DL with flagship ANSYS, Inc. products for advanced studies.
How does ANSYS Discovery Live change things?

Design engineers tell me frequently that several ideas go untested and they are totally dependent on the analysts. I could hardly do anything, but empathize with them. On the other hand, executing any simulation task leaves analysts with limited time to explore different design concepts.

With ANSYS DL, design and simulation engineers can quickly discover the behavior of their product live and instantaneously. ANSYS DL has created a fundamental shift by moving from design verification to experimenting and gaining deeper understanding. This is a huge benefit because you can evaluate several design iterations early in the design cycle. The ease of setting up the problem in ANSYS DL enables design engineers to quickly check the ideas in a shorter time frame. This also allows them to reduce dependency on the simulation engineer. The latter will still continue to perform traditional simulation tasks, but ANSYS DL gives design engineers more power to contribute to product development.

ANSYS DL marks the next step by ANSYS, Inc. to further democratize simulation adoption across different industries.

How can CADFEM help you?
  • Greater Understanding of Hardware for Simulations. Partnership with major brands such as HP and NVIDIA allows us to help you select the appropriate hardware for your simulation tasks.
  • Strong technical expertise will help you solve your engineering problem.
Download ANSYS DL & Attend Webinar

ANSYS DL is available as a Technology Preview until February 7. With this preview, you can test the pre-release locally on your machine by downloading or through your favorite internet browser.

Download ANSYS DL today. Also you must attend the ANSYS DL Webinar as we kick start the 2018 CADFEM Technical Webinar Series. You can do this by accessing the below links.

  • DOWNLOAD ANSYS Discovery Live (until Feb 7). You will need to register using a form and then you’ll get instant access to this exciting technology!
  • REGISTER for WEBINAR: Simulations are Now Accessible to Every Engineer (Feb 1 at 2:30 PM IST)
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How Fatigue Made Me Fall From The Chair?

This article explains the setup of a simple fatigue analysis in ANSYS Workbench using an example. For beginners, this article demystifies fatigue analysis.

Context

When I was ten years old, I was fond of a chair which was small and easily movable. After school, I used to sit on it and watch Aladdin tales on the television. One day, as usual, I sat on it. Suddenly the chair got broke in half and I fell on the floor in front of my sister. For obvious reasons, I got embarrassed and my sister made fun of me the whole day. I slept that day with few unanswered questions.

Why did the chair fail when it was working fine for a few years? Why didn’t it fail on the first day I sat on it?

Illustration of a broken chair as a result of fatigue
My broken chair! 🙁
Motivation

Fast forward to my engineering days, I was told that cyclic loading on any structure can make that structure fail – fatigue failure. Only then I could understand why my beloved chair failed.

Many of you might have heard stories like the one mentioned above or even experienced it yourself. However, the fact that majority of structures irrespective of their size experience a phenomenon like fatigue is real. If a simple structure with a simple load cycle could fail because of fatigue, imagine a complex structure with a complex loading cycle. Yes, the consequences are catastrophic for the manufacturer as well as the user.

According to NBS report, “between 80-90 % of all structural failures occur through a fatigue mechanism.” Incorporating fatigue simulation upfront into the product development cycle plays a vital role in optimizing the structural integrity of your product and it significantly reduces the cost of failure.

In this article, a simple fatigue analysis is shown which was carried out using ANSYS Fatigue Tool. If you wish to conduct the analysis as per FKM guidelines, you’ll be interested this CADFEM ANSYS Extension.

Workflow

For a fatigue analysis, static structural or transient analysis is a prerequisite. To achieve this, I consider a simple chair geometry for static structural analysis; appropriate loads and boundary conditions were defined. I define a point mass of 75 kg to act on the chair. This loading can be considered as a misuse for a child’s chair. Resultant static stress (24 MPa) did not exceed the yield strength (54 MPa) of the assigned material.

There! I got the answer to one of the questions from my story. The chair didn’t fail on the first day I sat on it because the load applied on the first day was not sufficient enough to exceed the yield strength of the material.

Analysis setup for fatigue study
Loads and Boundary Conditions
Results of static structural analysis before fatigue analysis
Equivalent von-Mises Stress

 

 

 

 

 

 

 

Setting up the analysis

Subsequent to the setup of static structural analysis, I launch the ANSYS Fatigue Tool using the following steps.

Setting up fatigue analysis
Solution>Insert>Fatigue>Fatigue tool

Analysis Type

ANSYS Fatigue Tool offers two methods to calculate fatigue life.

  • Strain Life
  • Stress Life

While strain life approach is widely used, at present, because of its ability to characterize low cycle fatigue (<100,000 cycles), stress life approach addresses high cycle fatigue (>100,000 cycles).

Specifying details in the fatigue tool
Details View of Fatigue tool

I chose the stress life approach to execute this example and subsequently I defined the appropriate S-N (Stress–Cycles) curve in the engineering data.

Loading Type

Contrary to static stress, fatigue damage occurs when stress at a point changes over time. Therefore, it is essential to define the way the load could repeat after a single cycle, in other words the type of fatigue loading determines how the load repeats over time.

Accordingly, I chose zero-based loading type for the current example, which means I apply the load and remove it, thereby resulting in an equivalent load ratio of 0. For a fully-reversed loading, I would apply a load and then apply an equal and opposite load which will result into a load ratio of -1.

Applying zero-based loading in fatigue analysis
Zero-Based loading

In both the cases the amplitude of load remains constant. Therefore looking at the single set of simulation results will give you an idea where fatigue failure might occur.

Mean Stress Theory

Now that I have defined analysis and loading types, I need to choose a mean stress theory.

Zero Mean Stress loading for fatigue analysis
Zero Mean Stress loading

Mean stress is the average of maximum and minimum stress during the fatigue load cycle. Mostly, fatigue data is assumed for zero mean stress, which means fully reversed loading. However, fully reversed loading conditions (zero mean stress) are rarely met in engineering practice. Hence Mean Stress Correction Theory has to be chosen to account for mean stress.

For stress life approach: If experimental data at different mean stresses exist, I can account for the mean stress directly by interpolating different material curves. However, it is unlikely to have experimental data at all mean stresses. Therefore, several empirical relations are available including Goodman, Soderberg and Gerber theories which use static material properties (yield strength and tensile strength) and S-N data to account for mean stress. In general, I don’t advise you to use empirical relations if multiple mean stress data (S-N curves) exists.

Different Mean Stress Theories for Fatigue Analysis
Different mean stress correction theories (Goodman Theory is highlighted)

Goodman Mean Stress Theory is a common choice for plastic materials, whereas Gerber Theory is a common choice for ductile metals. For the current analysis, I chose the Goodman Theory.

Fatigue Life

Like any other result in ANSYS Workbench, fatigue life can be scoped on a geometric entity. For stress life with constant amplitude loading, life at that point will be used if the equivalent alternating stress is lower than the lowest alternating stress defined in the S-N curve

For this example, 3,100,000 cycles is the expected life of the chair. This means that a person of 75 kg can sit on this child’s chair for 3.1 million times. If he ignores and continues to sit beyond the expected life, very soon he might face the same fate as the boy in the story.

Fatigue life extracted from ANSYS Fatigue Module
Fatigue life extracted from ANSYS Fatigue Tool
Conclusion

Wasn’t it easy? Yes, it is easy to perform this analysis provided you have the material data. In case you are not aware, ANSYS Mechanical Pro, Premium, Enterprise and ANSYS AIM offer ANSYS Fatigue Tool.

What are you waiting for? Start realizing your product promise using ANSYS products.

P.S. Just in case you were wondering what happened after the chair broke, my mother bought us a brand new chair the next day!

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Opening ANSYS Projects Made Easy!

This post is to describe a solution to a fairly regular problem that troubles many engineers opening ANSYS project files across multiple versions of ANSYS software.

Unless you’ve been living under a stone, you must be as excited as I am about the new ANSYS Release 18. Did you attend the Digital Webcast on January 31? There was so much on display. The new, innovative features of the release were much needed by the market.

Well, this has been the trend since Release 15 in terms of product development and innovation in ANSYS software. Over the past several years, ANSYS, Inc. brought in a many product releases with lots for improvements. Quite obviously, engineers at many of our customer sites have installed many of these versions of ANSYS software on their workstations.

The Problem

Due to several versions of ANSYS software installed on your workstations, double-clicking a project will open ANSYS in the last (need not be latest) installed version. For example: If ANSYS R16.2 is installed after installing ANSYS R17.0, then double-clicking the project (originally saved in ANSYS R16.0) will open the project in R16.2.

Due to this problem, there is a possibility that you will inadvertently save the project in a higher version of ANSYS software by mistake. When saved in the higher version, opening ANSYS project can’t be possible in (original) lower software version due to limitation of backward compatibility. For certain projects, retaining work in certain versions is quite important. Unfortunately there is no way to restore your project file to the older version in case you accidentally open and save it in a newer version.

Possible Solutions

In order to open ANSYS project file in desired version, one approach is for you to open the desired ANSYS version from Start Menu (in Windows). Once you open the desired version of ANSYS, you can open the respective project. Since this is a tedious approach, it is sub-optimal.

Another approach, that is easier and faster, is to RMB (right mouse button) click and select “Open with” and select the desired ANSYS executable. This reduces the turn around time of opening a file by 30-40% when compared to the previously-discussed approach. However many engineers have been confused because the file names of different ANSYS software versions in the “Open with” menu are same.

"Open with" menu in Windows OS for opening ANSYS project
“Open with” menu in Windows OS for opening ANSYS projects

Obviously engineers such as me get confused or do not always remember/know the version of the ANSYS executable in the “Open with” menu. Choice of version becomes more important since companies expect engineers to execute internal projects in different versions of ANSYS. To decode this confusion, we obviously need a better solution.

Optimal Solution for Opening ANSYS Projects

Since ANSYS Release 16, support is available for only Windows 7 and above. This solution is not applicable for other OS.

Step 1
Open start menu type regedit in search bar

Step 2
Follow the below path:
HKEY_CURRENT_USER > Software > Classes > Local Settings > Software > Microsoft > Windows > Shell > MuiCache

This page contain names of all programs and respective executable files as seen in “Open with” option after RMB click .

Screen grab of Registry Editor view that shows all programs and respective executable files
Registry Editor view of all programs and respective executable files

Step 3
You can select the ANSYS version whose name needs to be changed. RMB click on it and select “Modify…“.

"Edit String" window to update the executable name
“Edit String” window to update the executable name

Now change the Value Data to the desired name. For example, I chose to use file names such as RunWB2_R180.exe. You can complete the same exercise for renaming executable files of other ANSYS versions.

By doing so, the next time you RMB click on an ANSYS Workbench Project and select “Open with”, you will see different names as shown below.

Updated "Open with" menu after RMB click
Updated “Open with” menu after RMB click
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Debugging Convergence for Large Sliding Problems

This is the first part in a series of posts related to debugging convergence. This post talks about large sliding problems in particular.

Sliding contact is an imperative characteristic defining the functionality of many products. In this article, I aim to help in debugging convergence issues while modeling and simulating large sliding contact problems in ANSYS Mechanical.

A conventional practice for modeling contacts in a simulation environment tends to accommodate slight inter-penetration of mating parts in order to allow the solution to converge. Inter-penetration can pose serious concerns in the form of under prediction of force reactions and stresses for a sliding contact scenario. The lack of solution accuracy is in the name of solution convergence. In order to derive a reasonably accurate solution for a sliding contact scenario, we should strive to regulate contact penetration to a bare minimum.

Two Approaches to Sliding Contact Problems

Let’s get into the nitty-gritty of solving sliding contact problems. Now ANSYS Mechanical’s settings for penalty-based methods (Pure Penalty and Augmented Lagrange) allow for some penetration (depends upon contact stiffness) leading to easier convergence. Results are not accurate with the penalty-based method. Despite this, many chose to use this approach in order to achieve solution convergence.

Normal Lagrange formulation guarantees almost zero penetration, with good solution accuracy, because there is no contact stiffness in the normal direction. Instead, the method uses some additional contact degrees of freedom i.e. contact pressure acting normal to contacting surface in order to prevent penetration and a tangential contact stiffness based on penalty method.

So the Normal Lagrange formulation can handle large frictional sliding problems more effectively. It is not suited for sticking application, i.e. valid only for frictional/friction-less contacts. Conversely, this method can be used where penetration is undesirable – as in applications such as snap fit, gears & other sensitive applications where penetration leads to less accuracy in the results.

However Normal Lagrange formulation is not the proverbial knight in shining armor for these applications.

Solution has not converged after 12 iterations for contact status change!

Screenshot of ANSYS Mechanical solver output highlighting the lack of change of contact status. This image is used in support of the article on Normal Lagrange formulation

Achieving Solution Convergence with Normal Lagrange Formulation

While working with the Normal Lagrange formulation, many of you would have faced this challenge. In addition to it be very frustrating, the time consumed to achieve solution convergence reduces our engineering productivity.

Typically when we activate Normal Lagrange formulation, the ANSYS solver, by default, bisects at the 12th iteration due to contact status change even though the force convergence trend is good. The figure below illustrates this. If the bisection were not to happen, the solution were likely to converge in the next iterations.

Screenshot of a delayed solution convergence with Normal Lagrange formulation.

Can we increase this bisection limit? Yes! This, little known, undocumented key is available with the CUTCONTROL command.

Command Syntax: CUTCONTROL, NCSI, VALUE

In ANSYS Workbench, this command can be inserted in the tree under analysis system as shown in the below image.

Screenshot of ANSYS Workbench demonstrating the location to add the APDL command. This image is used in support of the article on Normal Lagrange formulation.

Seen below is the force convergence behavior of a demo case study with and without using the CUTCONTROL command.

Image of force convergence behavior of a test case shown using a plot without CUTCONTROL command in support of the article on Normal Lagrange formulation.
Without CUTCONTROL command
Image of force convergence behavior of a test case shown using a plot with CUTCONTROL command in support of the article on Normal Lagrange formulation
With CUTCONTROL command

Generally, in industry, there is a misconception that Normal Lagrange is not preferable for achieving convergence in many cases. As demonstrated, this contact formulation is best suited for large sliding problems which is both, accurate and faster.

If you encounter problems with large sliding contacts, please do try my suggestion and let me know your feedback. If you have a better solution in mind, please do share in the comments section.

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Weekly Simulation Round-Up | Issue 4

Banner for Weekly Simulation RoundupWelcome to this edition of Weekly Simulation Round-Up. As usual, we bring you the most interesting articles from this week.


Computational Fluid Dynamics for Patient-Specific Surgeries

In this article, a researcher of Cardiothoracic Surgery from the Shanghai Children’s Medical Center talks about simulation-driven medical surgeries. He states that “the long-term prognosis for babies born with single ventricle heart defects can depend on the location of vascular connections made during corrective surgery”. Based on the babies’ cardiovascular anatomy, the medical center researchers employ ANSYS CFD to determine the optimal personalized surgery for improving surgical effectiveness and to obtain a better quality of life for children (read more).


Simulation of “Material Other Than Grain” Separation Process

For farmers engaged in grain production, separation of stones, straw and dust from grains is a regular activity. Can simulation techniques help such farmers to reduce cost and time-to-market, and increase grain production ramp-up? The answer is yes!

Using Rocky DEM, a state-of-the-art discrete element particle simulator, along with computational fluid dynamics performed using ANSYS Workbench, the material other than grain (MOG) separation process can be simulated. There’s potential for the MOG equipment makers to redesign or improve for higher separation efficiency.


Optimus Prime, anyone? 

Antimon is a BMW 3-series car that transforms into a robot in under 30 secs. It converts from a BMW into a grand robot completed with powerful arm movements and a Transformers-like face. It took the company eight months to complete Antimon using an actual car (Watch on YouTube).


Diamonds Convert Nuclear Waste into Clean Energy

British Scientists have developed a method of turning nuclear waste into batteries using diamond. By encapsulating a short-range radioactive material in an artificial diamond, small electrical charge can be generated even after insulating harmful radiation. Researchers estimate that a carbon-based battery would generate 50% of its power in 5,730 years (read more).


Structural Design Optimization of Electrical Transformer Tanks

One of our customers, Crompton Greaves Ltd., presented their experiences with optimizing structural design of their electrical transformer tanks. To achieve this, their engineers used the state-of-the-art tool for optimization and variation analysis – optiSLang and ANSYS Mechanical. Through this exercise, they were able to obtain ~10% weight reduction and over 17% reduction in Equivalent Stress (read more).


So, folks, that was all for this week. We will be back again with a new edition next week. Do feel free to share your feedback or questions with us.

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