Models of Product Development - · PDF fileModels of product development ... M0 M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M11 M12 M13 M14 ... Top level aircraft specification Definition of basic

Mechanical Engineering

Models of Product

Development

Mechanical Engineering:

ME30294 – Product Design and Development

Models of product development

Product development = design + development

Design is "the process by which artefacts get the

dimensions they actually have".

Models of the product introduction process are used

to “add structure to a chaotic process”

They help focus attention on important aspects, and

they guide action in the process

Models are divided into descriptive models – that

describe design based on observation – and

prescriptive models – which suggest a best process



Models of product development

The conventional view: the design process involves a

series of stages from statement of "need" through

concept exploration to detail design

Traditional models of the design process are

sequential and iterative: e.g.

– BS7000

– Pahl and Beitz

– Pugh/SEED

– Ohsuga



Generic design process model

NEED

CONCEPT DESIGN

DETAIL DESIGN

MANUFACTURE

USE

EMBODIMENT



DESIGN ACTIVITIES

• Clarify task

• Elaborate the specification

• Identify essential problems

• Establish function structures

• Search for solution principles

• Combine into concept variants

• Evaluate against technical & economic criteria

• Develop preliminary layouts & form designs

• Select best preliminary layouts

• Refine against technical & economic criteria

• Optimise & complete form designs

• Check for errors & cost effectiveness

• Prepare preliminary parts list

• Prepare preliminary production documents

• Finalise details

• Complete detail drawings & production documents

• Check all documents

DESIGN STAGE

SPECIFICATION

DEFINITIVE

LAYOUT

PRELIMINARY

LAYOUT

TASK

DOCUMENTATION

SOLUTION

CONCEPT

DESIGN PHASE

TASK

CLARIFICATION

CONCEPTUAL

DESIGN

DETAIL

DESIGN

EMBODIMENT

DESIGN

TIM

E

UP

GR

AD

E &

IM

PR

OV

E

Pahl and Beitz Model Ref: G Pahl, W Beitz, Engineering

Design: a Systematic Approach, 2nd Ed,

Springer, 1995



Pugh/SEED design activity model

Reference: S Pugh, Total Design,

Addison-Wesley, 1991



Theory of Technical Systems

Technical System (TS) Purpose

– Achievement of desired transformation

TS Process Model

– Internal transformation of inputs to outputs

TS Function Structure

– TS in a state of being capable of working

TS Organ Model

– Organ – to realise functions

TS Component Model

– Component – means of realising functions

See separate sheets

Tech. process

TS

Effects Operand

states



BS7000 model

BS 7000-1:1999 Design management systems. Guide to

managing innovation


managing the design of manufactured products


managing service design


managing design in construction

BS 7000-5:2001 Design management systems. Design

management systems. Guide to managing obsolescence

BS 7000-10:1995 Design management systems. Glossary of

terms used in design management



BS7000 model


managing innovation


managing the design of manufactured products

BS 7000-3:1994 Design management systems. Guide to managing

service design

BS 7000-4:1996 Design management systems. Guide to managing

design in construction

BS 7000-5:2001 Design management systems. Design management

systems. Guide to managing obsolescence

BS 7000-10:1995 Design management systems. Glossary of terms

used in design management



BS7000:2 design process

Phase of project Process Output

Concept phase

Inception of new/improved product;

formation of team; analysis of

business concepts; formulation/

evaluation/approval of project

Opportunities; Business and

product concepts; Preferred

concept; project proposal;

permission to proceed

Feasibility phase

Planning, research and feasibility

studies -> proposal; develop of

functional spec.; development of

work programme; sanctioning of

project; forming of team

Criteria of acceptability; project

design brief; project and

resource plans; project approval;

preferred option;

roles/responsibility matrix

Implementation

phase

Concept development; outline

design; detailed design; construction/

testing of pre-production design.

Finalisation of design; design for

manufacture; product launch; selling

and use; monitoring “in-use”

Specification for product;

confirmation of performance inc.

reliability/ maintainability;

product package; product

availability; fulfilment of business

objectives; improvements

Termination

phase

Evaluation of project; termination of

project; design support for

decommissioning; disposal of

product

Handover of responsibilities;

continuing liability

Manufacturing stage

Liability starts

Design/development

stage

Internal to organisation

External to organisation



Design implementation process

Time scales

Cost

Performance

Profitability

Systematic

monitoring

against

design brief

by project

manager

Record

and

control

Verification by:

testing

reviews

repetition

competition

Formal

design

reviews

throughout

the design

process

Validation

by

usage

Evaluation:

customer

in-house

independent

BS7000:2 Design Implementation Process

De

sig

n p

roc

es

s

Itera

tion



Stage-gate models

Current company models often use “stage-gate”

models, risk management and design review

Stage gate model – Robert Cooper, McGill University

From www.stage-gate.com



Bombardier model

DETAIL

DESIGN

DEFINE SPEC

OBTAIN ITP

INITIAL

DESIGN

DELIVER TO

CUSTOMER

MANUFACTURE

& ASSEMBLY

TEST, ANALYSE

& CERTIFICATE

concept

review

initial

review

basic

review

compliance

review

external

(customer / supplier)

reviews as required

CONTINUOUS PRODUCT DEVELOPMENT

RISK MANAGEMENT



Airbus model

M0 M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M11 M12 M13 M14

Product idea established

Order released for project

Top level aircraft specification

Definition of basic concept

Concept for product selected

Instruction to proceed (ITP)

Authorisation to offer (ATO)

Go ahead

First metal cut

Begin final assembly

Power on

First flight

Type certification

Entry into service

End development phase for basic aircraft

A321-100 in-service Jan 1994

A321-100 certificate Dec 1993

A321-100 first flight Mar 1993

A321-100 go ahead Nov 1989

A321-100 DBD

PRODUCTION PHASE

IN-SERVICE PHASE

DEFINITION PHASE DEVELOPMENT PHASE



Risk management

Goal definition

Risk identification Continual monitoring

Budget levels

Risk prioritisation

Modelling relationships

Impact and

probability evaluation

Mitigation and

contingency planning



Systems engineering VEE model

Used in particular by electrical and computer-

systems engineers, but also by Peugeot and BMW in

their development processes

Distinguishes between systems and component

design



Systems engineering VEE model

Systems

design

Component

design



BMW Example



CAM’s Views

The design of an artefact is driven by the functional

requirements placed upon the artefact by the

customer

Designs that are proposed to meet these

requirements are characterised by solution

principle(s), configuration and physical arrangement.

They are defined within a design space bounded by

constraints

The design process can be viewed as proposing and

developing solution principles within the bounded

design space



The Product Model

The artefact is described by design parameters and

performance parameters

Design parameters are explicit, definitive or descriptive

– form, dimension, surface

condition, material

properties etc.

– Modelled by drawings,

diagrams, CAD models



Product Attributes

Performance parameters are judgements, emergent

properties, and indicate how well the design meets

functional requirements

– Analytical, experimental,

mathematical, test,

computational etc.

models are used to

make a judgement

– Obtained by considering

the artefact subject to

loads/external influences

– They are derived or implicit



Loads and Requirements

Performance parameters are obtained by considering

the artefact in an environment – e.g. subject to loads

and external influences

Performance parameters are used to judge the

performance of the emerging design with respect to

the design requirements, e.g.:

– Test conditions used to assess wear performance

– Analysis used to assess fatigue performance



Constraints and Design Space

The product is defined within bounds imposed by

constraints

– Some constraints are global - e.g. material limitations;

some local to the artefact - e.g. manufacturing process

constraints

The design space is defined by:

– the feasible values for design parameters;

– permissible values of performance parameters

The boundaries of the space are fuzzy/uncertain as are

our methods of estimating performance parameters



Model Transformation

The product development process involves developing multiple models representing aspects of the product

In particular:

– Design parameter, functional requirement and constraint models are developed and refined

– Assessments and judgements about the performance parameters are elaborated

– Auxiliary models (e.g. computational, mathematical) are created as required to help in estimation of performance parameters



Model Transformation

Function/ constraints

Loads

Design parameters

Auxiliary models

Performance parameters

Time

The Design Process



Create information for manufacture

and testing

Plan Manufacture

Test

Ohsuga’s Process Model

Conceptual

Design

Preliminary

(Embodiment)

Design

Detail

Design

Requirements

Build

Model Model 1

Modify and

Refine

Analyse and

Evaluate

Model 2

Modify and

Refine

Analyse and

Evaluate

Model n

Modify and

Refine

Analyse and

Evaluate Product

Drawings, CAD

models etc.

Models for

evaluation

purposes



Estimating performance parameters

The principal objective of design analysis,

experimental work and prototype test is to predict

and then validate the performance of the new

product.

A hierarchy of techniques is used:

– Classical analytical techniques

– Computer-based analysis

– Bench/laboratory test

– Prototype test



Computational analysis



Log (cost)

Log (error)

Error versus cost

E.g. Aerodynamic

coefficients; fatigue life

A: Classical analytical

techniques.

B: Computer-based

analysis - CFD, FEA +

damage accumulation

Bench/laboratory test:

servo-hydraulic test rig;

wind tunnel

Prototype test: track test;

flight test

A

B

C D



Alternative techniques

Adapted from:

http://www.cds.caltech.edu/conferences/1997/vecs/

tutorial/Examples/Cases/777.htm

Log (cost)

Number of

conditions

Computational

analysis

Physical test



Discussion

P Gerson suggests there are 5 basic approaches to

representing the process



The traditional view - design “thrown over the

wall” from department to department:

– Leads to delay before problems are corrected.

– Specialist expertise is applied once decisions have

been made

Concurrent engineering compresses the process

through parallel activities:

– Specialist expertise is applied early in the design

process.

Concurrent engineering



David Dilt – Owen at Vanderbilt



TIME

• individuals

• slow changes

• long lead time

• lower quality

S

Sequential Product

Development

Product Definition Requirements Definition Process Definition Production & Distribution

Embodiment Concept Detail

F

Errors, Changes and Corrections

S

• teams

• fast changes

• short lead time

• higher quality

Concurrent Product

Development

Requirements

Definition

Product Definition

Concept

Embodiment

Detail

Process

Definition

Production

& Distribution

F

CE Life Cycle Time Time Saved

Errors,

Changes

and

Corrections

Mechanical Engineering

Armand Hatchuel’s

C-K Theory



Hatchuel C-K model

Formal distinction

between spaces of

concepts “C” and

knowledge “K”

All propositions of K

have a logical status

(e.g. true/false)

Concepts are

propositions with no

logical status

Models the dynamics of

design as expansion of

C and K spaces

C K

C K

The

Design

Square

Expansion by

deduction or

experiment

Disjunction/partition/validation

Conjunction/activate

Expansion

by partition

or

inclusion



Conclusions

Models of the product introduction process are used

to explain or “add structure to a chaotic process”

The process involves a series of stages from

statement of "need" through concept exploration to

detail design

A number of model variations exist

Concurrent engineering compresses the process

time scale by overlapping steps

Documents

Models of Product Development - · PDF fileModels of product development ... M0 M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M11 M12 M13 M14 ... Top level aircraft specification Definition of basic