Enhancing engineering design and analysis interoperability,

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Enhancing engineering design and analysis
interoperability, Part 1. Constrained Objects
First M.I.T. Conference on Computational Fluid
and Solid Mechanics June, 2001 Miyako W. Wilson,
Russell Peak, and Robert E. Fulton Georgia
Institute of Technology
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Motivation

• The need for a unified physical behavior modeling
  representation with the following characteristics
• Has tailoring for design-analysis integration
  including supports for multi-fidelity
  idealization, product-specific analysis
  templates, and CAD-CAE tool interoperability.
• Supports product information-driven analysis
  (I.e., supports plugging in detail design objects
  and idealizing them into a diversity of analysis
  models).
• Has computer-processible lexical forms along with
  human-friendly graphical forms.
• Represents relations in a non-casual matter
  (I.e., enables multi-directional combinations of
  model inputs/outputs).
• Capture engineering knowledge in a modular
  reusable form

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Constrained Object (COB) Overview - Techniques
Leveraged

• Object-oriented modeling Lalonde Pugh, et
  al.1990, Muller 1997
• class vs instance
• inheritance
• Constraint graph techniques Borning, et al.
  1990
• relations without fixed input/output direction
• Declarative knowledge representation (non-casual)
• Characterized by entities, attributes, and
  relations

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COB RepresentationComponents
COB
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Example COB Structure (COS)Spring Primitive
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Example COB Instance (COI)Spring Primitive
Lexical COB Instance (COI)
Constraint Schematic-I
example 1, state 1.1
state 1.0 (unsolved) INSTANCE_OF spring
undeformed_length 20.0 spring_constant
5.0 total_elongation ? force
10.0 END_INSTANCE state 1.1
(solved) INSTANCE_OF spring
undeformed_length 20.0 spring_constant
5.0 start ? end ? length 22.0
total_elongation 2.0 force
10.0 END_INSTANCE
Basic Constraint Schematic-I Notation
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Multi-Directional I/O (non-causal)Spring
Primitive
Constraint Schematic-I
Lexical COB Instance (COI)
Design Verification
example 1, state 1.1
state 5.0 (unsolved) INSTANCE_OF spring
undeformed_length 20.0 spring_constant ?
start 10.0 length 22.0 force
40.0 END_INSTANCE state 5.1
(solved) INSTANCE_OF spring
undeformed_length 20.0 spring_constant
20.0 start 10.0 end 32.0 length
22.0 total_elongation 2.0 force
40.0 END_INSTANCE
Design Synthesis
example 1, state 5.1
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COB Representation Traditional Form Spring
System
System Figure
Free Body Diagrams
System-Level Relations (Boundary Conditions)
Variables and Relations
Spring 1
Spring 2
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COB Representation Constraint Graph Spring
System
Spring 1
Spring 2
System level
Constraint Graph-S
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COB Representation Extended Constraint Graph-S
Two Spring System
Constraint Graph-S
Extended Constraint Graph-S

• Groups objects relations into parent objects
• Object-oriented vs. flattened

partial (BC relations not included)
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COB Representation Constraint Schematic Spring
System
Constraint Graph-S
bc3
P
bc4
Constraint Schematic-S
bc1
F

F

1
k
k
2
1
2
r13
spring2
spring 1
r23
spring1
L
x
L
1
11
x
2
22
D
D
L
L
r11
1
2
r21
r12
r22
x
x
21
12
L
L
bc6
bc5
10
20
bc5
bc1
u
u
1
2
bc2
bc2
bc3
spring 2
bc4
P

• Encapsulated form (hides details)
• Template re-usage

bc6
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COB Representation Constraint Schematic-S
Spring System
Analysis Primitives with Encapsulated Relations
spring 1
System-Level Relations (Boundary Conditions)
bc5
bc1
bc2
bc3
spring 2
bc4
P
bc6
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COB Representation COS Language Spring System
COS Language
Constraint Schematic-S
COB spring_system spring1 spring
spring2 spring deformation1, ultsubgt1lt/subgt
REAL deformation2, ultsubgt2lt/subgt REAL
load, P REAL RELATIONS r1
"ltspring1.startgt 0.0" r2 "ltspring1.endgt
ltspring2.startgt" r3 "ltspring1.forcegt
ltspring2.forcegt" r4 "ltspring2.forcegt
ltloadgt" r5 "ltdeformation1gt
ltspring1.total_elongationgt" r6
"ltdeformation2gt ltspring2.total_elongationgt
ltdeformation1gt" END_COB
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COB Representation COB Instance (COI) Spring
System
Constraint Schematic-I
COI Language
state 1.0 (unsolved) INSTANCE_OF spring_system
spring1.undeformed_length 8.0
spring1.spring_constant 5.5
spring2.undeformed_length 8.0
spring2.spring_constant 6.0 load 10.0
deformation2 ? END_INSTANCE state 1.1
(solved) INSTANCE_OF spring_system
spring1.undeformed_length 8.0
spring1.spring_constant 5.5 spring1.start
0.0 spring1.end 9.818 spring1.force
10.0 spring1.total_elongation 1.818
spring1.length 9.818 spring2.undeformed_lengt
h 8.0 spring2.spring_constant 6.0
spring2.start 9.818 spring2.force 10.0
spring2.total_elongation 1.667
spring2.length 9.667 spring2.end 19.48
load 10.0 deformation1 1.818
deformation2 3.485 END_INSTANCE
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COB Representation Lexical and Graphical Views
COB Structure (COS)
COB Instance (COI)
Subsystem -S view
Constraint Schematic-S
COB Structure (COS)
Language
I/O Tables

Object Relationship Diagram
Constraint Graphs-S
Extended Constraint Graphs-S
HTML
Express-G
STEP
Express
HTML
Constraint Graph Constraint Network
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COB RepresentationComponents (see Wilson,2000)
COB
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COB Meta Information Model Protocol Generic
Nature
Generic Metadata
Meta Information Model
Protocol
COB Instance Definition Data
COB Structure Definition Data
Generic Data
COI
COS
Specific Structure Data
Specific Instance Data
Definition Languages
Example
Graphical Representations
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XaiTools X-Analysis Integration Toolkit
Java
COB Definition Files
Solvers
API
COB based Design/Analysis Tools
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Using Internet/Intranet-based Analysis Solvers
Thick Client Architecture
Users
Engineering Service Bureau
Client PCs
Host Machines
Thick Client
CORBA Daemon
Iona orbixdj
XaiTools
CORBA IIOP
CORBA Servers
Internet
XaiTools Ansys Solver Server
XaiTools Ansys Solver Server
XaiTools Math. Solver Server
XaiTools Ansys Solver Server
FEA Solvers
Ansys
Internet/Intranet
...
Math Solvers
Mathematica
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XaiTools COB BrowserSpring System

• Functionality
• View
• Change value
• Change I/O
• Activate/Disactivate
  relations

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Constrained Object (COB) Representation

• Capabilities features
• Various forms computable lexical forms,
  graphical forms
• Sub/supertypes, basic aggregates, multi-fidelity
  objects
• Multi-directionality (I/O change)
• Wrapping external programs as white box relations
• Analysis module/template applications (XAI)
• Product model idealizations
• Explicit associativity relations with design
  models other analyses
• White box reuse of existing tools (e.g., FEA,
  in-house codes)
• Reusable, adaptable analysis building blocks
• Synthesis (sizing) and verification (analysis)

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Constrained Objects (cont.) Representation
Characteristics Advantages

• Overall characteristics
• Declarative knowledge representation (non-causal)
• Combining object constraint graph techniques
• COBs (STEP EXPRESS subset) (constraint
  graph concepts views)
• Advantages over traditional analysis
  representations
• Greater solution control
• Richer semantics (e.g., equations wrapped in
  engineering context)
• Unified view of diverse capabilities
• Capture of reusable knowledge
• Enhanced development of complex analysis models