NASA Technical Reports Server (NTRS) 20020088424: A Framework for Creating a Function-based Design Tool for Failure Mode Identification

12 Pages·1.1 MB·English

by  NASA Technical Reports Server (NTRS)

Proceedings of DETC'02
ASME 2002 Design Engineering Technical Conference
and Computers and Information in Engineering Conference
Montreal, Canada, September 29 - October 2, 2002
DETC2002/DTM-34018
A FRAMEWORK FOR CREATING A FUNCTION-BASED DESIGN TOOL FOR FAILURE
MODE IDENTIFICATION
Robert B. Stone Ph.D. t
Srikesh G. Arunajadai
Assistant Professor
Graduate Research Assistant
Department of Basic Engineering
Department of Mechanical Engineering
University of Missouri-Rolla
University of Missouri -Rolla
Rolla, MO 65409
Rolla, MO 65409
573 341 4086
[email protected]
Irem Y. Turner Ph.D.
Research Scientist
Computational Sciences Division
NASA Ames Research Center
Moffett Field, CA 94035-1000
650 604 2976
[email protected]
INTRODUCTION
ABSTRACT
Knowledge of potential failure modes during design is
Scope
critical for prevention of failures. Currently industries use
In engineering design, the end goal is the creation of an
procedures such as Failure Modes and Effects Analysis
artifact, product, system or process that performs a function or
(FMEA), Fault Tree analysis, or Failure Modes, Effects and
functions to fulfill customer needs [1]. In today's competitive
Criticality analysis (FMECA), as well as knowledge and
market it is important that manufacturers meet the customer
experience, to determine potential failure modes. When new
requirements of a safe and reliable product that will have a
products are being developed there is often a lack of sufficient minimum down time during the expected life of the product.
knowledge of potential failure mode and/or a lack of sufficient
This is true for all kinds of markets, be it the industrial markets
experience to identify all failure modes. This gives rise to a
like the highly failure sensitive aerospace industry or the
situation in which engineers are unable to extract maximum
consumer market which demands high reliability at low cost.
benefits from the above procedures. This work describes a
This demand places a heavy burden on the shoulders of
function-based failure identification methodology, which would
designers and manufacturers to eliminate or at least minimize
act as a storehouse of information and experience, providing
possible malfunctions and failure modes from their products
useful information about the potential failure modes for the
and processes. This necessitates a broad knowledge of the
design under consideration, as well as enhancing the usefulness
common failures encountered. This paper mainly deals with
of procedures like FMEA. As an example, the method is
management of the declarative knowledge of recorded failure
applied to fifteen products and the benefits are illustrated.
cases and their link to component function.
This paper is based on a function-failure method,
KEYWORDS
developed by Turner and Stone [2], who have hypothesized that
Function-based decomposition; Failure mode identification;
similarities exist between different failure modes based on the
Functional modeling; Failure mode standardization; Failure-free
functionality of each component/product. We also adopt a
product design. modified form of the matrix method developed by Collins et
CorrespondingAuthor.SubmittedforreviewASMEDETC2002
Copyright © 2002 by ASME
arises in predicting failures at such an early stage when the
al.[3]todocumenfatiluredata.Majoremphashisasbeenlaid
structure of the component or product is hardly realized and no
onthestandardizatioofnthevocabulariny documentinthge
failuremodesT.hefunctionhsavebeenstandardizbeydthe specifications as to its materials and the use environment are
known. Beiter et al [5] developed the Assembly Quality
functionablasisdevelopebdy Hirtzetal.[1]andthefailure
Methodology (AQM) to predict defect levels of new products.
modebsythefailureclassificatiopnrovidebdyCollins,which
In this research we use a functional model, which is a
is to be furtherexpandetdo adaptto newandadvanced
functional diagram of the product expressed in the vocabulary
materialTs.heprincipleosfFailureModeEsffectsandAnalysis
of the functional basis to predict failure modes. This will give
(FMEA)havebeenadoptedto quantifythefailuremode
the designer a starting point for examining the possible failure
documentation.
In the remaindeorf the paper,we presentthe modes that the component and/or product might experience
motivationb,ackgrounadp,proacrhe,sultsandconclusionosf during use. Thus the method assists in specifying the
this research. component design and needed analysis methods at a very early
As specific motivation, we present some
stage and offers to minimize the cost of redesign. For instance,
applications for a common function-failure design vocabulary. the indication of a high cycle fatigue for a product with a
As background, we briefly summarize some research in the field "transmit rotation" function will prompt the designer to
of Failure Modes and Effects Analysis that are related to
perform a fatigue analysis to ensure that the corresponding
conceptual engineering design and some work related to the
component does not malfunction.
classification of failure modes and the methods proposed for
• A Source for Real-Time Failure Occurrence Data:
their documentation. The methodology and approach are
The FMEA analysis assigns a value to the Occurrence of
described and an example is provided to illustrate the
the failure by making a reasonable guess of the probability of
methodology. The paper concludes with insights gained from
the occurrence of the failure. This introduces certain amount of
the research process.
non-uniformity in the data recorded as the probability assigned
for a failure to occur depends on the experience of the designer
Motivations and Applications
and hence can vary from designer to designer. The function-
Several factors motivate the creation of a function-failure
failure method provides a realistic approach to obtain actual
method for design methodology. The following serve both as a
occurrence rates from the composite function-failure matrix.
motivation for and practical applications of the function-failure
• An Educational Tool for Novice Designers:
method developed in this research.
To design for failure or for the performance of tasks like
• Standardization of Vocabulary:
the Failure Modes and Effects Analysis, requires a lot of
Often different methods are employed in recording failure
experience. Today's market is flooded with products that might
data and the natural language is used for describing failure
not require the expertise of an experienced designer but at the
information. This makes the sharing of the valuable
same time is required to meet the customer's demand of
information difficult among different sections of the same
longevity and safety. It is quite natural to employ novice and
organization or even among individuals. Though researchers
fresh graduate designers for such products. The function-failure
have worked on the standardization of the function vocabulary
matrix can compensate for their lack of design experience, as it
and the failure modes on an individual basis, there has been
is in effect the collection of real-time data recorded in a
little effort on the combined standardization of the two. This
standardized form.
paper uses the functional basis developed by Stone and Wood
These are just some of the practical applications in
[4] and Hirtz et al. [1] and presents a standardized failure mode
sight. With the continued development of the function-failure
vocabulary. This uniformity and consistency in the
method, its usability and the areas in which it can be applied is
representation of function and failure knowledge provided by
bound to increase.
the function-failure method makes it an effective engineering
organizational learning tool whose knowledge base can be
shared not only among sections within the same organizations
BACKGROUND AND RELATED RESEARCH
but across organizations with the aid of web-based
technologies. Failure Modes and Effects Analysis (FMEA)
• Repeatability and Reusability: The FMEA procedure is an offshoot of the Military
It is very important for the failure mode data to be dynamic
Procedure MIL-P-1629 [6], developed by the United States
in nature indicating the latest status on the failure modes and
Military as a tool to determine and evaluate equipment failures.
its various characteristics like severity and occurrence. The
This was followed by ISO 9000 series issued by the
dynamic nature is essential to make the method repeatable and International Standards Organization and QS 9000 series, the
reusable. The uniformity in the description of the function-
automotive analogy of the ISO 9000, which were a set of
failure data along with archival techniques employed facilitates
business management standards that focused on customer needs
repeatability and effortless updating of the failure modes data.
and expectations. In 1993 the Automotive Industry Action
This data when used with conventional FMEA techniques is
Group (AIAG) and the American Society of Quality Control
envisioned to be a very useful design tool.
copyrighted the industry-wide FMEA standards, which
• Failure Data for New Products:
provided the general guidelines for preparing the FMEA.
To design for failure in the conceptual design stage has
always proved a challenge. This is because of the difficulty that
2 Copyright © 2002 by ASME
approachceosmplemeenatchotherastheyhavedifferenktinds
A rigorouslyperformeFdMEAcontainsvaluable
ofdetailsandareperformeadtdifferensttageisn theproduct
informatioanboutthevariouscomponenatnsdassemblioefs
cycleT. hehardwaraepproacihsevaluatebdyconsiderinthge
theproducwt,hichhelpsintheearlydetectioonfweaknessines
changethsatoccurin eachhardwaraendits effectsonthe
aproduct'dsesignT.heFMEAproceduirsestillconsiderebdy
mostorganizatioansslaboriouasndcostlybothintermsof neighborincgomponenhtardwaraendpropagatetodthenext
leveul p.Asthisrequiresspecificinformatioanboutthetypeof
moneyandtime.Moreoftentheeffortshavehadpoorresults
componenatnsdtheirindividuaplropertieist,canbeperformed
due to poor reusabilityarisingfrom the inconsistent
onlywhenthedesignhasbeenadequaterlyealized.The
descriptioonfsthefunctionosfthecomponenotrssystemasnd
functionaalpproachhowevecranbeundertakeinntheinitial
thefailurestheyundergoW.irthetal.[7]haveidentifiedtwo
stageosfproducdtevelopmenItt.involvetshedevelopmeonft
fundamenwtaelaknessinetsheconventionFaMl EA.Theseare:
functionaalndsystemschematdiciagramTs.hisapproacrehlies
thelackofmethodologicgaulidelinetoconducatnFMEA,
onthespecificatioonfthepurposeasndfunctionosfeachpiece
and,theemploymenotf naturallanguagien recordingthe
FMEArelatedinformationW. irthetal.haveaddressethde ofequipme[n1t2].
TheconcepotfapplyingmatrixtechniquetosFMEA
problemofnaturallanguagien thedescriptioonf functions
wasoriginallyintroducebdy Barbouirn 1977[15].Goddard
usingsystemandfunctiontaxonomiedserivedfromthesetof
andDussau[l1t6]developethdeAutomateAddvanceMdatrix
verbsandoperatoorsrfluxesprovidebdy Roth[8]andPahl
FMEA,whichwasa refinedextensioonf Barbour'swork,
andBeitz[9].Buttherecontinuetosbealackofconsistenicny
mainlyservinagsalogistictsool.Thematrixwasformedwith
thedescriptioonffailuremodesA.nengineemrightdescribe
thecolumnscomprisingof outputsof theassemblyunder
differenotccurrencoefsthesamefailureindifferenwtaysorthe
analysist,estpointsof analysisc,ommentsr,emarksand
samedescriptiofonrtwomarginaldlyifferenftailuresT.hislack
referencaensdtherowscomprisinogf inputstotheassembly
ofconsistencmyakestheclassificatioonffailuresthatmight
beinganalyzewdithappropriaftaeiluremodesfortheinputs
manifesat particulasretof symptomdsifficultto identify,
andthepartscontaineidn theassembblyeinganalyzewdith
whichotherwisweouldbeagreastourcoefhelpindiagnostic
theirfailuremodesH. enningandPaasch[17]alsoadopta
analysis[10]. Thusstandardizatioofnboththe function
matrix-basaepdproactho diagnospeotentiaflailurecasesin
vocabulaaryndfailuremodevocabulairsydesired.
Standardizatioofnvocabularayidsin theeffective proposeddesigns.
maintenanacnedutilizationofaknowledgbeaseA. knowledge
baseis thecombinatioonf "declarativea"nd"procedural" Mechanical Failure Modes
knowledg[e11,12].BluvbandandZilberber[g11]describe The increasing importance of reliability metrics is
"declarativkenowledgea"sasetoffactsandstatisticadlata fueling the advancement of reliability prediction methods,
aboutobjectsor events,and,"proceduraklnowledgea"s especially those used in new designs. Researchers have
informationaboutcourseosf actionandproductionrules. relentlessly worked to develop methods to classify and provide
Declaratikvneowledgiseacollectioonflibrariesandserveass failure mode data to designers at an early stage. Peecht and
theorganizationcso'llectivememoryC. lassicexampleosf Dasgupta [18] have discussed the application of the
declarativkenowledgleibrariesincludecomponenlitbraries methodology of the physics of failure approach to reliable
(componenfta, iluremodesand causes)c,orrectiveand product development. In this approach the designer specifies the
preventivaectionslibraryd,atabasdeescriptione,ndeffecat nd design requirements based on customer requirement and
severitylibraryt,estmethodlsibrary,detectabililtiybraryand supplier capability and also identifies the use environment.
currentcontrols.The proceduraklnowledgeconsistsof Next, stress analysis, along with the knowledge of stress
informatiornegardintgheeffecotfafailurepropagatetodthe response of the design materials, is used in identifying failure
nexthigherlevel. Forexamplefr,omthepartlevelto the sites, failure modes, and failure mechanisms. Once the potential
assemblleyveltheidentificatioonfthehighesetffectfailure failure modes are analyzed, a failure mechanism model is
modeisregardeadstheendeffecotfthesystem. obtained which enables a reliability assessment to be conducted
FMEAhastobeperformeadsearlyinthedesignstage on the product. This information thus obtained helps to
aspossibleasit wouldidentifypotentiaplroblemareasand determine whether a product will survive its intended
minimizethecostofchangetosbemadeinthedesignB.utif application life.
FMEAisperformeedarlieirnthedesignstagethenit hastobe Thornton [19] classifies failures into three categories:
repeatewdhenevtehredesignischangeTd.heprohibitivecost Safety, Functional and Ancillary. Within these categories,
andthetimeconsumeind repeatinFgMEAhaspushedthe failures are further classified into five general areas as design
FMEAprocedutroea laterstageintheproducdtevelopment deficiencies, construction deficiencies, material deficiencies,
cycle[13].FMEAperformeadtthef'masl tageosftheproduct administrative deficiencies and maintenance deficiencies. The
developmewnitll addlittleornovaluetotheproducta,sthe paper further states that as much as 52% of the failures is due
costinvolvedin makingdesignchangeastthisstagecanbe to design deficiencies, 25% due to construction, and 18% due
enormouTs.husthisnecessitatfeosllowinganapproacthhat to materials deficiencies.
willenablteheFMEAtobeperformeadtanearlystage. Svalbonas [20] classifies failure into five general
Therearetwomainapproachteosthe"DesignFMEA" groups as design, material selection, material imperfection,
accordintgotheAerospacReecommendPerdactice[14]:the material fabrication and service environment. Failures resulting
hardwaraepproacahndthefunctionaalpproach.Thetwo from design deficiencies are usually associated with poor
3 Copyright © 2002 by ASME
failure inducing agents to account for failure due to human
structurdael signaspectTsh. edesignphasiesdividedintofive
negligence such as improper maintenance or ignorance of
stages1:)settingdesignspecification2s),providingdesign
analysis3,) providingproperfabricatioanndinspection4,) processes [22].
settingrequireqdualityassuranpcreoceduarend5)providing
By selecting appropriate classification from the three categories
propeprurchassepecificatioAnn.errorinanyoftheabovefive
mentioned above Collins describes 23 commonly occurring
stageiss almosctertaintointroducaefailuremodeintothe
failure modes, which are listed in Table 2. For example the
product.
Collinset al [3, 21] haveintroducetdhematrix "Thermal Fatigue" failure mode is derived as follows:
1. Manifestation of Failure - Rupture or Fracture
approactohfailuremodedsatarecordinagsearlyas1976T. hey
2. Failure Inducing Agent
deviseadthreedimensionmalatrixinwhichtheaxesrepresent
Force - Transient
the failuremodes,elementaml echanicaflunctionsand
Temperature - Transient
correctivaectionsE. achfailedpartwasclassifiedby these
3. Failure location - Body type
attributeTs.heFailure-Experiemnacterixformedasoundbasis
The Collins classification is used as a starting point in this
forcataloguinfagiluredataandapotentiaelngineerindgesign
tool.Itseffectiveneasssadesigntoolliesin its abilityto research.
accepret adl ataandtogeneralizaendnormaliztehedataw, hich
canthenbeusedforaspecifiacpplication.
GENERAL APPROACH
TABLE 1. Categorization of failures
This section outlines the steps that lead to the formation of the
CATEGORY SUB-CATEGORY
function-failure matrix and concludes by describing how the
Manifestation of Failure function-failure method can be used in realizing the applications
Elastic Deformation described earlier. The procedure is outlined in Figure 1. The
function-component matrix is composed of the component
Plastic Deformation
vector (obtained from the bill of materials) and the function
Rupture or Fracture
vector (obtained from the bill of materials and the functional
Material Change Metallurgical
model).
Chemical
Nuclear
The component-failure matrix is obtained from the
=allure Inducing Agents component vector and the failure vector. The function-failure
matrix is obtained from the matrix multiplication of the two
Force
Transient matrices. The function-failure method naturally breaks into five
steps, which are described in detail in the following sections.
s-- ...................................
.___clic
Random
Time .........__Very__.Sh_or-.t...............
Short
.............................................. Long
l ',O ,LMOD]EL
Temperatu re Low
Room
Elevated
Steady / Transient
................................. ,___Cyclic
x
Random
Reactive Environment Chemical
IUOMPONENTFAILUREMATRIX" ]
Nuclear l FAILUREVECrOR_I_' ] _ CF
Human
Failure Locations
Bod_ ...............................................................
MATRIX- EF
Surface Type
FIGURE 1. Procedure Flowchart
In this paper we use the failure modes categorization
scheme enumerated by Collins [3]. Collins has classified
failures into three categories, as shown in Table 1: 1)
manifestations of failure, 2) failure inducing agents and 3)
locations of failure. The human category was added under
4 Copyright © 2002 by ASME
TABLE 2. Classification of Failure Modes by Collins (1981)
CATEGORY SUB.CATECag_Ry CATEGORY _Ul:l-l,d_ II_l'l T
mpact Fracture
Force and/or temperature induced deformation Impact
mpact Deformation
Yielding mpact Deformation
Brinelling
mpact Wear
Ductile Rupture mpact Fretting
Brittle Fracture
mpact Fatigue
Fatigue ' LHoigwh-C-cyyccllee FFaattiigguuee Fretting =retting Fatigue
=retting Wear
Thermal Fatigue
--retting Corrosion
Surface Fatigue
Impact Fatigue Creep
Corrosion Fatigue Thermal relaxation
Fretting Fatigue Stress Rupture
Direct Chemical Attack Thermal Shock
Co_osion
Galvanic Corrosion Galling and Seizure
Crevice Corrosion Spalling
Pitting Corrosion Radiation Damage
Intergranular Corrosion Buckling
Selective Leaching C_¢-epBuckling
Erosion Corrosion St_6_.i Corrosion
Cavitation Corrosion Corrosion Wear
Hydrogen Damage Corrosion Fatigue
Biological Corrosion Combined Creep and Fatigue
Stress Corrosion
Wear Adhesive Wear
Abrasive Wear
Corrosive Wear
Surface Fatigue Wear
Deforrnation Wear
Impact Wear ....
Fretting Wear
flow classes respectively [1]. The set of functions describing
the product set form an n-dimensional vector E.
Documenting Functional Data
The first step is to document the function information
Forming the Function-Component Matrix
detailing all possible functions performed by the component,
Next, the function-component matrix is created with the
assembly, or sub-system, and describe their physical
characteristics. This is accomplished by preparing a bill of help of the bill of materials and the functional model. The
components form the m columns of the matrix and the
materials and functional model for each product under study.
functions form the n rows of the matrix. For a given
The bill of materials is a list of the components
component a'l' is placed in the cell corresponding to the
making up the product [23]. It identifies the assembly to which
function it performs and a '0' is placed in the other cells. We
the component is a member, the quantity of the component
call this m x n matrix the EC matrix, shown in Figure 2.
used in the product, its physical description, and the process by
which it is manufactured along with the functions performed by
PRODUCT NAME
the component. The set of m components for a product or a
group of products isrepresented by an m-dimensional vector C.
The functional model is a description of a product or
FUNCTION - COMPONENT
process interms of the elementary functions that are required to
achieve its overall function or purpose [4]. The functional
0 0 0
c_ cD o
model is a flow diagram indicating the various functions of the
Function - 1 0 1 0 0 0 0
product and their connectedness through the flows of energy, !Function - 2 1 0 0 0 0 0
material and information. In both the bill of materials and the 0 0 0 0 1 0
functional model, the functional basis is used to describe the 0 0 1 0 0 0
functions and the flows. The functional basis is a design 0 0 0 0 0 0
language where product function is characterized in a verb- _Function - m 0 1 0 0 O 1
object (function-flow pair) format capable of describing the Figure 2. EC Matrix
mechanical design space. Tables 3 and 4 give the function and
5 Copyright © 2002 by ASME
TABLE 3. Function Classes md their Basic Categorizations
Class [ Material [ Signal [ Energy
Mechanical
Basic Human Status Human Electrical
Gas Signal Acoustic Electromagnetic Pneumatic
Biological Hydraulic Radioactive
Liquid
Solid Chemical Magnetic Thermal
Plasma
Mixture
TABLE 4. Flow Classes and their Basic Categorizations
II Class I Basic I1 Class I Basic
Class Basic
Sense
Actuate
Separate
Branch Distribute Control Regulate Signal Indicate
Process
Import Magnitude Change
Stabilize
Export Stop
Channel Transfer Convert Convert Support Secure
Position
Guide Store
Connect Couple Provision Supply
Mix
corresponding failure mode. Table 5 provides the primary
identifier, the secondary identifier and the corresponding failure
Documenting Failure Data
mode. The failure modes in italics indicate that they have been
The third step is to record failure data in a manner similar
merged and identified by a new name. The words in bold face
to the bill of materials. It is recorded in a tabular format with
serve as a visual aid in identifying the prominent
columns representing part name, function performed and
characteristics.
physical description (each obtained from the bill of materials During the course of this research some ambiguity was
and/or functional model). To this we add information about the
caused by three pairs of failure modes: 1) surface fatigue wear
failure modes, causes of the failure and the effects of these
and surface fatigue; 2) impact fatigue and impact wear; and 3)
failure modes on the components and the severity and
erosion corrosion and corrosive wear. The ambiguity arose due
occurrence values of the components.
the very similar characteristics in the development and
The failure modes are recorded using the descriptors
description of these failure modes. As different engineers or the
provided by Collins [3]. Though this paper uses only the
same engineer might describe the net result by two different
descriptors provided by Collins, during the course of this names, it was decided that these failure modes be combined
research we believe that more failure mode descriptors will be
into three classifications. Surface fatigue wear and surface
required to handle failure modes experienced by plastics, and
fatigue are combined as surface fatigue wear since surface
products made from composite materials and other new
fatigue wear is a result of surface fatigue and a design to prevent
advanced materials.
the former would take care of the latter. Similarly impact
We have added primary and secondary identifiers to the
fatigue and impact wear were combined under the heading
Collins failure modes to resolve any ambiguity in the
impact fatigue wear, as it would address both failures
designer's mind as to the selection of the appropriate failure simultaneously. Also, corrosive wear and erosive wear are
mode. The "primary identifier" provides information such as
combined as corrosive wear, since by definition there is little
the kind of load applied, the nature of the force, the kind of
distinction between the two and corrosive wear encompasses
material involved, the characteristic environment under which
erosive wear.
the failure mode occurs or the main characteristic of failure.
These were categorized as primary identifiers as it is absolutely
Forming the Component-Failure Matrix
necessary for the failure to have been associated with the given
From the failure data recorded as described in the previous
condition to be classified under the corresponding failure mode.
section, the fourth step is to form the component failure mode
The "secondary identifier" provides information such as
matrix, with p columns representing the failure modes and n
materials used, characteristics of failure, or presence of other
rows representing the components. This n x p matrix is called
factors or medium. The reason behind identifying this
the component-failure matrix, denoted by CF. As in the
information as secondary identifiers was because it is absolutely
necessary for the failure mode to fit into the description
provided by the primary identifier for it to be labeled by the
6 Copyright © 2002 by ASME
I information like severity or the risk priority numbers, which on
_RODUCTNAME
analysis by statistical procedures will provide some good
indicators for the relationship between component functions and
their associated failure modes, as well as the relationship
COMPONENT- FAILURE MODE :; _ among different failure modes or among functions.
Forming the Function-Failure Matrix
LL LL LL
Component- 1 0 1 0! 0 0 0 Finally, the function-failure matrix is obtained by the
matrix multiplication of the function-component matrix (EC)
Component - 2 1 0 0 0 0 0
0 0 0 0 1 0 and the component-failure mode matrix (CF):
0 0 I 0 0 0 EF = EC x CF (1)
0 0 0 0 0 0 The resulting m xp matrix is called the EF matrix. The cells of
Component- n 0 I 0 0 0 I this matrix provide information as to the number of occurrences
Figure 3. CF Matrix of aparticular failure mode for a given function.
function-component matrix, a '1' is placed for a component in The real advantage of the EF matrix as a design tool is
the cell corresponding to the failure mode it experienced and a obtained from the composite EF matrix from which occurrence-
'0' in the other cells. The component-function matrix is shown ranking values could be obtained using the probability of
in Figure 3. occurrence. The probability could be obtained from the ratio of
the number of occurrences of a failure to the total number of
This paper describes only the binary format of the C F instances of failure. The following section illustrates the
matrix where a 1 represents the existence of a particular failure application of the function-failure approach to a set of fifteen
mode for a component and 0 the absence. Research is in products.
progress wherein the cells of the CF matrices contain
TABLE 5. Failure Mode Identification
PRIMARY IDENTIFIER SECONDARY IDENTIFIER FAILURE MODE
Elastic Deformation Force ITemperatire induced deformation
Plastic Deformation Ductile Material Yieldin_
Static Force 1.Permanent surface discontinuity Brinelling
Curved Surfaces 2. Mating members
Plastic Deformation 1.Separate into 2 parts Ductile rupture
Ductile Material 2. Dull fibrous surface
Elastic Deformation 1.Separate into 2parts Brittle fracture
Brittle Material 2. Granular, multifaceted fracture surface
1.Sudden separation into 2 parts
Fluctuating Load / deformation 2. Magnitude of load such that more than High cycle Fatigue
10,000 cycles required
1.Sudden separation into 2 parts
2. Magnitude of load such that less than Low cycle Fatigue
Fluctuating Load / Deformation 10,000 cycles required
Fluctuatin[ Load / Deformation Caused by fluctuatin_ temperature Thermal Fatigue
1.Rolling surfaces in contact Surface Fatigue
Fluctuating Load / Deformation 2. Manifests as pittin[_, cracking, scalin_ Surface Fatigue Wear
Fluctuating Load / Deformation Impact Fatigue
Failure occurs by nucleation or crack
Impact Wear
Impact Load propagation
Elastic Deformation Impact Fatigue Wear
Fluctuating Load / Deformation Corrosion creates stress raisers which
accelerate fatigue which in turn exposes new Corrosion Fatigue
corrosion action layer to corrosion
1.Interface of 2solid bodies
Fluctuating Load / Deformation 2. Normal force Fretting Fatigue
3. At joints not intended to move
Attack by Corrosive Media Direct Chemical Attack
2 Dissimilar metals in electrical contact. Galvanic Corrosion
Electrochemical Corrosion circuit completed by Corrosive Medium
7 Copyright © 2002 by ASME
TABLE 5. Failure Mode Identification_ Contd.
PRIMARY IDENTIFIER SECONDARY IDENTIFIER FAILURE MODE
Localized in crevices, cracks and joints Presence of corrosive medium Crevice Corrosion
Development of array of holes or pits Presence of corrosive medium Pitting Corrosion
Grain boundries of Cu, Ch, Ni, AI, Mg, Zn Improprly heat treated [ntergranular Corrosion
alloys
Solid Alloy One element is removed Selective Leaching
Erosion Corrosion
Presence of Abrasive / Viscid material flow Corrosive Medium Corrosive Wear
Cavitation Erosion
Difference inVapor Pressure
Blistering, embritleement, decarburization Corrosive medium Hydrogen Damage
Food ingestion and waste elemination of living Products act as corrosive media Biological Corrosion
organisms
Applied Stresses Corrosive medium Stress Corrosion
High pressure
Undesirable change in dimension Plastic deformation Adhesive Wear
Rupture of sharp sites
Particles remvoved by harder mating surface Abrasive Wear
Mating Surfaces or by particles entrapped
Deformation Wear
Plastic deformation Impact loading
1. Mating parts
2. Normal force
Fretting Wear
2hange indimensions 3.Joints not intended to move
Impact load Separation into 2 or more parts Impact Fracture
?'lastic / Elastic deformation Impact load Impact Deformation
1.Mating parts
2. Normal force
Impact Fretting
mpact load 3. Joints not intended to move
1.Temperatute / stress Influence
Plastic deformation Creep stress Rupture
2. Rupture occurs depending on stress-time-
temperatire conditions
Thermal Relaxation
Prestarined or prestressed part Change in dimensions
Thermal gradients Differential strains Thermal Shock
1.Combination loads
2. Sliding velocity
3. Temperatures
4. Lubricants
Sliding surfaces 5. Surface destruction Galling and Seizure
6. 2parts virtually welded together
Spalling
Partilcle spontaneously dislodged from surface
Nuclear radiation Loss of ductility Radiation Dama[[e
I
High and/or point load Deflection increases greatly for slight increses Buckling
in load
Geometric configuration
1.Influence of temperature / stress
Plastic deformation 2.Rupture Creep Buckling
3.Exceed buckling limit
8 Copyright © 2002 by ASME
7
EXAMPLE
In this section we describe the function-failure method
applied to fifteen products [24]: Braun coffee grinder, Dremel
engraver, Dewalt sander, Mr. Coffee-Coffee Maker, Bissell
Hand-Vac, Air purifier, Ball shooter, B&D dust buster, Conair
hair drier, Hunt Boston sharpener, Mr. Coffee Iced tea maker, ! i i ',,, i
B&D palm sander, Popcorn popper, Skill screw driver and FUNCTION/FAILURE < '_i _ w _ i
spatula mixer and interpret the results for two functions.
Table 6shows the composite function-failure matrix for the
fifteen products. Before creating the composite function-failure
matrix the function-component and the component-failure
matrices are aggregated and the resulting matrices are multiplied
to get the composite function-failure matrix [2]. More details
on matrix aggregation are given in Stone et al. [25].
__ 0'0i0!1
Mathematically the aggregated function-failure matrix is:
EFt = Z EC x Z CF (2) Figure 4. Function-Failure Matrix.
The matrix for fifteen products gives a list of 25 failure
• Stop liquid - Corrosive wear, Force induced
modes occurring over 71 functions, as shown in Table 6. While
deformation and yielding.
designing a new product or redesigning an existing product we
• Secure Solid - Abrasive wear, corrosive wear, direct
follow the procedure described earlier in deriving the functions
chemical attack, ductile rupture, force induced
of the product. Now utilizing the composite function-failure
deformation, fretting fatigue, high cycle fatigue,
matrix we form the product specific function-failure matrix (EF)
temperature induced deformation, thermal fatigue,
by selecting the failure modes corresponding to the derived
thermal relaxation, thermal shock and yielding.
functions. For example say the product under study has the
With the possible failure modes identified, this gives us a
following functions: 1) stop liquid and 2) secure solid. Its
direction performing further analyses on candidate design
possible failure modes corresponding to its functions are shown
solutions. In particular, solutions for the stop liquid sub-
in Figure 4. The failure modes for these functions are:
function must be analyzed for strength and appropriate wear
characteristics.
We explain the above two functions and their
corresponding failure modes to illustrate the interpretation of
the function-failure matrix in Table 7.
Table 6. Composite Function-Failure Matrix EFt.
EOMPOSITE FUNCTION-FAILURE MATRIX
FUNCTION /FAILURE
rr
8
0
o Ii O_
0 _
ACTUATE ELECTRICITY oi olo O' 0 O! 0
ALLOW X-YDOF o! ol o Oi 0 oi 0i o
CHtkkGE ELEC.ENERGY
CHANGE FORM SOUD
CHANGE ROTATION I' 0
CI-IN4GETORQUE
CHANGE VELOCITY 71 71 1
CONVERT ELEO ENERGYTOROT.ENERGY
CONVERT ELEC.E TOMECH.E
CONVERT ELECTRICAL ENERGY TOTHERMAL ENERGY
Copyright © 2002 by ASME
TABLE 6. Composite Function-Failure Matrix EFt Contd.
FUNCTION /FAILURE
CONVERT HUMAN ENERGY TOTRANSLATIONAL ENERGY Ol Oi 0;
CONVERT ROT,ENERGY. TO PNEU. ENERGY
CONVERT ROT. ENERGY TO VIBRATIONAL ENERGY
CONVERT SOUD TO UQUID OL Oi 0 o o! oi
COUPLE MECH.ENERGY
COUPLE SOUD
DISSIPATE THERMAL ENERGY 0 01 0
DISTPJBUTE LIQUID 0 0: Ol Oi
DtS_ MECH.ENERGY
Ol 0 Ol 0
DISTPJBLr'I"EMOTION Ol 0 Ol 0 0; O_ Ol ol
DISTRIBUTE TORCXJE ol o oi o
EXPORT ELEC,ENERGY 0; o_ oi o ol o 2 0_ 0
EXPORT GAS
_o__oi o! oi 2 o_ o
EXPORT LIQUID
0i 0
XPORT SIGNAL 1: 11 O!
XPORT SOUD 0! 0i 0 1 Oi 0 2
3uIDE GAS O! 0 3i
IUIDELIQUID
3.UtDESOUD
MFORT ELEC,ENERGY
MPORT GAS
MPORT_D
I_,F=OORRTT HUUQMUAIDN ENERGY Oi O_ Oi 0i 0! 11 0
MFaDRT MEQ-IE]'JERGY 2_ oi o
_U_ORT SOLID 4! 0; o!
_Y
_11XGAS AND LIQUID
ol o, o! ol I oi
_!D
01 2:0 i 0
4IXSOUD AND LIQUID
O, Ol O_ 0 O_ 0
REFINE LIQUID
REGULATE ELECTRICrFY
REGULATE GAS
REGULATE MASS FLOW
FEGULATE MECH.F_NERGY
REGULATE ROTATION
REGULATE TRANSLATION
REMOVE SOLID
ROTATE SOLID
SECUF_ MECHANICAL ENERGY O_ 2!
SECURE SOUD
SEPARATE SOUD
STABILIZE MECH.ENERGY
STOP UQUID
STOP SOUD
lO Copyright © 2002 by ASME