Use of AP203 CAD Data for Engineering Analysis

1
Use of AP203 CAD Data for Engineering Analysis

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

2
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

3
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

4
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

5
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
6
Specific Application Thermal-radiative CAE

• STEP AP203 model import and NURB processing
  capability for ESARAD
• RD 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)
7
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

8
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.

9
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!

10
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!

11
Translate AP203 model to native ESARAD model
(4)Example from test-suite
12
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

13
Real World Example Test jig for METOP
spacecraftAP203 export from Catia
ISO-10303-21 HEADER FILE_DESCRIPTION((''),
'1') FILE_NAME('METOP FRAME UPPER

', '2000-09-25T0911380200',
(''), (''), 'CATIA.STEP
INTERFACE', 'CATIA SOLUTIONS V4
RELEASE 2.0 FR 4.2.0',
'') FILE_SCHEMA(('CONFIG_CONTROL_DESIGN')) ENDSE
C DATA 1APPLICATION_CONTEXT('configuration
controlled 3D designs of mechanical parts and
assemblies') 2APPLICATION_PROTOCOL_DEFINITION('
international standard','config_control_design',19
94,1) 3PERSON('111111','Last_Name','First_Name
',,,) ... 650VERTEX_POINT('NONE',649) 651
B_SPLINE_CURVE_WITH_KNOTS('CRV273',1,(652,653)
,.UNSPECIFIED.,.U.,.U.,(2,2),(0.00000000000,1.0000
0000000),.UNSPECIFIED.) 652CARTESIAN_POINT('NON
E',(-6663.00000000,2.51588360813,-18.6521285509))
16704TRIMMED_CURVE('CRV558',16703,(90.00000
00000),(108.628958036),.T.,.UNSPECIFIED.) 16705
B_SPLINE_CURVE_WITH_KNOTS('CRV559',5,(16706,167
07,16708,16709,16710,16711,16712,16713,1671
4,16715,16716,16717),.UNSPECIFIED.,.U.,.U.,(6,3
,3,6),(0.00000000000,1.00000000000,1.70960642440,2
.31910764281),.UNSPECIFIED.)
14
Real World Example Test jig for METOP
spacecraftTranslation 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_i
d_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_LOO
P ( num_curves 4, curves
15
Real World Example Test jig for METOP
spacecraftRaw 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

16
Real World Example Test jig for METOP
spacecraftFinal 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

17
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

18
Example NURB shapes now supported in ESARAD
ray-tracing
Some X-38-like concept -- no status -- just a
test model
19
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

20
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