Combining ANSYS Simulation with HPC

Engineering simulation has become much more prevalent in engineering organizations than it was even 5 years ago.  Commercial tools have gotten significantly easier to use whether you are looking at tools embedded within CAD programs or the standalone flagship analysis tools.  The driving force behind these changes are to ultimately let engineers and companies understand their design quicker with more fidelity than before.

Engineering simulation is one of those cliché items where everyone says “We want more!”  Engineers want to analyze bigger problems, more complex problems and even do large scale design of experiments with hundreds of design variations – and they want these results instantaneously.   They want to be able to quickly understand their designs and design trends and be able to make changes accordingly so then can get their products optimized and to the market quicker.

ANSYS, Inc. spends a significant amount of R&D in helping customers get their results quicker and a large component of that development is High Performance Computing, or HPC.  This technology allows engineers to solve their structural, fluid and/or electromagnetic analyses across multiple processors and even across multiple computing machines.  Engineers can leverage HPC on laptops, workstations, clusters and even full data centers.

PADT is fortunate to be working with Nimbix, a High Performance Computing Platform that easily allowed us to quickly iterate through different models with various cores specified.  It was seamless, easy to use, and FAST!

Let’s take a look at four problems: Rubber Seal FEA, Large Tractor Axle Model, Quadrocopter CFD model and a Large Exhaust CFD model.  These problems cover a nice spectrum of analysis size and complexity. The CAD files are included in the link below.

Click here to download geometry files that were used in the following benchmarks

TRACTOR AXLE FEA

This model has several parts all with contact defined and has 51 bolts that have pretension defined.  A very large but not overly complex FEA problem.  As you can see from the results, even by utilizing 8 cores you can triple your analysis throughput for a work day.  This leads to more designs being analyzed and validated which gives engineers the results they need quicker.

SUMMARY

  • 58 Parts
  • 51 x Bolts with Pretension
  • Gaskets
  • 928K Elements, 1.6M Nodes

Cores

Elapsed Time
[s]

Estimated Models Per 8 [hours]

2

14,525

2

4

9,710

3

8

5,233

6

16 4,009

7

 

RUBBER SEAL FEA

The rubber seal is actually a relatively small size problem, but quite complex.  Not only does it need full hyperelastic material properties defined with large strain effects included, it also includes a leakage test.  This will pressurize any exposed areas of the seal.  This will of course cause some deformation which will lead to more leaked surfaces and so on.  It basically because a pressure advancing solution.

From the results, again you can see the number of models that can be analyzed in the same time frame is signifcantly more.  This model was already under an hour, even with the large nonlinearity, and with HPC it was down to less than half an hour.

SUMMARY

  • 6 Parts
  • Mooney Rivlin Hyperelastic Material
  • Seal Leakage with Advancing Pressure Load
  • Frictional Contact
  • Large Deformation
  • 42K Elements, 58K Nodes

Cores

Elapsed Time
[s]
Estimated Models Per 8 [hours]

2

3,353

9

4

2,489

12

8 1,795

16

 


QUADROCOPTER DRONE CFD

The drone model is a half symmetry model that includes 2 rotating domains to account for the propellers.  This was ran as a steady state simulation using ANSYS Fluent.  Simply utilizing 8 cores will let you solve 3 designs versus 1.

SUMMARY

  • Multiple Rotating Domains
  • 2M Elements, 1.4M Nodes

Cores

Elapsed Time
[hours]
Speedup

2

2.1

1

4

1.2

1.8

6

0.8

2.6

8 0.7

3

 

EXHAUST CFD

The exhaust model is a huge model with 33 million elements with several complicated flow passages and turbulence.  This is a model that would take over a week to run using 1 core but with HPC on a decent workstation you can get that down to 1 day.  Leveraging more HPC hardware resources such as a cluster or using a cloud computing platform like Nimbix will see that drop to 3 hours.  Imagine getting results that used to take over 1 week that now will only take a few hours.  You’ll notice that this model scaled linearly up to 128 cores.  In many CFD simulations the more hardware resources and HPC technology you throw at it, the faster it will run.

SUMMARY

  • K-omega SST Turbulence
  • Multi-Domain
  • 33M Elements, 7M Nodes

Cores

Elapsed Time
[hours]
Speedup

16

26.8

1

32

13.0

2.1

64

6.8

3.9

96

4.3

6.2

128 3.3

8.2

As seen from the results leveraging HPC technology can be hugely advantageous.  Many simulation tools out there do not fully leverage solving on multiple computing machines or even multiple cores.  ANSYS does and the value is easily a given.  HPC makes large complex simulation more practical as a part of the design process timeline.  It allows for greater throughput of design investigations leading to better fidelity and more information to the engineer to develop an optimized part quicker.

If you’re interested in learning more about how ANSYS leverages HPC or if you’d like to know more about NIMIBX, the cloud computing platform that PADT leverages, please reach out to me at manoj@padtinc.com


Want to learn more about how ANSYS Simulation Software stacks up against CAD-Embedded Simulation tools?

Click the link below to register for our upcoming webinar covering both the why and the how of stepping up your simulation game by leaving CAD-Embedded Simulation behind!

This presentation will dispel common misconceptions, explain how to make the transition, and present topics that ANSYS can provide solutions for, such as:

  • Understanding fluid flow: accurate and fast CFD
  • Real parts that exist in assemblies
  • The importance of robust meshing
  • Advanced capabilities and faster solvers

Additive Manufacturing: 3D Printing a Metal Shift Knob for Faster Cooling

When Nathan Huber moved to Arizona from Colorado to join PADT he learned a lot, and one of the things he learned fast was that the inside of cars get very hot in the summer here.  In fact, the shift knob on his car was untouchable in July.  This coincided with his learning more about metal 3D Printing and an idea occurred, what about 3D Printing a metal shift knob designed to cool off faster, and that looked cool.  Oh, and use ANSYS to drive the design.

He blogged about it before (here and here), and Additive Manufacturing online picked up the story and added to it on their blog post “3D Printing a Metal Shift Knob for Faster Cooling”  Check it out, they did a nice job of explaining what we did and how Nathan used several of our tools like ANSYS Mechanical and our Concept Laser metal system to realize the design.

 

ANSYS Workbench Polyhedral Meshing

The ANSYS App Store contains all sorts of free and paid apps developed by ANSYS as well as trusted partners. These apps improve workflows and allow users to build in best practices. An app that has been of particular interest to me is Workbench Poly Meshing for Fluent

This app enables the power and capacity of Fluent Meshing, most notably the polyhedral meshing feature, with the ease of use of the ANSYS Workbench Meshing environment. In order to show the functionality of this app, I will demonstrate with the generation of a polyhedral mesh on a sample geometry from the Fluent Meshing tutorials.

To start out, I have imported a .igs file of an exhaust manifold into ANSYS SpaceClaim Direct Modeler, which has powerful repair and prepare tools that will come in handy. I notice that the geometry is comprised of 250 surfaces, which I need to fix in order to create a solid body. By navigating into the ‘Repair’ tab and selecting the ‘Stitch’ operation, SpaceClaim notes there are two stitchable edges in my geometry. I select the green check mark to perform this operation and am greeted with a solid geometry. I complete my tasks in SpaceClaim by extracting the fluid volume using the ‘Volume Extract’ tool in the ‘Prepare’ tab.

I setup my workflow in ANSYS workbench with my added ‘Fluent Meshing’ ACT module between the ‘Mesh’ module and ‘Fluent’ module. I can then proceed to create my desired surface mesh in ANSYS meshing and setup a few required inputs for Fluent Meshing.


Once this process has been completed, I can update my ‘Fluent Meshing’ cell and open the ‘Fluent’ setup cell to display my polyhedral mesh!

IMPORTANT NOTE: all named selections must be lowercase with no spaces, and the file path(s) cannot contain any spaces.


Want to learn more about how ANSYS Simulation Software stacks up against CAD-Embedded Simulation tools?

Click the link below to register for our upcoming webinar covering both the why and the how of stepping up your simulation game by leaving CAD-Embedded Simulation behind!

This presentation will dispel common misconceptions, explain how to make the transition, and present topics that ANSYS can provide solutions for, such as:

  • Understanding fluid flow: accurate and fast CFD
  • Real parts that exist in assemblies
  • The importance of robust meshing
  • Advanced capabilities and faster solvers

When the going gets tough, the tough use ANSYS for CFD Meshing

If you do CFD simulations then you know the struggle that is involved in meshing. It is a fine balance of accuracy, speed, and ease of set up. If you have complex geometry, large assemblies, or any difficulty meshing then this blog article is for you.

Why should I spend time making a good mesh?

The mesh is arguably one of the most important parts of any simulation set up. A good mesh can solve significantly faster and provide more accurate results. Conversely, a poor mesh can make the simulation have inaccurate results and be slow to converge or not converge at all. If you have done any simulation then you know that hitting the solve button can feel like rolling the dice if you don’t have a robust meshing tool.

When is it going to matter?

A good mesh is going to matter on a Friday afternoon when you need to get the simulation started before you leave for the weekend because it takes two days to run and you need to deliver results on Monday but you are up against the clock because you have to get to your kid’s soccer game by 5pm and the mesh keeps crashing.

A poor mesh can do more than just reorganizing you’re social agenda. A poor mesh can drastically change results like pressure drop in an internal flow passage or drag over a body. If you go into that meeting on Monday and tell your boss that the new design is going to perform 10% better than the previous design – you need to be confident that the design is 10% better not 10% worse.

What should I do when I need to create a good mesh?

If you’re the poor soul reading this on a Friday afternoon because you are trying to frantically fix you’re mesh so you can get your simulation running before the weekend – I pity you. Continue reading for my proprietary step by step approach titled “How to get you’re CFD mesh back on track!” (Patent pending).

Step 1) Know your tools

ANSYS has been developing its meshing technology since the beginning of time (not really but almost) – it’s no surprise that its meshing algorithms are the best in the business. In ANSYS you have a large number of tools at your disposal, know how to use them.

The first tool in your toolbox is the ANSYS automatic meshing technology. It is able to predictively apply settings for your part to get the most accurate automatic mesh possible. It has gotten so good that the automatic mesh is a great place to start for any preliminary simulations. If you want to get into the details, ANSYS meshing has two main groups of mesh settings – Global Meshing Parameters and Local Meshing Parameters. Global mesh parameters are great for getting a good mesh on the entire model without going into detailed mesh settings for each part.

But when you do have to add detailed meshing settings on a part by part basis then local mesh settings won’t let you down.

Step 2) Know your physics

What is your primary result of interest? Drag? Pressure drop? Max velocity? Stagnation? If you can quantify what you are most interested in then you can work to refine the mesh in that region so as to capture the physics accurately. ANSYS allows you set local sizing parameters on bodies, faces, lines, and regions which allow you to get the most accurate mesh possible but without having to use a fine mesh on the entire part.

Step 3) Know your mesh quality statistics

Mesh quality statistics can be a good way to gauge the health of your mesh. They are not a foolproof method for creating a mesh that will be accurate but you will be able to get an idea of how well it will converge. In ANSYS meshing there is a number of mesh quality statistics at your fingertips. A quick and easy way to check your mesh is to look at the Minimum Orthogonal Quality statistic and make sure it is greater than 0.1 and Maximum Skewness is less than 0.95.

Step 4) Know your uncertainty

Every test, simulation, design, process etc… has uncertainty. The goal of engineering is to reduce that uncertainty. In simulation meshing is always a source of uncertainty but it can be minimized by creating high quality meshes that accurately model the actual physical process. To reduce the uncertainty in meshing we can perform what is called a mesh refinement study. Using the concept of limits we can say that in the limit of the mesh elements getting infinitely small than the results will asymptotically approach the exact solution. In the graph below it can be seen that as the number of elements in the model are increased from 500 – 1.5million the result of interest approached the dotted line which we can assume is close to the exact solution.

By completing a mesh refinement study as shown above you can be confident that the mesh you have created is accurately capturing the physics you are modeling because you can quantify the uncertainty.

If you currently just skip over the meshing part of your CFD analysis thinking that it’s good enough or if your current meshing tool doesn’t give you any more details than just a green check mark or a red X then it’s time dig into the details of meshing and start creating high quality meshes that you can count on.

For more info about advanced meshing techniques in ANSYS – see this PDF presentation that is a compilation of ANSYS training material on the meshing subject.

Advanced Techniques in ANSYS Meshing_Blog

If you still haven’t figured out how to get your mesh to solve and its 5pm on Friday see below*

*Common pitfalls and mistakes for CFD meshing:

  • Choose your turbulence model wisely and make sure your mesh meets the quality metrics for that model.
  • Make sure you don’t have boundary conditions near an area of flow recirculation. If you are getting reverse flows at the boundary then you need to move your boundary conditions further away from the feature that’s causing the flow to swirl in and out of the boundary.

Want to learn more about how ANSYS Simulation Software stacks up against CAD-Embedded Simulation tools?

Click the link below to register for our upcoming webinar covering both the why and the how of stepping up your simulation game by leaving CAD-Embedded Simulation behind!

This presentation will dispel common misconceptions, explain how to make the transition, and present topics that ANSYS can provide solutions for, such as:

  • Understanding fluid flow: accurate and fast CFD
  • Real parts that exist in assemblies
  • The importance of robust meshing
  • Advanced capabilities and faster solvers

 

PADT Startup Spotlight – The Speed of Simulation

The Speed of Simulation  with Velox Motorsports

With thoroughly engineered components including the use of Finite Element Analysis (FEA), thermodynamics, heat transfer, and Computational Fluid Dynamics (CFD), PADT Startup Spotlight Velox Motorsports strives to produce aftermarket parts that can effectively outperform the factory components.

Join Velox Co-Owners Eric Hazen and Paul Lucas for a discussion on what they use ANSYS simulation software for and how they have benefited from it’s introduction into their manufacturing process.

This webinar will focus on two projects within which the engineers at Velox have see the impact of ANSYS, including:

Using Finite Element Analysis (FEA) to reverse engineer a Subaru fork, find the cause of failure and develop an improved replacement part.

Using Computational Fluid Dynamics (CFD) to rub a shape sensitivity study on Nissan GT R strakes, and develop a replacement that increases down-force without significantly increasing drag.

ANSYS 18 – SpaceClaim Webinar

In its latest release, ANSYS SpaceClaim further integrates its ease of use and rapid geometry manipulation capabilities into common simulation workflows. From large changes to behind the scenes enhancements, you’ll notice efficiency improvements across the board. You’ll save time automating geometry tasks with the expanded recording and replay capabilities of SpaceClaim’s enhanced scripting environment.

Join PADT’s Application Engineer Tyler Smith  for this webinar and learn about several improvements that are guaranteed to save time, enhance your designs and improve overall usability. We’ll cover:

  • Continued development of SpaceClaim’s scripting environment. With expanded recording capabilities and replayability of scripts on model versions, you’ll save time in the steps needed to automate geometry tasks.

  • Faceted data optimization and smoothing enhancements. You can greatly simplify and smooth topology optimized STL data for downstream printing, while preserving the integrity of localized regions.

  • Lattice Infilling for additive manufacturing. The Infilling functionality has greatly expanded to include several lattice infill types, all with custom options to ensure your 3-D printed component has an ideal strength-to-weight relationship.

  • Exploration of inner details of a model with the new fly-through capability. Without hiding components or using cross sections, this capability provides graphical feedback at your fingertips while making it even more enjoyable to work in a 3-D environment.

How-To: Connecting Shells Elements in Surface Models with ANSYS SpaceClaim and ANSYS Mechanical

By using the power of ANSYS SpaceClaim to quickly modify geometry, you can set up your surface models in ANSYS Mechanical to easily be connected.  Take a look in this How-To slide deck to see how easy it is to extend geometry and intersect surfaces.

PADT-ANSYS-Connecting-Shells-SpaceClaim-Mechanical

Coupling ANSYS Mechanical and Flownex

The below example demontrates how to couple Flownex and ANSYS mechanical using the Mechanical Generic Interface component.

For those that don’t know, Flownex is a thermal-fluid system modeling tool that is great for modeling heat, flow, pressure, etc… in systems.  At PADT we often connect it to ANSYS Mechanical to do more detailed component level simulation when needed. 

Why the need for the link in the fist place?

  • It is an automated workflow to couple Flownex and ANSYS through direct mapping of Flownex results (HTC and bulk temperatures) as boundary condition to an ANSYS thermal analysis.
  • Represents a conjugate heat transfer model with fluid calculations handled in Flownex
  • Allows one to easily/quickly investigate fluid flow and heat transfer properties under a wide range operating conditions.

First we will discuss the steady state thermal ANSYS Mechanical model that will be linked to Flownex.

We have a pipe Pipe with arbritraty geometry and material properties. Convection boundary conditions have been applied to both the internal and external pipe walls. The inernal Bulk Temperature will be supplied by Flownex.

  • External BC
    • HTC 100 w/m2K
    • Bulk Temperature 22C
  • Internal BC
    • HTC 1500 w/m2K
    • Bulk Temperature will be supplied by Flownex

A command snippet, which will calculate the total heat flow through the inner wall surface and write the value out into a text file called d_result, has been inlcuded in the ANSYS Mechanical model.

In order to achieve a bidirectional coupling, Flownex will execute the Mechanical APDL batch file. We can generate the Mechanical APDL batch file (ds.dat), from within Mechanical.

The soluiton procedure is as follows

  1. Flownex modifies the ds.dat file
  2. Flownex executes the modified ds.dat file
  3. The modified ds.dat file generates the d_result.txt file
  4. Flownex reads the d_result.txt file
  5. Flownex executes an iteration, using value from d_result.txt
  6. Repeat untill solutions are converged.

The next step after creating the ds.dat file is to set up your Flownex model.

The Flownex model comprises of a pipe component with arbritrary geomery, filled with air with an inlet temperature and pressure of 500˚C and 120 kPa respectilvy and a flow rate of approximatly 1kg/s.

We have connected the pipe component to the Mechanical Generic Interface using data transfer links.

The data transfer links pass the bulk fluid temperature form the pipe to the Mechanical Generic Interface component, and return the heat flow value calculated using ANSYS to the pipe.

Next we need place the ds.dat file in the AnsysMechanical_Files folder which is located in the Flownex project folder. It is necessary to create a copy of the ds.dat called ModifiedData.dat in the same location.

Let’s go over the inputs to the Mechanical Generic Interface component in Flownex:

1) Executable location

C:\Program Files\ANSYS Inc\v180\ansys\bin\winx64\Ansys180.exe

This is the path to ANSYS executable. Pay particular attention to the version number (eg 180, 172), as this will be different depending on the version of ANSYS you have installed.

2) Command line parameters

-b -i ModifiedData.dat -o results

Flownex will launch ANSYS, and execute the ModifiedData.dat Mechanical APDL batch file from the command line, using the above command a detailed description of command line options can be found in another blog post here.

3) Project files folder, Data file name and Modified data file name

Here we specify location of the Mechanical APDL batch files

4) Inputs

Here we will define where in ModifiedData.dat the value from Flownex, fluid temperature in this case, will be placed. This is done by determining what the boundary condition variable and ID is, and finding the prefix before the boundary condition value in the ds.dat file. Typically the variable for temperature is _loadvari and for HTC it is _convari.

It is possible to know the boundary condition ID by activating the appearance of Beta options in WB.

5) Outputs

Here we will specify the location of the d_result.txt that ANSYS generates. It should appear in the same folder as the Mechanical APDL batch files after successful execution.

Flownex and ANSYS will pass data back and forth every time step of a transient Flownex run.

The simulation should continue to run up to, and beyond the point where the Flownex and ANSYS simulation have converged. If we plot out the heat input or temperature value vs time we should be able to visualize convergence, akin to residual plots when running a CFD simulation, and then manually stop the simulation after values have stabilized.

Below we increase the fluid inlet temperature form 500˚C to 1000˚C after 10 iterations, and observed a increase in heat flow from ~1.4kW to ~2.8kW.

Increase your throughput and reduce manufacturing costs

Fast, easy to use lightweighting for structural analysis is now only a few clicks away thanks to the introduction of Topology Optimization in ANSYS 18.

Engineers who use Finite Element Analysis (FEA) can reduce weight, materials, and cost without switching tools or environments. Along with this, Topology Optimization frees designers from constraints or preconceptions, helping to produce the best shape to fulfill their project’s requirements.

Topology Optimization also works hand-in-hand with Additive Manufacturing; a form of 3D printing where parts are designed, validated, and then produced by adding layers of material until the full piece is formed. Pairing the two simply allows users to carry out the trend of more efficient manufacturing through the entirety of their process.

Join PADT’s simulation support manager Ted Harris for a live presentation on the full
benefits of introducing Topology Optimization into your manufacturing process. This webinar will cover:

  • A brief introduction into the background of Topology Optimization and Additive Manufacturing, along with an overview of it’s capabilities

  • An explanation of the features available within this tool and a run through of it’s user interface and overall usage

  • An in-depth look at some of the intricacies involved with using the tool as well as the effectiveness of it’s design workflow

ANSYS 18 Mechanical Ease of Use Webinar – Coming Soon

We here at PADT are proud to present the ease of use and productivity enhancements that have been added to ANSYS Mechanical in release 18.

With this new release, ANSYS Mechanical focuses on the introduction of a variety of improvements that help save the users time, such as smarter data organization and new hotkeys, along with additions that can help you to better visualize specific intricacies in your models.

This webinar is coming up soon

Join PADT’s Simulation Support & Application Engineer Doug Oatis for an overview of the current user friendly interfaces within ANSYS Mechanical, along with the numerous additions in this new release that help to improve efficiency tenfold, such as:

Pretension Beam Connection

A beam connection is a power idealization to connect parts without modeling the bolts. Now the beam connection can be pretensioned as well.

Register today to find out how you can use this highly requested feature and many others to improve your throughput and stay ahead of the curve!

Making Thermal Contact Conductance a Parameter in ANSYS Mechanical 18.0 and Earlier with an APDL Command Object

A support request from one of our customers recently was for the ability to make Thermal Contact Conductance, which is sort of a reciprocal of thermal resistance at the contact interface, a parameter so it can be varied in a parametric study.  Unfortunately, this property of contact regions is not exposed as a parameter in the ANSYS Mechanical window like many other quantities are.

Fortunately, with ANSYS there is almost always a way……in this case we use the capability of an APDL (ANSYS Parametric Design Language) command object within ANSYS Mechanical.  This allows us to access additional functionality that isn’t exposed in the Mechanical menus.  This is a rare occurrence in the recent versions of ANSYS, but I thought this was a good example to explain how it is done including verifying that it works.

A key capability is that user-defined parameters within a command object have a ‘magic’ set of parameter names.  These names are ARG1, ARG2, ARG3, etc.  Eric Miller of PADT explained their use in a good PADT Focus blog posting back in 2013

In this application, we want to be able to vary the value of thermal contact conductance.  A low value means less heat will flow across the boundary between parts, while a high value means more heat will flow.  The default value is a calculated high value of conductance, meaning there is little to no resistance to heat flow across the contact boundary.

In order to make this work, we need to know how the thermal contact conductance is applied.  In fact, it is a property of the contact elements.  A quick look at the ANSYS Help for the CONTA174 or similar contact elements shows that the 14th field in the Real Constants is the defined value of TCC, the thermal contact conductance.  Real Constants are properties of elements that may need to be defined or may be optional values that can be defined.  Knowing that TCC is the 14th field in the real constant set, we can now build our APDL command object.

This is what the command object looks like, including some explanatory comments.  Everything after a “!” is a comment:

! Command object to parameterize thermal contact conductance
! by Ted Harris, PADT, Inc., 3/31/2017
! Note: This is just an example. It is up to the user to create and verify
! the concept for their own application.

! From the ANSYS help, we can see that real constant TCC is the 14th real constant for
! the 17X contact elements. Therefore, we can define an APDL parameter with the desired
! TCC value and then assign that parameter to the 14th real constant value.
!
! We use ARG1 in the Details view for this command snippet to define and enable the
! parameter to be used for TCC.

r,cid ! tells ANSYS we are defining real constants for this contact pair
! any values left blank will not be overwritten from defaults or those
! assigned by Mechanical. R command is used for values 1-6 of the real constants
rmore,,,,,, ! values 7-12 for this real constant set
rmore,,arg1 ! This assigned value of arg1 to 14th field of real constant

! Now repeat for target side to cover symmetric contact case
r,tid ! tells ANSYS we are defining real constants for this contact pair
! any values left blank will not be overwritten from defaults or those
! assigned by Mechanical. R command is used for values 1-6 of the real constants
rmore,,,,,, ! values 7-12 for this real constant set
rmore,,arg1 ! This assigned value of arg1 to 14th field of real constant

You may have noticed the ‘cid’ and ‘tid’ labels in the command object.  These identify the integer ‘pointers’ for the contact and target element types, respectively.  They also identify the contact and target real constant set number and material property number.  So how do we know what values of integers are used by ‘cid’ and ‘tid’ for a given contact region?  That’s part of the beauty of the command object: you don’t know the values of the cid and tid variables, but you alsp don’t need to know them.  ANSYS automatically plugs in the correct integer values for each contact pair simply by us putting the magic ‘cid’ and ‘tid’ labels in the command snippet.  The top of a command object within the contact branch will automatically contain these comments at the top, which explain it:

!   Commands inserted into this file will be executed just after the contact region definition.
!   The type number for the contact type is equal to the parameter “cid”.
!   The type number for the target type is equal to the parameter “tid”.
!   The real and mat number for the asymmetric contact pair is equal to the parameter “cid”.
!   The real and mat number for the symmetric contact pair(if it exists)
! is equal to the parameter “tid”.

Next, we need to know how to implement this in ANSYS Mechanical.  We start with a model of a ball valve assembly, using some simple geometry from one of our training classes.  The idea is that hot water passes through the valve represented by a constant temperature of 125 F.  There is a heat sink represented at the OD of the ends of the valve at a constant 74 degrees.  There is also some convection on most of the outer surfaces carrying some heat away.

The ball valve and the valve housing are separate parts and contact is used to allow heat to flow from the hotter ball valve into the cooler valve assembly:

Here is the command snippet associated with that contact region.  The ‘magic’ is the ARG1 parameter which is given an initial value in the Details view, BEFORE the P box is checked to make it a parameter.  Wherever we need to define the value of TCC in the command object, we use the ARG1 parameter name, as shown here:

Next, we verify that it actually works as expected.  Here I have setup a table of design points, with increasing values of TCC (ARG1).  The output parameter that is tracked is the minimum temperature on the inner surface of the valve housing, where it makes contact with the ball.  If conductance is low, little heat should flow so the housing remains cool.  If the conductance is high, more heat should flow into the housing making it hotter.  After solving all the design points in the Workbench window, we see that indeed that’s what happens:

And here is a log scale plot showing temperature rise with increasing TCC:

So, excluding the comments our command object is 6 lines long.  With those six lines of text as well as knowledge of how to use the ARG1 parameter, we now have thermal contact conductance which varies as a parameter.  This is a simple case and you will certainly want to test and verify for your own use.  Hopefully this helps with explaining the process and how it is done, including verification.

 

 

 

Introducing: The PADT Startup Spotlight

In support of the ANSYS Startup Program, PADT is proud to introduce the PADT Startup Spotlight.

We here at PADT are firm believers in the opinion that today’s startup companies are tomorrow’s industry leaders and thus should be give every possible opportunity to thrive and succeed.

As a result we are offering full access to our promotional capabilities in order to help startup companies developing physical prototypes to grow and develop in a competitive environment.

We will look through those startups that have purchased the ANSYS Startup Package through PADT, and select one to feature and promote, that we believe clearly represents the drive and entrepreneurial spirit that is key in order to succeed in today’s day and age.

Presenting the first Startup Spotlight:

Since their inception in 2014, Velox Motorsports has always been focused on speed; whether that be the speed of the NASCAR teams they have worked with or the desire their customers have for speed, which drives their competitiveness and fuels the demand for their products.

They even show a passion for speed in the company’s name (Velox), which translates from Latin to “swift or speed”.

Visit www.padtinc.com/startupspotlight for more information on Velox Motorsports and The PADT Startup Spotlight.

ANSYS 18 – Mechanical Ease of Use Webinar

We here at PADT are proud to present the ease of use and productivity enhancements that have been added to ANSYS Mechanical in release 18.

With this new release, ANSYS Mechanical focuses on the introduction of a variety of improvements that help save the users time, such as smarter data organization and new hotkeys, along with additions that can help you to better visualize specific intricacies in your models.

Join PADT’s Simulation Support & Application Engineer Doug Oatis for an overview of the current user friendly interfaces within ANSYS Mechanical, along with the numerous additions in this new release that help to improve efficiency tenfold, such as:

  • Hotkey Additions
  • Box Geometry Creation Within Mechanical
  • Free Standing Remote Points
  • Improved Status Bar Information
  • Pretension Beam Connection
  • Solver Scratch Directory Specification
  • Improved Probe Annotations

Register today to find out how you can use these enhancements to improve your throughput and stay ahead of the curve!

We look forward to seeing you there.

Making Solids Water Tight in ANSYS Spaceclaim for ANSYS Workbench Meshing

Occasionally when solid geometry is imported from CAD into ANSYS SpaceClaim the geometry will come in as solids, but when a mesh is generated on the solids the mesh will appear to “leak” into the surrounding space. Below is an assembly that was imported from CAD into SpaceClaim. In the SpaceClaim Structure Window all of the parts can be seen to be solid components.

When the mesh is generated in ANSYS Mechanical it appears like the assembly has been successfully meshed.

However, when you look at the mesh a little closer, the mesh can be missing from some of the surfaces and not displayed correctly on others.

Additionally, if you create a cross-section through the mesh, the mesh on some of the parts will “leak” outside of the part boundaries and will look like the image below.

Based on the mesh color, the mesh of the part in the center of the assembly has grown outside of the surfaces of the part.
To repair the part you need to go back to SpaceClaim and rebuild it. First you need to hide the rest of the parts.

Next, create a sketch plane that passes through the problem part.

In the sketch mode create a rectangle that surrounds the part. When you return to 3D mode in SpaceClaim, that rectangle will become a surface that passes through the part.

Now use the Pull tool in SpaceClaim to turn that surface into a part that completely surrounds the part to be repaired, making sure to turn on the “No Merge” option for the pull before you begin.

After you have pulled the surface into a solid, it should like the image below where the original part is completely buried inside the new part.

Now you will use the Combine tool to divide the box with the original part. Select Combine from the Tool Bar, then select the box that you created in the previous step. The cutter will be activated and you will move the cursor around until the original part is highlighted inside the box. Select it with the left mouse button. The Combine tool will then give you the option to select the part of the box that you want to remove. Select the part that surrounds the original part. After it is finished, close the combine tool and the Structure Tree and 3D window will now look like the following:

Now move the new solid that was created with the Combine tool into the location of the original part and turn off the original one and re-activate the other parts of the assembly. The assembly and Structure Tree should now look like the pictures below.

Now save the project, re-open the meshing tool, and re-generate the mesh. The mesh should now be correct and not “leaking” beyond the part boundaries.

ANSYS 18 – AIM Enhancements Webinar

We here at PADT are excited to share with you the updates that ANSYS 18 brings to the table for AIM: The easy-to-use, upfront simulation tool for all design engineers.

ANSYS AIM is a single GUI, multiple physics tool with advanced ANSYS technology under the hood. It requires minimal training and is interoperable with a wide range of ANSYS simulation products.

Join PADT’s application engineer Tyler Smith as he covers the new features and capabilities available in this new release, including:

  • Magnetic frequency response
  • One-way FSI for shell structures
  • Model transfer to Fluent
  • One-way magnetic-thermal coupling
  • and many more!

ANSYS AIM is a perfect tool for companies performing simulation with a CAD embedded tool, design engineers at companies using high end simulation, and even companies who have yet to take the plunge into the world of simulation.

Register for this webinar today and learn how you can take advantage of the easy-to-use, yet highly beneficial capabilities of ANSYS AIM.