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Challenge

Producing a surface mesh of around 100 million elements required breaking down the

geometry into smaller models, whose surface areas needed to be individually small enough

for the surface meshing algorithm to efficiently mesh. This required integrating a mechanical

model into a microwave simulation tool and using EM solvers to generate high quality surface

meshes of electrically small elements.

All elements had to be electrically small, with a guideline of triangle edge length between

λ/8 and λ/12 to give a suitable compromise with solution stability and size of problem. Also,

generating a large quantity of small elements would have an impact on memory and runtime

requirements, so an optimum triangle length would be required.

Using HyperWorks to Generate Electrically Large Surface

Meshes for Radar Cross Section or Antenna PlacementSimulation

HyperWorks is a division of 

Case Study

Overview

Radar Cross Section (RCS) and installed antenna placement are important parameters for

aircraft designs. RCS is a measure of how detectable an object, such as an aircraft, is with

radar. A large RCS indicates that an object, such as a jet aircraft, is easily detected.

SELEX Galileo used HyperWorks to generate arbitrarily large surface meshes, with defined

electrical properties at the element level, for use with electromagnetic (EM) solvers to

calculate either RCS of an aircraft or to determine where to place an antenna for optimum

performance.

 

For this case study a fast-jet aircraft with approximately 100 million mesh elements was

assessed for radar tracking and avoidance capabilities.

Business Profle

SELEX Galileo, a Finmeccanica Company, is a leader in defence electronics markets, with a

distinctive strength in airborne mission critical systems and a wide range of capabilities for

 the battlefield and for homeland security applications.

SELEX Galileo is a truly global business and employs 7000 staff across 5 continents.

Fig. 1: Sample Installed Antenna Pattern for Fast-Jet

Fig. 2: Sample RCS of Fast-jet about

Elevation Plane

www.altairhyperworks.co.uk

“HyperWorks has given us 

the capability to generate 

large meshes easily which 

has led to reduced risk 

and costs for designs that 

have integral microwave 

elements” 

Rob Cook 

Selex Galileo 

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Altair Engineering Ltd Imperial House, Holly Walk, Royal Leamington Spa, CV32 4JG, UK

Phone: 01926 468 600 • Fax: 01926 468 601 • www.uk.altair.com • info@uk.altair.com

Solution

SELEX Galileo used HyperMesh to generate the large quantities of small elements andapplied the numerical Method of Moments (MOM) model to describe how large, complex

structures would interact with EM fields.

A formula known as the Multi-Level Fast Multipole Method (MLFMM) was developed to better

deal with large structures by an iterative boxing of the structure into smaller and smaller

sections. This allows a reduction in the problem size, both in terms of memory requirements

and runtime.

To help generate these models, Altair developed an automation process that enabled SELEX

Galileo to sub-divide the full model. Once the full model was divided into small enough

components, a mesh was applied to the curves that defined the interfaces between each

component. This produced a series of nodes that bridged the sub-components.

Each of the sub-models that made up the full model was then written to an individual file.

Once the submodels were checked they were assigned electrical properties with various

parameters for each element, checked to ensure correct element properties, and then

assigned electrical properties specific to the EM solver in question.

Altair HyperWorks

Modeling and AssemblyRobust Design

Optimization

Design Analysis

Visualization

Reporting 

Virtual Manufacturing 

Process Automation

Data Management

For more information please visit

www.altairhyperworks.co.uk

Fig. 4: Example of Nodes Defined

Between Adjacent Components to

Ensure Mesh Continuity 

Fig. 5: Sub-Divided Model of Fast

  Jet Aircraft ~3 Million Elements per 

Component

Fig. 3: Distributions of Triangle Edge Length

0 5 10 15 20 25 30

Triangle Edge Length

   N  o  r  m  a   l   i  s  e   d   P  o  p  u   l  a   t   i  o  n   D  e  n  s   i   t  y Unacceptable

Acceptable

OptimisedFailure Region

Results

A process automation toolset was developed using HyperMesh to generate 100 million high

quality surface mesh elements for RCS and installed antenna performance simulations. It

demonstrated that mesh quality requirements could be aligned between meshing algorithms

and the EM solver, reducing need to rework exported meshes. This process allowed the

generation of arbitrarily large meshes without a limit set by local computing resources.

Integration with an EM solver based on MLFMM has given SELEX Galileo engineers the

capability to set electrical properties of the model in a GUI environment, which was previously

not available. The integration with the EM solver also allowed legacy models to be read into

a meshing environment, modified and have electrical properties assigned.

HyperWorks has helped SELEX Galileo designers to reduce development time of large EM

models, which will drive cost out of design activities.