# Presentation: 066874

## Use of AP203 CAD Data for Engineering Analysis

- Hans Peter de Koning - ESA/ESTEC - The Netherlands
- Hans-Peter.de.Koning@esa.int
- Sandrine Fagot - Simulog - France
- Sandrine.Fagot@simulog.fr
- STEP for Aerospace Workshop, NASA-JPL, 16-19 January 2001

**Notes:**
<Simulog est une société fondée à l’initiative de l’INRIA (INSTITUT NATIONAL DE RECHERCHE EN INFORMATIQUE ET AUTOMATIQUE) il y a plus de 10 ans, en 1984.
La définition de la mission de l’entreprise  est basée sur l’objectif initial de ses initiateurs: être un pont entre l’industrie et la recherche publique.

La mission de l’entreprise comporte deux points qui reflètent notre stratégie mais aussi le marché sur lequel Simulog évolue:
L’objectif numéro 1 est de fournir une gamme de prestation complète: Simulog doit intégrer les solutions proposées dans l’environnement industriel préexistant de ses clients.
Cette connaissance approfondie des besoins du client , de son métier et de son environnement permet d’atteindre plusieurs objectifs positifs: 1. la mise en confiance du client, qui facilite le dialogue lors de la phase de spécification des besoins (meilleure compréhension des besoins) et lors de l’apport des solutions nouvelles (plus grande facilité à obtenir l’adhésion du client). 2. la fidélisation du client, qui permet d'accroître l’efficacité et la rentabilité des études au fur et à mesure.
L’objectif numéro 2 consiste à s’adapter aux nouvelles technologies pour offrir au client une solution industrielle à un problème ne pouvant être traité par les méthodes classiques.
>

## Agenda

- Recap: Usage of CAD to create CAE model
- Use of AP203 as input
- Specific application for thermal-radiative CAE (ESARAD)
- Real world example
- Further plans

- STEP for Aerospace Workshop - NASA-JPL

- 16-19 Jan 2001

## Recap: Why use CAD geometry to construct CAE models?

- Main objectives:
- To reduce CAE model construction effort
- To improve CAE model accuracy and fidelity
- To transfer and retain product structure and part identification information
- To improve consistency between CAE models for different engineering disciplines -- CAD model as ‘master digital mock-up’
- Avoid duplication of effort
- If it has been modelled in CAD already, why do it again?
- CAD modeller is probably richer in shape creation functionality than the CAE modeller

- STEP for Aerospace Workshop - NASA-JPL

- 16-19 Jan 2001

## Potential pitfalls with usage of CAD for CAE

- CAE virtually always needs idealised shape
- Idealised shape = geometric represention of the object under analysiswhich is appropriate, adequate and sufficiently detailedfor the analysis task at hand
- Who said engineering is a hard science?
- Lot of engineering judgement involved
- Depends on environmental conditions, operational context
- Depends on engineering life cycle stage
- Nevertheless, still serious benefits from automated transfer of CAD models to CAE when used with caution

- STEP for Aerospace Workshop - NASA-JPL

- 16-19 Jan 2001

## Use of AP203 for CAD - CAE model transfer

- Nearly all CAD tools now have reliable, good quality AP203 import/export functionality
- Very attractive for CAE tools to support AP203
- Good investment: one interface supports all CAD tools
- First import of AP203 models, later perhaps also export
- But also problems
- Most CAE tools can not directly handle all AP203 shapes
- NURB curves and surfaces, trimming loops, general surface of revolution, etc.
- Different CAD tools generate different AP203 models
- For example: many different ways to define a cylindrical surface

**NURB = **
**Non-Uniform **
**Rational B-spline**

- STEP for Aerospace Workshop - NASA-JPL

- 16-19 Jan 2001

## Specific Application: Thermal-radiative CAE

- STEP AP203 model import and NURB processing capability for ESARAD
- R&D activity in 2000 under ESA contract
- ALSTOM Power Technology Centre (UK)
- ESARAD tool vendor
- Management, integration and test
- Simulog (France)
- AP203 to ESARAD import translator
- Formal Software Construction Ltd. (UK)
- ESARAD NURB surface processing

**ESARAD = **
**Thermal-radiative analysis tool ****(Monte-Carlo raytracer)**

- STEP for Aerospace Workshop - NASA-JPL

- 16-19 Jan 2001

## Usage scenario: Construct CAD/AP203 to ESARAD

- Identify CAD model for export
- Optionally prepare ‘CAE view’ in CAD tool
- Suppress features, filter small details, flatten hierarchy, remove irrelevant parts
- Export to STEP AP203 part 21 file
- Translate AP203 model to native ESARAD model
- Clean-up and adapt model in ESARAD modeller
- Add thermal-radiative features
- meshing, properties, environmental conditions, kinematics, ...
-  Ready to run ESARAD analysis

- STEP for Aerospace Workshop - NASA-JPL

- 16-19 Jan 2001

## Translate AP203 model to native ESARAD model (1)

- Problem: Mapping of AP203 shapes to ESARAD shapes
- ESARAD is a surface modeller
- primitive surface shapes
- triangular, rectangular, quadrilateral plate
- disc (-sector, -annulus)
- cylinder (-segment)
- cone, sphere, paraboloid (-segment, truncated-)
- compound surfaces (union of primitive or compound surfaces)
- boolean cut surfaces (e.g. plate with circular hole)
- Most CAD tools export AP203 evaluated BREP solid models
- AP203 CC4, CC5, CC6 models with lots of advanced shapes using NURB, trimming loops, etc.

- STEP for Aerospace Workshop - NASA-JPL

- 16-19 Jan 2001

## Translate AP203 model to native ESARAD model (2)

- Approach
- Develop heuristic algorithm to recognise / deduct as much as possible primitive shapes in the CAD AP203 export
- Transfer any remaining shapes as NURB surfaces (with trimming loops)
- Retain model hierarchy and axis placements
- Retain shape identification labels, etc.
- Translator is a stand-alone Unix filter type tool
- Simple, maintainable, easily extendible to support new output formats
- Upgrade ESARAD to accept NURB surfaces
- In shape definition, but also in ray-tracing algorithm!

- STEP for Aerospace Workshop - NASA-JPL

- 16-19 Jan 2001

## Translate AP203 model to native ESARAD model (3)

- Target Catia v4 as first CAD export tool for testing
- Is most used CAD tool in European space industry
- Developed Catia generated AP203 test suite
- Artificial little CAD models containing different ways to construct the primitive shapes (also asking different engineers)
- Replicated the STEP-TAS test suite using Catia
- Real world CAD models, including a complete detailed spacecraft CAD model (generates more than 220,000 instances in Part 21 file)
- Developed heuristic algorithm
- As much as possible works on generic STEP p42 concepts
- As little as possible tuned to Catia specific constructs / oddities
- Outcome is a translator that works!

- STEP for Aerospace Workshop - NASA-JPL

- 16-19 Jan 2001

## Translate AP203 model to native ESARAD model (4)Example from test-suite

- STEP for Aerospace Workshop - NASA-JPL

- 16-19 Jan 2001

## Real World Example: Test jig for METOP spacecraft

- METOP: earth observation satellite for Eumetsat
- Sun-synchronous polar orbit - similar to ERS, Envisat, NASA-EOS
- Modelled in detail in ESARAD (more than 4000 surfaces)
- Currently in Phase C/D - Starting thermal balance test predictions
- Task: Create ESARAD model of test jig
- Test jig for thermal test, containing cold targets and guard heaters
- Complicated shape - geometry available in Catia v4

- STEP for Aerospace Workshop - NASA-JPL

- 16-19 Jan 2001

## Real World Example: Test jig for METOP spacecraftAP203 export from Catia

- HEADER;
- FILE_DESCRIPTION((''), '1');
- FILE_NAME('METOP FRAME UPPER                                                               ',
-           '2000-09-25T09:11:38+02:00',
-          (''),
-          (''),
-           'CATIA.STEP INTERFACE',
-           'CATIA SOLUTIONS V4   RELEASE 2.0 FR 4.2.0',
-           '');
- FILE_SCHEMA(('CONFIG_CONTROL_DESIGN'));
- ENDSEC;
- DATA;
- #1=APPLICATION_CONTEXT('configuration controlled 3D designs of mechanical parts and assemblies');
- #2=APPLICATION_PROTOCOL_DEFINITION('international standard','config_control_design',1994,#1);
- #3=PERSON('111111','Last_Name','First_Name',$,$,$);
- ...
- #650=VERTEX_POINT('NONE',#649);
- #651=B_SPLINE_CURVE_WITH_KNOTS('*CRV273',1,(#652,#653),.UNSPECIFIED.,.U.,.U.,(2,2),(0.00000000000,1.00000000000),.UNSPECIFIED.);
- #652=CARTESIAN_POINT('NONE',(-6663.00000000,2.51588360813,-18.6521285509));
- ...
- #16704=TRIMMED_CURVE('*CRV558',#16703,(90.0000000000),(108.628958036),.T.,.UNSPECIFIED.);
- #16705=B_SPLINE_CURVE_WITH_KNOTS('*CRV559',5,(#16706,#16707,#16708,#16709,#16710,#16711,#16712,#16713,#16714,#16715,#16716,#16717),.UNSPECIFIED.,.U.,.U.,(6,3,3,6),(0.00000000000,1.00000000000,1.70960642440,2.31910764281),.UNSPECIFIED.);

**Real World Example: Test jig for METOP spacecraft****AP203 export from Catia**

- STEP for Aerospace Workshop - NASA-JPL

- 16-19 Jan 2001

## Real World Example: Test jig for METOP spacecraftTranslation into ESARAD definition language

- /* ESARAD GENERATED FILE FROM STEP AP203 FILE			 */
- /* ------------------------------------------			 */
- /* INFORMATION ON STEP AP203 FILE :				 */
- /*   COMPANY              :  */
- /*   LOCATION             : location */
- /*   SERVICE              : service name */
- /*   PERSON               :  */
- /*   PROJECT              : project name */
- /*   PREPROCESSOR_VERSION : CATIA.STEP INTERFACE */
- /*   ORIGINATING_SYSTEM   : CATIA SOLUTIONS V4   RELEASE 2.0 FR 4.2.0 */
- /*   DATE                 : 25/9/2000 */
- BEGIN_MODEL MetopFrameUpper
- SHELL generated_id_1;
- generated_id_1 = SHELL_DISC(
-  point1 = [ -6.763000, 1.125000, 0.160000],
-  point2 = [ -6.762765, 1.125882, 0.159592],
-  point3 = [ -6.763000, 1.127516, 0.165447],
-  point5 = [ -6.763000, 1.122903, 0.155461]);

- SHELL generated_id_3;
- generated_id_3 = SHELL_NURB_SURFACE(
-  u_dim = 9,
-  v_dim = 2,
-  points = {[-6.727706, 1.254837, 0.093422], [-6.698294, 1.365131, 0.042479],
-            [-6.733537, 1.256119, 0.092830], [-6.704126, 1.366413, 0.041887],
-            [-6.733537, 1.258635, 0.098277], [-6.704126, 1.368929, 0.047334],
-            [-6.733537, 1.261150, 0.103724], [-6.704126, 1.371445, 0.052781],
-            [-6.727706, 1.259869, 0.104316], [-6.698294, 1.370163, 0.053373],
-            [-6.721874, 1.258587, 0.104908], [-6.692463, 1.368881, 0.053965],
-            [-6.721874, 1.256071, 0.099461], [-6.692463, 1.366365, 0.048518],
-            [-6.721874, 1.253555, 0.094014], [-6.692463, 1.363850, 0.043071],
-            [-6.727706, 1.254837, 0.093422], [-6.698294, 1.365131, 0.042479]},
-  weights = {1.000000, 1.000000,
-             0.707107, 0.707107,
-             1.000000, 1.000000,
-             0.707107, 0.707107,
-             1.000000, 1.000000,
-             0.707107, 0.707107,
-             1.000000, 1.000000,
-             0.707107, 0.707107,
-             1.000000, 1.000000},
-  u_degree = 2,
-  v_degree = 1,
-  u_knots = {0.000000, 0.000000, 0.000000, 1.570796, 1.570796, 3.141593, 3.141593, 4.712389, 4.712389, 6.283185, 6.283185, 6.283185},
-  v_knots = {0.150000, 0.150000, 0.275000, 0.275000},
-  num_loops = 1,
-  loops = {
-   DEFINE_NURB_TRIM_LOOP (
-    num_curves = 4,
-    curves = {

- STEP for Aerospace Workshop - NASA-JPL

- 16-19 Jan 2001

## Real World Example: Test jig for METOP spacecraftRaw AP203 export in ESARAD

- Produced with first beta version of translator Sep-2000
- All NURB-related shapes removed, because at that stage not yet supported in ESARAD visualisation and ray-tracing
- Still a large amount of useful reference surfaces and points

- STEP for Aerospace Workshop - NASA-JPL

- 16-19 Jan 2001

## Real World Example: Test jig for METOP spacecraftFinal jig model positioned on spacecraft

- After adaptation in ESARAD modeller and adding thermal features
- Estimated 25% reduction in model construction effort
- So, even without NURB support already significant savings

- STEP for Aerospace Workshop - NASA-JPL

- 16-19 Jan 2001

## Ray-tracing with NURB surfaces

- Status:
- Algorithm works functionally
- First round of performance tuning done
- Just before workshop delivered to ESA for acceptance testing
- Functionality will be incorporated in next industrial release of ESARAD

- STEP for Aerospace Workshop - NASA-JPL

- 16-19 Jan 2001

## Example NURB shapes now supported in ESARAD ray-tracing

- Some X-38-like concept -- no status -- just a test model

- STEP for Aerospace Workshop - NASA-JPL

- 16-19 Jan 2001

## Conclusions

- Import from CAD to ESARAD is working well
- Could not have been done sensibly without STEP
- Very promising development
- Emphasis is on improving the engineering analysis cycle
- NURB support in ESARAD is for most cases not really needed from the thermal analysis point of view
- Striving to increase the efficiency and effectivity of the engineer, not optimising on CPU or other computer resource usage
- However, high-fidelity NURB surfaces can be appropriate in some special cases thermal or thermal/optical analysis
- Mirror optics
- Parasitic heatloads infra-red sensors, passive cooler baffles

- STEP for Aerospace Workshop - NASA-JPL

- 16-19 Jan 2001

## Future

- Complete testing
- Testing with exports from other CAD packages - enhancement of heuristic shape recognition
- Improve transfer of product and part info (meta data)
- AP203 to STEP-TAS converter?
- AP203 import and NURB ray-tracing in next major industrial release of ESARAD

- STEP for Aerospace Workshop - NASA-JPL

- 16-19 Jan 2001