ISem Presi II Embodiment Design

Engineering Design Methodology Principles and Guidelines of Embodiment Design

Dr.-Ing. Alex Brezing

September 3, 2012

The Sirindhorn International Thai-German Graduate School of Engineering, KMUTNB

Institute for Engineering Design, RWTH Aachen University

2

Review - Overview

„method knowledge“

„rules knowledge“

• Requirements list

• Function structure

• Effects structure

• Principle solution

• Selection of a solution

Working out solutions

“Embodiment Design”

• Basic embodiment

design rules

• Principles of embodiment

design

• Design for X



Embodiment Design

3

1. Process View



General Process of Engineering Design

WHAT? Problem exploration

and documentation

HOW? Identify working

principle / concept

GO! Define and

document

geometry

4



5

Steps of Embodiment Design 1



Steps of Embodiment Design 2

6



Embodiment Design

7

2. Implications on CAD



8

CAD Strategy?

• qualitative -> quantitative: parametric modeling

• abstract -> concrete: use skeletons

... allowing for a top-down/bottom-up approach

• main functions -> auxiliary functions

• rough -> detailed



9

Parametric CAD: qualitative -> quantitative



Use skeletons: abstract -> concrete

10



Top-down / bottom-up: rough / detailed

11



Top-down / bottom-up: main / auxiliary

12



Embodiment Design

13

3. Embodiment Elements



Embodiment Elements

The embodiment of a technical artefact is made up of embodiment

elements

Embodiment elements can have different degrees of complexity:

• points, corners, bits,

• line pieces, edges,

• partial surfaces,

• components,

• assemblies,

• machines, devices, apparatus

In a technical system, an embodiment element is the smallest element

that can still be influenced by the embodiment design.

14



Levels of Complexity: Embodiment Elements

Level Subsyst. emb. el. Explanations Example Level Subsyst.

emb. el. Explanations Example

1 corner, point

intersection point of component edges, partial component surfaces taping off to a point

6 part

a part of a technical artefact that cannot be further disassembled

2

edge, 1st and 2nd order, area boundary

boundary of an area, edge- or tangent-shaped transition between two partial surfaces (1st or 2nd section discontinuous)

7 assembly

independent (own cradle) functionable subsystem consisting of at least two components

3

partial surface, working surface

parts of the surface of a component

8 machine, device, apparatus

technical system for realization of a certain energy, material or information conversion process

4 working surface pair

interacting partial surfaces of two components

9 systems, installa-tions, units

technical system consisting of several machines, devices and/or apparatus

5 subbodies

subbodies which can be imagined for the composition of a component

10 technical system

complex technical systems, e.g. flight system (aeroplanes, airport, air traffic control), vehicle systems (car, road) etc 15



Plant: Examples

People-Mover

System

Baggage conveyor

Refinery

16



Assemblies and Components

Source: MZ-B Vertriebs GmbH, www.motorradtechnikbarnim.de

17



Embodiment Design

18

4. Design Rules - Overview



19

Guidelines („design for X“)

Basic

Rules

Principles

• “Simple, Clear, Safe”

• Violation will result in bad products

• Affect function structure, concept

and embodiment

• 5 kinds of principles

• If applicable

• Affect concept and

embodiment

• Countless catalogues

• If applicable

• Affect embodiment

Design Rules



Rules – apply when?

Principles: often connected to principles, consider during rough embodiment design

Guidelines: mostly relevant during detailing

Basic rules: not only relevant for product properties but also documentation

20



Embodiment Design

21

5. Basic Rules: Clear



• Clear assignment of functions and their inputs/outputs

• (Mathematically) clear interrelations of inputs and outputs

(applicable also on loads and resulting stresses)

• Enforce the correct operation

• Complete documentation (incl. production drawings)

• Assembly sequences that prevent wrong assembly, transport

aids

• Clearly defined intervals for service, inspection ...

• Identify materials, clear division between incompatible

materials

Clear Embodiment Design

Referring to the contents of the guideline about embodiment design 22



“Clear” Assignment of Functions

Clear bearing arrangement

clear separation of radial and

axial forces)

No clear bearing arrangement

(division of radial and axial forces)

23 acc. to Pahl/Beitz



Embodiment Design

24

6. Basic Rules: Simple



• A low number of procedures and components for the

realization of the function

• (Mathematically) Simple geometric shapes

• Use symmetry

• Obvious MMI

• Few production procedures

• Easily identifiable parts

• Uncomplicated assembly procedures

• Simple error detection

• Materials suitable for production processes and operation

Simple Embodiment Design

Referring to the contents of the guideline about embodiment design 25



Simple: Slide Valve

strive for

simple shapes

casting

braze parts 26



Embodiment Design

27

7. Basic Rules: Safe



Safety: Definition

Is this car save??

Yes: It meets NCAP crash regulations

Will I survive this accident? 28 acc. to www.focus.de



Definition: Safety

Risk limit

is the largest still acceptable system-specific risk relating to a particular technical process

or situation

Protection

is the reduction of risk by suitable means to reduce the frequency of the occurrence or

the extent of damage or both

Safety

is a state in which the risk is smaller than the risk limit

29 Quelle: DIN EN 292



Safety Aspects of a System

energy flow

material flow

sequences

danger

safe

control

safe

regulation

safe

monitoring

design

measures

safety measures

30



• Direct safety

Choosing a solution that precludes danger from the outset (in

general to be strived for)

• Indirect safety

The danger is isolated via construction of special protective systems

and arrangement of protective barriers

• Warnings

Dangers are pointed out and made clear (only to be used as an

additional measure)

Safe Embodiment Design

Consider DIN 31000 and DIN/EN 292 Parts 1 and 2! 31



Example: Fail-Safe

Crane brake:

safety brake, has to be vented

for lifting or lowering of the

load.

Compression spring:

also ensures jaw contact force

in case of a fracture.

32



Redundant Arrangement: Protective Devices

Principle redundancy Parallel connection

Protective devices:

• safety valve (SV)

• bursting disc (BD)

SV

SV

BS

SV

33 acc. to Pahl/Beitz



Embodiment Design

34

8. Principles: Force Transmission (Direct and Short Force Transmission Path, Principle of Matched Deformations, Principle of Balanced Forces)



Target:

• minimum use of materials

• minimum resulting

deformations

reached, if:

• only tension or

• compressive forces

are transmitted

Direct and Short Force Transmission Path

35

uniform stress-level and

thus optimal utilization

of the material



Direct and Short Force Transmission

All three transmission units have the

same load and the same stress

(rectangular cross section of the same

thickness)

direct force transmission

indirect but closed force

transmission

indirect force transmission

1

2

3

36 acc. to: Ehrlenspiel

1

2

3



Direct and Short Force Transmission

1

2

3

37 acc. to: Meißner, Hoenow

2 3

The clevis represents variant 2 and

the crane hook represents variant 3



Direct Force Transmission: Relief Notches

relief notches support the

direct flow of forces

38 falsch richtig wrong right

flow of

forces

relief notches

notch zone

notch plane



Matched Deformation: Drive Shaft

same angle of torsion of the gears

due to matched deformation of the

shaft sections by an asymmetric gear

arrangement

symmetric gear arrangement ensures

synchronous running

synchronization problems due to

unsymmetrical gear arrangement

39 Quelle: Pahl/Beitz



Principle of Balanced Forces

The forces acting outwards

neutralize one another

acc. to Pahl/Beitz 40



Embodiment Design

41

9. Principles: Division of Tasks



Principle of the Division of Tasks

• Clear production processes

• Clear assembly operations

• Increased safety (clearness)

• Number of components

• Number of parts

• Spatial requirements (interfaces)

• Increased weight

One function carrier

for each function

One function carrier

for several functions

The dilemma

42



Embodiment Design

43

10. Principles: Self-Help (Self-Reinforcing, Self-Balancing)



Self-Reinforcing: Tyre Valve

The sealing force of the valve

and the tyre on the rim increases

with increasing tyre pressure

44 acc. to: Pahl/Beitz



Self-Reinforcing: Seals

Internal pressure, P,

increases the sealing

effect




Self-Reinforcing: Drum Brake

Brake with two brake cams: Two

brake shoes running up

Brake with two brake cams, self-

centering

Standard design: one brake

shoe running up and one

running down

46 acc. to: Niemann



Self-Balancing: Turbine Blade

Conventional solution,

the blade stands straight Self-balancing:

due to the leaning of the blade the centrifugal

force counterbalances the bending stress


Potential of increased

performance by

enlarged blades!



Embodiment Design

48

11. Principles: Stability/Bi-Stability



Common examples of Bi-Stability

49



Bi-Stability principle

50

Energy Storage Medium

spring, pressure vessel, heat

accumulator, Hook-medium

stable Low energy level

stable Low energy level

labile High energy level

Auxiliary Energy

• potential

• kinetic

• electrical



Rocker I

stable starting

position labile balance second stable

position

Energy Level

51



Embodiment Design

52

12. Design Guidelines: Df Cutting



Cutting

Turning Millling

53



Influencing Factors

Manufacturing Costs

material Manufacturing method

machine

(new/old)

setup-, process-, auxiliary time

tool

wear

dimension

quantity

tolerances

surface

54



Costs

0123456789

101112131415161718192021

6 10 14 20 24 28 32 36 40 45 50

Co

sts

Bore diameter d [mm]

Drilling on boring mill

Drilling , opening, reaming

drilling, opening

drilling

Boring mill

Drilling machine

55



Fine machining of cogwheels

0

1

2

3

4

5

6

7

8

Co

sts

56



Turning I

shaped tool standard tool

consider the

necessary tool

runout

target: improve quality

Use simply

shaped tools


inappropriate appropriate

57



Turning II

internal turning:

avoid grooves

and narrow

tolerances

target: reduce effort

provide

adequate

chucking

surfaces


inappropriate appropriate

58



Embodiment Design

59

13. Design Guidelines: Df Assembly



Course of Assembly

ordered

storing,

stacking

storing

the parts

identifying,

seizing,

moving

the parts

handling

the parts

adjusting

and

aligning

for joining

positioning

the parts

form fit and

material

fitting,

joining

elements

joining

the parts

balance of

tolerances,

adjustment

of clearances

setting,

adjusting securing

ensure a lasting

function of the

joining

controlling

carry out set-

actual

comparison,

correct

deviations 60



Building Structure for Ease of Assembly




Design for Ease of Assembly




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ISem Presi II Embodiment Design