CDEDS (Constraint Driven Engineering Design Synthesis) Methodology - PowerPoint PPT Presentation

About This Presentation
Title:

CDEDS (Constraint Driven Engineering Design Synthesis) Methodology

Description:

CDEDS (Constraint Driven Engineering Design Synthesis) methodology is used in conceiving new solutions to solve a problem by recognizing the “Concept – PowerPoint PPT presentation

Number of Views:76

less

Transcript and Presenter's Notes

Title: CDEDS (Constraint Driven Engineering Design Synthesis) Methodology


1
CDEDS (Constraint Driven Engineering Design
Synthesis) Methodology
2
CDEDS (Constraint Driven Engineering Design
Synthesis) Methodology
Introduction
  •  Design is defined as creation of new things and
    Synthesis is the creative step itself in
    conceiving new solutions to solve a problem.
    Engineering is a subset of these design
    activities and it focuses more on the technical
    aspects of performance of designed systems.
    Engineering Design Synthesis is therefore key to
    defining effective methodologies and selection of
    appropriate software tools. 

 
http//cadvisionengineers.com/
3
CDEDS (Constraint Driven Engineering Design
Synthesis) Methodology
Different Stages of CDEDS Design Synthesis
  • The methodology has recognized two stages of
    Design Synthesis, Namely
  • Concept Phrasing  (non-detail)
  • Concept Detailing

 
http//cadvisionengineers.com/
4
CDEDS (Constraint Driven Engineering Design
Synthesis) Methodology
1. Concept Phrasing
  • During the creative stage of Concept Phrasing,
    an engineer is interested in answering the how
    of the problem.
  • Multiple concepts are to be invented and
    evaluated.
  • Conditions of acceptance typically relate to form
    and function and less to fit, physics or
    performance.

 
http//cadvisionengineers.com/
5
CDEDS (Constraint Driven Engineering Design
Synthesis) Methodology
1. Concept Phrasing
  • Using a office cabinet door flap example, lets
    look into the functional requirements

Specification Requirement
  • Design a door flap for a wall mounted office
    cabinet measuring Height 3 x Width 2 x Depth
    2.

http//cadvisionengineers.com/
6
CDEDS (Constraint Driven Engineering Design
Synthesis) Methodology
1. Concept Phrasing
Concept 1 Design a swing door flap that can
swing 90 degree for complete cabinet access.
http//cadvisionengineers.com/
7
CDEDS (Constraint Driven Engineering Design
Synthesis) Methodology
1. Concept Phrasing
  • The large swing radius of Concept 1 is not
    convenient on cabinet doors that are taller than
    2.5 (or more than average arm length). 
  • We need a door flap with smaller swing radius and
    yet provide full access to inside of cabinet.

http//cadvisionengineers.com/
8
CDEDS (Constraint Driven Engineering Design
Synthesis) Methodology
1. Concept Phrasing
Concepts 2A and Concepts 2B
Below images shows two candidate concepts. 
http//cadvisionengineers.com/
9
CDEDS (Constraint Driven Engineering Design
Synthesis) Methodology
1. Concept Phrasing
Concepts 2A and Concepts 2B
From the image we can conclude that,
  • Concept 2A uses a sliding door flap.
  • Concept 2B uses a split door flap that folds on
    itself.
  • Both provide reduced swing radius but suffer from
    reduced access to the top shelf.
  • We need clear passage to all the cabinet shelves
    in addition to reduced swing radius.

http//cadvisionengineers.com/
10
CDEDS (Constraint Driven Engineering Design
Synthesis) Methodology
1. Concept Phrasing
Concept 3
It Shows a shorter swing radius.
http//cadvisionengineers.com/
11
CDEDS (Constraint Driven Engineering Design
Synthesis) Methodology
1. Concept Phrasing
Concept 3
  • The door flap is moved vertically up by a
    parallelogram mechanism. 
  • It also provides clear passage to the all the
    shelves.
  • Since the door flap is at least 3 tall and opens
    upwards.
  • The installation of this mechanism demands a high
    roof clearance not usually available in offices
    with false roofing. 
  • So we now need a design that has reduced swing
    radius.

http//cadvisionengineers.com/
12
CDEDS (Constraint Driven Engineering Design
Synthesis) Methodology
1. Concept Phrasing
Concept 4
Key take-away from Concept Phrasing example
http//cadvisionengineers.com/
13
CDEDS (Constraint Driven Engineering Design
Synthesis) Methodology
1. Concept Phrasing
Concept 4
Key take-away from Concept Phrasing example
  • The first three concepts above, differ vastly
    from one another on how they approach the problem
    and so the mechanisms are also different. 
  • The fourth one, is a variation of the
    parallelogram concept 3.
  • It clearly shows that in the early stages of
    phrasing we need variety and also a bulk of
    ideas.
  • Seeing the operational constraints early during
    ideation saves time and cost compared to seeing
    them later in the project life cycle.

http//cadvisionengineers.com/
14
CDEDS (Constraint Driven Engineering Design
Synthesis) Methodology
1. Concept Phrasing
Concept 4
Key take-away from Concept Phrasing example
  • One can also notice that different working
    mechanisms result from different functional
    constraints being overlaid on the basic
    specification.
  • These constraints, more so during Phrasing, can
    be translated to fundamental physical parameters
    like dimensional height, weight, area etc.
  • The concepts can be sketched by hand or drawn
    using software but the key requirements are
    variety and bulk.

http//cadvisionengineers.com/
15
CDEDS (Constraint Driven Engineering Design
Synthesis) Methodology
2. Concept Detailing
  • In Concept Detailing, one (or more) concepts
    from phrasing stage are typically subjected
    to Engineering rigor. 
  • They are integral to making concepts practical
    beyond just dimensional requirements. 
  • Depending on where you would want to stop, this
    step can actually end in well-conceived design
    solutions.
  •  This are practical, meet engineering rigor and
    meet marketing specifications.

http//cadvisionengineers.com/
16
CDEDS (Constraint Driven Engineering Design
Synthesis) Methodology
2. Concept Detailing
Take Excavator example
  • This example shows the selection of appropriate
    tools to address this stage of Engineering Design
    Synthesis.

Design Specification
  • Design an excavator work group for a 23 ton
    tracked excavator that includes a boom, a dipper
    arm and a 1.2 cu.m bucket that delivers the range
    dimensions given.

http//cadvisionengineers.com/
17
CDEDS (Constraint Driven Engineering Design
Synthesis) Methodology
2. Concept Detailing
Take Excavator example
Design Specification
  • The boom pivot point on the turntable should be
    at least 1200 mm from ground and at least 100 mm
    from slew centre to provide clearance for other
    machinery

http//cadvisionengineers.com/
18
CDEDS (Constraint Driven Engineering Design
Synthesis) Methodology
2. Concept Detailing
Take Excavator example
  • The Engineering Manager can be in three different
    situations relating to this requirement and he
    would react differently for each situation
  • Situation 1 The specification is an extension of
    an existing design within the factory then the
    kinematic lengths of boom, dipper and bucket are
    almost known and the problem reduces to iterating
    the four-bar mechanism at the bucket end and
    arriving at the cylinder sizes.
  • Situation 2 The specification is of a competing
    machine not within the factory  then the manager
    would conduct a competitive bench-mark exercise
    and arrive at starting lengths from the study.
  • Situation 3 Specification is not a known
    configuration anywhere in the market If you
    address this last situation, then other
    situations are automatically addressed.

http//cadvisionengineers.com/
19
CDEDS (Constraint Driven Engineering Design
Synthesis) Methodology
2. Concept Detailing
  • Concept Phrasing, have to be translated to
    boundary conditions or design constraints.
  • Once the constraints are identified, solution to
    the problem can be found by applying the
    following methodology, described broadly below
  • Each specification parameter, say maximum reach,
    is a configuration arising from two things.
  • The kinematic lengths (of boom, dipper arm and
    bucket) and a particular orientation of the parts

http//cadvisionengineers.com/
20
CDEDS (Constraint Driven Engineering Design
Synthesis) Methodology
2. Concept Detailing
  • Since different configurations arise from just
    changes to orientation of the parts, we recognize
    that lengths between pivot points should remain
    same between the different configurations.
  • We can model other specification parameters, max
    depth, cutting height etc., using the same
    variables for length between pivots.
  • Other design criteria, can now be brought in as
    either more variables or more mathematical
    functions.
  • Once we have equations for forces, section
    stresses can be described and consequently weight
    of parts can be estimated.

http//cadvisionengineers.com/
21
CDEDS (Constraint Driven Engineering Design
Synthesis) Methodology
2. Concept Detailing
  • This methodology now suggest that the design
    synthesis problem can be solved numerically by
    applying multi-criteria optimization methods.
  • The specification targets now described as
    Objective functions. 
  • Simpler problems like those of door flap or
    Situations 1, 2 described above, can be solved
    using simpler numerical optimization methods.
  • The seed/start/guess values for variables of
    lengths between pivots can always be generated
    from regression analysis of dimensions over
    weight of machine for different sizes. This is
    known to work.

http//cadvisionengineers.com/
22
CDEDS (Constraint Driven Engineering Design
Synthesis) Methodology
CDEDS Methodology Summary
  • Attempt to get a variety and bulk of ideas in the
    Concept Phrasing stage.
  • More concepts can be generated by adding/removing
    functional requirements arising from context of
    application.
  • A tool that enables simplified modelling, should
    be used to distil the concepts to a handful of
    candidate solutions. 
  • The software tool should have some simulation capa
    bility and should be able to handle dimensions. 

http//cadvisionengineers.com/
23
CDEDS (Constraint Driven Engineering Design
Synthesis) Methodology
CDEDS Methodology Summary
  • Once a concept is chosen, to bring engineering
    rigor, express all functional requirements
    as constraint variables.
  • Dimension, weight, force or some physical
    parameter that enables further use of software
    tools.
  • Ensure that the selected software can handle all
    forms of constraint expression. 
  • A dead 2D drawing tool, 3D sketcher, spreadsheet,
    popular math and simulation tools 

http//cadvisionengineers.com/
24
CDEDS (Constraint Driven Engineering Design
Synthesis) Methodology
CDEDS Methodology Summary
  • Build a math model describing various operating
    conditions as configurations.
  • The configurations are nothing but Objective
    functions for optimization.
  • Key step Solve the math model numerically as
    multi-objective optimization problem.
  • This guarantees that that ensuing solution is a
    consequence of the Simultaneous Action of all
    the Design constraints.
  • Fine-tune the solution by defining bounding
    values for constraint variables.

http//cadvisionengineers.com/
25
CDEDS (Constraint Driven Engineering Design
Synthesis) Methodology
Conclusion
  • Whether such an interlinked mathematical
    description of geometry and constraints is
    possible would depend on the quality of the
    software tool(s) used for the purpose of Design
    Synthesis. And whether such a construct would
    result in a viable engineering solution would
    depend on the skill of the engineer. The ultimate
    measure however is the quality of the engineering
    solution delivered.

http//cadvisionengineers.com/
26
CDEDS (Constraint Driven Engineering Design
Synthesis) Methodology
Write a Comment
User Comments (0)
About PowerShow.com