A Structured Methodology For

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A Structured Methodology for

the Design and Development of

Textile Structures in a Concurrent

Engineering FrameworkR. Rajamanickam

a, S. Park

a& Sundaresan Jayaraman

a

aSchool of Textile and Fiber Engineering, Georgia

Institute of Technology , Atlanta, GA, US

Published online: 30 Mar 2009.

To cite this article:R. Rajamanickam , S. Park & Sundaresan Jayaraman (1998) A

Structured Methodology for the Design and Development of Textile Structures in aConcurrent Engineering Framework, Journal of The Textile Institute, 89:3, 44-62, DOI:

10.1080/00405009808658682

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A Structured Methodology for the Design andDevelopment of Textile Struc tures in aConcurrent Engineering FrameworkR. Rajamanickam, S. Park, and Sundaresan Jaya ram anSchool of Textile and Fiber Engineering, Georgia Institute of Technology,Atlanta, GA, USReceived as an invited paper , . To whom correspondence must be addressedA structured methodology for the design and development of textile structure.s within aconcurrent eugineering framework ha.s been proposed and developed. The framework hasbeen validated using the design and development of a Sensate Liner for Combat Casualty Care(or Sensate Liner) as an example. Key requirements for tbe product are identified using amodified QFD-type (Quality Function Deployment) approacb and other tools used inconcurrent engineering; and tbe design and developmentframework is ^tablisbed. This isfollowed by an in-deplh analysis of tbe various issues involved in tbe design of the SensateLiner (fabric/garment structure, materials and fabrication technologies) to meet tbe desiredperformance criteria. Candidate solutions are proposed with appropriate justifications.Finally, the successful application of tbe structured metbodology in realizing tbe product iscovered.1 . I NT R ODUC T I ONThe engineering design of textile structures is a complex task. The task is made even morecomplex hecause of the significant interactions between the different design parametersthat ultimately determine the properties of a textile structure. To illustrate this, considerTahle I which depicts the interrelationships between major design param eters and functionalcharacteristics of woven structures (Anon., 1987). The variables in the first column (fiherlinear density, yam count, thread spacing, etc.) have a significant influence on the resultingfunctional properties of the fabric (tensile strength, air permeability, tlexural rigidity,etc.) shown in the other columns. Thus, if we try to increase the fabric tensile strength byincreasing the thread density, it will make the fabric stiffer and reduce air-permeability.Therefore, engineering the desired end-use properties into textile structures requires manytrade-offs and becomes more complicated if the design has to accommodate additionalconstraints imposed by fabrication technologies, marketing, and so on.

Traditionally, the various operations in developing a fabric or garment, such as design,engineering, manufacturing, and marketing, have been carried out sequentially and asseparate fu nctions. This leads to conflicting goals for the various functions and the strategicintent of the enterprise is lost. To avoid this prohlem, more and more enterprises areresorting to cross-functional teams and techniques such as Quality Function Deployment(QFD). Design for Manufacturing (DFM), and Total Quality Management (TQM). As aresult, the time from concept to market is typically reduced (Jayaraman, 1995, pp.239-269). This technique of integrating all the steps in the product life-cycle - from designconceptualization to marketing - during the product design process is called concurrentengineering.

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A Methodology for the Design and D evelopment of Textile Structures in an Engineering FrameworkTable IEngineering Design of Woven Structures from Anon . t987 ))

Increase Only

Fibci Linear DeiurityCross-SectionalArea)

Yarn Linear Den sity

Ym Twist

Threads/inch

Inlcrlacmjis perUnit AreaWeave Patteni)

TensileStreng*

RRi

Ini i ialModulus

titi

TearingStrenglh

ii

BendingStiffiiess

Ai l Per-meability

tiii

AbrasionResiiitsncc

R

ShearResistance

ReiuralEnUurancc

iRRii

Thickresi

r

In this paper, a structured framework for designing textile structures using the concurrentengineering approach is presented using the design and development of a Sensate Linerfor Cotnbat Casualty Careas the case study o r real-world exam ple. The paper is organizedas follows: The relevant tools and techniques used in concurrent engineering are discussedin Section 2. In Section 3, the proposed design and development framework is discussedusing the Sensate Liner as the example. The realization of the product design is discussedin Section 4. The overall conclusions from this research are presented in Section 5.2. LITERATURE REVIEW2.1 OverviewIn this section, the concept of Quality Futiction Deployment is discussed along with anoverview of the Seven Management and Planning Tools that can be applied in the practiceof concurrent engineering.2.2 Quality Function Deployment2.2.1 The ConceptThe concept of Quality Function Deployment (QFD) was introduced in Japan by YojiAkao in 1966 (Akao et ai 1983, pp.61-67). According to Akao (Akao, 1990), QFD 'is amethod for developing a design aimed at satisfying the consumer and then translating theconsumer's demand into design targets and major quality assurance points to be usedthroughout the production phase.... (QFD) is a way to assure design quality while theproduct is still in the design stage*. Akao points out that, when appropriately applied,QFD has demonstrated the reduction of developm ent time by one-halft one-third. Sullivan(1986) says that 'The main objective of any manufacturing company is to bring out newproducts to market sooner than the competition with lower cost and improved quality. Themechan ism to do this is called Quality Function D eploym ent.... (QFD ) is an overall conceptihat provides a means of translating customer requirements into the appropriate technicalrequirements for each stage of product development and production (i.e. marketingstrategies, planning, product design and engineering, prototype evaluation, productionprocess developm ent, produ ction, sales).... In QF D . all operations are driven by the voiceof the customer ; QFD therefore represents a change from manufacturing-process quality

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Rajamanickam Park and Jayaramancontrol to product-development quality control'. SuHivan further notes that 'The QFDsystem has been used by Toyola since 1977, following four years of training and preparation .Results have been impress ive.... Between January 1977 and April 1984.Toyo ta introducedfour new van-type vehicles. Using 1977 as a base. Toyota reported a 20% reduction instart-up costs on the launch of the new van in October 1979; a38% reduction in November1982: and a cumulative 6 % reduction in April 1984. During this period, the productdevelopment cycle (time to market) was reduced by one-third with a correspondingImprovement in quality because of a reduction in the number of engineering changes'.Dean (1992) viewsQ FDas a system etigineering process that transforms the desires of thecustomer/user into the language required by the design process. It also provides the gluenecessary, at all project le vels, to tie all com ponents together and to manage them. It is anexcellent method to ensure the customer obtains a high value from the product; actuallythe intended purpose of QFD.

At its core , QF D is a structured p rocess that uses a visual language and a set of interlinkedengineering and management charts to transform customer requirements into design,production, and tiianufacturing process characteristics. The result is a systems engineeringprocess which prioritizes and links the product development process to the design so thatit assures product quality as defined by the customer. Additional power is derived whenQFD is used within a concurrent engineering environment.2.2.2 The House of QualityThe full benefit of the QFD process comes from tailoring a sequence of m atrices to guideproduct or service development decisions. When many people hear the term QFD, theythink of theHouse of Q uality.QF D is actually a process that uses many m atrices, only oneof which is the famed House of Quality. The H ouse of Quality is the most comm only usedmatrix, and many teams do not go beyond it, tnissing a lot of additional ben efits. B ecausethe House of Quality is so commonly used in QFD. a brief description is in order. Fig. 1illustrates the House of Quality (Guinta and Praizler, 1993).

Cud a n aNeeds andRdatiueImportance

Q uality Charactaistics

Rdatimd a r mO Mei tA Weak

o A

hips9m

P rit r it is Pa ftrmanceMff ia i e^ an dTar^tValus

MarketAnalyasand roduct

Planning

Fi g. I House of Quality

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A Methodology for the Design and Development of extileStructures in an Engineering FrameworkThe 'ho us e' is divided into several room s', each completed in a logical sequence. Thefirst section.C ustomer needs is a structured list of what customers are looking for, typicallyobtained through qualitative market research such as interviews and focus groups. Theyare staled in the customers' words and language.Quaniitalive data fills out the second section known as Market Analysis and Product/

Service Planning. This data typically consists of the relative importance of the customerneeds contained in the first section, customer satisfaction ratings of the com pan y's currentofferings and customer satisfaction ratings of the comp etition 's offerings. Using this data,the QFD team sets goals for improving new products or services relative to the com petition,and calculates the final priority of the customer needs that the team will use.Using the expertise of the cross-functional team, the Quality Characteristics of theplanned product or service are listed in the third section. These characteristics are expressedin the company's terminology of products and services. (Quality Characteristics are alsosometimes called the com pan y's Technical Re spon se'.)The central room of the House of Quality contains the team 's judgm ent of how stronglyeach Quality Characteristic (or Technical Response) contributes to meeting each customerneed.The 'ro of of the House of Quality is not always used, but can illuminatetrade-offs thatmay exist among the Quality Characteristics. For example, apparel buyers may want botha durable, soft fab ric' and a garment that is 'easy to care fo r'. Th ese wants tnay be reflectedin quality characteris tics of fabric areal density and fiber type. The roofisused to documentthese trade-offs, as well as other positive or negative interrelationships.Lastly, the teatn computes the rank ordering of the quality characteristics, using therelative priorities of the customer needs and the strength of the relationships from thecentral room of the Hou se. The team also includes Performance Measu res of how w ell thecotiipetition's product or service performs, which are used to set Target Values forimplementing the quality characteristics.

2.3The Seven New anagement and Planning Tools2.3.1 OverviewAccording to M Izuno and Akao (19 94), the seven new tools are the products ofth JapaneseSociety for Quality Control Technique Development. After a worldwide search, in 1976they proposed the following new tools useful for the practice of concurrent engineering:(i) Affinity diagram(ii) Interrelations hip digraph ' .

(iii) Tree diagram(vi) Matrix diagram(v) Prioritization ma trices(vi) Process decision program chart(vii) Activity network diagram

They were chosen to meet the following criteria: the ability to complete tasks; the ability to eliminate failure; the ability to assist in the exchange of information; the ability to dissemina te information to concem ed parties; and the ability to use unfiltered express ion '. .

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Rajamanickam, Park, and JayaramanThe seven new tools constitute a rich visual language that allows the user to easily exploreand decompose complexity which cannot be dealt with otherwise. The first step in usingthese tools is brainstorming - a process that promotes the free expression of ideas in ateam setting without imm ediate comments, criticisms or analysis from fellow team m emb ers.The results of the brainstonning session are then structured using the Seven Managementand Planning Tools to yield productive and pragmatic solutions that can be implementedto realize the overall goals of the design project. ,2.3.2 Affinity Diag ram . , -The Affinity Diag ram is a tool for organ izing languag e data Fig. 2) . After ideas arebrainstonne d and w ritten on card s, they are grouped together w ith similar ideas. A headercard is created which captures the meaning of each group of ideas.

Fi g. 2 Affinity diagram , * ,

2.3.3 tnterrelationship DigraphThe interrelationship digraph shows the relationships between items by drawing an arrowfrom one idea that causes ano ther idea, to an idea that is the result Fig. 3). Som etimes thearrow is drawn from one action that occurs before another action. The items that havemostly arrows going in are long-range targets, and the items with most arrows going outare initial action items.

Fig . 3 Interrelationship digraph

2.3.4 Tree Diagram

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A Methodology for the Design and Development of Textile Structures in an Engineering FrameworkThe tree diagram takes a purpose and logically breaks it into action items, When readfrom left to right (Fig. 4), it goes in a logical progression from general to specific. If it isread from left to right, it answers the question how is the process acco m plish ed? . If it isread from right to left, it answ ers the question w hy? .

Fig . 4 Tree diagram

2.3.5 Matrix DiagramThe matrix diagram shows the relationship between two or more sets of items. It can bevery useful in facilitating an analysis of the relationship of each item in one set to all itemsin the other set. This often triggers some thinking that would not have happened if thisorganized approach were not used. It is also helpful to see pattem s of relationships: whichitems do n t relate to anything and which on es are critical.

c d

Fig. 5 Matrix diagram

2.3.6 Prioritization MatrixThe p rioritization matrix enables the selection of priority items by app lying a set of criteriato each item. Sometim es the list of criteria is fairly simple; other tim es it is weighted witha great deal of precision.

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A Methodology for the Design and Development ofTextile Struclurci in an Engineering Framework

fi g. 8 Activity network diagram

3 . METHODOLOGY FOR DESIGN AND DEVELOPMENT OF THE SENSATELINER3.1 OverviewIn this section, the methodology for the design and development of the sensate liner usingsome of the tools described in Section 2 is presented.3.2 Broad Performance RequirementsThe US Department of Navy put out a broad agency announ cemen t inviting white(concept) p apers to create a system for the soldier that was capahle of alerting the medicaltriage unit (stationed near the battlefield) when a soldier was shot, along with someinformation on the sold ier s cond ition characterizing the extent of injury. A s such, thisannouncement was very broad in the definition of the requirements and specified thefollowing two key broad objectives of the Sensate Liner:

Detect the penetration of a projectile (e.g. bullets and shrapn el); and M onitor the soldier s vital signs.The vital signs would be transmitted to the triage unit by interfacing the Sensate Linerwith a Personal Status Monitor developed by the US Defense Advanced Research ProjectsAgency (DARPA).3.3 Design Conceptualization: Detailed Analysis of the Key PerformanceRequirementsThe goals of the research project undertaken at Georgia Tech and reported in this paperhave been to conceptualize a system that would meet the two broad performancerequirem ents, design the system applying the principles of concurrent enginee ring, producethe Sensate Liner, and demonstrate the realization of the pertbrmance requirements.

The first step in the QFD process is to clearly identify the various characteristic s requ iredby the customer in the product being designed. Therefore, using the information obtained(Anon., ]996a,b at pre-proposal briefings from the US Navy (the custo m er ) on the twokey performance requirements for the proposed Sensate Liner, an extensive analysis wascarried out. A detailed and more specific set of performance requirements was defmed;the result is shown in Fig. 9. These are Functionality, Usability in Combat, Wearability,

Georg ia Institute of Techn ology subtnitted a white paper conceptualizing the system to meet these two broadperformance requirements and outlined Ihe research methodology lo realize this concept (sysiem). The Navy invitedGeo rgia Tech to submit a detailed propo sal that was subsequ ently selected for funding to carry out this research./ Te xt lust.. 1 998, 89 Pan 3 Textile InsUtule 5 |

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Fig 9 Sen sate Liner performance requirements

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A Methodology for the Design and Development of Textile Structures in an Engineering FrameworkDurability. Manufacturability, Maintainability, Connectability and Affordability. The nextstep was to exam ine these requiremen ts in-depth and to identify the key factors associatedwith each of them. These are also shown in the figure. For example.Functionality impliesthat the Sensate Liner must be able to detect the penetration of a projectile and should alsomonitor hody vital signs - these are the two requirements identified in the broad agencyannouncement from the Navy.

The factors deemed critical in battlefield conditions are shown under sahilitvin Cotnbatin the figure. These include providing physiological thermal p rotection, providing resistanceto petroleum products and EMI (electromagnetic interference), minimizing signaturedetectability (thermal, acoustic, radar, and visual), offering hazard protection whilefacilitating electrostatic charge decay and being flame- and directed-energy retardant.Likewise, as shown in the figure, Wearability implies that the Sensate Liner should belightweight, breathable, comfortable (form-fitting), easy to wear andtake-off and provideeasy access to wounds - critical requirements in combat conditions so that the soldier's

performance is not hampered by the protective garment. Durabilityof the Sensate Liner isanother important performance requirement; it should have a wear life of 120 combatdays and should withstand repeated flexure and abrasion - both of which are characteristicof combat conditions. Manufacturability is another key requirement since the design(garment) should be eventually produced in large quantities over the size range for thesoldiers; moreover, it should be compatible with standard issue clothing and equipment.Maintainability of the Sensate Liner is an important requirement for the hygiene of thesoldiers in combat conditions; it should withstand/JeW laundering, should dry easily andbe easily repairable (for minor damages). The developed Sensate Liner should be easilyconnectable to sensors and to the Personal Status Monitor (PSM) on the soldier. Finally,affordabilityof the proposed Sensate Liner is another major requiremen t so that the garmentcan be made widely available to all comb at soldiers to ensure their security, and hence thatof the nation.

Thus, in the first step of the design conceptualization process, the broad performancerequirements were translated into a larger set of clearly defined requirements along withthe associated factors (Fig. 9).3.4 Design and Development FrameworkOnce the detailed performance requirements were defined, the need for an overall designand development framework became obvious. Since no comprehensive framework wasfound in the literature, one was developed. Fig. 10 shows the resulting overall SensateLiner Design and Development Framework and it encapsulates the modified QFD-typemethodology developed for achieving the project goals. As shown at the top of the figure,the first step has been to identify the key performance requirements for the Sensate Liner(details shown in Fig. 9). These Requirements are then tran.slated itito appropriateProperties of the Sensate Liner: sets of Sensing and Comfort properties. The Propertieslead to the specific Design for the Sensate Liner: dual structure meeting the twinrequirem ents of 'sensing' and comfort'. These Properties in the Design are achievedthrough the appropriate choice of Materials Fabrication Technologies by applyingthe corresponding Design Parameters as shown in the figure. These major facets in theproposed framework are linked together as shown by the arrows between the dotted boxesin Fig. 10.This overall comprehensive design and developme nt framework is now analyzedin greater detail in the following sections.

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Rajamanickam, Park,and Jayaraman

Fig 10 Sensate Liner design and development framework

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A Methodology for the Design and Development of Textite Structures in an Engineering Framework3.5 rriving a t the Design3.5. OverviewThe next step in the design process has been to translate the performance requirements (inFig. 9) intospecific properties that must be engineered into the Sensate Liner, leading toits design. The resu lts of this step are shown in tbe second dotted box in the framework inFig. 10.

3.5.2 Desired Set of PropertiesThe desired properties have been divided into Sensing and Comfort characteristics. Forexample, the Sensing properties include electrical/optical conductivity, resistance to signaldisturbances, minimum signal attenuation due to deformation during manufacturing and/or use, good mechanical properties and low weight. The key Comfort properties includefabric hand (e.g. how soft the fabric/garment feels to touch ), air perm eability and moistureabsorption lo ensure a breathable and comfortable garm ent, static dissipation, strelchab ilityto ensure a form-fitting garment, etc. Bending rigidity, flexural endurance, weight, andtensile properties are the comm on set of properties that are derived from oiherperformancerequirements in Fig. 9. Manufacturability and cost are the two underlying parameters ofthe proposed design.3.5.3 Proposed Design and StructureBased on a critical analysis of the set.s of Sensing and Comfort properties required of theSensate Liner, the next step has been to propose adesign to achieve the desired propertiesin the most cost-effective manner while ensuring manufacturability, The Sensate Linerwill be an integrated structure comprising the major components shown at the bottom ofthe second dotted box (Design) in the framework in Fig. 10:

Penetration Sensing Com ponent PSC): will pinpoint the location of projectilepenetration and will be linked to the Personal Status Monitor (PSM) through theconnectors at the hip level; Electrical Conducting Com ponent ECC):will monitor body vital signs includingpulse rate, temperature and blood pressure through sensors on the body and will

be linked to the PSM at the hip level; Com fort Com ponent CC}:will be in im med iate contact w ith the so ldier s skinand will provide the necessary comfort properties for the garment (similar to theregular issue undershirt); Form-fitting Component FFC):will provide the necessary form-fit to the so ldier;more impo rtantly, it will keep the sensors in place on the sold ier s body duringcombat conditions; and Static Dissipating Com ponent SDC): will quickly dissipate any built-up staticcharge during usage.

The integrated structure will be produced using appropriate fabrication technologiesdiscussed in the following section.

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Rajamanickam. Park, and Jayaraman3 6 Realizing the Design; Materials and Fabrication Technologies3.6.1 OverviewAs shown in the framework in Fig . 10. the next step is to identify the mate rials andfabrication technologies that can be utilized to achieve the proposed design of the SensateLiner w ith the desired properties. The results of the steps are shown in the third dotted boxin the figure. The design parameters associated with the materials and fahricationtechno logies (shown at the far end ofthethird dotted box) denote the correspond ng variablesthat can be modified to achieve the desired properties and performance in the SensateLiner.3.6.2 Materials Evaluation and Selection3.6.2.1 M erhod The Sensate Liner Performance Requ irements and Prop erties in Figures 9and 10 were used to develop the criteria for evaluating the materials for the variouscom pon ents of the Sensate L iner. Based on these criteria, several m aterials were evaluatedfor each Sensate Liner component using a weighted prioritization matrix approach. Theresulting matrix was used to identify the candidate materials for various components ofthe Sensate Liner. The candidate choices and corresponding design parameters are shownin the third dotted box in Fig. 10. This structured approach to the evaluation of multiplealternatives during product design ensures that the right choice is made.3.6.2.2 Materials for Penetration Sensitjg Componen t PSC ) Penetration alert can beachieved by the use of either an electrically c onductive mesh or an optical fiber m esh. Theresponse time of an electrical mesh has been shown to be too slow to 'catch a bullet'(Anon., \996b). Also, conductive fibers are susceptible to electromagnetic interferenceand have to be shielded to prevent shorting w hen wet. Optical fibers do no t suffer fromthese limitations. Based on these relative merits, optical fibers have been chosen overconductive fibers for the PSC.

For sensing the penetration of the projectile, the choice has been narrowed down tosilica-based optical fibers and plastic optical fibers (Kitazawa et ai, 1991 ; Ch ai, 1990).The design evaluation matrix shown in Table provides a comparative evaluation of thetwo candidate materials for the PSC. The evaiuation criteria in the first column have beenderived from the performance requirements (Fig. 9) and properties of the PSC (Fig. 10).The relative weights of these evaluation criteria are listed in the second column in thetable. The weight denotes the importance of the specific criterion towards the performanceof the Sensate Liner. For example, optical conductivity has the greatest impact on theperformance of the PSC (and hence the Sensate Liner), and is therefore assigned thehighest weight(20%).This is followed by resistance to electromagnetic interference (1 5% ),attenuation of signal (15%), and so on. For each evaiuation criterion, a score is assignedto the material based on its ability to meet that criterion (0-poor to 4-best). For example,the bending rigidity/flexural endurance of silica-based optical fiber is considerably poorwhen compared to that of plastic optical fiber. Therefore, the former is assigned 1 wh ilethe latter is assigned 3 in the table. Based on the individual weights and correspondingscores, a weighted score (Iweight,*score.) is computed for each material choice and isshown in the last line of the table. The higher the fmal weighted score, the greater theprobability tbat the material will successfully meet all the evaluation criteria and hencethe higher the chance of producing an effective Sensate Liner for combat conditions.

Based on the prioritization matrix in Table II, plastic optical fiber has been chosen forthe PSC in the Sensate Liner.

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A Methodology for ihe Design and Develupment of Textile Structures in an Engineering FrameworkTable IIDesign Evaluation Ma trix, Penetration Sensing Component PSC)

Property(Evaluation Criterion)Optical cond uctivityResistance to electromagneticinterferenceAttenuation of signalBending rigidity/flexuralenduranceManufacturabilityElongation and creep recoveryWeightTensile strength and modulusAvailabilityCostTotal and weighted score

Weight{ )201515IS107.57.552.52.5

100

Silica OpticalFiber (Score)4431122242

2.7

Plastic OpticalFiber (Score)4433334342

3.4Score: scale of (worst) to 4 (best).

3 6 2 3 Materials for Electrical Conducting Component ECC ) The ECC will monitorbody vital signs, including pulse rate, temperature, and blood pressure, through sensorson the body and will be linked to the PSM at belt level. The two key candidate materialsinitially considered for the ECC are: (i) thin copper wire with a polyethylene sheath, and(ii) polyacetylene filament w ith a polyethy lene sh eath. The design evaluation matrix shownin Table III provides a com parative evaluation of these two candidate materials. The m atrixwas derived along the lines of Tab le II. Based on the relative m erits of the fibers shown inthe table, the metallic fiber, i.e. copper core with polyethylene sheath, was chosen for theECC in the Sensate Liner.

TableIIIDesign Evaluation Matrix, Electrical Conducting Component (ECC)Property(Evaluation Criterion)

Electrical condu ctivityStability (chemical, thermal, water)Resistance to electromagneticinterferenceBending rigidity/flexuralenduranceAvailabilityElongation and creep recoveryWeightTensile strength and modulusCostTotal and weighted score

Weight( )

30201510105552.5

100

Copper CorewithPolyethyleneSheath (Score)4423421433.43

PolyacetyleneCoatedFibers withPolyethyleneSheath (Score)1123t34311.73

Score: scale of 0 (wo rst) to 4 (best).3 6 2 4Materials for Com fort Component CC)The CC will be in immediate contact withthe soldier's skin and will provide the necessary comfort properties for the garment;therefore, the choice of material becomes critical and the one chosen should provide atleast the same level of comfort and fit as the undershirt currently issued to the soldiers.

The design evaluation matrix for the set of fibers for the CC is shown in Table IV. Theevaluation criteria have been derived from Figures 9 and 10. Since the Sensate Liner willJ. T ext. Inst., I99S 89 P art 3 Textile Institute 57

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Riijaniankkam. Park, and Jayaramanbe in contact with the body, the material chosen should provide a good fabric hand, airpermeability, moisture absorption and stretchability to the Sensate Liner and thereforethese parameters are weighted high in the table.

Tab le IV 'Design Evaluation Matrix, Comfort Component (CC)

Property(Evaliiaiion C riterion)Fabric handAir perm eabilityMoisture absorptionStrelchability (elasticity/recovery)Bending rigidityWeightTensile propertiesManufaciurabilityCostTotal and weighted score

Weight(%)

1515151510101055

100

Cotton(Score)4443332443.5

MeraklonPolypropyleneFibers (Score)3443344443.6

MicrodenierPolyester(Score)32'2 '443 ^413

Poly-cottonBlend(Score)

3 4

... 4t3.423.1

Gore-TexFilm Liner(Score)

2344243323.1

Score: scale of (worst) to 4 (best).As shown in the table, the major fibers evaluated for use in the CC are cotton, M eraklon ,microdenier polyester, polyester/cotton blend and Gore-Tex film liner. Cotton and M eraklonare the two top choices for the CC. Based on the relative merits of the fibers shown in thetable. Meraklon has been chosen for the CC in the Sensate Liner. Additionally, since one

of the issue items to soldiers is underwear made from polypropylene fibers, the choice ofMeraklon is fiarther justified.3.6.2.5 Materials for Form-Fitting Com ponent FFC )The FFC will provide the necessaryform-fit to the soldier; more importantly, it will keep the sensors in place on the soldier'sbody during combat conditions. Therefore, the material chosen should have a high degreeof stretch to provide the required form-fit and, at the same time, be compatible with thematerials chosen for the other components of the Sensate Liner.

Spandex fiber is a block polymer with urethane groups. Its elongation at break rangesfrom 500 to 600% and thus can provide the necessary form-fit to the Sensate Liner. Itselastic recovery is also extremely high (99% recovery from 2-5% stretch) and its strengthis in the 0.6-0.9 grams/denicr range. It is resistant to chemicals, and withstands repeatedmachine washing s and the action of pe rspiration. It is available in a range of linear d ensitiesand is widely used in swimsuits. Therefore, Spandex has been chosen for theFFC of theSensate Liner.3.6.2.6 Ma terials for Static Dissipating Com ponent SDC ) The purpose of the SDC is toquickly dissipate any built-up static charge during the usage of the Sensate Liner. Undercertain conditions, several thousand volts may be generated and this can damage thesensitive electronic components in the PSM Unit. Therefore, the material chosen mustprovide adequate Electrostatic Discharge (ESD) protection in the Sensate Liner.

Nega-Stat, a bicomponent fiber produced by DuPont has a trilobal-shaped conductivecore that is sheathed by either polyester or nylon. This unique trilobal conductive coreneutralizes the surface charge on the base material by induction, and dissipates the chargeby air ionization and conduction; it covers the charge dissipation range required of theSensate Liner (Anon., 1996/>). The nonconductive polyester or nylon surface of Nega-Stat58 J. Text. Inst.. 1998. 89 Fart 3 Textile Insiituu

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A Methodology for the Design and Development ofTextile Structures in an Engineering F rameworkfiber controls the release of surface charges from the thread to provide effective staticcontrol of material in the grounded or ungrounded applications according to specific end-use requirem ents. The outer shell of polyester or nylon ensures effective wear-lifeperformance with high wash and wear durability and protection against acid and radiation.Therefore, Nega-Stat has been chosen for the SDC in the Sensate Liner.3.6.3 Evaluation of Fabrication TechnologiesThe key fabrication technologies evaluated for creating the integrated Sensate Linercomprising the various components are shown in the framework in Fig. 10, along with thecorresponding design parameters. These include tubular weaving, in-lay knitting, full-fashioned kn itting, and em broide ry on two different substrates; a knitted fabric and aGore-Tex film. Table V shows the design evaluation matrix for the candidate fabricationtechnologies.

TableDesign Evaluation Matrix Fabrication TechaologiesPropertyForm fitting(elasticity/flexural endurance)Fabric handAir permeability(brealhability)DurabilityManufacturabilityTechnology complexityCostTotal

Weight(%)3020151010105

10 0

TubularWeaving

33443323.2

in-layKnitting

44434423.7

Full-fashionedKnitting44432243.7

Embroideryon Knit22332232.4

Embroideryon Gore-Tex31132222.2

Score:scale of 0 (worst)to4 (best),Since form-fitting and fabric hand are the two principal performance requirements(Figures 9 and 10), they are weighted high when evaluating the technologies. TubularWeaving and In-Lay knitting are the two top fabrication technologies for producing theSensate Liner. Although Full-Fashioned Knitting (FFK) also ranks high, its technologicalcomplexity precludes its usage in the developmen t phase of the Sensate Liner. M oreover,the design of the Sensate Liner is such that the technological complexity outweighs someof the advantages of FFK. Since the two fabrication technologies (Tubular Weaving andIn-Lay knitting) are ranked high and have distinctive characteristics required, they havebeen selected for manufacturing the Sensate Liner.Thus, the proposed Design and Development Framework and the methodology havebeen very effective in translating the cus tom er's' broad requirem ents into a produ ct designand into engineering design parameters that can be varied (based on underlying fundamentalprinciples) to ultimately arrive at the right materials, the right structure, and the rightfabrication technology to create the Sensate Liner with the optimal performance.

4. DESIGN REALIZATION: PRODUCTION OF WOVEN SENSATE LINER4.1 The Sensate LinerThe specific baselinedesign for the Sensate Liner has been developed based on the resultsfrom the extensive analysis presented in Section 3, covering performance requirements,the overall components, and the choice of materials and fabrication technologies. As the

J. Text. In.tt. 1998 89 Part} Textile Institute 5 9

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A Methodology for the Design and Development of Textile Structures in an Engineering FrameworkIn the monitoring mode, the Sensate Liner will not include the penetration detectioncom ponent and it will he used to monitor the vital signs of individuals very effectively andin a less cumbersome manner than is possible today. Th us, in this m ode, the Sensate Linerwill he used mainly by space explorers, medical patients, and athletes (Giri, 1998, p.65).It could also he used to monitor the conditions of pets under acute care.

4 2 2 Operation ofth Sensate Liner: Penetration Alert(i) Prec isely timed pulses from the first transceiver at belt level are sent to the secondtransceiver near the shoulder through the POF integrated into the Sensate Liner.(ii) If there is no rupture of the PO F, the signal pulses are received hy the secondtransceiver and an acknow ledgment' is sent to the PSM Unit indicating thatthere is no penetration,(iii) If the optical fibers are ruptured at any point due to penetration by a projectile, the

signal pulses bounce back to the first transceiver from the point of impact, i.e. therupture point. The time elapsed between the transmission and acknowledgmentof the signal pulse indicates the length over which the signal has traveled until itreached the rupture point, thus identifying the exact point of penetration.(iv) The PSM unit transmits a penetration alert via the transmitter mounted in thebackpack to the field command unit specifying the location of the penetration.The two transceivers are then switched-off to conserve power.

4 2 3 Operation ofth Sensate Liner: Vital Signs Monitoring(i) The signals from the sensors are sent to the PSM Unit through the ElectricalConducting Component (ECC) of the Sensate Liner,(ii) If the signals from the sensors are within the normal range and if the PSM Unit

has not received a penetration alert, the vital sign readings are recorded by thePSM unit for later processing,(iii) Howeve r, if the readings deviate from the normal, or if the PSM unit has receiveda penetration alert, the vital sign readings are transmitted to the field control unitusing the transmitter mounted in the soldier's backpack.

Thus, the design and development framework developed as part of this research has beenthe key to the realization of the research goals.5. C O N C L U SI O N SA structured methodology for the design and development of textile structures has beendeveloped and its usefulness has been clearly demonstrated through the design anddevelopment of a Sensate Liner'. This is a generic methodology for product design anddevelopment in a concurrent engineering environment. In this methodology, cu.stomerrequirements aretranslatedinto appropriate prop erties that the textile structure m ust possessto fulfill the requirem ents. The Prop ertiesleadtothe specific design for the textile structure.These Properties in the Design are achieved through the appropriate choice of Materials

During the latter stages of the research, the name 'Wearable Motherboard' was coined to better describe andencapsulate the overall concept and realization oftheSensate L iner. Just as chips and other devices can be plugge dinto a computer motherboard, sensors and other informaiion processing devices can be plugged into the SensateLiners produced during the course of the research . Therefore, the name Wearable Motherboard is apt for thenexible . wearable, and comfortable Sensate Liners, This name - Wearable M otherboard - represents a naturalevolution oftheearliernam es Sensate Liner and Woven Motherboard.J Text Inst , /998 S9 Part S Textile Institute 6 1

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Rajamanickam Park and Jayaraman& Fabrication Technologies by applying the corresponding design parameters. All the.semajor facets in the proposed framework are linked together and help the product designteam make the logical progression from general ideas to specific parameters andinstantiations.

This m ethodology has been validated by successfully designing and fabricating a SensateLine r for the US Navy. The concurrent eng ineering approach led to a design b eing realizedin the short time of 6 mo nths, requiring very few design mod ifications during the productionand testing phases . Th us, the textile/apparel industry can adopt tbis framework for productdesign in a concurrent engineering environment and become successful in the context of adramatically decreasing 'concept-to-market' timeframe and the highly competitive globalmarketplace.ACKNOWLEDGEMENTSThe authors would like to thank Dr E. Lind of the US Department of Navy, Mr D.O Brienof the US Defense Lo gistics Agency, and Dr R. Satava of DAR PA for identifying the needfor a soldier protection system, and for providing the funds to carry out this research underContract # N66001-96-C-8639. They also thank the Navy, DARPA. the US DefenseLogistics Agency, and Georgia Tech Research Corporation for helping fund the research.REFERENCESAka o. Y.. Ono. S., Harada. A.. Tanaka. H., and Iwasawa, K., 1983.Quality Deployment Including Cost, Reliability,and Technology.Quality 13. 3.Akao . Y. (ed.). 1990.Quality Function D eployment Productivity Press, Cam bridge, MA, US .Anon.. 1987.Mhimy inicvnmonaX Albany tnt. Res. Newsletter W\ 1.Anon,,1996a.Proceedings of the DLA/ARPA/NRaD Sensate Liner Workshop April 11,Colum bia, Soulh Carolina,US.Anon.. 996b.Proceedings of tbe Pre-Propo. ialSensate Liner W orkshop.June 27, Phoenix. Arizona, US.Chai. Y., \990. Handbook of Fiber Optics ~ Theory and Applications Academic Press Inc., New York, NY, US.Dean . E.B .. 1992. Quatiiy Function Deploym ent for Large System s. Proceedings of the 1992 internationalEngineering Management Conference 25-28 October. Eatontown, NJ, US.Giri,P., 1998. 'Smart Shirt'in'21 Breakthroughs thai Could Change your Life in the2]st Century .Z7F.SpecialIssue onMedical Miracles for the Ne.xtM illennium Fall 1998, New Y ork, NY, US .Guinia. L.R., and Praizler, N.C .. 1993.The QFD Book American Management A ssociation, New York, NY, US.Jayaram an. S., 1993. On Concurrent Engineering in the Textile/Apparel C omp lex, Proceeding .^ of the 9thinternational Conference on Engineering D esign August 17-19, The Hagu e. The Netherlands.Jayaraman, S..1995.Computer-Aided D esign and Manufacmring: Textile-Apparel Perspective,la AdvancementsiirtdApplications of Mechaironics Design in Textile Engineering Acar, M., ed.), Kluwer Academic Publishers,The Netherlands.Kitazawa, M ., KreidI, J.F.. and Steele, R.E. (eds.), 1991. Plastic Optical Fib ers, SPIE Proceedings SPIE -international Society of Optical Engineering September, Boston, MA , US.M izuno. S.. and Akao, Y. (ed s.). 1994.QFD: TheCustomer-drivenApproach toQualityPlanning and DewlopmentAsian Productivity Organ ization, Tokyo, Japan, available from Quality Resource s, One W ater Strcec. White Plains.NY,US, U)60l .Sullivan, L.P, 1986. Quality Function Deployment. Quality Progress June.

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