Updates & Additions in ANSYS Mechanical 2019 R3 – Webinar

With ANSYS structural analysis software, users are able to solve more complex engineering problems, faster and more efficiently than ever before. Customization and automation of structural solutions is much easier to optimize thanks to new and innovative finite element analysis (FEA) tools available in this product suite. 

From designers and occasional users looking for quick, easy and accurate results, to experts looking to model complex materials, large assemblies and nonlinear behavior, ANSYS has you covered. The intuitive interface of ANSYS Mechanical enables engineers of all levels to get answers fast and with confidence.

Join PADT’s Specialist Mechanical Engineer Joe Woodward, for an in-depth look at what’s new in the latest version of ANSYS Mechanical, including updates regarding:

  • Software User Interface
  • Design Elements
  • Composites
  • Acoustics
  • External Modeling
  • And much more

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New Options for 3D Printing with Nylon Filament, Including Diran

NOTE 10/28/2019: See updated information regarding Diran extruder heads, below.

Does the idea of 3D printing parts in semi-aromatic polyamides (PA) sound intriguing? Too bad it has nothing to do with making nicely scented models – but it has everything to do with reaping the benefits of the Nylon family’s molecular ring structure. Nylon 6, Nylon 12, carbon-filled Nylon 12 and now a new, smoother Nylon material called Diran each offer material properties well-suited for additive manufacturing on industrial 3D printers. Have you tried Holden’s Screen Supply? It has the emulsions and reclaimers needed for screen printing. To get more information about 3D printers, Go through PrtWd.com website.

Stratasys Nylon 12 Battery Box
3D printed Nylon 12 Battery Box. (Image courtesy Stratasys)

Quick chemistry lesson: in polyamides, amine sub-groups containing nitrogen link up with carbon, oxygen and hydrogen in a ring structure; most end up with a strongly connected, semi-crystalline layout that is key to their desirable behaviors. The number of carbon atoms per molecule is one way in which various Nylons (poly-amines) differentiate themselves, and gives rise to the naming process.

Now on to the good stuff. PA thermoplastics are known for strength, abrasion-resistance and chemical stability – useful material properties that have been exploited since Nylon’s discovery at Du Pont in 1935. The first commercial Nylon application came in 1938, when Dr. West’s Miracle Tuft Toothbrush closed the book on boar’s-hair bristle use and let humans gently brush their teeth with Nylon 6 (then called “Exton”) fibers.

Today’s Nylon characteristics translate well to filament-form for printing with Stratasys Fused Deposition Modeling (FDM) production-grade systems. Here’s a look at properties and typical applications for Nylon 6, Nylon 12, Nylon 12 CF (carbon-fiber filled) and Diran (the newest in the Stratasys Nylon material family), as we see their use here at PADT.

When Flexibility Counts

Nylon 12 became the first Stratasys PA offering, filling a need for customized parts with high fatigue resistance, strong chemical resistance, and just enough “give” to support press (friction-fit) inserts and repetitive snap-fit closures. Users in aerospace, automotive and consumer-goods industries print Nylon 12 parts for everything from tooling, jigs and fixtures to container covers, side-panels and high vibration-load components.

3D Printed Nylon 12 bending example. (Image courtesy Stratasys)
3D Printed Nylon 12 bending example. (Image courtesy Stratasys)

Nylon 12 is the workhorse of the manufacturing world, supporting distortion without breaking and demonstrating a high elongation at break. Its ultimate tensile strength in XZ part orientation (the strongest orientation) is 6,650 psi (46 MPa), while elongation at break is 30 percent. Users can load Nylon 12 filament onto a Stratasys Fortus 380mc CF, 450mc or 900mc system.

As evidenced by the toothbrush renaissance, Nylon 6 has been a popular thermoplastic for more than 80 years. Combining very high strength with toughness, Nylon 6 is great for snap-fit parts (middle range of flexing/stiffness) and for impact resistance; it is commonly used for things that need to be assembled, offering a clean surface finish for part mating.

Nylon 6 displays an XZ ultimate tensile strength of 9,800 psi (67.6 MPa) and elongation at break of 38%; it is available on the F900 printer. PADT customer MTD Southwest has recently used Nylon 6 to prototype durable containers with highly curved geometries, for testing with gasoline/ethanol blends that would destroy most other plastics.

Prototype gas-tank made of Nylon 6, printed on a Stratasys system, using soluble support. (Image courtesy MTD Southwest)
Prototype gas-tank made of Nylon 6, printed on a Stratasys system, using soluble support. (Image courtesy MTD Southwest)

Both Nylon 12 and Nylon 6 come as black filament that prints in tandem with a soluble brown support material called SR-110. Soluble supports make a huge difference in allowing parts with internal structures and complicated overhangs to be easily 3D printed and post-processed.

Getting Stronger and Smoother

As with these first two PA versions, Nylon 12CF prints as a black filament and uses SR-110 soluble material for support; unlike those PAs, Nylon 12CF is loaded at 35 percent by weight with chopped carbon fibers averaging 150 microns in length. This fiber/resin combination produces a material with the highest flexural strength of all the FDM Nylons, as well as the highest stiffness-to-weight ratio.

Nylon 12 CF (carbon-filled) 3D printed part, designed as a test brake unit. (Image courtesy Stratasys)
Nylon 12 CF (carbon-fiber filled) 3D printed part, designed as a test brake unit. (Image courtesy Stratasys)

That strength shows up in Nylon 12 CF as a high ultimate XZ tensile strength of 10,960 psi (75.6 MPa), however, similar to other fiber-reinforced materials, the elongation at break is lower than for its unfilled counterpart (1.9 percent). Since the material doesn’t yield, just snaps, the compressive strength is given as the ultimate value, at 9,670 psi (67 MPa).

Nylon 12 CF’s strength and stiffness make it a great choice for lightweight fixtures. It also offers electrostatic discharge (ESD) protection properties better than that of Stratasys’ ABS ESD7, yet is still not quite conductive, if that is important for the part’s end-use. (For more details on printing with Nylon 12 CF, see Seven Tips for 3D Printing with Nylon 12 CF.) The material runs on the Fortus 380mc CF, 450mc or 900mc systems.

Just announced this month, Stratasys’ Diran filament (officially Diran 410MF07) is another black Nylon-based material; it, too, features an infill but not of fibers – instead there is a mineral component listed at seven percent by weight. This filler produces a material whose smooth, lubricious surface offers low sliding resistance (new vocabulary word: lubricious, meaning slippery, with reduced friction; think “lube job” or lubricant).

Robot-arm end printed in Diran, a smooth Nylon-based filament. (Image courtesy Stratasys)
Robot-arm end printed in Diran, a smooth Nylon-based filament. (Image courtesy Stratasys)

This smooth surface makes Diran parts perfect for applications needing a non-marring interface between a tool and a workpiece; for example, a jig or fixture that requires a part to be slid into place rather than just set down. It resists hydrocarbon-based chemicals, displays an ultimate tensile strength of 5,860 psi (40 MPa), and has a 12 percent elongation at break.

Close-up of Diran's smooth surface finish. (Image courtesy Stratasys)
Close-up of Diran’s smooth surface finish. (Image courtesy Stratasys)

(Revised) For the first time, Diran also brings the benefits of Nylon to users of the Stratasys office-environment, plug-and-play F370 printer. The system works with the new material using the same extruder heads as for ABS, ASA and PC-ABS, with just a few material-specific requirements. 

To keep thermal expansion consistent across a model and any necessary supports, parts set up for Diran automatically use model material as support. A new, breakaway SUP4000B material comes into play as an interface layer, simplifying support removal. The higher operating temperature also requires a different build tray, but the material’s lubricious properties (just had to use that word again) make for easy part removal and allow that tray to be reused dozens of times.

Read more about this intriguing material on the Diran datasheet:

and contact PADT to request a sample part of Diran or any of these useful Nylon materials.

PADT Inc. is a globally recognized provider of Numerical Simulation, Product Development and 3D Printing products and services. For more information on Stratasys printers and materials, contact us at info@padtinc.com.

All Things ANSYS 049: Predicting & Controlling Environmental Pollution with ANSYS Simulation


Published on: October 21st, 2019
With: Eric Miller & Clinton Smith

In this episode, your host and Co-Founder of PADT, Eric Miller is joined by PADT’s CFD Team Lead Engineer Clinton Smith for a discussion on how ANSYS fluids tools are being used to help predict and control environmental pollution. This information is helping engineers in a variety of ways, such as understanding the formation and dispersion of pollutants such as NOx, SOx, CO and soot.

If you would like to learn more about what this application is capable of, check out our webinar on the topic here: https://www.brighttalk.com/webcast/15747/374571

If you have any questions, comments, or would like to suggest a topic for the next episode, shoot us an email at podcast@padtinc.com we would love to hear from you!



Predicting & Controlling Environmental Pollution with ANSYS Simulation – Webinar

Environmental pollution has been a fact of life for many centuries, though it became a real issue after the start of the industrial revolution. An estimated 6.5 million premature deaths have been linked to air pollution every year.

In order to properly combat this growing issue, the world’s leading minds have turned to a more effective tool for environmental analysis; numerical simulation. Computational fluid dynamics has proven to be a powerful tool when it comes to predicting and controlling air, water, and noise pollution.

Join PADT’s CFD Team Lead Engineer Clinton Smith to learn how ANSYS fluid mechanics solutions provide insight and detailed understanding of the formation and dispersion of pollutants such as NOx, SOx, CO & Soot as well as effective ways for modelling pollution control equipment such as ESP’s, bag filters, and wastewater treatment plants.

Register Here

If this is your first time registering for one of our Bright Talk webinars, simply click the link and fill out the attached form. We promise that the information you provide will only be shared with those promoting the event (PADT).

You will only have to do this once! For all future webinars, you can simply click the link, add the reminder to your calendar and you’re good to go!

ANSYS Mechanical – Overcoming Convergence Difficulties with the Semi-Implicit Method

In our last blog, we discussed using Nonlinear Adaptive Region to overcome convergence difficulties by having the solver automatically trigger a remesh when elements have become excessively distorted.  You can read it here:  http://www.padtinc.com/blog/ansys-mechanical-overcoming-convergence-difficulties-with-automatic-remeshing-nonlinear-adaptive-region/

This time we look at another tool for overcoming convergence difficulties, the Semi-Implicit method.  ANSYS, Inc. describes the semi-implicit method as a hybrid, combining features of both implicit and explicit finite element methods.

In highly nonlinear problems involving significant deformations we may get a solver error like this one: 

*** ERROR ***                           CP =   18110.688   TIME= 11:58:42
Solution not converged at time 0.921 (load step 1 substep 185).           Run terminated. 

Like it does with other problems that lead to convergence failures, the Solution branch will have telltale red lightning bolts, indicating the solution was not able to complete due to nonconvergence.

In this case, it can be difficult to determine from the error message in the solution output exactly what the problem is.  Plotting the Newton-Raphson residuals can be a good starting point.  In order to plot the Newton-Raphson residuals, though, we need to turn them on prior to solving.  See this older Focus blog for instructions on how to do that:


A plot of the Newton-Raphson residuals shows us where the highest force imbalance is in the model:

That’s a nice looking plot, but doesn’t tell us much without knowing more about the simulation.  The model is of a plastic bottle, subject to a force load tending to ‘crush’ the bottle from top to bottom.  There is a slight off center load as well, so that the force is not purely in the downward direction. 

The bottle is constrained with a fixed support on the bottom flat surface, and contact elements between the outer surface of the bottle and a fixed surface representing a table or floor.  This is to prevent the bottle from deflecting below the plane of that surface.

The material used is a polyethylene plastic, from the ANSYS Granta Materials Data for Simulation add-on, which is a great tool to get access to hundreds of materials for ANSYS simulations.  The geometry of the bottle was created in SpaceClaim as a surface body and meshed with shell elements in ANSYS Mechanical. 

The solution was run as nonlinear static, with large deflection effects turned on.  Automatic Time Stepping was manually activated with a starting and minimum number of substeps set to 200 and a maximum number of substeps set to 1000.

With these settings, the solution ran to about 92% of the full load, where it failed to solve after bisecting to the maximum number of substeps (minimum ‘time’ step).  The force convergence plots showed the bisections and failed convergence attempts started at about iteration 230 and ‘time’ 0.92.  (If you are not familiar with the convergence plots from a Newton-Raphson method solution, please see our Focus archives for an article on the topic – look for the link to the GST Plot:  http://www.padtinc.com/blog/wp-content/uploads/oldblog/PADT_TheFocus_08.pdf).

Even though our solution has not converged, it is probably helpful to view the deformation results for substeps which did converge (at partial load) as well as the unconverged results which will be written as the last set of results.

This plot shows the total deformation at the last converged substep (time value 0.92):

This plot shows the unconverged solution, ‘extrapolated’ to time 1.0:

From the unconverged deformation plot we can see that the top of the bottle is tending to experience very large deformations.  It’s not surprizing that convergence difficulties are being encountered.

One of the techniques we can utilize to get past this problem is the Semi-Implicit method in ANSYS Mechanical.  As of 2019 R2, this needs to be activated using a Mechanical APDL command object, but it can be as simple as adding a single word within the Static Structural branch:


There are some optional fields on that command, but minimally just the one word command is needed.

Once the semi-implicit method is activated, if the solver detects the default implicit solver is having trouble, it automatically switches to the semi-implicit solving scheme.  Like a traditional explicit solver, the semi-implicit method can better handle very large deformation, transitory-like effects.  The method can switch back to implicit if conditions warrant for a more efficient solution and in fact can switch back and forth between the two schemes.

The solver output will tell us if the semi-implicit scheme has been activated:



     DISP CONVERGENCE VALUE   =  0.3918      CRITERION=   1.448     <<< CONVERGED

     LINE SEARCH PARAMETER =  0.4113     SCALED MAX DOF INC =  0.3918   

     FORCE CONVERGENCE VALUE  =   44.44      CRITERION=  0.9960   

     MOMENT CONVERGENCE VALUE =   3.263      CRITERION=  0.1423   

    Writing NEWTON-RAPHSON residual forces to file: file.nr001





 *** LOAD STEP     1   SUBSTEP   185  COMPLETED.    CUM ITER =    284

 *** TIME =  0.920010         TIME INC =  0.100000E-04

    Kinetic Energy = 0.2157        Potential Energy =  60.59   



There are some ‘symptoms’ of the switch from implicit to explicit.  The most obvious is probably that the force convergence plot will stop updating. 

Changing the Solution Output to the Solver Output will show the explicit scheme being used in that case.  The telltale is the information on Response Frequency and Period (the example shown is a static structural solution).

Deformation plot trackers and contact trackers continue to work as expected during the solution, however.

Using the semi-implicit method, the solution was able to successfully converge to the full load, and converged results are available at the last time point:

We also used the new keyframe animation technique to animate the results time history.

The semi-implicit method is well documented within the Mechanical APDL 2019 R2 Help, in the Advanced Analysis Guide, chapter 3 on Semi-Implicit Method.  We suggest reviewing that information to get a much better handle on the technique.

We hope this is helpful in getting your nonlinear solutions to converge the full value of applied loads.

Press Release: PADT Recognized for its Contribution to Arizona’s Tech Community with Two Awards: Top Tech Exec by Phoenix Business Journal and Special AZBio Award

It was a special week for PADT when we received two awards for our activities in the Arizona business community. Every time anyone at PADT, or the company as a whole is recognized, it reflects the long term commitment our employees have made to our community, their focus on our customers, and their continued effort to simply be good at what they do.

The details for these two awards are given in the press release below. You can see a list of the fifteen awards PADT has received since 2002 here.

A big thank you to everyone who contributed to our success over the years. We are humbled by this type of recognition, so we don’t have much else to say.

The official press release is available as HTML or PDF.

PADT Recognized for its Contribution to Arizona’s Tech Community with Two Awards: Top Tech Exec by Phoenix Business Journal and Special AZBio Award

PADT Co-founder Eric Miller Honored in the CEO Category by the Phoenix Business Journal and PADT’s 25Years of Contributions Recognized by AZBio

TEMPE, Ariz., Oct. 8, 2019 PADT, a leader in numerical simulation, product development, and 3D printing, is honored to announce that Principal and Co-founder, Eric Miller, is a winner of the Phoenix Business Journal’s 2019 Top Tech Exec Award in the CEO category.  On the heels of that honor, the state’s bioscience industry organization, AZBio, recognized the contributions PADT has made to the local medical technology community over the past 25 years with a special trophy presented at the 2019 AZBio Awards ceremony on October 2, 2019.

PBJ Top Tech Exec Award

“Thank you to the Phoenix Business Journal for recognizing our dedication to Phoenix’s innovation landscape,” said Miller. “We work hard to ensure the success of our clients, and I’m extremely proud of the company my co-founders and I have built together here at PADT. When our clients and employees are happy, there’s no limit to what we can achieve.”

Each year, the Phoenix Business Journal recognizes individuals for their involvement and influence in the technology industry with the AZ Top Tech Exec Awards. Miller was selected for his role in establishing PADT as an integral part of the local manufacturing ecosystem, providing market-leading numerical simulation tools from ANSYS, Inc., and the 3D printing systems from Stratasys across the Southwest.  PADT also assists companies through engineering consulting for design, test, and simulation and is the state’s largest provider of 3D printing services. Companies come to PADT for the tools and consulting they need to design and manufacture better products.

In addition to PADT’s extensive business victories, Miller was also chosen as a result of his continuous involvement in the Phoenix technology community. Miller is an angel investor with Arizona Tech Investors, and he frequently lends his time to advise entrepreneurs. He is also an active mentor for ACA’s Venture Ready Program and was recently named Vice-Chair of the Arizona Technology Council’s Board of Directors. He is also on the board of directors of BioAccel and is a regular guest contributor of articles on technology, business, and the local tech scene to the Phoenix Business Journal.

“Congratulations to Eric Miller and all of the 2019 Top Tech Execs,” said Ray Schey, market president and publisher, Phoenix Business Journal. “Eric is one of the key contributors to the Valley’s incredible growth in the technology sector. This recognition is acknowledgement of his, and the work of the other talented tech execs, in the industry. Arizona is being noticed both nationally and internationally for its innovation and growth in technology.”

AZBio Recognition

During the 2019 AZBio Awards, the Arizona Bioindustry Association recognized PADT’s 25th anniversary with a special award in recognition of the contribution the company has made to Arizona’s biotechnology community.  It was a special honor for PADT to receive the iconic double-double helix trophy that PADT has been 3-D printing for the AZBio awards for eight years.  

“Since it was founded in Arizona in 1994, PADT’s dedicated employees have provided their knowledge of innovation and enthusiasm for collaboration to advance our common goal of making Arizona a top-tier bioscience state,” said Joan Koerber-Walker, president and CEO, AZBio. “It was a privilege to recognize this trail-blazing company that’s grown to be the largest of its kind in the Southwest for its contributions.”

Although PADT provides products and services to companies across industries, the Bioscience sector has been a special focus of the company because of its disproportionately positive impact on the overall community. PADT’s involvement in groups like AZBio is way for the company to amplify its impact.

“PADT Co-founder Mark Johnson started our special commitment to the medical device industry and our contributions to the bioscience community early in the company’s history,” said Rob Rowan, director of Engineering, PADT. “Although Mark is unfortunately no longer with us, we continue to execute on his vision of bringing aerospace quality engineering to the medical sector, helping companies large and small translate their innovative ideas into viable products that improve patient outcomes across applications.”

About Eric Miller

As a Co-founder of PADT in 1994, Miller was able to pursue his interests in simulation, 3D printing, operations, and small business management. He is often called upon to write and speak on simulation, design, and 3D Printing as well as on startups and the high-tech sector. In addition, Miller is a board member for several tech-related organizations and Vice-Chair of the Arizona Technology Council. He holds a B.S. in Mechanical Engineering from UC Berkeley.

About PADT

PADT is an engineering product and services company that focuses on helping customers who develop physical products by providing Numerical Simulation, Product Development, and 3D Printing 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 90 employees, PADT services customers from its headquarters at the Arizona State University Research Park in Tempe, Arizona, and from offices in Torrance, California, Littleton, Colorado, Albuquerque, New Mexico, Austin, Texas, and Murray, Utah, as well as through staff members located around the country. More information on PADT can be found at www.PADTINC.com.

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All Things ANSYS 048: Topology Optimization & Simulation for Additive Manufacturing in ANSYS 2019 R3


Published on: October 7th, 2019
With: Eric Miller & Doug Oatis

In this episode, your host and Co-Founder of PADT, Eric Miller is joined by PADT’s simulation support & application engineer Doug Oatis for a discussion on what is new in ANSYS 2019 R3 with regards to tools and applications for topology optimization and additive manufacturing.

If you would like to learn more about what’s new in this latest release, check out our webinar on the topic here: https://www.brighttalk.com/webcast/15747/372133?

If you have any questions, comments, or would like to suggest a topic for the next episode, shoot us an email at podcast@padtinc.com we would love to hear from you!



Frequency Dependent Material Definition in ANSYS HFSS

Electromagnetic models, especially those covering a frequency bandwidth, require a frequency dependent definition of dielectric materials. Material definitions in ANSYS Electronics Desktop can include frequency dependent curves for use in tools such as HFSS and Q3D. However, there are 5 different models to choose from, so you may be asking: What’s the difference?

In this blog, I will cover each of the options in detail. At the end, I will also show how to activate the automatic setting for applying a frequency dependent model that satisfies the Kramers-Kronig conditions for causality and requires a single frequency definition.


Recalling that the dielectric properties of material are coming from the material’s polarization


where D is the electric flux density, E is the electric field intensity, and P is the polarization vector. The material polarization can be written as the convolution of a general dielectric response (pGDR) and the electric field intensity.


The dielectric polarization spectrum is characterized by three dispersion relaxation regions α, β, and γ for low (Hz), medium (KHz to MHz) and high frequencies (GHz and above). For example, in the case of human tissue, tissue permittivity increases and effective conductivity decreases with the increase in frequency [1].

Fig. 1. α, β and γ regions of dielectric permittivity

Each of these regions can be modeled with a relaxation time constant


where τ is the relaxation time.


The well-known Debye expression can be found by use of spectral representation of complex permittivity (ε(ω)) and it is given as:


where ε is the permittivity at frequencies where ωτ>>1, εs is the permittivity at ωτ>>1, and j2=-1. The magnitude of the dispersion is ∆ε = εs.

The multiple pole Debye dispersion equation has also been used to characterize dispersive dielectric properties [2]


In particular, the complexity of the structure and composition of biological materials may cause that each dispersion region be broadened by multiple combinations. In that case a distribution parameter is introduced and the Debye model is modified to what is known as Cole-Cole model


where αn, the distribution parameter, is a measure of broadening of the dispersion.

Gabriel et. al [3] measured a number of human tissues in the range of 10 Hz – 100 GHz at the body temperature (37℃). This data is freely available to the public by IFAC [4].

Frequency Dependent Material Definition in HFSS and Q3D

In HFSS you can assign conductivity either directly as bulk conductivity, or as a loss tangent. This provides flexibility, but you should only provide the loss once. The solver uses the loss values just as they are entered.

To define a user-defined material choose Tools->Edit Libraries->Materials (Fig. 2). In Edit Libraries window either find your material from the library or choose “Add Material”.

Fig. 2. Edit Libraries screen shot.

To add frequency dependence information, choose “Set Frequency Dependency” from the “View/Edit Material” window, this will open “Frequency Dependent Material Setup Option” that provides five different ways of defining materials properties (Fig. 3).

Fig. 3. (Left) View/Edit Material window, (Right) Frequency Dependent Material Setup Option.

Before choosing a method of defining the material please note [5]:

  • The Piecewise Linear and Frequency Dependent Data Points models apply to both the electric and magnetic properties of the material. However, they do not guarantee that the material satisfies causality conditions, and so they should only be used for frequency-domain applications.
  • The Debye, Multipole Debye and Djordjevic-Sarkar models apply only to the electrical properties of dielectric materials. These models satisfy the Kramers-Kronig conditions for causality, and so are preferred for applications (such as TDR or Full-Wave SPICE) where time-domain results are needed. They also include an automatic Djordjevic-Sarkar model to ensure causal solutions when solving frequency sweeps for simple constant material properties.
  • HFSS and Q3D can interpolate the property’s values at the desired frequencies during solution generation.

Piecewise Linear

This option is the simplest way to define frequency dependence. It divides the frequency band into three regions. Therefore, two frequencies are needed as input. Lower Frequency and Upper Frequency, and for each frequency Relative Permittivity, Relative Permeability, Dielectric Loss Tangent, and Magnetic Loss Tangent are entered as the input. Between these corner frequencies, both HFSS and Q3D linearly interpolate the material properties; above and below the corner frequencies, HFSS and Q3D extrapolate the property values as constants (Fig. 4).

Fig. 4. Piecewise Linear Frequency Dependent Material Input window.

Once these values are entered, 4 different data sets are created ($ds_epsr1, $ds_mur1, $ds_tande1, $ds_tandm1). These data sets now can be edited. To do so choose Project ->Data sets, and choose the data set you like to edit and click Edit (Fig. 5). This data set can be modified with additional points if desired (Fig. 6).

Fig. 5. (Left) Project data set selection, (right) defined data set for the material.
Fig. 6. A sample data set.

Frequency Dependent

Frequency Dependent material definition is similar to Piecewise Linear method, with one difference. After selecting this option, Enter Frequency Dependent Data Point opens that gives the user the option to use which material property is defined as a dataset, and for each one of them a dataset should be defined. The datasets can be defined ahead of time or on-the-fly. Any number of data points may be entered. There is also the option of importing or editing frequency dependent data sets for each material property (Fig. 7).

Fig. 7. This window provides options of choosing which material property is frequency dependent and enter the data set associated with it.


This model was developed initially for FR-4, commonly used in printed circuit boards and packages [6]. In fact, it uses an infinite distribution of poles to model the frequency response, and in particular the nearly constant loss tangent, of these materials.


where ε is the permittivity at very high frequency,  is the conductivity at low (DC) frequency,  j2=-1, ωA is the lower angular frequency (below this frequency permittivity approaches its DC value), ωB is the upper angular frequency (above this frequency permittivity quickly approaches its high-frequency permittivity). The magnitude of the dispersion is ∆ε = εs-ε∞.

Both HFSS and Q3D allow the user to enter the relative permittivity and loss tangent at a single measurement frequency. The relative permittivity and conductivity at DC may optionally be entered. Writing permittivity in the form of complex permittivity [7]


Therefore, at the measurement frequency one can separate real and imaginary parts




Therefore, the parameters of Djordjevic-Sarkar can be extracted, if the DC conductivity is known


If DC conductivity is not known, then a heuristic approximation is De = 10 εtan δ1.

The window shown in Fig. 8 is to enter the measurement values.

Fig. 8. The required values to calculate permittivity using Djordjevic-Sarkar model.

Debye Model

As explained in the background section single pole Debye model is a good approximation of lossy dispersive dielectric materials within a limited range of frequency. In some materials, up to about a 10 GHz limit, ion and dipole polarization dominate and a single pole Debye model is adequate.


The Debye parameters can be calculated from the two measurements [7]


Both HFSS and Q3D allow you to specify upper and lower measurement frequencies, and the loss tangent and relative permittivity values at these frequencies. You may optionally enter the permittivity at high frequency, the DC conductivity, and a constant relative permeability (Fig. 9).

Fig. 9. The required values for Single Pole Debye model.

Multipole Debye Model

For Multipole Debye Model multiple frequency measurements are required. The input window provides entry points for the data of relative permittivity and loss tangent versus frequency. Based on this data the software dynamically generates frequency dependent expressions for relative permittivity and loss tangent through the Multipole Debye Model. The input dialog plots these expressions together with your input data through the linear interpolations (Fig. 10).

Fig. 10. The required values for Multipole Debye model.

Cole Cole Material Model

The Cole Cole Model is not an option in the material definition, however, it is possible to generate the frequency dependent datasets and use Frequency Dependent option to upload these values. In fact ANSYS Human Body Models are built based on the data from IFAC database and Frequency Dependent option.


Frequency-dependent properties can be plotted in a few different ways. In View/Edit Material dialog right-click and choose View Property vs. Frequency. In addition, the dialogs for each of the frequency dependent material setup options contain plots displaying frequency dependence of the properties.

You can also double-click the material property name to view the plot.

Automatically use causal materials

As mentioned at the beginning, there is a simple automatic method for applying a frequency dependent model in HFSS. Select the menu item HFSS->Design Setting, and check the box next to Automatically use casual materials under Lossy Dielectrics tab.

Fig. 11. Causal material can be enforced in HFSS Design Settings.

This option will automatically apply the Djordjevic-Sarkar model described above to objects with constant material permittivity greater than 1 and dielectric loss tangent greater than 0. Keep in mind, not only is this feature simple to use, but the Djordjevic-Sarkar model satisfies the Kramers-Kronig conditions for causality which is particularly preferred for wideband applications and where time-domain results will also be needed. Please note that if the assigned material is already frequency dependent, automatic creation of frequency dependent lossy materials is ignored.

If you would like more information or have any questions about ANSYS products please email info@padtinc.com


  • D.T. Price, MEMS and electrical impedance spectroscopy (EIS) for non-invasive measurement of cells, in MEMS for Biomedical Applications, 2012, https://www.sciencedirect.com/topics/materials-science/electrical-impedance
  • W. D. Hurt, “Multiterm Debye dispersion relations for permittivity of muscle,” IEEE Trans. Biomed. Eng, vol. 32, pp. 60-64, 1985.
  • S. Gabriel, R. W. Lau, and C. Gabriel. “The dielectric properties of biological tissues: III. Parametric models for the dielectric spectrum of tissues.” Physics in Medicine & Biology, vol. 41, no. 11, pp. 2271, 1996.
  • Dielectric Properties of Body Tissues in the Frequency Range 10 Hz – 100 GHz, http://niremf.ifac.cnr.it/tissprop/.
  • ANSYS HFSS Online Help, Nov. 2013, Assigning Materials.
  • A. R. Djordjevic, R. D. Biljic, V. D. Likar-Smiljani, and T. K. Sarkar, “Wideband frequency-domain characterization of FR-4 and time-domain causality,” IEEE Trans. on Electromagnetic Compatibility, vol. 43, no. 4, p. 662-667, Nov. 2001.
  • ANSYS HFSS Online Help, 2019, Materials Technical Notes.

Useful Links

Piecewise Linear Input

Debye Model Input

Multipole Debye Model Input


Enter Frequency Dependent Data Points

Modifying Datasets.

Mars, Hearts, Spaceships, and Universities: 2019 Colorado Additive Manufacturing Day a Success

Engineers, educators, and enthusiasts gathered on the green lawn of beside the Platte River at the Blind Faith Brewing to talk about Additive Manufacturing. Over 170 attendees (and two dogs) met each other, caught up with old colleagues, and shared their AM journey during the breaks and listened to 13 presenters and panelists. 12 antipasto platters and 30 pizzas were consumed, and 298 beers or sodas were imbibed. By the numbers and by type of interaction we saw, a successful event all around.

This was the fourth annual gathering, hosted by PADT and sponsored by our partners at this brewery. We could not have put this event on without the support of Stratasys, ANSYS, ZEISS, and Desktop Metal. We also want to thank our promotional partners, Women in 3D Printing and Space for Humanity who both brought new people to our community. Carbon, Visser and a student project with Ball Aerospace did their part as exhibitors.

Check out the Slideshow at the end of this post to get a visual snapshot of the day.

We want to thank the true stars of our event, the speakers and panelists who shared their knowledge and experience that turned a great gathering into a learning experience.

We started the morning off with an inspirational keynote from Dr. Robert Zubrin. A visionary in the space community and long term champion of going to Mars, Dr. Zubrin shared with us his observations about the new space race with his talk: “The Case for Space: How the Revolution in Spaceflight Opens Up a Future of Limitless Possibilities.” He left the packed audience energized and ready to do our part in this next step in humanities exploration of the universe. He stayed after to talk with people and sign copies of his book, which you can find here.

We then heard from user David Waller of Ball Aerospace on his experience with their Desktop Metal system. He went over the testing, lessons learned, and usage of their Studio system. It was a great in-depth look at someone implementing a new technology. There is a lot of interest around this lower-cost approach to producing metal parts, and the audience was full of questions.

Sticking with the Desktop Metal technology, PADT’s very own Pamela Waterman talked about how PADT is using our in-house Zeiss Optical Scanning hardware and software to inspect the parts we are making with our Desktop Metal System. She shared what we have learned about following the design guidelines that are developing for this technology and how scanning is a fast and accurate way to determine the final geometry created in the three-step process of building a green part, debinding, and sintering.

Next up was Christopher Robinson form ANSYS, Inc. to talk about recent additions to the ANSYS Additive products. He shared how customers are using simulation to design parts for metal powder bed fusion AM and then model the build process to predict and avoid failures as well as compensate for the distortion inherent in the process. The key takeaway was that simulation is the solution for getting parts built right the first time.

After a short break, and some AM trivia that won some PADT25 T-Shirts for people who knew the history of 3D Printing, we heard all about the new V650 Flex Stereolithography system that Stratasys recently introduced. Yes, Stratasys now makes and sells an SL system and it is literally a dream machine designed by people with decades of AM and Stereolithography experience. Learn more about this open and powerful system here.

Another AM technology was up next when Nick Jacobson spoke about Voxel Printing with PolyJet technologies. He discussed how he varies materials and colors spacially to create unique and realistic replicas for medicine and engineering. He also showed how the voxel-based geometry he creates can be used to create Virtual Reality representations of objects. Much of their work revolves around the visualization of hearts for adults and children to improve surgery planning. While we had been focused on space at the start of the afternoon, he reminded us of the immediate and life saving medical applications of AM.

And then we moved back to space with a presentation from Lockheed Martin‘s Brian Kaplun on how they are using AM to create parts that will fly on the Orion Spacecraft. Making production parts with 3D Printing has been a long-term goal for the whole industry, and Lockheed Martin has done the long and hard work of design, test, and putting processes in place to make this dream a reality. One of the biggest takeaways of his talk was how once the Astronauts saw a few AM parts in the capsule, they started asking of its use to redesign other tools and components. The ultimate end-users, they saw the value of lightweight and strong parts that could be made without the limitations of traditional manufacturing.

We finished up the day, after another break and some more trivia, with a fascinating panel on AM at Colorado’s leading Universities. We were lucky to have Ray Huff from Wohlers Associates moderate a distinguished group of deans, directors, and professors from four outstanding but different institutions:

  • Martin Dunn PhD,  Dean of Engineering, CU Denver
  • Jenifer Blacklock PHD, Mechanical Engineering Professor – Colorado School of Mines
  • David Prawel PhD, Director, Idea-2-Product 3D Printing Lab, Colorado State University 
  • Matt Gordon, PhD,  Chair, Mechanical Engineering, University of Denver 

Their wide-ranging discussion covered their education and research around AM. A common theme was industry cooperation. Each school shared how they use AM to help students not just make things, but also understand how parts are made. The discussion was fantastic and ended far too soon, which is always an indicator of a great group of experts.

And that sums up our great day, leaving out several hundred side conversations that went on. Check out this slide show to get a feel for how energetic and interesting the afternoon was.

As everyone left, some reluctantly and after one more beer, the common comment was that they can’t wait to get together again with everyone. We hope that next year we will have more speakers and participants and continue to support the growth of Additive Manufacturing in Colorado.

A quick note about the location: You are not wrong if you remember a different name for the three previous events. St. Patricks’s is now Blind Faith and the new owners could have not been more welcoming. Plus, they have more Belgian’s, which I am a big fan of.

Topology Optimization & Simulation for Additive Manufacturing in ANSYS 2019 R3 – Webinar

ANSYS offers a complete simulation workflow for additive manufacturing (AM) that allows you to transition your R&D efforts for metal additive manufacturing into a successful manufacturing operation. This best-in-class solution for additive manufacturing enables simulation at every step in your AM process. It will help you optimize material configurations and machine and parts setup before you begin to print. As a result, you’ll greatly reduce — and potentially eliminate — the physical process of trial-and- error testing.

Through the use of ANSYS tools such as Additive Prep, Print, and Science, paired with topology optimization capabilities in ANSYS Mechanical Workbench, the need for physical process of trial-and-error testing has been greatly reduced.

Join PADT’s Simulation Support and Application Engineer Doug Oatis for an exploration of the ANSYS tools that help to optimize additive manufacturing, and what new capabilities are available for them when upgrading to ANSYS 2019 R3. This presentation includes updates regarding:

  • Level-set based topology optimization
  • The export of build files directly to AM machines
  • Switching between viewing STL supports, mesh, or element densities
  • Multiple support being made in a single simulation (volume-less & solid supports)
  • And much more

Register Here

If this is your first time registering for one of our Bright Talk webinars, simply click the link and fill out the attached form. We promise that the information you provide will only be shared with those promoting the event (PADT).

You will only have to do this once! For all future webinars, you can simply click the link, add the reminder to your calendar and you’re good to go!

All Things ANSYS 047: Mechanical Solver, Element, & Contact Enhancements in ANSYS 2019 R3


Published on: September 24th, 2019
With: Eric Miller, Joe Woodward, Doug Oatis, & Ted Harris

In this episode, your host and Co-Founder of PADT, Eric Miller is joined by PADT’s simulation support manager Ted Harris, specialist mechanical engineer Joe Woodward, and simulation support & application engineer Doug Oatis for a discussion on what is new in ANSYS 2019 R3 with regards to the mechanical solver, element, and contact enhancements.

If you would like to learn more about what’s new in this latest mechanical release, check out our webinar on the topic here: https://www.brighttalk.com/webcast/15747/371263

If you have any questions, comments, or would like to suggest a topic for the next episode, shoot us an email at podcast@padtinc.com we would love to hear from you!



Mechanical Solver, Element, & Contact Enhancements in ANSYS 2019 R3 – Webinar

ANSYS 2019 R3 brings a whole host of improvements to various mechanical features, designed to enhance overall optimization and ease of use. Key updates such as those made in regards to the mechanical solver, MAPDL elements, and contact modeling capabilities help make this release essential for performing effective analyses, and deriving valuable results from said analyses. 

For example, being able to simulate contact correctly means that engineers can simulate the change in load paths when parts deform and confidently predict how assemblies will behave in the real world.

Join PADT’s Simulation Support Manager Ted Harris, for a look at the latest mechanical solver, element, and contact updates available in ANSYS 2019 R3. This presentation includes enhancements made for:

Improved scaling for various solvers

Surface stress evaluation for axisymmetric solid elements

Piezoelectric analyses

Nonlinear radial gap elements

And much more

Register Here

If this is your first time registering for one of our Bright Talk webinars, simply click the link and fill out the attached form. We promise that the information you provide will only be shared with those promoting the event (PADT).

You will only have to do this once! For all future webinars, you can simply click the link, add the reminder to your calendar and you’re good to go!

All Things ANSYS 046: The Founding of CFX


Published on: September 9th, 2019
With: Eric Miller, Paul Galpin, & Brad Hutchinson

In this episode, your host and Co-Founder of PADT, Eric Miller is joined by Paul Galpin and Brad Hutchinson, two founders of the Computational Fluid Dynamics (CFD) simulation tool now owned by ANSYS, called CFX. They discuss how they initially got into the world of simulation, the current state of CFD, and what is important to be aware of as it continues to grow and develop.

If you would like to learn more about what’s new in the latest version of CFX, check out PADT’s webinar on fluids updates in ANSYS 2019 R3 here: https://www.brighttalk.com/webcast/15747/369903

If you have any questions, comments, or would like to suggest a topic for the next episode, shoot us an email at podcast@padtinc.com we would love to hear from you!



Fluids Innovations in ANSYS 2019 R3 – Webinar

Products such as ANSYS Fluent, CFX, and Ensight work together in a constantly improving tool kit that is developed to provide ease of use improvements for engineers simulating fluid flows and the impact those flows have on physical models. 

Fluids simulation users will find that ANSYS 2019 R3 includes many enhancements that further simplify the user experience and broaden use to new applications. The new Fluent experience has been improved so you can enjoy more CFD in less time, with less training.

Join PADT’s Simulation Support and Application Engineer, Sina Ghods, for a look at what is new and improved for fluids simulation tools in ANSYS 2019 R3. This presentation includes updates regarding: 

  • Usability Enhancements
  • Watertight Geometry Workflow
  • TurboGrid & BladeEditor
  • Meshing Enhancements
  • And many more innovative capabilities

Register Here

If this is your first time registering for one of our Bright Talk webinars, simply click the link and fill out the attached form. We promise that the information you provide will only be shared with those promoting the event (PADT).

You will only have to do this once! For all future webinars, you can simply click the link, add the reminder to your calendar and you’re good to go!

Video Interview: Topology Optimization versus Generative Design

While attending the 2019 RAPID + TCT conference in Detroit this year, I was honored to be interviewed by Stephanie Hendrixson, the Senior Editor of Additive Manufacturing magazine and website. We had a great chat, covering a lot of topics. I do tend to go on, so it turned into two videos.

The first video is about the use of simulation in AM. You should watch that one first, here, because we refer back to some of the basics when we zoomed in on optimization.

Generative design is the use of a variety of tools to drive the design of components and systems to directly meet requirements. One of those tools, the most commonly used, is Topological Optimization. Stephanie and I explore what it is all about, and the power of using these technologies, in this video:

You can view the full article on the Additive Manufacturing website here.

If you have any questions about how you can leverage simulation to add value to your AM processes, contact PADT or shoot me an email at eric.miller@padtinc.com.