ANSYS Mechanical is great at applying tabular loads that vary with an independent variable. Say time or Z. What if you want a tabular load that varies in multiple directions and time. In part one of this series, I covered who you can use the External Data tool to do just that. In this second part, I show how you can alternatively use APDL commands added to your ANSYS Mechanical model to define the tabular loading.PADT-ANSYS-Tabular-loads-2
We are pleased to publish this very useful post from Nicolas Jobert from Synchrotron SOLEIL in France. Nicolas is a Mechanical Engineer with more than 20 years of experience using ANSYS for engineering design and analysis in academia and industry. He currently is Senior Mechanical Engineer at Synchrotron SOLEIL, the French synchrotron radiation facility. He also teaches various courses on Design and Validation in the field of structural and optomechanics. He graduated from the Ecole Centrale Marseille, France, and is a EUSPEN member.
As Time Goes By
Do you remember the moment you first heard about ANSYS introducing APDL Math?
I, for one, do, and I have a vivid memory of thinking “Wow, that can be a powerful tool, I’m dead sure it won’t be long before an opportunity arises and I’ll start developing pretty useful procedures and tools”. Well, that was half a decade ago, and to my great shame, nothing quite like that has happened so far. Reasons for this are obvious and probably the same for most of us: lack of time and energy to learn yet another set of commands, fear of the ever present risk of developing procedures that are eventually rejected as nonstandard use of the software and therefore error-prone (those of you working under quality assurance, raise your hand!), anxiety of working directly under the hood on real projects with little means to double check your results, to name a few.
That said, finally an opportunity presented itself, and before I knew it, I was up and running with APDL Math. The objective of this article is to showcase some simple yet insightful applications and hopefully remove the prevention one can have regarding using these additional capabilities.
For the sake of demonstration, I will begin with a somewhat uncommon analysis tool that should nevertheless ring a bell for most of you, that is: modal analysis (and yes, the pun is intended). You may wonder what is the purpose of using APDL Math to perform a task that is a standard ANSYS capability since say revision 2.0, 40 years ago? But wait, did I mention that by modal analysis, I mean thermal modal Analysis?
Thermal Modal Analysis at a Glance
Although scarcely used, thermal modal analysis is both an analysis and a design validation tool, mostly used in the field of precision engineering and or optomechanics. Specifically, it can serve a number of purposes such as:
Q: Will my system settle fast enough to fulfill design requirements?
A: Compute the system Thermal Time Constants
Q: Where should I place sensors to get information rich / robust measurements?
A: Compute Thermal modes and place your sensors away for large thermal gradients
Q: Can I develop a reduced model to solve large transient thermal mechanical problems?
A: Modal basis allows for the construction of such reduced problem effectively converting a high-order coupled system to a low order, uncoupled set of equations.
Q: How to develop a reduced order state-space matrices representation of my thermal system (equivalent to SPMWRITE command)?
A: Modal analysis provides every result needed to build those matrices directly within ANSYS.
Although you might only be vaguely familiar with many or all of those topics, the idea behind this article is really to show that APDL Math does exactly what you need it to do: allow the user to efficiently address specific needs, with a minimal amount of additional work. Minimal? Let’s see what it looks like in reality, and you will soon enough be in a position to make your own opinion on the matter.
Thermal Modal Analysis using APDL Math
To begin with, it is worth underlining the similarities and differences between structural (vibration) modes and thermal modes.
Mathematically, both look very much the same, i.e. modes are solutions of the dynamics equation in the absence of forcing (external) term:
[K] is the stiffness matrix
[K] is the conductivity matrix
Now, the fundamental difference is that the eigenvalues have completely different physical interpretations (This is a direct consequence of the fact that dynamical systems are 2nd order systems, whereas thermal systems a 1st order systems. While after being disturbed the former will oscillate around equilibrium position, the latter will return to its initial state via exponential decay. Mind you, there is no such thing as thermal resonances!) :
- Structural : λ=ω², i.e. the square of a circular frequency
- Thermal: λ=1/τ, i.e. the inverse of time constant
No big deal, right? Hence, the APDL Math code for Thermal Modal Analysis should be a straightforward adaption of the original. As it turns out, the modifications are quite small. Below is a table comparing input codes to perform both type of analyses, using APDL Math.
! Setup Model … ! Make ONE dummy transient solve ! to write stiffness and mass ! matrices to .FULL file /SOLU ANTYPE,TRANSIENT TIME,1 WRFULL,1 SOLVE ! Get Stiffness and Mass *SMAT,MatK,D,IMPORT,FULL,,STIFF *SMAT,MatM,D,IMPORT,FULL,,MASS ! Eigenvalue Extraction Antype,MODAL modopt,Lanb,NRM,0,Fmax *EIGEN,MatK,MatM,,EiV,MatPhi ! No need to convert eigenvalues ! to frequencies, ANSYS does ! it automatically ! Done !
! Setup Model … ! Make TWO dummy transient solve ! to separately write conductivity ! and capacitances matrices to .FULL file /SOLU ANTYPE,TRANSIENT TIME,1 NSUB,1,1,1 TINTP,,,,1 WRFULL,1 ! Zero out capacitance terms … SOLVE ! Get Conductivity Matrice *SMAT,MatK,D,IMPORT,FULL, Jobname.full,STIFF ! Restore capacitance and zero out ! conductivity terms … SOLVE ! Get Capacitance Matrice *SMAT,MatC,D,IMPORT,FULL,,STIFF ! Eigenvalue Extraction Antype,MODAL modopt,Lanb,NRM,,0,1/(2*PI*SQRT(Tmin)) *EIGEN,MatK,MatC,,EiV,MatPhi ! Convert Eigenvalues for Frequency ! to Thermal time Constants ! *do,i,1,EiV_rowDim Eiv(i)=1/(2*PI*Eiv(i))**2 *enddo ! Done !
The only data requested from the users is the number of requested modes (NRM) as well as the upper frequency (or for that matter, the shortest time constant of interest). Also, note that in the thermal case, one needs to perform two separate dummy analyses to store the conductivity and capacitance matrices, since internally those are merged into an equivalent stiffness (conductivity) matrix:
If you are familiar with APDL, some important differences are apparent here:
- Results from the eigenvalues are stored in a vector (EiV) and a matrix (MatPhi), which need not be declared but are created when executing the *EIGEN command (no *DIM required).
- For each APDL Math entity, ANSYS automatically maintains variables named Param_rowDim and Param_colDim, hence removing the burden to keep track of dimensions.
But where on Earth is my eye candy?
Now that we have some procedure and results, we would like to be able to show this to the outside world (and to be honest, some graphical results would also help getting confidence in results).
The additional task to do so is really minimal. What we need to do is simply to put back those numerical results into the ANSYS database so that we can use all the conventional post-processing capabilities. This can be made using the appropriate POST1 commands, essentially: DNSOL. And, while we are at it, why not do a hardcopy to an image file? Here is the corresponding input.
… User should place all nodes with non-prescribed temperatures in a component named MyNodeComponent … First, convert Eigenvectors from solver to BCS ordering ! Conversion needed *SMAT,Nod2Bcs,D,IMPORT,FULL,Jobname.full,NOD2BCS *MULT,Nod2Bcs,TRAN,MatPhi,,MatPhi ! Then, read in mapping vector to convert to user ordering *VEC,MapForward,I,IMPORT,FULL,Jobname.full,FORWARD ! Put the results in ANSYS database /POST1 *do,ind_mode,1,NRM cmsel,s,MyNodeComponent curr_node=0 *do,i,1,ndinqr(0,13) curr_node=ndnext(curr_node) curr_temp=MatPhi(MapForward(curr_node),ind_mode) dnsol,curr_node,TEMP,,curr_temp *enddo Tau=1/(2*3.14*EiV(ind_mode))**2 To=NINT(Tau*10)/10 ! compress to 1 digit after comma /title,Mode #%ind_mode% - Tau=%To%s plnsol,temp ! Hardcopy to BMP file /image,SAVE,JobName_Mode%ind_mode%,bmp *enddo
This way, modes can be displayed, or even written to a conventional .RTH file (using RAPPND), and used as any regular ANSYS solver result.
Nice, but an actual example wouldn’t hurt, would it?
Now you may wonder what the results look like in reality. To remain within the field of precision engineering, let’s use a support structure typically designed for high-stability positioning. From a structural point of view, it must have a high dynamic stiffness and a low total mass so that a Delta shaped bracket is appropriate. Since we want the system to rapidly evacuate any heat load, we choose aluminum as candidate material. We do know from first principles that any applied disturbance will exponentially vanish and the system will go back to equilibrium state. Now, what will be the time constants of this decay?
For the sake of simplicity we restrict the analysis to a highly simplified, 2D model of such a support. PLANE55 elements are used to model the structural part while the heat sink is accounted for using SURF151. Boundary conditions are enforced using an extra node.
After applying boundary conditions, we execute the modal solution to obtain say – the first 8 modes.
|Index||Time Constant [s]||Comment|
|1||535.9||Quasi-uniform temperature field (i.e. “rigid body” mode)|
|2||32.1||1st order (one wavelength along perimeter)|
|3||23.8||1st order (one wavelength along perimeter)|
|4||8.1||2nd order (two wavelengths along perimeter)|
|5||6.8||2nd order (two wavelengths along perimeter)|
|6||3.5||3rd order (three wavelengths along perimeter)|
|7||3.1||3rd order (three wavelengths along perimeter)|
|8||2.2||4th order (four wavelengths along perimeter)|
The output is strictly the same as the one a standard modal analysis, except for the two additional lines at the end of the solving sequence.
Allocate a  Vector : EIV Allocate a  Dense Matrix : MatPhi
Please note that the solution has 227 DOFs whereas the entire problem has 228 DOFs. This is the consequence of having introduced the boundary conditions as an enforced temperature on a node, which DOF is therefore removed from the DOF set to be obtained by the solver.
Also, we might want to use the modal shapes information to decide which locations are best suited to capture the entire temperature field on the structure. Without knowledge of the excitation source, one straightforward way to do so is to retain for each mode the node that has the largest amplitude. This is made even easier in this situation, since we have normalized each mode to have unit maximum amplitude we just need to select nodes having modal amplitude equal to 1 (or -1). On the figure below, each temperature sensor location is marked with a ‘TSm’ label where m is the mode index.
Doing so, we reach a pretty satisfactory distribution for the sensors locations, completely consistent with intuition. In numerical terms, we can also check that the modal matrix [Φ]_sensors, i.e. the original full matrix restricted to the selected DOF, has an excellent condition number. But there are many other things we could do starting from this. For example, with additional information, such as the location and the frequency content of the temperature fluctuations, one could further restrict the set of needed temperature sensors by running a dummy transient analysis and choosing locations where the correlation between sensors readings is as low as possible (using *MOPER,,,CORR). Even better, one can estimate the thermally induced displacements and select locations best suited to build an empirical model (typically using AR or ARMA), allowing one to predict structural displacements induced by temperature fluctuations using just a couple of sensors. This in turn can be used to select control strategies, check modal controllability… all within ANSYS.
APDL Math was presented as an alternate route for users who need to include specialized steps in an otherwise standard FE process, and in my opinion it does just that. The benefits can be immense and the learning curve is steep but short. As long as the user knows what he/she is doing, there is little possibility to get lost: after all, APDL Math only comprises 18 additional commands.
What hindered me so far was the necessity to account for internal, BCS and user ordering, but it really is not a big deal, as seen from the above example.
What is more, the possibility to store the created results in the Mechanical APDL database (DNSOL and RAPPND are your friends!) provides every means to control your results and finally to build confidence in your developments.
And for those of us who prefer to stay within Workbench environment, there is nothing preventing from including APDL Math procedures into Workbench command snippets.
This was just an introductory example, since many other applications could be found, to name a few just in the fields of precision engineering and/or opto-mechanics:
- Speed up transient thermal mechanical analyses
- Perform harmonic analysis of thermal models
- Virtual testing of physical setup, including real-time control systems (model based)
- Modal testing, error localization, automated model updating
Let us know your opinion on the matter, and if further introductory articles on APDL Math could be of use to the ANSYS users community.
By now you’ve probably heard that ANSYS versions 18.0, 18.1, and 18.2 have all been released in 2017. While 18.0 was the ‘point’ release in January, it should be noted that 18.1 and 18.2 are not ‘patches’ or service packs, but are full releases each with significant enhancements to the code. We’ll present some significant and useful enhancements for each.
Number 1: First and foremost – info on the new features is more readily accessible with the Mechanical Highlights list. The first time you launch Mechanical, you’ll see a hyperlinked list of new release highlights.
One you actually do something in Mechanical, though, that list goes away. There is a simple way to get it back: Click on the Project branch in the Mechanical tree, then click on the Worksheet button in the menu near the top of the window.
Clicking on the hyperlinks in the list or simply scrolling down gives us more information on each of the listed enhancements. Keep in mind the list is only highlights and by no means has all of the new features listed. A more detailed list can be found in the ANSYS Help, in the Release Notes.
Number 2: A major new feature that became available in 18.0 is Topology Optimization. We’ve written more about Topology Optimization here
Number 3: Another really useful enhancement in 18.0 is the ability to define a beam connection as a pretensioned bolt. This means we no longer need to have a geometry representation of a bolt if we want a simpler model. We can simply insert a beam connection between the two sides of the bolted geometry, and define the pretension on that resulting beam.
Beam connections are inserted in the Connections branch in Mechanical. Once the beam is fully defined, it can have a bolt pretension load applied to it, just like as if the beam geometry was defined as a solid or beam in your geometry tool. Here you can see a beam connection used for bolt pretension on the left, with a traditional geometric representation of a pretensioned bolt on the right:
Number 4: A very nice capability added in version 18.1 is drag and drop contact regions for contact sizing in the Mesh branch. Contact elements work best when the element sizes on both sizes of the interface are similar, especially for nonlinear contact. ANSYS Mechanical has had Contact Sizing available as a mesh control for a long time. Contact Sizing allows us to specify an element size or relevance level once, for both sides of one or more contact regions.
What’s new in 18.1 is the ability to drag and drop selected contacts from the Connections branch into the Mesh branch. Just select the desired contact regions with the mouse, then drag that selection into the Mesh branch. Then specify the desired mesh sizing controls for contact.
This is what the dragging and dropping looks like:
After dropping into the Mesh branch, we can specify the element size for the contact regions:
This shows the effect of the contact sizing specification on the mesh:
Number 5: An awesome new feature in 18.2 is element face selection, and what you can do with it. There is a new selection filter just for element face selection, shown here in the red box:
Once the element face select button is clicked, element faces can be individually selected, box selected, or paint selected simply by holding down the left mouse button and dragging. The green element faces on the near side have been selected this way:
The selected faces can then be converted to a Named Selection, or items such as results plots can be scoped to the face selection:
Number 6: Finally, to finish up, some new hotkeys were added in 18.2. Two really handy ones are:
- Z = zoom fit or zoom to the current selection of entities
- <Ctrl> K = activate element face selection
- F11 = make the graphics window full screen!
- Click F11 again to toggle back to normal size
Please realize that this list is just a tiny subset of the new features in ANSYS 18. We encourage you to try them out on your own, and investigate others that may be of benefit to you. Keep the Mechanical Highlights list from Number 1 in mind as a good source for info on new capabilities.
Yesterday ANSYS, Inc. did a webinar about a technology that was going to “Change the way simulation is done.” If you have been around the world of FEA and CFD for the 30+ years I have you have heard that statement before. And rarely does the actual product change match the hype. Not true for ANSYS Discovery Live. If anything, I think they are holding back. This is disruptive, this is a tool that will change how people do simulation. In this post I’ll share my thoughts on what it is and why I think it is so transformative, and then in the second half (go ahead, if you don’t want to listen to me go on and on about how much I like this tool, skip ahead) there are some tips on how to get your hands on it to see for yourself.
What is ANSYS Discovery Live?
ANSYS Discovery Live is a new multiple physics simulation platform that combines several key ingredients to produce a software tool that engineers can use to do almost instantaneous virtual prototypes of the behavior of their designs directly from their solid models. The developers at ANSYS, Inc. have combined their knowledge of advanced solver technology, making solvers parallel for Graphical Processor Units (GPUs, high-end graphics cards), direct solid modeling (SpaceClaim), and some advanced stuff on the discretization side I don’t think I can talk about. All of those things embedded inside SpaceClaim make ANSYS Discovery Live.
Once you have a solid model in the tool, you simply define what physics you want to solve and some boundary conditions, then it solves. In almost real time. Right there in front of you. The equivalent steps of meshing, building the model, solving it, extracting results, and displaying the results are done automatically. It may iterate a few times to converge on a solution, but in a few seconds, you will have a good enough answer to give you insight into your design.
And that is the key point. This is not a replacement for ANSYS Mechanical, FLUENT, or HFSS. It is a tool for exploring your designs and gaining insight into their behavior. It allows the design engineer, with very little training or expertise, to exercise their design and see what happens.
The product lives inside ANSYS Spaceclaim and can be installed on its own. It runs on Windows and requires a NVidia graphics card with a newer GPU (see below for more on that). Right now the product is in pre-release mode and anyone, yes anyone, can go to www.ansys.com/discovery and download it and try it out. And please, share your feedback. Expect the product to be released in the first quarter of 2018. Pricing and bundling have not been firmed up yet, but from what we have seen the plans are reasonable and make sense.
Why is it Unique in the Industry?
Some of the first comments I saw on social media about ANSYS Discovery Live after the webinar were that it is not a unique tool. There are other GPU based solvers out there. That is true. But even though those tools are super fast at solving, they have not been widely adopted. The ANSYS product is unique because it: 1) combines GPU based solvers for multiple physics and 2) is built into a fully functioning solid modeling tools. A third might be that it is also an ANSYS product, which means it will be backed technically and supported well.
Why I think that the Simple Fact that it Exists is Important?
During an interview for a magazine article about innovation in product development this week I was asked what is keeping innovation from happening more often. My answer was that most companies with the resources, both money and people, to innovate are choosing to acquire rather than innovate internally. They let others raise money, take all the risk, work out all the problems, deal with all the issues of trying to make something new. And then when they succeed, they buy them. There is nothing morally wrong with that approach, it is just inefficient and inaccurate. Every innovation has to not only survive its technical challenges, it has to survive being a startup.
What ANSYS, Inc. has done is the opposite. They could have purchased a GPU based solver startup and checked the box. But instead, they took people from different business units, several that were acquired, and put them together and said: “innovate… but make it something very useful.” And they did. The fact that they executed on the logistics of a new product that used new and old technology across physics and across software development realms, is fantastic. It makes me feel good about ANSYS, Inc’s true dedication to improving their products.
How will it Change Simulation?
In my career, I have had the same conversation dozens of times “Let me go out to the lab and tinker with it, I’ll figure out what is going on.” That is the way you had to explore your product to get a “feel” for what is going on. Simulation took too long and you became so wrapped up in the process of building and running a model that you could not really explore the behavior of your product. Now we can.
ANSYS Discovery Live is called Discovery Live not because anyone at ANSYS is a marketing genius (sorry guys…) but because that is what it lets you do. Discover the behavior of your product live. You simply play with it and see what happens. And this will change simulation because we know can move from verification or optimization to simply experimenting and gaining a deeper understanding, early in the design process. We will still do what is now I guess called traditional simulation. We will need more accuracy, more complex physics, loads, and behavior. But early on we can learn so much by virtually experimenting.
Is it the Perfect Tool Right out of the Box?
This is not a perfect-does-everything tool. First off, it is a pre-release. The basic functionality to make it useful is there. More than I thought would be available in a first release. But there are limitations because it is new, or because of the approach. It is not as accurate as more traditional approaches. The way it works takes some shortcuts on geometry and can’t include some behaviors. This should improve over time but it will never be accurate as more time-consuming approaches that simply have more functionality.
Over the next two to three years we will see it mature and add functionality and accuracy. The GPU’s the tool depends on will offer more performance for less money as well. This is a journey, but right now everyone I have talked to who has actually played with the pre-release is very happy with the functionality and accuracy that is there now. Because it is sufficient to do the experimentation and exploration it was designed to allow.
ANSYS, Inc. realized that this type of tool demos so well, and is so different, that a skeptical group of engineers will not accept what they see in a webinar as accurate. So they have made the pre-release available for use. You can download it and install it, or explore with it in the cloud through your browser.
- To get started, go to www.ansys.com/discovery and look around. The videos are awesome! When you are ready to try it out, click on Download Now. Fill out the form. Don’t complain. Yes you will get a few emails and a salesperson (gasp!) may call you. It’s worth some emails and maybe a phone call.
- Set yourself up there. There is a verification code step and once you put that in and create your login, you have to click on some legal agreements, including export controls. Save your login info, you will need it to get back in.
- After that either start the download or the Cloud Trial Option. The cloud trial didn’t work for me, read below how I got to that function.
- If you chose download it will download a big Zip File, over 1 GB. It is a full solid modeler and CFD/Structural/Thermal solver… so it is big.
- Once it is there, unzip, and run Setup.exe. follow the steps and you will be there.
- If you don’t have a graphics card that will run this, then use the cloud demo. Like I said above, the button didn’t work for me. If you have that problem or you want to use it after your first login, go to:
- https://discoveryforum.ansys.com/ and click on “Getting Started.”
- Scroll down a bit and find the “Cloud Trial” post. That one takes you to the page where you can find a server near you to try things out on. It’s pretty slick.
- If you need to get back here, use https://discoveryforum.ansys.com/ and log in with the email and password you gave at registration,
The only sticky bit about this whole thing is that it run a subset of Nvidia graphics cards. So you have to have one of those cards. According to the information in the forum:
ANSYS Discovery Live relies on the latest GPU technology to provide its computation and visual experience. To run the software, you will require:
– A dedicated NVIDIA GPU card based on the Kepler, Maxwell or Pascal architecture. Most dedicated NVIDIA GPU cards produced in 2013 or later will be based on one of these architectures.
– At least 4GB of video RAM (8GB preferred) on the GPU.
Also, please ensure you have the latest driver for your graphics card, available from NVIDIA Driver Downloads. You can also refer to the post on Graphics Performance Benchmarks. Performance of Discovery Live is less dependent on machine CPU and RAM. A recent generation 64-bit CPU running Windows, and at least 4GB of RAM will be sufficient. If you do not have a graphics card that meets these specifications, the software will not run. However, you can try ANSYS Discovery Live through an online cloud-based trial, which requires only an internet browser and a reasonably fast internet connection.
I didn’t know if my GPU on my laptop would work, so I went to https://www.techpowerup.com and put in my card model (nvidia m500m) and it told me it was Maxwell technology.
Go Forth and Discover, and Share
Don’t hesitate, download this and try it out. Even if you are a high-end combustion simulation expert that will never need it, if you are interested in Simulation you should still try it out. Use the forum to share your thoughts and questions. The gallery is already filling up with some fantastic real world examples.
So this is just a quick post to point out a handy feature in ANSYS Workbench, the ACT Console. There are times when you want some functionality in Mechanical that just is not yet there. In this example, a customer wanted the ability to get a text list of all the Named Selections in his model. A quick Python script does just that.
So to use a piece of Python code, like this, we use the ACT Console in Mechanical. To access the ACT Console in Mechanical 17.0, or later, just hit this icon in the toolbar.
The Console allows you to type, or paste, text directly into the black command line at the bottom. But if we are going to reuse this code, then the use of Snippets is the way to go. In R17.0 they were called ‘Bookmarks’, but they worked the same way.
When you add a Snippet, a new window allows you to name the snippet and type in, or paste in, your code.
When you hit Apply, your named snippet is added to the list
From then on, to use the snippet you just click on it, and hit ‘Enter’. The text is basically, repasted into the command window, so you can set any variables needed prior to hitting your snippet.
The snippets are persistent and remain in the console, so they are available for all new projects. Using snippets is a great way to reduce time for repetitive tasks, without having to create a full blown ACT extension.
Here in the Phoenix area, we weren’t treated to the full total eclipse that others in the USA got to see. Our maximum coverage of the sun was a bit over 60%. Still, there was an eclipse buzz in the PADT headquarters and although we had some rare clouds for a few minutes, the skies did part and we did get to view the partial eclipse from the parking lot.
So, how did ANSYS help us view the eclipse? It was in an indirect way – via a pinhole camera I made from an old ANSYS installation software box. The software box, a hobby knife to cut out a viewing port, a couple of post-it notes to allow for a small hole and a clear projection area, and a thumb tack were all that was needed, along with a couple of minutes to modify the box.
Here we can see the viewing port cut into the software box. On the opposite side is a pin hole to allow the sun’s light to enter the box.
After heading out to the eclipsing grounds (the parking lot), we quickly lined up the pin hole and the projection screen and got our views of the partially obscured sun:
Here is a close up of the sun’s image projected inside the box:
Others viewing the eclipse here at PADT HQ had a range of filters, eclipse glasses, etc. With the projection method as shown above, though, we don’t have to worry about eye damage. So, in a way, ANSYS did help us view the eclipse safely, by providing a box that was easy to convert to a pinhole camera.
While we enjoyed the partial eclipse here in Arizona, we did have a couple of PADT colleagues in the path of totality. Here is a picture from one of my coworkers who viewed the eclipse in South Carolina:
We hope you enjoyed the eclipse as well, either in person or via images on the web. We’re looking forward to the next one!
Finally, In case you missed an earlier astronomical rarity back in 2012, here is a photo of the planet Venus transiting in front of the sun’s disk (black dot on the left side). The next one of these won’t be until December, 2117.
We’ve discussed topological optimization in this space before, notably here:
If you’re not familiar with topological or topology optimization, a simple description is that we are using the physics of the problem combined with the finite element computational method to decide what the optimal shape is for a given design space and set of loads and constraints. Typically our goal is to maximize stiffness while reducing weight. We may also be trying to keep maximum stress below a certain value. Frequencies can come into play as well by linking a modal analysis to a topology optimization.
Why is topology optimization important? First, it produces shapes which may be more optimal than we could determine by engineering intuition coupled with trial and error. Second, with the rise of additive manufacturing, it is now much easier and more practical to produce the often complex and organic looking shapes which come out of a topological optimization.
ANSYS, Inc. has really upped the game when it comes to utilizing topology optimization. Starting with version 18.0, topo opt is built in functionality within ANSYS. If you already know ANSYS Mechanical, you already know the tool that’s used. The ANSYS capability uses the proven ANSYS solvers, including HPC capability for efficient solves. Another huge plus is the fact that SpaceClaim is linked right in to the process, allowing us to much more easily make the optimized mesh shape produced by a topological optimization into a more CAD representation set for use in validation simulations, 3D printing, or traditional manufacturing.
The intent of this blog is to show the current process in ANSYS version 18.1 using a simple example of an idealized motorcycle front fork bracket optimization. We don’t claim to be experts on motorcycle design, but we do want to showcase what the technology can do with a simple example. We start with a ‘blob’ or envelope for the geometry of our design space, then perform an optimization based on an assumed set of loads the system will experience. Next we convert the optimized mesh information into solid geometry using ANSYS SpaceClaim, and then perform a validation study on the optimized geometry.
Here we show our starting point – an idealized motorcycle fork with a fairly large blob of geometry. The intent is to let ANSYS come up with an optimal shape for the bracket connecting the two sides of the fork.
The first step of the simulation in this case is a traditional Static Structural simulation within ANSYS Workbench. The starting point for the geometry was ANSYS SpaceClaim, but the initial geometry could have come from any geometry source that ANSYS can read in, meaning most CAD systems as well as Parasolid, SAT, and STEP neutral file formats.
A single set of loads can be used, or multiple load cases can be defined. That’s what we did here, to simulate various sets of loads that the fork assembly might experience during optimization. All or a portion of the load cases can be utilized in the topological optimization, and weighting factors can be used on each set of loads if needed.
Here we see the workflow in the ANSYS Workbench Project Schematic:
Block A is the standard static structural analysis on the original, starting geometry. This includes all load cases needed to describe the operating environment. Block B is the actual topological optimization. Block C is a validation study, performed on the optimized geometry. This step is needed to ensure that the optimized shape still meets our design intent.
Within the topology optimization, we set our objective. He we choose minimizing compliance, which is a standard terminology in topology optimization and we can think of it as the inverse which is maximizing stiffness.
In the static structural analysis, 7 load cases were used to describe different loading situations on the motorcycle fork, and here all have been used in the optimization.
Further, we defined a response constraint, which in this example is to reduce mass (actually retain 15% of the mass):
Another quantity that’s often useful to specify is a minimum member constraint. That will keep the topology optimization from making regions that are too small to 3D print or otherwise manufacture. Here we have specified a minimum member size of 0.3 inches:
Since the topological optimization solution uses the same ANSYS solvers for the finite element solution as a normal solution, we can leverage high performance computing (distributed solvers, typically) to speed up the solution process. Multiple iterations are needed to converge on the topology optimization, so realize that the topo opt process is going to be more computationally expensive than a normal solution.
Once the optimization is complete, we can view the shape the topo opt method has obtained:
Notice that only a portion of the original model has been affected. ANSYS allows us to specify which regions of the model are to be considered for optimization, and which are to be excluded.
Now that we have a shape that looks promising, we still need to perform a validation step, in which we rerun our static simulation with the loads and constraints we expect the fork assembly to experience. To do that, we really want a ‘CAD’ model of the optimized shape. The images shown above show the mesh information that results from the topo opt solution. What we need to do next is leverage the ANSYS SpaceClaim geometry tool to create a solid model from the optimized shape.
A simple beauty in the ANSYS process is that with just a couple of clicks we proceed from Block B to Block C in the Workbench project schematic, and can then work with the optimized shape in SpaceClaim.
As you can see in the above image, SpaceClaim automatically has the original geometry as well as the new, optimized shape. We can do as much or as little to the optimized shape as we need, from smoothing and simplification to adding manufacturing features such as holes, bosses, etc. In this case we simply shrink wrapped it as-is.
Continuing with the validation step, the geometry from SpaceClaim automatically opens in the Mechanical window and we can then re-apply the needed loads and constraints and then solve to determine if the optimized shape truly meets our design objectives. If not, we can make some tweaks and run again.
The above image shows a result plot from the validation step. The geometry efficiently comes through SpaceClaim from the optimization step to the validation step. The needed tools are all nicely contained within ANSYS.
Hopefully this has given you an idea of what can be done with topology optimization in ANSYS as well as how it’s done. Again, if you already know ANSYS Mechanical, you already know the bulk of how to do this. If not, then perhaps what you have seen here will spark a craving to learn. We can’t wait to see what you create.
I recently had a chance to run a series of benchmarks on one of our latest CUBE numerical simulation workstations. I was amazed by the impressive benchmark numbers and wanted to share with you the details for the SP-5 benchmark using ANSYS 18.1. Hopefully this information will help you make the best decision the next time you need to upgrade your numerical simulation C Drive from whatever to now is the time to buy a Non-Volitile Memory Express drive. Total speedup using identical CUBE hardware, except for the INTEL DC P3700 NVMe drive @32 Cores is a 1.19x speedup!
- Time Spent Computing Solution ANSYS SP-5 Benchmark
- 161.7 seconds vs. 135.6 second
- ANSYS 17.1 & ANSYS 18.1 Benchmarks
The link below is to a great article that I think will catch you up to speed regarding NVMe, PCIe and SSD Technology.
HDD Magazine hints NVME is coming, I say NVMe is already here…
CUBE w32iP Specifications (July 2017)
- CUBE Mid-Tower Super Quiet Chassis (900W PS)
- CPU: 32 INTEL Cores – 2 x INTEL e5-2697A V4 firstname.lastname@example.orgGHz/3.6GHz Turbo
- OS: INTEL NVMe – 1 x 1.6TB INTEL Enterprise Class SSD
- Mid-Term Storage: – 1 x 10TB Enterprise Class SATA 6Gbp/s, 256M, Helium sealed
- RAM: 256GB DDR4-2400MHz LRDIMM RAM
- GRAPHICS: NVIDIA QUADRO P6000 (24GB GDDR5X RAM)
- MEDIA: DVD-RW/Audio 7.1 HD
- Windows 10 Professional
Just how much faster the INTEL NVME drive performs over previously run ANSYS Benchmarks?
Check out the data for yourself:
- ANSYS Benchmark Test Case Information.
- ANSYS HPC Licensing Packs required for this benchmark
- I used (2) HPC Packs to unlock all 32 cores.
- 1.19x Total Speedup!
- Please contact your local ANSYS Software Sales Representative for more information on purchasing ANSYS HPC Packs. You too may be able to speed up your solve times by unlocking additional compute power!
- What is a CUBE? For more information regarding our Numerical Simulation workstations and clusters please contact our CUBE Hardware Sales Representative at SALES@PADTINC.COM
- Designed, tested and configured within your budget. We are happy to help and to listen to your specific needs.
ANSYS SP-5 Benchmark Details
|Analysis Type||Static Nonlinear Structural|
|Number of Degrees of Freedom||6,000,000|
|July 2017||TIME SPENT COMPUTING SOLUTION||TOTAL CPU TIME FOR MAIN THREAD||ELAPSED TIME|
|CUBE w32iP||CUEB w32iP||CUBE w32iP|
|# of Cores||CUBE w32iP||CUBE w32iP||CUBE w32iP|
|WO/GPU Acceleration||WO/GPU Acceleration||WO/GPU Acceleration
July 2017, drjm, PADT, Inc.
CUBE W32iP SP-5 Benchmark Graph
Click Here for more information on the engineering simulation workstations and clusters designed in-house at PADT, Inc.. PADT, Inc. is happy to be a premier re-seller and dealer of Supermicro hardware.
PADT recently hosted the Aerospace & Defence Form, Arizona Chapter for a talk and a tour. The talk was on “Additive Manufacturing & Simulation Driven Design, A Competitive Edge in Aerospace” and it was very well received. So well in fact, that we decided it would be good to go ahead and record it and share it. So here it is:
Aerospace engineering has changed in the past decades and the tools and process that are used need to change as well. In this presentation we talk about how Simulation and 3D Printing can be used across the product development process to gain a competitive advantage. In this webinar PADT shares our experience in apply both critical technologies to aerospace. We talk about what has changed in the industry and why Simulation and Additive Manufacturing are so important to meeting the new challenges. We then go through five trends in each industry and keys to being successful with each trend.
If you are looking to implement 3D Printing (Additive Manufacturing) or any type of simulation for Aerospace, please contact us (email@example.com) so we can work to understand your needs and help you find the right solutions.
This video will show you how you can set up a two-way connection between Solidworks and ANSYS HFSS so you can modify dimensions as you are iterating through designs from within HFSS itself. This prevents the need for creating several different CAD model iterations within Solidworks and allows a more seamless workflow. Note that this process also works for the other ANSYS Electromagnetic tools such as ANSYS Maxwell.
Importing solid 3D Mechanical CAD (or MCAD) models into ANSYS HFSS has always been and remains to be a fairly simple process. After opening ANSYS Electronics Desktop and creating an HFSS design, from the menu bar, select Modeler > Import. A dialog box will open to navigate to and directly open the model.
The CAD will automatically be translated and loaded into the HFSS 3D Modeler. If the geometry is correct and does not require any editing, the import process is complete and analysis can begin! However, if there are any errors with the geometry, there is excessive or invalid detail, or if it’s not organized into separate bodies conducive for electromagnetic analysis, you may soon realize that the editing capability is limited to scaling, reorienting, or Boolean operations. This approach can be particularly troublesome when portions of the model (or all of the model) which consist of different materials are not split into different objects. For example, notice the outer conductor, inner conductor, and dielectric of the imported SMA below are all one solid object.
Unless you’re lucky enough to work with the creator of the CAD, you will need to find a way to split this model into the inner and outer conductors, and the dielectric. However, since the release of ANSYS R18.1, the power of SpaceClaim Direct Modeler (SCDM) and the MCAD translator will be packaged together. The good news is, the process described above will continue to work. The better news is, SCDM offers new capabilities to directly edit or clean imported geometry. So, here are a few simple steps to quickly split this SMA connector using SCDM. You can download a copy of this model here to follow along. If you need access to SCDM, you can contact us at firstname.lastname@example.org. It’s worth noting, at this point, that the processes discussed throughout this article work the same for HFSS-IE, Q3D, and Maxwell designs as well.
 First, after opening ANSYS SpaceClaim, the step file can be imported through the menu File > Open or by simply dragging and dropping the file into the SCDM window.  To separate the dielectric from the outer conductor, select Design > Intersect > Split Body.  Click and hold the center mouse button to rotate the model so the boundary between the dielectric and outer conductor is visible. Hold the Ctrl key and click the center mouse button to pan, and use the center mouse scroll to zoom in and out. Finally, press ‘z’ on the keyboard to fit the view window.  When positioned, click on the object to split (in this case it is the entire model).  Then, click on the face which defines the boundary between the dielectric and outer conductor.  Finally, press the Esc key. The first split is done!
Repeat the Split Body process to separate the center conductor from the dielectric. Notice under the structure tree that there are now three separate objects.
The split body function is also useful to simplify a structure for analysis. For example, the female side of the SMA could be simplified as a solid center conductor.  Reposition the connector to view the female side. - Control the visibility of each body with the object’s checkbox in the structure tree.  Measure the length of the female side by pressing the letter ‘e’ on the keyboard and selecting the top edge (note the line length of 2.95mm for later).  Then, repeat the Split Body process to split the center conductor at the boundary between the male and female sides. - However, rather than pressing the Esc key, click on the female receiver to automatically remove the body.
 To extend the center pin to its original length, select Design > Edit > Pull.  Click on the face where the female side was originally attached and select the Up To option.  Type in the previously measured length of 2.95mm.  Finally, press Enter (press Esc 3x to exit the Pull command).
Repeat the Split Body and Pull processes until the model has been divided into different bodies for each material type and is sufficiently simplified.
Once the model is ready, select File > Save As to save the geometry as the preferred format. Perhaps the most familiar approach to HFSS users would be to save the new model as a STEP file, then to import the model into HFSS as described in the first paragraph.
One of the tough challenges in creating meshes for CFD simulations is the requirement to create a mesh that works with very different geometry. With Overset meshing you can create the ideal mesh for each piece of geometry in your model, and let them overlap where they touch and the program handles the calculations at those boundaries. All of this is handled simply in the ANSYS Workbench interface and then combined in ANSYS FLUENT.PADT-ANSYS-Fluent-Overset-Meshing-2017_07_05-1
One of the more common questions we get on thermal expansion simulations in tech support for ANSYS Mechanical and ANSYS Mechanical APDL revolve around how the Coefficient of Thermal Expansion, or CTE. This comes in to play if the CTE of the material you are modeling is set up to change with the temperature of that material.
This detailed presentation goes in to explaining what the differences are between the Secant and Instantaneous methods, how to convert between them, and dealing with extrapolating coeficients beyond temperatures for which you have data.PADT-ANSYS-Secant_vs_Instantaneous_CTE-2017_07_05
You can download a PDF of the presentation here.
The PADT sales and support team focused on simulation solutions is best known for our work with the full ANSYS product suite. What a lot of people don’t know is that we also represent a fantastic simulation tool called Flownex. Flownex is a system level 1-D program that is designed from the ground up to model thermal-fluid systems.
What does Flownex Do?
Flownex Simulation Environment is an interactive software program that allows users to model systems to understand how fluids (gas and/or liquid) flow and how heat is transferred in that same system due to that flow. the way it works is you create a network of components that are connected together as a system. The heat and fluid transfer within and between each node is calculated over time, giving a very accurate, and fast, representation of the system’s behavior.
As a system simulation tool, it is fast, it is easy to build and change, and it runs in real time or even faster. This allows users to drive the design of their entire system through simulation.
Need to know what size pump you need, use Flownex. Want to know if you heat exchanger is exchanging enough heat for every situation, use Flownex. Tasked with making sure your nuclear reactor will stay cool in all operating conditions, use Flownex. Making sure you have optimized the performance of your combustion nozzles, use Flownex. Time to design your turbine engine cooling network, use Flownex. Required to verify that your mine ventilation and fire suppression system will work, use Flownex. The applications go on and on.
Why is Flownex so Much Better than other System Thermal-Fluid Modeling Solutions?
There are a lot of solutions for modeling thermal-fluid systems. We have found that the vast majority of companies use simple spreadsheets or home-grown tools. There are also a lot of commercial solutions out there. Flownex stands out for five key reasons:
- Breadth and depth of capability
Flownex boasts components, the objects you link together in your network, that spread across physics and applications. Whereas most tools will focus on one industry, Flownex is a general purpose tool that supports far more situations. For depth they have taken the time over the years to not just have simple models. Each component has sophisticated equations that govern its behavior and user defined parameters that allow for very accurate modeling.
- Developed by hard core users
Flownex started life as an internal code to support consulting engineers. Experienced engineering software programmers worked with those consultants day-in and day-out to develop the tools that were needed to solve real world problems. This is the reason why when users ask “What I really need to do to solve my problem is such-and-such, can Flownex do that?” we can usually answer “Yes, and here are the options to make it even more accurate.”
- Customization and Integration
As powerful and in-depth as Flownex is, there is no way to capture every situation for every user. Nor does the program do everything. That is why it is so open and so easy to customize and integrate. As an example, may customers have very specific thermal-pressure-velocity models that they use for their specific components. Models that they developed after years if not decades of testing. Not a problem, that behavior can be easily added to Flownex. If a customer even has their own software or a 3rd party tool they need to use, it is pretty easy to integrate it right into your Flownex system model.Very common tools are already integrated. The most common connection is Matlab/Simulink. At PADT we often connect Excel models from customers into our Systems for consulting. It is also integrated into ANSYS Mechanical.
- Nuclear Quality Standards
Flownex came in to its own as a tool used to model the fluid system in and around Nuclear Reactors. So it had to meet very rigorous quality standards, if not the most stringent they are pretty close. This forced to tool to be very robust, accurate, and well documented. And the rest of us can take advantage of that intense quality requirement to meet and exceed the needs of pretty much every industry. We can tell you after using it for our own consulting projects and after talking to other users, this code is solid.
- Ease of Use
Some people will read the advantages above and think that this is fantastic, but that much capability and flexibility must make it difficult to use. Nothing could be further from the truth. Maybe its because the most demanding users are down the hallway and can come and harangue the developers. Or it could be that their initial development goal of keeping ease of use without giving up on functionality was actually followed. Regardless of why, this simulation tool is amazingly simple and intuitive. From building the model to reviewing results to customization, everything is easy to learn, remember, and user. To be honest, it is actually fun to use. Not something a lot of simulation engineers say.
Why does buying and getting support from PADT for Flownex make a Difference?
The answer to this question is fairly simple: PADT’ simulation team is made up of very experienced users who have to apply this technology to our own internal projects as well as to consulting jobs. We know this tool and we also work closely with the developers at Flownex. As with our ANSYS products, we don’t just work on knowing how to use the tool, we put time in to understand the theory behind everything as well as the practical real world industry application.
When you call for support, odds are the engineer who answers is actually suing Flownex on a customer’s system. We also have the infrastructure and size in place to make sure we have the resources to provide that support. Investing in a new simulation tool can generate needs for training, customization, and integration; not to mention traditional technical support. PADT partners with our customers to make sure they get the greatest value form their simulation software investment.
Reach out to Give it a Try or Learn More
Our team is ready and waiting to answer your questihttp://www.flownex.com/flownex-demoons or provide you with a demonstration of this fantastic tool. . You can email us at email@example.com or give us a call at 480.813.4884 or 1-800-293-PADT.
Still want to learn more? Here are some links to more information:
- Check out our Flownex page.
- The Flownex website if full of great info.
- This video is a great introduction that gives you a feel of how powerful and intuitive it is.
- Check out the Flownex SE video page on YouTube. It has examples for many different industries where you can get a feel for the power and ease-of-use.
- The Flownex FAQ is fantastic. All those questions you have about “Can Flownex do this?” are there… along with some application specific questions they get a lot.
- Sign up for a demo.
- Contact us at firstname.lastname@example.org or Flownex at email@example.com
Sometimes everything happens at once. This June 22nd was one of those days. Three key events were scheduled for the same time in three different states and we needed to be at all of them. So everyone stepped up and pulled it off, and hopefully some of you reading this were at one of these fantastic events. Combined they are a great example of PADT’s commitment to the local technology ecosystem, showing how we create true win-win partnerships across organizations and geographies. Since the beginning we wanted to be more than just a re-seller or just consultants, and this Thursday was a chance to show our commitment to doing just that.
Albuquerque: New Mexico Technology Council 3D Printing Peer Group Kickoff
Everyone talks about how they thing we should all work together, but there never seems to be someone who is willing to pull it all together. That is how the additive manufacturing committee in New Mexico was until the New Mexico Technology Council (NMTC) stepped up to host a peer group around 3D Printing. Even though it was a record 103f in Albuquerque, 35 brave 3D Printing enthusiasts ventured out into the heat and joined us at Rio Bravo Brewing to get the ball rolling on creating a cooperative community. We started with an introduction from NMTC, followed by an overview of what we want to achieve with the group. Our goals are:
- Create stronger cooperation between companies, schools, and individuals involved in 3D Printing in New Mexico
- Foster cooperation between organizations to increase the benefits of 3D Printing to New Mexico
- Make a contribution to New Mexico STEM education in the area of 3D Printing
To make this happen we will meet once a quarter, be guided by a steering committee, and grow our broad membership. Anyone with any involvement in Additive Manufacturing in the state is welcome to join in person or just be part of the on-line discussion.
Then came the best part, where we went around the room and shared our names, orginization, and what we did in the world of 3D Printing. What a fantastic group. From a K-12 educator to key researchers at the labs, we had every industry and interest representing. What a great start.
Here are the slides from that part of the presentation:NMTC-PADT-3D-Printing-Peer-Group-2017_06_22
Once that was done PADT’s Rey Chu gave a presentation where it went over the most important developments in Additive Manufacturing over the last year or so. He talked about the three new technologies that are making an impact, new materials, and what is happening business wise. Check out his slides to learn more:NMTC-PADT-New-3D-Printing-2017_06_22
After a question and answer period we had some great conversations in small groups, which was the most valuable part.
If you want to learn more, please reach out to firstname.lastname@example.org and we will add you to the email list where we will plan and execute future activities. We are also looking for people to be on the steering committee and locations for our next couple of meetings. Share this with as many people as you can in New Mexico so that next event can be even better!
Denver: MSU Advance Manufacturing & Engineering Sciences Building Opening
Meanwhile, in Denver it was raining. In spite of that, supporters of educating the next generation of manufacturers and engineers gathered for the opening of the Advanced Manufacturing and Engineering Sciences Building at Metropolitan State University. This 142,000 sqft multi-disciplinary facility is located in the heart of downtown Denver and will house classes, labs, and local companies. PADT was there to not only celebrate the whole facility, but we were especially excited about the new 3D Printing lab that is being funded by a $1 million gift from Lockheed Martin. A nice new Stratasys Fortus 900 is the centerpiece of the facility. It will be a while before the lab itself is done, so watch for an invite to the grand opening. While we wait we are working with MSU, Lockheed Martin, Stratasys, and others to put a plan together to develop the curriculum for future classes and making sure that the engineers needed for this technology are available for the expected explosion of use of this technology.
Stratasys and PADT are proud to be partners of this fantastic effort along with many key companies in Colorado. If you want to learn more about how we can help you build partnerships between industry and academia, please reach out to email@example.com or give us a call.
Phoenix: 2017 Aerospace, Aviation, Defense + Manufacturing Conference
The 113f high in Phoenix really didn’t stop anyone from coming to the AADM conference. This annual event was at ASU SkySong in Phoenix and is sponsored by the AZ Tech Council, AZ Commerce Authority, and RevAZ. PADT was proud to not only be a sponsor, but also have a booth, participate in the advanced manufacturing panel discussion, and do a short partner presentation about what we do for our Aerospace and Defense Customers.
Here is Rob’s presentation on PADT:PADT-AeroConf-AZTC-2017
We had great conversations at our booth with existing customers, partners, and a few people that were new to us. This is always one of the best events of the summer, and we look forward to next year.
If you want to know more about how PADT can help you in your Aerospace, Defense, and Manufacturing efforts, reach out and contact us.