The role of the Engineering Analysis Core Model in STEP

1
The role of the Engineering Analysis Core Model
in STEP

• Presentation to ISO TC184/SC4 (Change Management)
• by David Leal

2
EACM objectives - 1
integration of analysis in the business process

• Activities and states are principal objects
  alongside product
• activities and states are designed - not merely
  analysed
• activities and states have configuration
  management
• activities and states have test data
• Trace back of all data to source
• link to a design decision, an analysis
  calculation or a test data reduction process

3
EACM objectives - 2
independent of discipline or solution method

• Generic approach to all properties
• shape, material, environment, analysis results,
  test data
• dictionary of property types
• formal approach to field representation
• use of ISO 10303-50
• field descriptions using b-splines or meshes,
  independent of analysis model
• reusable by any analysis

4
Backbone of the EACM
PDM
product
activity
state
design and analysis processes
deemed or predicted possession of property
property
mathematical description of fields
description
mathematics
5
Shape defined function
maths
Linear function
B-spline function
representation
Elementary function
Maths function
Externally defined function
Distribution mapping
Property identification
Tabular function
Maths value
Product activity and state space parameterisation
Maths space
Property space
Mesh function
Property distribution
Property dictionary
Property
Possession of property statistics and probability
FEA defined mesh function
Activity or state space
Product feature space
Mesh
Possession of property
Structured mesh
State
Possession of property validity
FEA defined mesh
Unstructured mesh
Product specification or set
Activity
mesh
definition
Behaviour
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EACM schedule
EACM (part 107) NWI

• part 51 (CD October 2000)
• mathematical representations - extensions to 43
• mesh and mesh function - extensions to 42 and 50
• EACM modules (DTS - technically complete by June
  2000)
• 30 modules parts 10
• activity passes to AP 235 (MATINF), and the
  proposed fluid dynamics AP

7
Content of presentation

• Why PDM applies to activities and states
• How the EACM relates to workflow management and
  best practice advice
• How the EACM uses part 50
• Impact on the IRs
• Why STEP part 41 has limitations!

8
PDM for activities and states
activity something that happens
Products undergo/perform activities during
manufacture and in service. An activity takes a
product through a sequence of states.
state condition of a product at an instant
A state of a product is caused by a
previous activity and is an initial state for a
future activity.
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Versions for products and activities
part family ABC
shut down for ABC
variants
variants
compatibility ?
ABC/1
ABC/2
ssd/1
ssd/2
succession
succession
variants
variants
ABC/2/ arctic
ABC/2/ tropical
ssd/2/ loc
ssd/2/ lohs
product versions
activity versions
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Structure for products and states
part version ABC/1
ABC running
assembly
assembly
ABC_X/1
ABC_Y/1
ABC_X stopped
ABC_Y idling
assembly
assembly
ABC_Y1/1
ABC_Y2/1
ABC_Y1 open
ABC_Y2 shut
product structure
state structure
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Workflow management and BPA
A property can be
deemed by a design activity
measured by a test activity
calculated by an analysis activity.
audit trail record the activity and its type
WFM specify the activity and its type
BPA document best practice for types of activity
Activity types are modelled and held in a
dictionary
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Source for properties
design process
analysis process
deems
predicts
state op/2 for part ABC
410 degrees Celsius operating temperature
power output of 100 MW
power output of 95 MW
test process (after data reduction)
predicts
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Type of activity
stored as data in a dictionary
controls
analysis objectives
analysis guidelines
conduct FEA analysis
shape information
displacement field information
material information
loading information
stress field information
boundary condition information
outputs
inputs
FEA analysis code
computer system
mechanisms
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Actual activity
recorded by WFMS
controls
widget analysis objectives document widget_xyz_ana
l.doc
J. Bloggs widget analysis guidelines document widg
et_guide.doc
conduct FEA analysis on widget xyz
shape data file widget_xyz_shape.stp
material data file widget_xyz_material.stp
displacement results file widget_xyz_disp.stp
loading data file widget_xyz_load.stp
stress results file widget_xyz_stress .stp
boundary condition data file widget_xyz_bc.stp
outputs
inputs
ABAQUS_ 5_1.exe
my PC on 1999-01-06
mechanisms
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Material test activity
environment
test specimen
test laboratory
material test
test machine
test engineer
results
16
Use of mathematics
A mathematical function can describe the
variation of a property with respect to position
within a product, state within an activity or
both, where
function domain parameterises the product,
activity or both
function range represents the property space
temperature variation within widget XYZ during
activity widget_XYZ start up
function R4
R1
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Choice of function
discrete property variation
tabular function
as in ESA NRF
values for sensors and time steps
b-spline function
using CAD parameterisation as in DT-NURBS
continuous property variation
interpolated values
mesh function
using structured or unstructured mesh
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Value, space and function
representation
maths value
property value
my stress
0.2, 0.0, 0.1, 0.0, 0.3, 0.0 0.1, 0.0. 0.4)
product feature space state space
parameterisation
points in my_widget
maths space
real 3 arrays
real 33 matrices
property space
scale/context
stress
representation
property distribution
maths function
stress distribution in my_widget
my_function over my_mesh
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Impact on the IRs

• extensions to part 43 to reference maths_value,
  maths_space and maths_function (in 51?)
• subtype of product_definition for state (in AM?)
• subtypes for property_value, property_space and
  property_distribution (in AM?)
• extensions to part 42 for structured and
  unstructured mesh topology (in 51?)
• extensions to part 50 for mesh_function (in 51?)

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Why part 41 has limitations
The structures above product_definition (i.e.
product_ category, product and product_definition_
formation) are arbitrary and limit the use of
STEP.
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A product configuration
1992 envoy suspension system
1992 envoy paint specification
1992 envoy
Vauxhall cavalier
motor car
L206 VGK
22
The part 41 entities
product_definition
product_definition
product_definition_ formation
product
product_category
product_definition
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Some set theory relationships
product_category
motor car
SET 1,? products
specialisation
product
Vauxhall cavalier
specialisation
of_product
product_definition_formation
1992 envoy
intersection
classification
formation
product_definition
1992 envoy suspension system
1992 envoy paint specification
L206 VGK
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The limitations of part 41

• A product_definition cannot have versions.
• The 1992 envoy paint specification cannot have
  versions.
• A product_definition is part of only one
  product_definition_formation.
• The 1993 envoy cannot have the 1992 paint
  specification, but a different suspension system.
  
• Different instances of product_definition cannot
  be intersected to create a new product_definition.
  
• The 1993 envoy paint specification cannot be
  defined as the intersection of a chemical
  specification and a curing specification.

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Making the set theory rigorous
superclass
class
specialisation_of_class
subclass
result
intersection_of_class
SET2,? operand
product_category
motor car
product
Vauxhall cavalier
product_definition_formation
1992 envoy
product_definition
1992 envoy suspension system
1992 envoy paint specification
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Connection and composition
Connection and composition are relationships betwe
en instances of product_definition.

• The 1992 envoy electrical definition can have the
  electrical definition of the Bloggs and Co. ABC_1
  type wiper motor as a part.
• The 1992 envoy cannot have the Bloggs and Co.
  ABC_1 type wiper motor as a part.

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Generic product structure

• Connection and composition of product_category
• motor car has one or more wiper motors
• Connection and composition of product
• Vauxhall Cavalier has a Bloggs ABC type wiper
  motor
• Connection and composition of product_definition_f
  ormation
• 1992 Vauxhall Cavalier envoy has a Bloggs ABC_1
  model wiper motor
• Connection and composition of product_definition
• 1992 Vauxhall Cavalier envoy electrical
  definition contains a Bloggs ABC_1 model wiper
  motor electrical definition

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Composition for product class
whole
class
composition
part
A 1992 Vauxhall Cavalier envoy has a Bloggs model
ABC_1 wiper motor
product_category
product
product_definition_formation
product_definition
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EACM approach to Part 41

• A state is a subtype of product_definition,
  whether a category, formation or
  definition.
• An activity is a subtype of action, whether a
  category, formation or definition.

This is cheating, but will do for now.
Part 50 generalises part 42 and gives it a more
rigorous mathematical basis. We need to do the
same for part 41.