## PID Thermostat Boundary Condition ACT Extension for ANSYS Mechanical

PADT is pleased to announce that we have uploaded a new ACT Extension to the ANSYS ACT App Store.  This new extension implements a PID based thermostat boundary condition that can be used within a transient thermal simulation.  This boundary condition is quite general purpose in nature.  For example, it can be setup to use any combination of (P)roportional (I)ntegral or (D)erivate control.   It supports locally monitoring the instantaneous temperature of any piece of geometry within the model.  For a piece of geometry that is associated with more than one node, such as an edge or a face, it uses a novel averaging scheme implemented using constraint equations so that the control law references a single temperature value regardless of the reference geometry.

The set-point value for the controller can be specified in one of two ways.  First, it can be specified as a simple table that is a function of time.  In this scenario, the PID ACT Extension will attempt to inject or remove energy from some location on the model such that a potentially different location of the model tracks the tabular values.   Alternatively, the PID thermostat boundary condition can be set up to “follow” the temperature value of a portion of the model.  This location again can be a vertex, edge or face and the ACT extension uses the same averaging scheme mentioned above for situations in which more than one node is associated with the reference geometry.  Finally, an offset value can be specified so that the set point temperature tracks a given location in the model with some nonzero offset.

For thermal models that require some notion of control the PID thermostat element can be used effectively.  Please do note, however, that the extension works best with the SI units system (m-kg-s).

## A Guide to Crawling, Walking, and Running with ANSYS Structural Analysis

At PADT, we apply a Crawl, Walk, Run philosophy to just about everything we do. Start with the basics, build knowledge and capability on that, and then continue to develop your skills throughout your career. Unfortunately, all too often I run across some poor new grad, two weeks out of school, contending with a problem that’s more befitting someone with about a decade of experience under his or her belt.

Now, the point of this article isn’t to call anyone out. Rather, I sincerely hope that managers and supervisors see this and use it as a guideline in assigning tasks to their direct reports. Note that the recommendations are relative and general. Some people may be quite competent in the “run” categories after just a few months of usage and study while others may have been using the software for a decade and still have trouble figuring out how to even start it. It’s also possible that, for certain projects, the “crawl” categories may actually end up being more difficult to contend with than the “run” categories.

With those caveats in mind, here is our list of recommendations for Crawling, Walking, and Running with ANSYS. Note that these apply to structural analysis. I fully plan to hit up my colleagues for similar blog posts about heat transfer, CFD, and electrical simulation.

## Crawl

• Linear static
• Basic modal
• Eigenvalue (linear) buckling, but don’t forget to apply a knock-down factor

## Walk

• Nonlinearities
• Large Deflection
• Rate-independent plasticity
• Nonlinear contact (frictionless and frictional)
• Dynamics
• Modal with linear perturbation
• Spectrum analyses (running the analysis is easy; understanding what you’re doing and interpreting results correctly is hard)
• Shock/Single point response
• Random Vibration (PSD)
• Harmonic analysis
• Fatigue

## Run

• Nonlinearities
• Hyperelasticity
• Rate-dependent phenomena
• Creep
• Viscoelasticity
• Viscoplasticity
• Other advanced material models such as shape memory alloy and gaskets
• Element birth and death
• Dynamics
• Transient dynamics (implicit)
• Explicit dynamics (e.g. LS-Dyna and Autodyn)
• Rotordynamics
• Fracture and crack growth

So what’s the best, quickest way to move from crawling to walking or walking to running? Invest in general or consultative (or even better, both) ANSYS training with PADT. We’ll help you get to where you need to be.

## Be a Pinball Wizard with Contact Regions in ANSYS Mechanical

I had a very cool music teacher back in 6th or 7th grade in the 1970’s in upstate New York.  Today we’d probably say she was eclectic.  In that class we listened to and discussed fairly recent songs in addition to general music studies.  Two songs I remember in particular are ‘Hurdy Gurdy Man’ by Donovan and ‘Pinball Wizard’ by The Who.  If you’re not familiar with Pinball Wizard, it’s from The Who’s rock opera Tommy, and is about a deaf, mute, blind young man who happens to be adept at the game of pinball.  Yes, he is a Pinball Wizard.  This sing popped into my head recently when we had some customer questions here at PADT regarding the pinball region concept as it pertains to ANSYS contact regions.

I’m not sure if the developers at ANSYS, Inc. had this song in mind when they came up with the nomenclature for the 17X (latest and greatest) series of contact elements in ANSYS, but regardless, you too can be a pinball wizard when it comes to understanding contact elements in ANSYS Mechanical and MAPDL.

Fans of this blog may remember one of my prior posts on contact regions in ANSYS that also had a musical theme (bringing to mind Peter Gabriel’s song “I Have the Touch”):

In this current entry we will go more in depth on the pinball region, also known as the pinball radius.  The pinball region is involved with the distance from contact element to target element in a given contact region.  Outside the pinball region, ANSYS doesn’t bother to check to see if the elements on opposite sides of the contact region are touching or not.  The program assumes they are far away from each other and doesn’t worry about any additional calculations for the most part.

Here is an illustration.  The gray elements on the left represent the contact body and the red elements on the right represent the target body (assuming asymmetric contact).  Target elements outside the pinball radius will not be checked for contact.  The contact and target elements actually ‘coat’ the underlying solid elements so they are shown as dashed lines slightly offset from the solid elements for the sake of visibility.  Here the pinball radius is displayed as a dashed blue circle, centered on the contact elements, with a radius of 2X the depth of the underlying solid elements.

So, outside the pinball region, we know ANSYS doesn’t check to see if the contact and target are actually in contact.  It just assumes they are far away and not in contact.  What about what happens if the contact and target are inside the pinball region?  The answer to that question depends on which contact type we have selected.

For frictionless contact (aka standard contact in MAPDL) and frictional contact, the program will then check to see if the contact and target are truly touching.  If they are touching, the program will check to see if they are sliding or possibly separating.  If they are touching and penetrating, the program will check to see if the penetration exceeds the allowable amount and will make adjustments, etc.  In other words, for frictionless and frictional contact, if the contact and target elements are close enough to be inside the pinball region, the program will make all sorts of checks and adjustments to make sure the contact behavior is adequately captured.

The other scenario is for bonded and no separation contact.  With these contact types, the program’s behavior when the contact and target elements are within the pinball region is different.  For these types, as long as the contact and target are close enough to be within the pinball region, the program considers the contact region to be closed.  So, for bonded and no separation, your contact and target elements do not need to be line on line touching in order for contact to be recognized.  The contact and target pairs just need to be inside the pinball region.  This can be good, in that it allows for some ‘slop’ in the geometry to be automatically ignored, but it also can have a downside if we have a curved surface touching a flat surface for example.  In that case, more of the curved surface may be considered in contact than would be the case if the pinball region was smaller.  This effect is shown in the image below.  Reducing the pinball radius to an appropriate smaller amount would be the fix for eliminating this ‘overconstraint’ if desired.

There is a default value for the pinball region/radius.  It can be changed if needed.  We’ll add more details in a moment.  First, why is it called the “pinball” region?  I like to think it’s because when it’s visualized in the Mechanical window, it looks like a blue pinball from an actual pinball arcade game, but I’ll admit that the ANSYS terminology may predate the Mechanical interface.  The image below shows what I mean.  The blue balls are the different pinball radii for different contact regions.

Note that you don’t see the pinball region displayed as shown in the above image unless you have manually changed the pinball size in Mechanical.  The pinball region can be changed in the Mechanical window in the details view for each contact region by changing Pinball Region from Program Controlled to Radius, like this:

In MAPDL, the pinball radius value can be changed by defining or editing the real constant labeled PINB.

By now you’re probably wondering what is the default value for the pinball radius?  The good news is that it is intelligently decided by the program for each contact region.  The default is always a scale factor on the depth of the underlying elements of each contact region.  In the first pinball region image shown near the beginning of this article, the example plot shows the pinball region/radius as two times the depth of the underlying elements.

The table below summarizes the default pinball radius values for most circumstances for 2D and 3D solid element models.  More detailed information is available in the ANSYS Help.

Default Pinball Radius ValuesLarge Deflection Off
Flexible-Flexible
Large Deflection On
Flexible-Flexible
Frictionless and Frictional1* Underlying Element Depth2*Underlying Element Depth
Bonded and No Seperation0.25*Underlying Element Depth0.5*Underlying Element Depth
Rigid-Flexible Contact: Typically the Default Values are Doubled

Summing it all up:  we have seen how the default values are calculated and also how to change them.  We have seen what they look like as blue balls in a plot of contact regions in Mechanical if the pinball radius has been explicitly defined.  We also discussed what the pinball radius does and how it’s different for frictionless/frictional contact and bonded/no separation contact.

You should be well on your way to becoming a pinball wizard at this point.

Does performing simulation in ANSYS make you think of certain songs, or are there songs you like to listen to while working away on your simulations an addition to The Who’s “Pinball Wizard” and Peter Gabriel’s “I Have the Touch”?  If so, we’d love to hear about your song preferences in the comments below.

## 7 Reasons why ANSYS AIM Will Change the Way Simulation is Done

When ANSYS, Inc. released their ANSYS AIM product they didn’t just introduce a better way to do simulation, they introduced a tool that will change the way we all do simulation.  A bold statement, but after PADT has used the tool here, and worked with customers who are using it, we feel confident that this is a software package will drive that level of change.   It enables the type of change that will drive down schedule time and cost for product development, and allow companies to use simulation more effectively to drive their product development towards better performance and robustness.

## It’s Time for a Productivity Increase

If you have been doing simulation as long as I have (29 years for me) you have heard it before. And sometimes it was true.  GUI’s on solvers was the first big change I saw. Then came robust 3D tetrahedral meshing, which we coasted on for a while until fully associative and parametric CAD connections made another giant step forward in productivity and simulation accuracy. Then more recently, robust CFD meshing of dirty geometry. And of course HPC improvements on the solver side.

That was then.  Right now everyone is happily working away in their tool of choice, simulating their physics of choice.  ANSYS Mechanical for structural, ANSYS Fluent for fluids, and maybe ANSYS HFSS for electromagnetics. Insert your tool of choice, it doesn’t really matter. They are all best-in-breed advanced tools for doing a certain type of physical simulation.  Most users are actually pretty happy. But if you talk to their managers or methods engineers, you find less happiness. Why? They want more engineers to have access to these great tools and they also want people to be working together more with less specialization.

## Putting it all Together in One Place

ANSYS AIM is, among many other things, an answer to this need.  Instead of one new way of doing something or a new breakthrough feature, it is more of a product that puts everything together to deliver a step change in productivity. It is built on top of these same world class best-in-bread solvers. But from the ground up it is an environment that enables productivity, processes, ease-of-use, collaboration, and automation. All in one tool, with one interface.

## Changing the Way Simulation is Done

Before we list where we see things changing, let’s repeat that list of what AIM brings to the table, because those key deliverables in the software are what are driving the change:

• Improved Productivity
• Standardized Processes
• True Ease-of-Use
• Inherent Collaboration
• Intuitive Automation
• Single Interface

Each of these on their own would be good, but together, they allow a fundamental shift in how a simulation tool can be used. And here are the seven way we predict you will be doing things differently.

### 1) Standardized processes across an organization

The workflow in ANSYS AIM is process oriented from the beginning, which is a key step in standardizing processes.  This is amplified by tools that allow users, not just programmers, to create templates, capturing the preferred steps for a given type of simulation.  Others have tried this in the past, but the workflows were either too rigid or not able to capture complex simulations.  This experience was used to make sure the same thing does not happen in ANSYS AIM.

### 2) No more “good enough” simulation done by Design Engineers

Ease of use and training issue has kept robust simulation tools out of the hands of design engineers.  Programs for that group of users have usually been so watered down or lack so much functionality, that they simply deliver a quick answer. The math is the same, but it is not as detailed or accurate.  ANSYS AIM solves this by give the design engineer a tool they can pick up and use, but that also gives them access to the most capable solvers on the market.

### 3) Multiphysics by one user

Multiphysics simulation often involves the use of multiple simulation tools.  Say a CFD Solver and a Thermal Solver. The problem is that very few users have the time to learn two or more tools, and to learn how to hook them together. So some Multiphysics is done with several experts working together, some in tools that do multiple physics, but none well, or by a rare expert that has multi-tool expertise.  Because ANSYS AIM is a Multiphysics tool from the ground up, built on high-power physics solvers, the limitations go away and almost any engineer can now do Multiphysics simulation.

### 4) True collaboration

The issues discussed above about Multiphysics requiring multiple users in most tools, also inhibit true collaboration. Using one user’s model in one tool is difficult when another user has another tool. Collaboration is difficult when so much is different in processes as well.  The workflow-driven approach in ANSYS AIM lends itself to collaboration, and the consistent look-and-feel makes it happen.

### 5) Enables use when you need it

This is a huge one.  Many engineers do not use simulation tools because they are occasional users.  They feel that the time required to re-familiarize themselves with their tools is longer than it takes to do the simulation. The combination of features unique to ANSYS AIM deal with this in an effective manner, making accurate simulation something a user can pick up when they need it, use it to drive their design, and move on to the next task.

### 6) Stepping away from CAD embedded Simulation

The growth of CAD embedded simulation tools, programs that are built into a CAD product, has been driven by the need to tightly integrate with geometry and provide ease of use for the users who only occasionally need to do simulation. Although the geometry integration was solved years ago, the ease-of-use and process control needed is only now becoming available in a dedicated simulation tool with ANSYS AIM.

If you have been doing simulation since the 80’s like I have, you probably remember a day when every company had scripts and tools they used to automate their simulation process. They were extremely powerful and delivered huge productivity gains. But as tools got more powerful and user interfaces became more mature, the ability to create your own automation tools faded.  You needed to be a programmer. ANSYS AIM brings this back with recording and scripting for every feature in the tool, with a common and easy to use language, Python.

## How does this Impact Me and or my Company?

It is kind of fun to play prognosticator and try and figure out how a revolutionary advance in our industry is going to impact that industry. But in the end it really does not matter unless the changes improve the product development process. We feel pretty strongly that it does.  Because of the changes in how simulation is done, brought about by ANSYS AIM, we feel that more companies will use simulation to drive their product development, more users within a company will have access to those tools, and the impact of simulation will be greater.

To fully grasp the impact you need to step back and ponder why you do simulation.  The fast cars and crazy parties are just gravy. The core reason is to quickly and effectively test your designs.  By using virtual testing, you can explore how your product behaves early in the design process and answer those questions that always come up.  The sooner, faster, and more accurately you answer those questions, the lower the cost of your product development and the better your final product.

Along comes a product like ANSYS AIM.  It is designed by the largest simulation software company in the world to give the users of today and tomorrow access to the power they need. It enables that “sooner, faster, and more accurately” by allowing us to change, for the better, the way we do virtual testing.

The best way to see this for yourself is to explore ANSYS AIM.  Sign up for our AIM Resource Kit here or contact us and we will be more than happy to show it to you.

## Video Tips: Fluid Volume Extraction

This video shows a really quick and easy way to extract a fluid domain from a structural model without having to do any Boolean subtract operations.

## Free ANSYS AIM Resource Kit — Expert Advice, Insights and Best Practices for Multiphysics Simulation

We have been talking a lot about ANSYS AIM lately.  Mostly because we really like ANSYS AIM and we think a large number of engineers out there need to know more about it and understand it’s advantages.  And the way we do that is through blog posts, emails, seminars, and training sessions.  A new tool that we have started using are “Resource and Productivity Kits,” collections of information that users can download.

Earlier in the year we introduced several kits, including ANSYS Structural, ANSYS Fluids, and ANSYS ElectroMechanical.  Now we are pleased to offer up a collection of useful information on ANSYS AIM.  This kit includes:

• “Getting to know ANSYS AIM,” a video by PADT application engineer Manoj Mahendran
• “What I like about ANSYS AIM,” a video featuring insights on the tool
• Six ANSYS AIM demonstration videos, including simulations and a custom template demonstration
• Five slide decks that provide an overview of ANSYS AIM and describe its new features
• An exclusive whitepaper on effectively training product development engineers in simulation.

Watch this blog for more useful content on AIM in the future.

## To Use Large Deflection or Not, That Is the Question

It seems like I’ve been explaining large deflection effects a lot recently. Between co-teaching an engineering class at nearby Arizona State University and also having a couple of customer issues regarding the concept, large deflection in structural analyses has been on my mind.

Before I explain any further, the thing you should note if you are an ANSYS Mechanical simulation user is this: If you don’t know if you need large deflection or not, you should turn it on. There is really no way to know for certain if it’s needed or not unless you perform a comparison study with and without it.

So, what are large deflection effects? In simple terms the inclusion of large deflection means that ANSYS accounts for changes in stiffness due to changes in shape of the parts you are simulating. The classic case to consider is the loaded fishing rod.

In its undeflected state, the fishing rod is very flexible at the tip. With a heavy fish on the end of the line, the rod deflects downward and it is then easy to observe that the stiffness of the rod has increased. In other words, when the rod is lightly loaded, a small amount of force will cause a certain downward deflection at the top. When the rod is heavily loaded however, a much larger amount of force will be needed to cause the tip to deflect downward by the same amount.

This change in the force amount required to achieve the same change in displacement implies that we do not have a linear relationship between force and displacement.
Consider Hooke’s law, also known as the spring equation:

F = Kx

Where F is the force applied, K is the stiffness of the structure, and x is the deflection. In a linear system, doubling the force results in double the displacement. In our fishing rod case, though, we have a nonlinear system. We might need to triple the force to double the displacement, depending on how much the rod is loaded relative to its size and other properties, and then to double the displacement again we might need to apply four times that force, just using numbers out of my head as examples.

So, in the case of the fishing rod, Hooke’s law in a linear form does not apply. In order to capture the nonlinear effect we need a way for the stiffness to change as the shape of the rod changes. In our finite element solution in ANSYS, it means that we want to recalculate the stiffness as the structure deflects.

This recalculation of the stiffness as the structure deflects is activated by turning on large deflection effects. Without large deflection turned on, we are constrained to using the linear equation, and no matter how much the structure deflects we are still using the original stiffness.

So, why not just have large deflection on by default and use it all the time? My understanding is that since large deflection adds computation expense to have it on, it’s off by default. It’s the same as for a lot of advanced usage, such as frictionless or frictional contact vs. the default bonded (simpler) behavior. In other words, turning on large deflection will trigger a nonlinear solution, meaning multiple passes through the solver using the Newton Raphson method instead of the single pass needed for a linear problem.

Here is an example of a simplified fishing rod. The image shows the undeflected rod (top), which is held fixed on the left side and has a downward force load applied on the right end. The bottom image shows the final deflected shape, with large deflection effects included. The deflection at the tip in this case is 34 inches.

In comparison running the same load with large deflection turned off resulted in a tip deflection of 40 inches. Thus, the calculated tip deflection is 15% less with large deflection turned on, since we are now accounting for change in stiffness with change in shape as the rod deflects.

Below we have a force (horizontal axis) vs. deflection (vertical axis) plot for a nonlinear simulation of a fishing rod with large deflection turned on. The fact that the curve is not a straight line confirms that this is a nonlinear problem, with the stiffness (slope of the curve) not constant. We can also see that as the force gets higher, the slope of the curve is more horizontal, meaning that more force is needed for each incremental amount of displacement. This matches our observations of the fishing rod behavior.

So, getting back to our original point, it’s often the case that we don’t know if we need to include large deflection effects or not. When in doubt, run cases with and without. If you don’t see a change in your key results, you can probably do without large deflection.

Here is an example using an idealized compressor vane. In this case, the deflections and stresses with and without large deflection effects are nearly the same (the stress difference is about 0.2%).

Large Deflection On:

Small Deflection:

Bottom line: when in doubt, try it out, with and without large deflection. In ANSYS Mechanical, Large Deflection effects are turned on or off in the details of the Analysis Settings branch.

It’s worth noting that turning on large deflection in ANSYS actually activates four different behaviors, known as large deflection which include large rotation, large strain, stress stiffening, and spin softening. All of these involve change in stiffness due to deformation in one way or another.

If you like this kind of info, or find it useful, we cover topics like this in our training classes. For more info, check out our training pages at http://www.padtinc.com/support/software/training.html.

## Presentation: Leveraging Simulation for Product Development of IoT Devices

The local SEMI chapter here in Arizona held a breakfast meeting on Monetizing Internet of Things (IoT) and PADT was pleased to be one of the presenters. Always a smart group, this was a chance to sit with people making the sensors, chips, and software that enable the IoT and dig deep in to where things are and where they need to be.

The event was hosted by one of our favorite customers, and neighbor right across the street, Freescale Semiconductor.  Speakers included IoT experts from Freescale, Intel, Medtronics, ASU, and SEMICO Research.

Not surprisingly I talked about how Simulation can play a successful role in product development of IoT devices.

UPDATE (11/9/2015): Great write-up by Don Dingee on this event in the SemiWiki. Click here to read it. It includes a great summary of the other speakers.

You can also see more details on how people use Simulation for this application on the ANSYS, Inc. website here.  We also like this video from ANSYS that shows some great applications and how ANSYS is used with them:

A couple of common themes resonated across the speakers:

1. Price and size need to come down on the chips used in IoT (this was a semiconductor group, so this is a big part of their focus)
2. Lowering power usage and increasing power density in batteries is a key driver
3. The biggest issue in IoT is privacy and security. Keeping your data private and keeping people from hacking in to IoT devices.
4. Another big problem is dealing with all the data collected by IoT devices. How to make it useful and how to store it all.  One answer is reducing the data on the device, another is only keeping track of what changes.
5. It is early, standards are needed but they are still forming.

If you look at this list, the first two problems are addressable with simulation:

PADT has a growing amount of experience with helping customers simulate and design IoT devices as well as the chips, sensors, and antenna that go in to IoT devices.  To learn more, shoot us an email at info@padtinc.com or call 480.813.4884.

## Free Training and Evaluation for ANSYS AIM

PADT is hosting a series of free training classes to introduce users to ANSYS AIM.  We have pasted the invitation below.  You can register here.  We are very excited about this new tool from ANSYS, Inc. and are eager to share it with everyone. Look for more AIM information on this blog in the near future.

## Free Training and Evaluation for ANSYS® AIM™. Register Today – Seats Are Limited.

Discover how to design your next product
better… and faster

## ANSYS AIM: Integrated Multiphysics Simulation Environment for All Engineers

### Free Training and Evaluation for ANSYS® AIM™ – An Integrated Multi-physics Simulation Environment for All Engineers

As a special offer, PADT Inc. is offering FREE “Jump Start” training and hands-on evaluation for ANSYS® AIM™. Design engineers, method engineers and managers seeking to learn the latest simulation software, boost adoption and usability for the occasional user, or extend their existing CAD-based tool’s limited functionality will benefit from this no-obligation course.

Register Today – Seats are limited and will be filled on a first-come, first-served basis. On completion of the class, you’ll be qualified to receive and use a FREE 30-day ANSYS AIM download for evaluation.

All classes will be held from 9:00 a.m. – 4:00 p.m. local time and include a complimentary lunch.

PADT’s support team of ANSYS experts will help attendees understand where ANSYS AIM fits in to their organization and workflow. The class will address both situations and how ANSYS AIM provides the integration of CAD based systems and the ease of use of a modern tool in a product that steps the occasional user through the process without limiting functionality.

Watch this short video to learn more about the capabilities and benefits of ANSYS® AIM™ for the simulation of 3-D physics and multiphysics

## NICE Desktop Cloud Visualization

In a previous post I argued that engineers do magic (read it here). And to help them do their magic better PADT Inc. introduced CoresOnDemand.com.

Among the magical skills engineers use in their daily awesomeness is their ability to bend the time fabric of the universe and perform tasks in almost impossible deadlines. It’s as if engineers work long hours and even work from home, while commuting and even at the coffee shop. Wait, is that what they actually do?

Among a myriad of tools that facilitate remote access and desktop redirection available, one stands out with distinction. NICE-Software developed a tool called Desktop Cloud Visualization (DCV for short). DCV has numerous advantages that we will get into shortly. The videos below give a general idea of what can be achieved with NICE-DCV.

Here is a video from the people at NICE:

And here is one of two PADT Employees using an iPhone to check their CFD results:

## Physical location of cluster/workstation or the engineers becomes irrelevant

Because engineers have fast, efficient and secure access to their workstations and clusters, they no longer need to be in the same office or on the same network segment to utilize the available compute resources. They can utilize NICE-DCV to create a fast, efficient and encrypted connection to their resources to submit, monitor and process results. The DCV clients are supported on Windows, Linux & IOS and even have a stand-alone Windows client that can be run on shared or public computers. In a recent live test, one of our engineers was travelling on a shuttle bus to a tiny ski town in Colorado, he was able to connect over the courtesy Wifi, check the status of his jobs and visualize some of the results.

## The need for a powerful laptop or remote workstation to enable offsite work is no longer the only solution

There is no need for offsite engineers lug around a giant laptop in order to efficiently launch and modify their designs or perform simulation runs. Users launch the DCV client, connect to their workstation or cluster and are immediately given access to their desktop. No need to copy files, borrow licenses or transfer data. Engineers don’t need to create copies of files and carry them around on the laptops or on external storage which is an unnecessary security risk.

## “If it ain’t broken don’t fix it!”

Every engineer uses ANSYS in his own special way. Some prefer the good old command line for everything even when a flashy GUI option is available. Others are comfortable using the Windows like GUI interface and would

## Opens the door for GUI-only users to utilize large cluster resources without a steep learning curve or specialized tools.

Nice-DCV makes the use of ANSYS on large HPC clusters within reach for everyone. Engineers can log into pre-configured environments with all of the variables needed for parallel ANSYS runs already defined. Users can use can have their favorite ANSYS software added to the desktop as shortcuts or system admins can write small scripts or programs that serve as an answer file for custom job scripts.

## From 0-60 in about…10 Minutes

For an engineer with the smallest amount of system administration skills it takes about 10 minutes to install the Nice-DCV server and launch the first connection. It’s surprisingly simple and straightforward on both the server and the client side. The benefits of Nice-DCV can be immediately realized in both simplified cluster administration and peace of mind for both the engineers and the system admins.

The CoresOnDemand service that PADT introduced last year utilizes the Nice-DCV tool to simplify and enhance the user experience. If you are interested in a live demo on Nice-DCV or the CoresOnDemand environment contact us either by phone: 480-813-4884 or by email cod@padtinc.com. For more information please visit: CoresOnCemand.com

(Note: some of the social media posts had a typo in the title, that was my fault (Eric) not Ahmed’s…)

## Press Release: Southern California Expansion Grows PADT’s ANSYS Product Development Software Distribution Business

Palm trees and movie stars.  Endless beaches and deserts that fade to the horizon.  Aerospace companies, world class universities, med device developers, and toy manufacturers.  Oil, freeways, and big construction. Southern California. A place larger and more diverse than most countries in the world.  PADT has done work in the area since our first weeks in business. As our business continued to grow, our customers started asking when we were opening up a local office, but the time never seemed right. Until now.

PADT is pleased to announce that we will be loading furniture and computers in a truck and head on the I-10 to Torrance, California where we will open up a new office.  ANSYS, Inc. has expanded our sales territory to include small and medium sized new accounts in the Southern California area.  The focus of this new office will be building that business.

You can read the official details in the press release below, or the PDF here.  As usual, we want to share some more informal information with our blog readers.

The office will be started with an engineer and a salesperson who have been with us for a while, and another pair that we are hiring locally. This combination of company experience and local knowledge should get us going quickly. Over time, the plan is to grow the Torrance office, and add at least two more. Long term we would like to have between 3 and 10 employees per office in Southern California.

Our team will conduct training and seminars from this office and use it as a base to spread the word on simulation driven product development across Southern California. The initial focus for sales will be on small and medium sized businesses that are currently not using ANSYS products, that want to work with a technical sales and support team who can provide more than the software tool – customers who want a partner who can also help them apply the tools effectively. The dense hotbeds of engineering along the coast will be an obvious area of concentration. We also aim to represent the value of ANSYS products in less visited areas of the region, including the high deserts, “in-between” towns, and inland locations beyond LA, Orange County, and San Diego.

The good news is that we are not starting from scratch. This first office is right down the street from the California campus of PADT’s largest and oldest customer.  We also have over one hundred customers who have used PADT for simulation services, training, rapid prototyping, and product development, and we will be reaching out to them shortly to start building our local network even further.  And then, our new employees who we will hire locally will be contacting their network as well.

Before the end of the summer we hope to have a grand opening event, as well as several seminars that will continue through the end of the year. If you live in the area and want to be invited, visit here to register as someone who want to be on the California contact list.

This blog and social media will be used to post our progress. The entire sales and technical team is looking forward to meeting everyone in the area in the coming months.

Below is a copy of the press release, or you can view the “official” version here.

Press Release:

PADT opens Torrance office to provide consultant-focused ANSYS Product Sales and Support for small and medium sized engineering businesses in the region

Tempe, Ariz., August 24, 2015 —Phoenix Analysis & Design Technologies, Inc. (PADT) the Southwest’s largest provider of Numerical Simulation, Product Development, and 3D Printing services and products, today announced the addition of Southern California to its ANSYS, Inc. Product Sales and Support territory. PADT is a long time ANSYS Channel Partner who has built a reputation for outstanding technical abilities and customer support in Arizona, New Mexico, Colorado, Utah, and Nevada. The company is now taking the same customer focused approach to selling and supporting the world’s leading product development simulation tools from ANSYS to new customers in Southern California.

“We are honored by ANSYS’ trust in PADT and are eager to start working more closely with their team in Southern California,” said Bob Calvin, PADT’s manager of Simulation Sales. “We have been doing business in this area since PADT was founded 21 years ago. Expanding our offering to include ANSYS products and support is something that makes sense for users, ANSYS and PADT.”

Located in Torrance California, PADT’s new office will be staffed by two sales people and two application engineers.  Aggressive growth will follow.

“We selected Torrance for our new Southern California office because it’s centrally located, easily accessible and right down the street from the California campus of our largest customer,” said Ward Rand, co-owner, PADT. “Having staff with real world industry experience located nearby will strengthen our ability to drive our customer’s product development process, resulting in higher quality products, improved performance and lower costs.”

PADT will open additional offices across the Southern California region in the coming two years with the long term goal of three total offices with three to ten employees each.  The location of these offices, just like the initial Torrance facility, will be chosen to provide service where the demand is greatest.

The ANSYS Channel Partner program is unique in the industry because it allows customers the option to purchase software and support from ANSYS directly, or from highly technical local consulting companies like PADT. Since Southern California has not had an ANSYS Channel Partner for thirteen years, PADT’s engineering experience and ANSYS product expertise will be a tremendous help to small and medium sized companies seeking to discover the power of ANSYS products, and efficiently implement Simulation Driven Product Development (SDPD).

Events, both on-line and face-to-face, will be announced in the coming months to celebrate the arrival of PADT in the area. Those interested in following PADT’s progress, can subscribe to any of the company’s social media outlets, PADT California emails, or visit the new PADT California web page (www.padtinc.com/socal). Anyone needing immediate information can contact PADT at info@padtinc.com or call 480.813.4884.

About Phoenix Analysis and Design Technologies

Phoenix Analysis and Design Technologies, Inc. (PADT) is an engineering product and services company that focuses on helping customers who develop physical products by providing Numerical Simulation, Product Development, and Rapid Prototyping solutions. PADT’s worldwide reputation for technical excellence and experienced staff is based on its proven record of building long term win-win partnerships with vendors and customers. Since its establishment in 1994, companies have relied on PADT because “We Make Innovation Work.” With over 75 employees, PADT services customers from its headquarters at the Arizona State University Research Park in Tempe, Arizona, and from offices in Littleton, Colorado, Albuquerque, New Mexico, and Murray, Utah, as well as through staff members located around the country. More information on PADT can be found at http://www.PADTINC.com.

# # #

Company contact:
Eric Miller
480.813.4884

Media contact:
Linda Capcara
TechTHiNQ
480-229-7090
linda.capcara@techthinq.com

# Engineers Do Magic

In the world of simulation there are two facts of life. First, the deadline of “yesterday would be good” is not too uncommon. Funding deadlines, product roll-out dates, as well as unexpected project requirements are all reliable sources for last minute changes. Engineers are required to do quality work and deliver reliable results in limited time and resources. In essence perform sorcery.

Second, the size and complexity of models can vary wildly. Anything from fasteners and gaskets to complete systems or structures can be in the pipeline. Engineers can be looking at any combination of hundreds of variables that impact the resources required for a successful simulation.

Required CPU cores, RAM per core, interconnect speeds, available disk space, operating system and ANSYS version all vary depending on the model files, simulation type, size, run-time and target date for the results.

Engineers usually do magic. But sometimes limited time or resources that are out of reach can delay on-time delivery of project tasks.

# At PADT, We Can Help

PADT Inc. has been nostrils deep in engineering services and simulation products for over 20 years. We know engineering, we know how to simulate engineering and we know ANSYS very well. To address the challenges our customers are facing, in 2015 PADT introduced CoresOnDemand to the engineering community.

CoresOnDemand offers the combination of our proven CUBE cluster, ANSYS simulation tools and the PADT experience and support as an on demand simulation resource. By focusing on the specific needs of ANSYS users, CoresOnDemand was built to deliver performance and flexibility for the full range of applications. Specifics about the clusters and their configurations can be found at CoresOnDemand.com.

CoresOnDemand is a high performance computing environment purpose built to help customers address numerical simulation needs that require compute power that isn’t available or that is needed on a temporary basis.

# Call Us We’re Nice

CoresOnDemand is a new service in the world of on-demand computing. Prospective customers just need to give us a call or send us an inquiry here to get all of their questions answered. The engineers behind CoresOnDemand have a deep understanding of the ANSYS tools and distributed computing and are able to asses and properly size a compute environment that matches the needed resources.

Call us we’re nice!

# Two Halves of the Nutshell

The process for executing a lease on a CoresOnDemand cluster is quite straight forward. There are two parts to a lease:

## PART 1: How many cores & how long is the lease for?

By working with the PADT engineers – and possibly benchmarking their models – customers can set a realistic estimate on how many cores are required and how long their models need to run on the CoresOnDemand clusters. Normally, leases are in one-week blocks with incentives for longer or regular lease requirements.

Clusters are leased in one-week blocks, but we’re flexible.

## Part 2: How will ANSYS be licensed?

An ANSYS license is required in order to run on the CoresOnDemand environment.  A license lease can be generated by contacting any ANSYS channel partner. PADT can generate license leases in Arizona, Colorado, New Mexico, Utah & Nevada. Licenses can also be borrowed from the customer’s existing license pool.

An ANSYS license may be leased from an ANSYS channel partner or borrowed from customer’s existing license pool.

# Using the Cluster

Once the CoresOnDemand team has completed the cluster setup and user creation (takes a couple of hours for most cases), customers can login and begin using the cluster. The CoresOnDemand clusters allow customers to use the connection method they are comfortable with. All connections to CoresOnDemand are encrypted and are protected by a firewall and an isolated network environment.

## Step 1: Transfer files to the cluster:

Files can be transferred to the cluster using Secure Copy Protocol which creates an encrypted tunnel for copying files. A graphical tool is also available for Windows users (& it’s freeJ). Also, larger files can be loaded to the cluster manually by sending a DVD, Blu-ray disk or external storage device to PADT. The CoresOnDemand team will mount the volume and can assist in the copying of data.

## Step 2: Connect to the cluster and start jobs

Customers can connect to the cluster through an SSH connection. This is the most basic interface where users can launch interactive or batch processing jobs on the cluster. SSH is secure, fast and very stable. The downside of SSH is that is has limited graphical capabilities.

Another option is to use the Nice Software Desktop Cloud Visualization (DCV) interface. DCV provides enhanced interactive 2D/3D access over a standard network. It enables users to access the cluster from anywhere on virtually any device with a screen and an internet connection. The main advantage of DCV is the ability to start interactive ANSYS jobs and monitor them without the need for a continuous connection. For example, a user can connect from his laptop to launch the job and later use his iPad to monitor the progress.

Figure 1. 12 Million cell model simulated on CoresOnDemand

The CoresOnDemand environment also has the Torque resource manager implemented where customers can submit multiple jobs to a job queue and run them in sequence without any manual intervention.

Customers can use SCP or ship external storage to get data on the cluster. SSH or DCV can be used to access the cluster. Batch, interactive or Torque scheduler can be used to submit and monitor jobs.

# All Done?

Once the simulation runs are completed customers usually choose one of two methods to transfer data back. First is to download the results over the internet using SCP (mentioned earlier) or have external media shipped back (External media can be encrypted if needed).

After the customer receives the data and confirms that all useful data was recovered from the cluster, CoresOnDemand engineers re-image the cluster to remove all user data, user accounts and logs. This marks the end of the lease engagement and customers can rest assured that CoresOnDemand is available to help…and it’s pretty fast too.

At the end of the lease customers can download their data or have it shipped on external media. The cluster is later re-imaged and all user data, accounts & logs are also deleted in preparation for the next customer.

## ANSYS Launches Free Student Version

This week ANSYS, Inc. made a fantastic announcement that has been in the works for a while, and that we think will greatly benefit the simulation community:  A free ANSYS Student product.  This is an introductory product that is focused on students who are learning the fundamentals of simulation who also want to learn the full power and capability of the ANSYS product suite.  It includes ANSYS® Multiphysics™ , ANSYS® CFD™ , ANSYS® Autodyn®, ANSYS® Workbench™, ANSYS® DesignModeler™and ANSYS®DesignXplorer™

Yes you read that right, all of the flagship products for free. No features or capabilities are turned off. It is the exact same software as the commercial product, but the size of problems that you can solve is limited.  It runs on MS Windows. Perfect for students.

PADT is excited about this because it gives students access to the ability to learn FEA and CFD simulation with the world’s most popular and capable simulation tool, without running in to brick walls. Want to do a flat plate with a hole in it? No Problem. Want to model fluid-solid-interaction on a flexible membrane valve? No Problem.  Want to model explosive forming? No Problem.  Want to model combustion with complex turbulence? No problem.

All in the same interface as students will use when they enter the work force or do research at University.

This is great news and we can’t wait to see what schools and students do with this access.

## How to Get It – The New Academic Web Pages

The previous Student Portal is being replaced with an Academic Web area on the ansys.com site: ansys.com/academic.

## The “Pictures”

Let me state categorically that PADT was not consulted on the image that ANSYS, Inc. used for the “student” user that was so happy to find out that there is now a free version of the ANSYS software suite.  Here is their picture:

We would have preferred something like this:

Just kidding. We were happy to see this product come out and thought the picture was hilarious.  In all seriousness, we will also plug the  recent #ilooklikeanengineer twitter hash tag , highlighting the diversity of female engineers. that was awesome and we would love to see more chances for engineers to show their true selves.

## Major Enhancements in FLOWNEX 2015: Combustors, Importers, and Pipes

Simulation has revolutionized flow and heat transfer dependent systems over the past decades by minimizing costly physical testing and accelerating time to operation around the world. But for many companies, such simulation has largely focused on components and proved to be very time consuming. The technology advancements delivered by Flownex SE now offer a fast, reliable, and accurate total system and subsystem approach to simulation.

With the release of FLOWNEX 2015, users now have access to advanced combustor system level modeling and they can interact with more system and component simulation tools. This is on top of the already considerable capabilities found in the  tool

## Gas Turbine Combustor Heat Transfer Library

During the Preliminary design phase or when considering modifications to existing combustor designs it’s essential to make realistic predictions of  mass flow splits through the  various air admission holes, total pressure losses liner temperatures along the length of the combustor etc.

Although very powerful, 3D CFD solutions of combustors are specialized, time consuming processes and therefore are seldom exclusively used during initial sizing of a combustor.

It has been demonstrated that 1D/2D network tools, like Flownex, are capable of predicting with reasonable accuracy the same trends as more detailed numerical models.

The advantage, however, is Flownex’s rapid execution, which allows design modifications and parametric studies to be conducted more simply than ever before. The ease of use and incredible speed of Flownex allows 1000s of preliminary designs to be evaluated under all modes of operation for steady state and dynamic cases. Furthermore, the data obtained from the one-dimensional analysis can be used as boundary conditions for a more detailed three-dimensional model, ultimately supplementing a typical combustor design work flow.

While the simulation of combustor systems was previously possible in the Flownex environment, much of the work of implementing industry standard heat transfer correlations was left to the user through scripting .Now in Flownex SE 2015 it’s all been built in to the tool, while maintaining the flexibility required to model any combustor configuration.

New components include

• Film convection component
• Jet impingement heat transfer component

To sum up Flownex allows more accurate initial designs, less time is spent on advanced 3D combustor simulations and rig tests, thus reducing development time and cost.

Here is a Video that shows off these features:

## Added importers and integration features

### AFT Fathom/Impulse/Arrow importer

An importer was added to import the file formats of AFT products. The importer imports all the diameters, loss factors heights, etc. so 90% of the effort is done, and in some cases the networks solve without any modifications.

ROHR2 Integration (pipe stress analysis software)

Flownex has the ability to calculate forces during dynamic simulations. This is very useful in pipe stress analysis for surge or water hammer cases. The ability to import complete geometries from ROHR2 and export results in the format that ROHR2 expects natively has been added. This means a user can perform these combined analysis now with ROHR2 with the minimum of effort.

Fluid Importers

An Importer was added to import liquid and gas properties from CoolProp an open source fluid property library. The existing Aspen/Hysys fluid importer was changed to be a generic Cape-Open compliant importer. This means that fluid properties can now be imported from any Cape-Open compliant server software.

## Donny Don’t – Thin Sweep Meshing

It’s not a series of articles until there’s at least 3, so here’s the second article in my series of ‘what not to do’ in ANSYS…

Just in case you’re not familiar with thin sweep meshing, here’s an older article that goes over the basics.  Long story short, the thing sweep mesher allows you to use multiple source faces to generate a hex mesh.  It does this by essentially ‘destroying’ the backside topology.  Here’s a dummy board with imprints on the top and bottom surface:

If I use the automatic thin sweep mesher, I let the mesher pick which topology to use as the source mesh, and which topology to ‘destroy’.  A picture might make this easier to understand…

As you can see, the bottom (right picture) topology now lines up with the mesh, but when I look at the top (left picture) the topology does not line up with the mesh.  If I want to apply boundary conditions to the top of the board (left picture), I will get some very odd behavior:

I’ve fixed three sides of the board (why 3?  because I meant to do 4 but missed one and was too lazy to go back and re-run the analysis to explain for some of future deflection plots…sorry, that’s what you get in a free publication) and then applied a pressure to all of those faces.  When I look at the results:

Only one spot on the surface has been loaded.  If you go back to the mesh-with-lines picture, you’ll see that there is only a single element face fully contained in the outline of the red lines.  That is the face that gets loaded.  Looking at the input deck, we can see that the only surface effect element (how pressure loads are applied to the underlying solid) is on the one fully-contained element face:

If I go back and change my thin sweep to use the top surface topology, things make sense:

The top left image shows the thin sweep source definition.  Top right shows the new mesh where the top topology is kept.  Bottom left shows the same boundary conditions.  Bottom right shows the deformation contour.

The same problem occurs if you have contact between the top and bottom of a thin-meshed part.  I’ll switch the model above to a modal analysis and include parts on the top and bottom, with contact regions already imprinted.

I’ll leave the thin sweeping meshing control in place and fix three sides of the board (see previous laziness disclosure).  I hit solve and nothing happens:

Ah, the dreaded empty contact message.  I’ll set the variable to run just to see what’s going on.  Pro Tip:  If you don’t want to use that variable then you would have to write out the input deck, it will stop writing once it gets to the empty contact set.  Then go back and correlate the contact pair ID with the naming convection in the Connections branch.

The model solves and I get a bunch of 0-Hz (or near-0) modes, indicating rigid body motion:

Looking at some of those modes, I can see that the components on one side of my board are not connected:

The missing contacts are on the bottom of the board, where there are three surface mounted components (makes sense…I get 18 rigid body modes, or 6 modes per body).  The first ‘correct’ mode is in the bottom right image above, where it’s a flapping motion of a top-mounted component.

So…why don’t we get any contact defined on the bottom surface?  It’s because of the thin meshing.  The faces that were used to define the contact pair were ‘destroyed’ by the meshing:

Great…so what’s the take-away from this?  Thin sweep meshing is great, but if  you need to apply loads, constraints, define contact…basically interact with ANYTHING on both sides of the part, you may want to use a different meshing technique.  You’ve got several different options…

1. Use the tet mesher.  Hey, 2001 called and wants its model size limits back.  The HPC capabilities of ANSYS make it pretty painless to create larger models and use additional cores and GPUs (if you have a solve-capable GPU).  I used to be worried if my model size was above 200k nodes when I first started using ANSYS…now I don’t flinch until it’s over 1.5M

Look ma, no 0-Hz modes!
2. Use the multi-zone mesher.  With each release the mutli-zone mesher has gotten better, but for most practical applications you need to manually specify the source faces and possibly define a smaller mesh size in order to handle all the surface blocking features.

Look pa, no 0-Hz modes!Full disclosure…the multi-zone mesher did an adequate job but didn’t exactly capture all of the details of my contact patches.  It did well enough with a body sizing and manual source definition in order to ‘mostly’ bond each component to the board.
3. Use the hex-dominant mesher.  Wow, that was hard for me to say.  I’m a bit of a meshing snob, and the hex dominant mesher was immature when it was released way back when.  There were a few instances when it was good, but for the most part, it typically created a good surface mesh and a nightmare volume mesh.  People have been telling me to give it another shot, and for the most part…they’re right.  It’s much, much better.  However, for this model, it has a hard time because of the aspect ratio.  I get the following message when I apply a hex dominant control:

4. The warning is right…the mesh looks decent on the surface but upon further investigation I get some skewed tets/pyramids.  If I reduce the element size I can significantly reduce the amount of poorly formed elements:
5. That’s going on the refrigerator door tonight!

And…no 0-Hz modes!
• Lastly…go back to DesignModeler or SpaceClaim and slice/dice the model and use a multi-body part.
3 operations, ~2 minutes of work (I was eating at the same time)

Modify the connection group to search/sort across parts

That’s a purdy mesh!  (Note:  most of the lower-quality elements, .5 and under, are because there are 2-elements through thickness, reducing the element size or using a single element thru-thickness would fix that right up)

And…no 0-Hz modes.

Phew…this was a long one.  Sorry about that.  Get me talking about meshing and look what happens.  Again, the take-away from all of this should be that the thin sweeper is a great tool.  Just be aware of its limitations and you’ll be able to avoid some of these ‘odd’ behaviors (it’s not all that odd when you understand what happens behind the scenes).