Internal Charging

Topic: EMA3D-Internal: A Comprehensive Platform for 3D Internal Space Charging

When: Thursday, April 13, 2017 10:00 am
Mountain Daylight Time (Denver, GMT-06:00)

To Register: Click Here

Abstract:
featured-scaled down-spacecraft-internal-charging-simulation-and-analysisIn this webinar, we present the newly developed fully 3D internal space charging software tool: EMA3D-Internal.  Spacecraft charging is a well-known problem for space vehicles.  Advanced evaluation of spacecraft charging threats to a particular mission can inform design and drastically reduce the risk for space programs.  We present a new tool, EMA3D-Internal, for performing a thorough evaluation of spacecraft internal charging risks.  The tool can be run entirely from the graphical user interface and allows geometry import and development from within CADfix, an advanced CAE platform.  The user can specify an arbitrary and realistic radiation spectrum, such as what might be obtained using the AP9/AE9 framework.  In the webinar, we will demonstrate applications of EMA3D-Internal for realistic mission environments, showing the steps involved in importing and preparing the model, running the simulation and analyzing results. internal space charging

E3 Tools

Webinar: Dealing with cables, cavities and platform antennas in a PRACTICAL way

Presented by: Dr. Tim McDonald

Abstract:

EMC and E3 engineers have real challenges in dealing with cables, cavities and platform antennas in real electronics equipment, aircraft and vehicles.

It is reasonably easy to solve for a perfect cable illuminated by a perfect plane wave, but what about a real cable in a real enclosure. What about cable branching? One never wants to overdesign for lightning because it adds mass. However, how do you accurately predict the levels? Many have tried computer simulation tools, but dealing with cables and enclosure cavities is such a headache! Further, simulating antenna effects typically requires more detail about the antenna than the EMC engineer even has access to!

EMA3D was created by EMC and E3 engineers for our everyday work. It can automatically simplify cables from the real CAD. You can simply put each pin at its real path by following the actual wiring diagram. EMA3D’s harness module includes a library of common cable parameters, such as transfer impedance and resistance, based on the wire gauge that is a result of real testing of Glenair and Alpha brand cable shields.

Our cavity tool from IDS can solve for the shielding of real cavities instantly by making assumptions about the seams and the losses. Further, our antenna tools from IDS can model antennas without having the full CAD of the antenna. You only need the gain patterns and related specifications, and the tool can generate a reasonable source.

EMA3D simulations of cables have been validated against testing for over 30 years. It has been part of the direct FAA certification basis since 1993 (The MD-90) and as recently as this year. There have been two transport category aircraft that received a type certificate from their airworthiness authority based on EMA3D simulations in the past two years. Our cavity tool and antenna tools from IDS has a similarly strong validation heritage.

In this webinar, we will discuss tools from EMA and IDS to deal with cables, cavities and platform antennas in a PRACTICAL way, with simplifications that are accurate but save you time and headaches.

Presentaion:


If you are  having trouble viewing the presentation, the slides can be downloaded: HERE

 

Video:

If you are having trouble viewing the video of the webinar, you can download the video: HERE

Surface Discharges

 

Using EMA3D to Calculate Surface to Surface Discharge Transients

When a space vehicle undergoes surface charging in a space plasma environment, there is the potential for discharges and arcing to occur.  These discharges may cause damage to surfaces or may couple electromagnetic energy to antennas and cables.  In this blog entry we discuss how to estimate the coupling of energy to an antenna during a surface to surface discharge using EMA3D.

The basic setup is shown in the Figure.  There is a conductive surface (in cyan) with a smaller dielectric surface (in magenta) under which is an antenna.

1-spacecraft-space-vehicle-surface-charging-em-simulation-model-setup

 

The geometry setup shown here is very simple but is fine for estimating the fields seen by the antenna.  EMA3D is built on the CADfix CAE platform which supports complicated geometry import and development for the interested user.  In our model, there are nine discharge channels shown in the inset.  These will serve as the path for the surface to surface current discharge.

To constrain the discharge waveform the user must first perform a surface charging analysis using a program like Nascap-2K.  The surface charging analysis will provide a voltage differential between the conductor and the dielectric.  We can then constrain the discharge to a total charge using the capacitance of the system.

EMA3D has pre- and post-processing interface with Nascap-2K, so the user can apply the same geometrical model for the entire analysis.  Here, we assume we have a voltage differential already supplied.

2-spacecraft-surface-charging-waveform-antenna-transients

We first apply a slow waveform to charge up the dielectric.  After reaching steady state, we then discharge the dielectric onto the conductor and evaluate the transients at the antenna.  Our discharge waveform is a fast double-exponential fit to empirical observations of spacecraft discharges.

The time domain result is shown in the Figure above.   Notice how the electric field shows a slow buildup to the saturating value as we charge the dielectric and then there is a rapid discharge back to the conductor as the electric field goes back down to zero.

3-spacecraft-surface-charge-electric-field-interference

We also evaluate the frequency domain result for the electric field, shown in the Figure above.  In this case, the user may be interested to see the interference in the region of the antenna’s operating frequency.

In this short blog post, we have demonstrated a simple way to estimate electromagnetic energy coupling to an antenna during a surface to surface spacecraft discharge event.  The techniques shown here can easily be applied to surface to space discharges and vehicle to vehicle discharges, as EMA has shown in a previous webinar (link here).

Using EMA3D’s pre- and post-processing interface with Nascap-2K, a sophisticated user can apply the same geometry to the complete spacecraft charging simulation analysis, as well as a wide range of EMC problems including lightning and HIRF.

EMA3D and CADfix

EMA3D Lightning Simulation

International TechGroup Incorporated Contact: Margo Spurgeon
International TechneGroup Incorporated
Phone: 513-576-3858
Email: margo.spurgeon@iti-global.com
5303 DuPont Circle
Milford, OH 45150
www.iti-global.com

International TechneGroup Incorporated (ITI) and EMA3D/CADfix integration drives efficiency for electromagnetic simulation

Milford, Ohio, October 4, 2016 – International TechneGroup Incorporated (ITI) is pleased to announce the release of a new case study describing the use of its CADfix solution for geometry handling and meshing for the EMA3D advanced electromagnetic simulation software. Electromagnetic Applications Inc. (EMA) has developed a set of integration tools that allow CADfix to act as a pre- and post-processor for the EMA3D multi-physics solver suite. EMA customers use CADfix for model import, repair, simplification, analysis property definition and meshing, ahead of export to EMA3D.

Aerospace companies seek the most thorough, efficient and accurate methods to achieve FAA certification. One aspect of this involves testing to ensure safety during a lightning strike. Because physical testing is expensive, requires significant resources, and limits potential scenarios that engineers can measure, the use of electromagnetic simulation as a method of achieving compliance is increasing. This is made possible by advances in simulation capabilities and validation accuracy; and requires justified and verified analysis models.

The CAD master model drives the electromagnetic analysis, and while CAD systems provide the geometry for the master models, it takes time to prepare and verify the geometry. The innovative EMA and CADfix integration delivers a suite of validated tools designed to enhance electromagnetic testing, and enables analysts to begin with more robust geometric definitions. EMA uses CADfix as a pre- and post-processor to expedite this process. “Every step of the process for us involves CADfix,” stated Tim McDonald, PhD, Chief Scientist at EMA.

BEM-Mesh-in-EMA-CADfix

EMA3D spacecraft charging simulation

CADfix for EMA3D screenshot

EMA3D and CADfix

Through their integration with CADfix, EMA has implemented new system-modeling approaches to simulate the interaction of systems and their electronics with electromagnetic environments – saving time, increasing accuracy, and saving money. According to Cody Weber, Senior Scientist at EMA, “CADfix is the central working hub that interfaces with all of our solvers.”

“We have partnered with EMA for over twenty years. It is a pleasure to work with the team of electromagnetic analysis experts at EMA and to see how CADfix helps to automate their CAD to CAE processes and allows EMA customers to work more efficiently. We look forward to the partnership continuing for many years to come.” commented Andy Chinn, Commercial Director from ITI’s UK CADfix development office.

Read more about how EMA uses CADfix to deliver key integration and simulation solutions, enabling them to provide their customers with validated tools to help design safer and lower cost systems.

 

EMA3D CADfix Case Study:

To view or download the PDF: CLICK HERE 

About International TechneGroup Inc. (ITI) International TechneGroup Incorporated began in 1983 with a mission to help manufacturers drive innovation and time to market by applying computer-aided product development to engineering problems. Today, ITI is the global leader providing reliable interoperability, validation and migration solutions for product data and related systems. Our customers recognize the value in having a trusted solution partner that provides more than just software. ITI solves complex product data interoperability problems so that the world’s leading manufacturers can focus on making great products. www.iti-global.com
About Electromagnetic Applications Inc.(EMA) EMA is a world leader in the analysis of electromagnetic effects, and helps businesses and government entities solve electromagnetic design and certification challenges. From commercial airliners to wireless communication providers, EMA provides consulting and analysis software solutions to a wide variety of industries. www.ema3d.com

CADfix is a registered trademarks of International TechneGroup Incorporated. All trademarks or registered trademarks are the property of their respective holders, used with permission. All other rights reserved.

OCT Method

Oversized Cavity Theory for RE/RS Assessment up to 40GHz

The Oversized Cavity Theory (OCT) is a numerical technique for aerospace systems including aircraft and communication satellites radiated emissions and susceptibility (RE/RS) assessment. The method is based on a power-balance approach, i.e. on the premise that, with statistical fields present in an electrically large cavity, the power entering the cavity is equal to the power dissipated by all the loss mechanisms acting in the cavity.

The high frequency region, where the electrical dimension of the cavity is large, is undoubtedly the most interesting region from an applicative point of view. The modelling of the EM phenomena of interest can be really challenging for any “standard” simulation methods.

In this webinar, we will present how to use OCT for practical EMC problems of interest in aerospace applications.
 

Webinar Video:


 

Webinar Presentation:

Surface Charging

Surface Charging Simulations of an Orion-like Spacecraft in a Geo Space Plasma

Abstract:

Surface charging in a space plasma environment is a critical safety issue for many space vehicles. This is particularly true for vehicles that spend time in geosynchronous altitudes. We present results on surface charging for an Orion-like spacecraft in a geosynchronous plasma environment, examining sensitivities to material input parameters and sunlight illumination scenarios. Our surface charging simulation is performed using the Nascap2k spacecraft charging software suite. In our approach, we have created and implemented EMA3D software tools that enable the user to generate Nascap-2k objects for simulation from an external CAD platform, resulting in realistic geometries with reduced development time. We demonstrate our geometry development techniques and present results on differential voltages between adjacent surfaces, normal surface E-fields, voltage to plasma, and numerical stability of our simulations.

 

Presentaion:

Farnborough

Farnborough International Airshow 2016

11th – 15th July, Farnborough UK. This year EMA will be attending the Farnborough International Airshow, one of the world’s premier airshows. Along with our European partners Ingegneria Dei Sistemi, we will be showcasing our electromagnetic modeling and simulation tools for the aircraft and satellite industries, as well as one of our UAV’s configured to perform EMC/EMI assessments.

The EMA and IDS booth will be hosted at the Regione Lazio – Lazio Innova stand, Hall 1, Booth A118, where we will also be holding a series of workshops covering the uses of electromagnetic modeling and simulation:

Date: Tuesday 12th
Time: 15.45 – 16.30
Title: The Expanding Role of Electromagnetic Simulation in Aircraft Type Certification
Description: 
New regulations and new aerospace materials drive up the cost and complexity of type certification. Advances in simulation capability and validation accuracy have greatly increased the use of electromagnetic simulation as a method of compliance to combat the rise in cost and program schedules. In this presentation, we describe the new role for these tools along with how they can be used to enhance testing to reduce overall program cost, duration and risk.

Date: Wednesday 13th
Time: 15.00 – 15.45
Title: New Electromagnetic Tools for New Space
Description: 
There is a growing interest in human spaceflight, which will require levels of safety and reliability akin to commercial air travel. Concurrently, there are dramatic shifts in space programs toward lower cost, reusability and higher production rates. As a result, electromagnetic requirements for space are shifting away from rigid rules to an approach where everything must be justified and verified carefully in an extremely short period of time. In this presentation, we describe an emerging class of simulation tools that provide these new space teams with suite of validated tools to quickly and accurately design safe and low cost systems with a high degree of confidence.

Date: Thursday 14th
Time: 15.00 – 15.45
Title: Advanced Electromagnetic Modelling for Space application
Description: 
The seminar will discuss the benefits of high fidelity EM modelling in standard applications such as antenna siting on satellites. Further, we will deal with non-conventional EMC (electromagnetic compatibility) problems such as the modelling of antennas mounted on re-entry vehicles in the presence of plasma cloud and analysis of the interaction of antennas with plasma plume emitted by ion thrusters.
This seminar is based on the experiences gained by IDS in more than 30 years as a consulting company participating in satellite programs such as Sicral, Lisa pathfinder, SAC-D, Oceansat, Galileo, SmallGeo and Cosmo SkyMed.

Plasma Discharge

Topic: Space Plasma Discharge Transients from EMA3D

Presenter: Bryon Neufeld

Abstract: We demonstrate EMA3D’s ability to predict discharge transients from surface charging in a space plasma.  In our analysis, we obtain surface charging results in a space plasma environment and then evaluate discharge transients to cables and antennas.  We consider spacecraft-to-plasma, surface-to-surface, and spacecraft-to-spacecraft (rendezvous) discharges.  From a single geometric model, EMA3D allows the user to perform the entire space charging analysis, as well as seamlessly transition to other EMC simulations including lightning, HIRF, and conducted emissions.

 Webinar Video Recording:

Webinar PPT:

Lightning Class

HIGH INTENSITY RADIATED FIELDS (HIRF) COURSE

Electromagnetic Effects Compliance for Aircraft
HIRF/Lightning Design, Test Methods, and Regulatory Compliance

September 13-16, 2016

8:00AM – 5:00PM (T, W, TR)

8:00AM – 3:00PM (F)

National Institute for Aviation Research
Environmental Test Lab
3800 S. Oliver
Building 13L
Wichita, KS 67210

Fee:

  • $2,500 if registered before August 12, 2016
  • $2,750 if registered after August 12, 2016

Contact:
Andrew Nguyen
Email: environmental_lab@niar.wichita.edu
Phone: 978-5049

Register Here

About the course:
This comprehensive workshop will provide an awareness of all aspects HIRF and Lightning systems and aircraft testing in regard to compliance to the existing rules. In addition, with recent revisions to guidance material and FAA policy towards Fuel Tanks (25.981) and PED tolerance, it is critical that anyone working in this field be up to date on the developments.

For any questions about the class, feel free to Contact EMA

Topics include:

  • Background and Why HIRF is important?
  • The FAA/European requirements to demonstrate compliance – FAA/EASA Harmonized HIRF         and Lightning requirements
  • Equipment Qualification
  • Aircraft certification, modeling and testing (HIRF and IEL)
  • Pitfalls and problems
  • Design issues
  • Discussion of 25.981 Rule Revision Status
  • Using CEM Analysis to Support 25.981 Aircraft Certification Programs
  • Discussion on PED tolerance Policy

With emphasis on practical measurement and design guidance, this workshop is particularly relevant to engineers and technicians involved in aircraft HIRF and Lightning Clearance. As part of the practical presentations, the class will be providing demonstrations concerning critical aspects of the HIRF/IEL testing.

Presenters:

Billy Martin (NIAR: EME Lab Director: Regarded as one of the technical experts on HIRF and Lightning in the United States), Dave Walen (FAA’s Chief Scientific and Technical Advisor for HIRF, EMC and Lightning), Jeff Phillips (NIAR: Senior Research Engineer), Dr. Vignesh Rajamani, Ph.D. (Senior Associate, Technology Development Practice), Cody Weber (Senior Scientist at Electro Magnetic Applications, Inc.), Tim McDonald (Ph.D. Chief Scientist at Electro Magnetic Applications, Inc.).

Mesh Sensitivity

 

Finite Element Mesh Variation as Quality Assurance in Space Charging

EMA3D has tools which, when used in combination with Nascap-2K, provide the user a comprehensive and sophisticated space charging analysis framework.  One of the key capabilities that EMA3D provides is the ability to control the finite element mesh which serves as the basis for a Nascap-2K simulation object.

Control over the mesh within the EMA3D set of tools includes control over both the meshing algorithm and the mesh resolution.  Both of these aspects of the mesh are important to an analysis program.  Different mesh algorithms may represent different areas of the vehicle more accurately.  Some are stronger at maintaining the curvature of surfaces, while others are better at providing uniformity in the mesh gradient.

A finer mesh resolution generally provides more accurate results than a coarser mesh, however, a finer mesh takes longer to simulate.  In Nascap-2K the simulation time scales as the number of elements squared.  It is then desirable to find the coarsest mesh resolution which is still numerically accurate.

By using different simulation mesh algorithms and resolutions, the user can get a sense of the numerical accuracy and stability of their simulation results.  We present a flow chart that represents one possible strategy for using multiple meshes as the foundation of an accurate and stable simulation program:

 

1-mesh-algorithms-flow-chart

 

In this post, we flesh out some of the details of our flow chart and show how using multiple meshes can provide insight and confidence in the numerical accuracy of simulation results.

We show our simulation model in the figure below, where we have chosen three different mesh algorithms with roughly the same resolution to begin our sensitivity analysis with.  In the EMA3D/CADfix framework, the user starts with a geometrical model, assigns materials, and then meshes the geometry which gets directly exported as a Nascap-2K object.  The user can easily generate new meshes using a convenient mesh wizard.  New objects can be exported quickly, with the appropriate materials already assigned.

 

2-simulation-model-mesh-examles-for-nascap-nascap2k

 

Our model shown in the Figure is a simple model with just four materials: solar panels (cyan), elimstat paint (magenta), windows (blue) and FRSI thermal material (red).  The three different meshes are generated by three different algorithms that provide different combinations of curvature sensitivity and uniformity.

We simulate the model out to 10,000 seconds in a geosynchronous ‘worst case’ plasma.  We consider both a shaded (eclipse) environment and one in which there is illumination on the back side of the vehicle (away from windows and FRSI).

We start by looking at the results for the shaded scenario across these three algorithms.  We will look at sensitivity to the mesh resolution further down.  Our results are shown in the Figure below, where we plot the absolute maximum voltage to plasma on the vehicle minus the absolute minimum voltage to plasma on the vehicle, all scaled relative to the DELM mesh result.  By plotting in this way, we have an easy comparison across meshes for a relatively intuitive physical quantity.

When looking the plot, a couple of observations are in order.  First, the green curve corresponding to the DELC mesh (curvature sensitive mesh) shows a discrepancy relative to the other two meshes.  Second the green curve also appears to have some numerical fluctuations early in the simulation.  Taken together, our initial impression is that the DELC mesh is less accurate than the DELM and DELT meshes.  Our initial impression is also that these two meshes, DELM and DELT, are likely accurate since they are stable and agree with each other. However, in order to confirm these initial impressions, we look at the 3D plot of the voltage to plasma at the end of the simulation, which we show in the following Figure.

3-nascap-simulation-voltage-to-plasma-plot

4-3d-simulation-voltage-to-plasma-plot

 

The Figure shows a color representation of the induced voltages at the final moment of simulation.  We have included both the DELM and DELC meshes in the plot.  When looking at the 3D plot, we see that the DELC mesh has trouble capturing the spatial gradient on the solar arrays.  The results are choppy, especially compared to the smooth variation seen in the DELM mesh.  This confirms our initial impression that the DELC mesh results should be viewed with skepticism for this scenario.

We now consider a variation in the resolution of the mesh.  We have limited our analysis here to variations in the DELM mesh resolution.  The figure shows results in the same format as above for three different resolutions – labeled Fine, Medium and Coarse.  The number of mesh elements for each mesh is shown in the parenthesis next to the plot legend.

5-nascap-simulation-voltage-to-plasma-plot

When looking at variations in the mesh algorithm there is always some uncertainty as to which mesh should represent ‘baseline’.  However, when looking at variations in the mesh resolution, we can usually safely assume that the finer mesh is more reliable.  Looking at the results in the Figure we see that the Coarse mesh (776 elements) shows clear discrepancy with the Fine mesh (3622 elements), but that the Medium mesh (2050 elements) agrees relatively well with the Fine mesh.  In this case, the user may make a judgment based on the need for simulation speed versus the importance of numerical precision whether the Fine or Medium mesh is more suitable for their needs.  It is also possible that another mesh, perhaps with 2500 elements, would be a good compromise.

We now consider the results across the three algorithms for the scenario with illumination, which are shown in the Figure.  It is interesting to note in these results how much the DELC mesh results fluctuate relative to the other two meshes early in the simulation, but then they all converge toward later times.

6-nascap-simulation-voltage-to-plasma-plot

While it is reassuring to see consistency across the meshes in the ‘steady state’ of the results, the early fluctuations seen in the DELC mesh again indicate this mesh should be viewed with skepticism.  Although we have only plotted results relative to the DELM results as a ratio, the user can also plot the minimum and maximum voltages for each mesh separately.  Doing that would highlight clearly that the DELC mesh shows numerical instability at early times.

In this post, we have presented a strategy for using multiple meshes as the foundation of an accurate and stable space charging simulation program.  Our strategy takes advantage of the mesh and material capabilities present within the EMA3D/Nascap-2K interface.  Within this interface, the user can quickly generate simulation objects from different mesh algorithms and resolutions.  We have seen that numerical results can fluctuate between these different meshes and that by careful analysis the user can start to pinpoint which meshes are reliable and how fine a mesh resolution is required.  These capabilities help lay the groundwork for an accurate and reliable space charging analysis program.