Materials and Design 54 (2014) 473–482

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Materials and Design

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Technical Report

Conceptual design of kenaf fiber polymer composite automotiveparking brake lever using integrated TRIZ–Morphological Chart–AnalyticHierarchy Process method

0261-3069/$ - see front matter � 2013 Elsevier Ltd. All rights reserved.http://dx.doi.org/10.1016/j.matdes.2013.08.064

⇑ Corresponding author. Tel.: +60 3 89466318; fax: +60 3 86567122.E-mail address: sapuan@eng.upm.edu.my (S.M. Sapuan).

M.R. Mansor a,b, S.M. Sapuan a,⇑, E.S. Zainudin a, A.A. Nuraini a, A. Hambali c

a Department of Mechanical and Manufacturing Engineering, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysiab Faculty of Mechanical Engineering, Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, 76100 Durian Tunggal, Melaka, Malaysiac Faculty of Manufacturing Engineering, Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, 76100 Durian Tunggal, Melaka, Malaysia

a r t i c l e i n f o a b s t r a c t

Article history:Received 12 April 2013Accepted 18 August 2013Available online 28 August 2013

This paper presents the conceptual design of kenaf fiber polymer composites automotive parking brakelever using the integration of Theory of Inventive Problem Solving (TRIZ), morphological chart and Ana-lytic Hierarchy Process (AHP) methods. The aim is to generate and select the best concept design of thecomponent based on the product design specifications with special attention to incorporate the use ofnatural fiber polymer composites into the component design. In this paper, the TRIZ contradiction matrixand 40 inventive principles solution tools were applied in the early solution generation stage. Theprinciple solution parameters for the specific design characteristics were later refined in details usingthe aid of morphological chart to systematically develop conceptual designs for the component. Five(5) innovative design concepts of the component were produced and AHP method was finally utilizedto perform the multi-criteria decision making process of selecting the best concept design for thepolymer composite automotive parking brake lever component.

� 2013 Elsevier Ltd. All rights reserved.

1. Introduction

Conceptual design is among the most crucial stage in earlyproduct development where in general, possible solutions are pro-duced to satisfy the required design intent of the product. In gen-eral, the overall conceptual design stage can be divided into four(4) main areas which are concept clarification, concept generation,concept selection and concept development [1]. Within thoseareas, there are various methods available to assist designers insystematically generating ideas for design concepts of the productas well as performing the concept design selection process in theconcept development stage. Sapuan [2] demonstrated the use ofmorphological chart in generating ideas for new automotive pedalsconceptual designs using polymer composites. The method wasbased on function analysis where new design concepts were gen-erated through the combination of multiple design features basedon the product functions. Apart from that, Cascini et al. [3] reportedthe application of Theory of Inventive Problem Solving or TRIZmethod in developing new concept design of sheet metal snips.The idea generation for the new sheet metal snips concept designproposed based on the TRIZ contradiction matrix and the final de-sign concept was further enhanced using CAD-based design opti-mization tool.

On the other hand, among the available method applied inproduct development for the concept selection purposes are theAnalytic Hierarchy Process (AHP) and Technique for Order Prefer-ence by Similarity to Ideal Solution (TOPSIS) methods [4,5]. Bothmethods have the advantage in providing crucial solution in thedecision making process where multiple attribute and design alter-natives have to be analyzed simultaneously to suit the intendeddesign specification and also able to be applied in group decisionmaking process.

In this paper, a new automotive parking brake lever componentusing kenaf fiber polymer composites is developed to replace theexisting steel-based parking brake lever in order to reduce thecomponent’s weight while maintaining the required structuralstrength for safety and functionality performances. Based on theproject requirements, a new concurrent engineering approachusing the integration of TRIZ, morphological chart and AHP meth-ods approach was applied in the development of conceptual designfor polymer composites automotive parking brake lever compo-nent. Four (4) main stages were involved during the developmentprocess which are: idea generation, idea refinement, concept de-sign development and concept design selection using the men-tioned methods. Five (5) new concept designs of the componentwere produced in the end of the development process and the bestconcept design was selected based on the product designspecifications.

Table 1Summary of the application of TRIZ in concurrent engineering for product development.

Application of TRIZ in concurrent engineering Application in productdevelopment

References

TRIZ, QFD Notebook casing [12]Washing machine [13]

TRIZ, AHP Dual layer tread tire, correctiontape device

[14]

Automated communicationconnector machine

[15]

TRIZ, AHP, Eco-Design elements Bottle casing [9]TRIZ, Fuzzy AHP Automated communication

connector machine[16]

TRIZ, optimization tool Sheet metal snips [3]TRIZ, FMEA, Eco-Design Vacuum cleaner [17]TRIZ, axiomatic design, mixed integer programming Locomotive ballast [6]TRIZ, axiomatic design Sink faucet, electrical switch [18]TRIZ with non-TRIZ tools such as constraint analysis (opportunity identification stage), feasibility study (problem

selection stage), multi-criteria decision analysis (solution selection stage), work breakdown structure (projectexecution stage), product platform analysis (application exploration stage)

High concentrated photovoltaicsystem

[8]

474 M.R. Mansor et al. / Materials and Design 54 (2014) 473–482

2. Applications of TRIZ in concurrent engineering for newproduct development

The TRIZ method was founded by G. Altshuller in 1946 fromRussia where by the method is based on studies of inventive prin-ciples applied in patents to generate ideas for the design solutions[6]. Among the main characteristics of the TRIZ method is it aim toeliminate any trade-off that may arise from the solution found byfocusing on the problem root cause and clearly identifying the pur-pose of the subject. There are four (4) main approaches to the solu-tion that can be selected through the TRIZ method depending onthe level of complexity of the problem which are Su-field modelingand 76 Standard Inventive Solutions, 40 inventive principles, Pre-diction of Technology Trends and Algorithms of Inventive ProblemSolving (ARIZ) [7]. The main advantage of TRIZ especially as theproblem solving tool is it provides a systematic opportunity iden-tification and innovation approach to address the problem unlikeconventional brain-storming innovation approach which are oftenad hoc and highly dependent on luck [8].

The applications of TRIZ in concurrent engineering for productdevelopment purposes are gaining higher attention as reportedby many researchers. Among them is the integration of TRIZ withAHP in developing environmental friendly bottle casing productas reported by Chen et al. [9]. In their study, three new design con-cepts of the bottle casing was produced using the TRIZ method andthe best design concept selection was performed using AHP meth-od based on the eco-efficiency elements requirements as definedby the World Business Council for Sustainable Development(WBCSD) such as reducing the material intensity in producingthe product as well as enhancing the recyclability of the materialselected [10,11]. Apart from that, the TRIZ method was also appliedby combining it with a four phase Quality Function Deployment

Fig. 1. Parking brake lever com

(QFD) method in developing new notebook casing product [12].Using the QFD method, customer’s needs were translated into re-quired design attributes, components/modules, process operationsand production and within all the four QFD stages, TRIZ inventiveprinciples were applied satisfy the needs as well as achieving thegoal of producing an environmental friendly and energy efficientsolution for the product. Table 1 summarizes several examples ofthe application of TRIZ in concurrent engineering for productdevelopment.

3. Application of TRIZ–Morphological Chart–AHP methods inconceptual design: a new product development case study onautomotive parking brake lever component

Fig. 1 shows an example of an automotive parking brake levertogether with its assembly. The parking brake lever transfers theforce from by the drivers hand to the ratchet mechanism of theparking brake thus actuating the locking and unlocking processof the drum brake at the rear car wheel to enable the car to besafely maintain in stationary condition while at stop and idling.Based on market research, the component is made generally madefrom automotive grade SPHC steel (also referred to as Hot RolledMild Steel Plates).

Due to recent change of automotive related legislations world-wide regarding environmental protection, automakers are nowalso going deep into producing lighter vehicles and subsequentlycomponents to meet the newly imposed regulations to sustaintheir market share as well as assuring continuous growth for thefuture [19]. Thus, among the emerging solution to the weight sav-ing objective is by using kenaf fiber polymer composites as thesubstitution material in developing automotive components,hence in this project, the attention is given to the parking brake

ponent and its assembly.

Table 2Contraction matrix for the kenaf fiber composites parking brake lever design [7].

Improving features Worsening features TRIZ solution principles

39 Engineeringparameters

39 Engineeringparameters

40 Inventive principles

#2. Weight of movingobject

#14. Strength #28. Mechanicssubstitution#27. Cheap short-livingobjects#18. Mechanicalvibration#40. Composite materials

#27. Reliability #1. Segmentation#3. Local quality#11. Beforehandcushioning#27. Cheap short-livingobjects

#32. Ease ofmanufacture

#36. Phase transitions

#1. Segmentation#28. Mechanicssubstitution

M.R. Mansor et al. / Materials and Design 54 (2014) 473–482 475

lever component. The kenaf fiber polymer composites not only of-fer lightweight advantage but also provide eco-friendly propertiessuch as recyclability and renewable source of materials [20,21].

Despite such advantages, the main issue concerning theapplication of kenaf fiber polymer composites in automotive sectoris due to lower mechanical strength and compared to conventionalengineering materials such as steel thus limiting their applicationto non-structural components [22]. Thus, the new concurrent engi-neering approach using the integration of TRIZ–MorphologicalChart–AHP method is applied to explore the suitable solutionsfor the issue especially in the conceptual design stage for the devel-opment of automotive parking brake lever component using kenaffiber polymer composites. The TRIZ method was applied as thesolution tool for idea generation while morphological chart wasapplied as idea refinement tool based on the TRIZ recommendedsolutions for concept design developments. Finally, the AHP meth-od was implemented as concept design selection tool based on theautomotive parking brake lever product design specifications.Fig. 2 shows the overall TRIZ–Morphological Chart–AHP concur-rent engineering conceptual design approach applied in thisproject.

#27. Cheap short-livingobjects

3.1. Defining the design intents and identifying the improving andworsening parameters of the engineering system

The new engineering system and its improving as well asworsening parameters were first defined. The purpose is to clearlyidentify the design intents and any subsequent negative effect orcompromise which may arise while fulfilling the requirements.

Fig. 2. The overall TRIZ–Morphological Ch

In this project, the main design intent is to replace steel hand oper-ated parking brake lever with kenaf fiber polymer compositesmaterial to reduce the component weight but subsequently the ini-tiative will also decreases the component strength, reliability and

art–AHP conceptual design approach.

476 M.R. Mansor et al. / Materials and Design 54 (2014) 473–482

ease of manufacture. Based on that statement, the identified engi-neering system in this case is the kenaf fiber composite parkingbrake lever component and the improving parameter involved inthe engineering system is the weight of component while theworsening parameters related to it are decreasing the componentstrength, reliability and ease of manufacture. All the improvingand worsening parameters identified is later matched with the listsof 39 engineering parameters available inside the TRIZ solutionapproach.

3.2. Matching the problems with the 39 engineering parameters andidentify the appropriate TRIZ solution principles in the contradictionmatrix

After identifying the possible contradictions for in achieving thedesign goal, the improving and worsening parameters are correctlymatched with the list of the TRIZ 39 engineering parameters. Theobjective is to form a contradiction matrix between the improvingand worsening parameters and finally identify appropriate solu-tion principles for the problem based on TRIZ 40 inventive princi-ples technique. Table 2 shows the contradiction matrix developedwith respect to the design intent of this project and the solutionsprinciples recommended to achieve it based on the TRIZ 40 inven-tive principles.

3.3. Developing solutions using 40 inventive principles method

Based on the solution principles suggested on the contradictionmatrix, the results are analyzed and the most relevant principlesare selected as guideline to develop the new parking brake leverconcept designs. In order to achieve reduce weight of the parkingbrake lever using kenaf fiber polymer composites and avoidingthe loss of strength, reliability and ease of manufacture comparedto the current steel based component, the inventive principleschosen to be applied are segmentation (#1), local quality (#3)and composite materials (#40). Table 3 explains briefly the designstrategy that can be adopted based on the identified TRIZ solutionprinciples to produce the new parking brake lever component.

3.4. Refining selected solution principles into relevant alternativesystem elements

In this stage, the appropriate TRIZ solution principles previouslyidentified are further refined into relevant alternative system ele-ments using morphological chart method. In general, the morpho-logical chart is a based on product functional analysis and providedesign feature of ideas visually during the idea generation process

Table 3Design strategy based on identified TRIZ solution principles.

TRIZ solutionprinciples

Solutiondescriptions

#1. Segmentation (i) Divide an object into independent parts(ii) Make an object easy to disassemble

(iii) Increase the degree of fragmentation or segmentation

#3. Local quality (i) Change an object’s structure from uniform to non-unifochange an external environment (or external influenfrom uniform to non-uniform

(ii) Make each part of an object function in conditions msuitable for its operation

#40. Compositematerials

(i) Change from uniform to composite (multiple) materials

as well as help designers to identify sub-solutions for each sub-functions of the design. Development of concept designs was madeby matching the individual solution idea for each function andcombining them to create a whole new total design solution forthe product [23,24].

The integration the morphological chart with TRIZ is conductedas to further enhance the effectiveness of the TRIZ tool in order toexplore in details the possible specific design features of the rec-ommended TRIZ solution. As shown in previous section, althoughTRIZ provide the specific inventive solution principles to solvethe problem root cause through eliminating the contradictionwhich may rise during the problem solving process, the inventivesolutions given are still very abstract in nature and requires furtherinterpretation by the designer on how to convert the general solu-tion into specific design features in order for it to be applied for thedevelopment of the concept designs. Therefore, the successfulapplication of TRIZ method is significantly dependent on thedesigner’s ability and knowledge to imagine and construct thespecific features of the proposed solution principles in generatingthe desired concept design.

For example, based on the segmentation solution principle (#1),there are three (3) description on how it can be applied which areeither dividing the original object into independent parts, makingthe object easy to disassemble or by increasing the degree offragmentation or segmentation for the object. The general solutionrecommended is too broad and requires further interpretation onhow to apply them to the design. Thus, by integrating TRIZ withmorphological chart method, designer can quickly translate thegeneral TRIZ solutions into their specific idea of design featuresin systematic method and order. The use of morphological chartalso helps the designers to visualize the idea more clearly priorto combine them together to generate conceptual designs of theproduct. Fig. 3 shows the morphological chart matrix for the TRIZsolution principles and the specific functional design featuresrelevant to the solution principles.

3.5. Development of kenaf fiber polymer composites parking brakelever conceptual designs based on the combination of the identifiedsystem elements

Using the design strategy adopted from the TRIZ solution prin-ciples and the morphological chart, five (5) new parking brake le-ver concept designs were developed as shown in Fig. 4. All theconcept designs were modeled into 3-dimensional computer aideddesign (3D CAD) models in 1:1 scale to better visualize the productdesign features. In general, all the proposed concept designsencompassed several similar features as follows:

Design strategydescriptions

(i) Product the component in different sections and the sectionsshould be asymmetric as possible to simplify and ease the designand manufacturing process

(ii) Joining the sections using pin-and-boss method for easy assemblyand disassembly process

rm,ce)

ost

(i) Vary the thickness of the component according to the stress con-centration value. Thicker component at higher stress locationpoints

(ii) Brake lever body casing designed with ribs to reinforce andstrengthened the structure as well as with pin-and-boss featuresto provide quick and easy assembly method. Joint different func-tioning feature together to the same component

(i) Use hybrid composition where kenaf fiber is combined with stron-ger and stiffer glass fiber to increase the composite strength andstiffness

Fig. 3. Morphological chart of the TRIZ solution principles and their related functional design features.

Fig. 4. 3D CAD model of the new parking brake lever concept designs.

M.R. Mansor et al. / Materials and Design 54 (2014) 473–482 477

Fig. 5. Automotive parking brake lever product design specifications.

Table 4Parking brake lever PDS elements and their equivalent design indicators.

PDS main elements PDS sub-elements Equivalent design indicators

Performance Strength Von Mises stress (N/m2)Stiffness Deformation (mm)

Weight Density Mass (g)Size Volume (m3)

Cost Raw material cost Raw material cost (RM)Manufacturing cost Shape complexity

478 M.R. Mansor et al. / Materials and Design 54 (2014) 473–482

(1) Using hybrid kenaf/glass fiber polymer composites composi-tion to increase the material strength and stiffness mechan-ical properties [25,26]. The strengthening mechanism iscontributed by the stiffer and stronger synthetic glass fiber,and the impermeability property of the glass fiber alsoreduces moisture absorption of the hybrid composites thusincreasing its dimensional stability [27]. The hybridizationapproach also offers a balance solution between perfor-mance and cost to the design which is very useful in devel-oping higher load bearing automotive components [28,29].

(2) Divided into two sections asymmetric construction featureto simplify and ease the design and manufacturing processsuch as injection moulding. Both parts have circular

Fig. 6. AHP hierarchy framework for the kenaf fiber polymer

pin-and-boss features which function as to provide quickand easy assembly process of the component to each otheras well as to other components in the overall brake leverassembly. The parking brake cable mounting feature is alsoembedded with one of the brake lever body casing designto reduce overall number of components.

(3) Shell feature for the body design to reduce componentweight with varying thickness based on the stress concen-tration intensity and location as the result from the loadapplied to the handle section of the brake lever.

(4) Square tube profile cross-section design for the handle sec-tion to provide higher rigidity in both bending and torsionload cases compared to U-profile and double-T profilecross-section design [30].

(5) Ribs incorporated with the lever to add additional strengthand stiffness to the composite component construction.The rib feature also helps to improve mouldability aspectof injection molded polymeric based composite automotivecomponents by hasting the melt flow in the direction ofthe rib [31].

The significant difference between all proposed concept designsis the rib design where three type of ribs namely I-type, V-type andX-type are used for concept design 1, concept design 2 and conceptdesign 3 respectively. Meanwhile, concept design 4 and concept

composites parking brake lever concept design selection.

M.R. Mansor et al. / Materials and Design 54 (2014) 473–482 479

design 5 utilized the combination of I- and V-type of ribbing pat-tern and the combination of I- and X-type of ribbing patternrespectively.

Tabl

e5

Sum

mar

yof

kena

ffi

ber

poly

mer

com

posi

tes

park

ing

brak

ele

ver

conc

ept

desi

gnov

eral

lat

trib

utes

.

Des

ign

sele

ctio

nat

trib

ute

sC

once

ptde

sign

s

12

34

5

Perf

orm

ance

Max

.str

ess

(Von

-Mis

es)

(N/

m2)

2.61�

107

2.49�

107

2.57�

107

2.75�

107

2.75�

107

Max

.def

orm

atio

n(m

m)

0.52

80.

515

0.50

10.

512

0.50

0W

eigh

tM

ass

(g)

67.5

469

.00

72.6

469

.96

73.5

8V

olu

me

(m3)

6.75

4�

10�

56.

900�

10�

57.

264�

10�

56.

996�

10�

57.

358�

10�

5

Cos

tR

awm

ater

ial

cost

(RM

)0.

680.

690.

730.

700.

74Sh

ape

com

plex

ity

Low

Low

Low

Med

ium

Med

ium

Not

e:Fo

rco

mpa

riso

npu

rpos

es,a

ssu

med

that

ken

affi

ber

poly

mer

com

posi

tes

den

sity

is10

00kg

/m3

and

its

raw

mat

eria

lco

stis

RM

10.0

0pe

rkg

.

3.6. Performing final concept design selection using AnalyticHierarchy Process method based on the product design specifications

The Analytic Hierarchy Process (AHP) is among the most uti-lized selection method especially in vehicle design [32,33]. Themain advantages of AHP method lies the ability to provide sys-tematic and thorough multi-criteria decision making processthrough the present of pair-wise comparison technique as wellas consistency index indicator during the judging and analysisprocess [34]. In this project, the AHP method was utilized in thefinal concept design selection among the five (5) conceptualdesigns developed earlier. The selection process is made basedon the product design specifications (PDSs) for the parking brakelever component as shown in Fig. 5. From the overall PDS docu-ment, three (3) main elements and their subsequent sub-elements are selected which are performance, weight and costfor the concept design selection purpose. Apart from that, allthe initial sub-elements were also translated into equivalentdesign indicators as listed in Table 4.

Other elements shown in the overall PDS namely disposal andenvironment are not incorporated in the concept design selec-tions due to both are related to the material selection require-ments for the overall brake lever design requirements and allconcept designs analyzed used similar kenaf based polymer com-posites material for their construction. The standard PDS elementwhich refers to the United States FMVSS No.571.135 testingrequirements for the parking brake system and its componentoperation in actual condition is also not taken into account inthe concept design selection process.

The PDS elements as shown in Table 4 were later used to de-fine the main criteria and sub-criteria for the AHP hierarchyframework. A 4-level AHP hierarchy was formulated using theavailable information as shown in Fig. 6. At level-1, the goal ofthe project was defined and followed by the design selectionmain criteria and sub-criteria at level-2 and level-3 respectively.Finally, all the five design concepts for the polymer compositesparking brake lever are listed as alternatives at level-4 of thehierarchy.

Based on the AHP method, the judgment process between allthe concept designs with respect to each selection main criteriaand sub-criteria were made using pair-wise comparison tech-nique. Relative importance between each compared informationwere assigned numerical values based on the design attributesestablished for each concept design as shown in Table 5. By con-verting the developed conceptual design into 3D CAD models, amore thorough examination on the attributes of every designconcepts with respect to the weight selection criteria (mass andvolume) was able to be performed compared to conceptualdesign made using sketch method. Finite element structural anal-ysis was also performed for each of the concept design to predicttheir structural performance based on the generated stress anddeformation values. Apart from that, the weight attribute whichis the mass property identified from the CAD models are thenfurther used to estimate the raw material cost for each conceptdesign generated. As for shape complexity design attribute whichis related to the manufacturing cost criteria in the PDS document,a relative performance rating was used to define each concept de-signs based high, medium and low complexity values. An exam-ple of the pair-wise judgment process between the conceptdesigns with respect to the maximum Von Mises stress valuefor stress sub-criteria using the AHP method is shown in Fig. 7.

Fig. 7. Pair-wise comparison between alternative concept designs with respect to the maximum Von Mises stress value for strength sub-criteria.

Fig. 8. Overall AHP results of the concept design selection.

Fig. 9. Sensitivity graph of main criteria with respect to goal when priority vector of Performance is increased by 20% (from 54.0% to 74.0%).

Table 6Rank of alternative priorities obtained by simulating three scenarios of sensitivity analysis for different main criteria with respect to goal.

Rank Performance Weight CostIncreased by 20% Increased by 20% Increased by 20%

Concept designs Priority vector (%) Concept designs Priority vector (%) Concept designs Priority vector (%)

1 Concept 2 20.7 Concept 2 20.7 Concept 2 21.32 Concept 3 20.4 Concept 1 20.7 Concept 1 21.13 Concept 1 20.2 Concept 3 20.1 Concept 3 20.84 Concept 4 19.3 Concept 4 19.5 Concept 4 18.55 Concept 5 19.3 Concept 5 19.0 Concept 5 18.2

480 M.R. Mansor et al. / Materials and Design 54 (2014) 473–482

Fig. 10. Stress distribution for concept design 2.

M.R. Mansor et al. / Materials and Design 54 (2014) 473–482 481

The pair-wise comparison data were then synthesized into ma-trix form and the priority vector values, w were calculated usingEq. (1) [35].

w ¼ 1n

Xn

j¼1

aijPai¼1aij

; i; j ¼ 1;2; . . . ;n ð1Þ

where w is the priority vector (or eigenvector), aij is the importancescale, i.e. 1, 3, 5, . . ., and n is the number of criteria.

For example, based on the pair-wise comparison data shown inFig. 7 and Eq. (1), the priority vector, w of concept design 1 (CS1)with respect to Von Mises stress sub-criteria is calculated as:

w CS1 ¼ ð1=5Þ � fð1=4:975Þ þ ½ð1=1:050Þ=4:725Þ�þ½ð1=1:020Þ=4:880� þ ð1:050=5:230Þ þ ð1:050=5:230Þg ¼ 0:201

The overall priority vector values obtained through the analysisreflects the overall rank for the alternatives listed in the AHP hier-archy. Finally, the consistency ratio, CR value for the judgmentsmade were later determined using Eq. (2) [36].

CR ¼ CI=RI ð2Þ

where CR is the consistency ratio, CI is the consistency index basedon the principal Eigen values and matrix size, and RI is the randomconsistency index of the same order matrix.

The overall AHP screening results of the concept design selec-tion is shown in Fig. 8. Concept design 2 (with V-shape ribbingpattern) scored the highest priority value of 20.8% compared tothe other four (4) concept designs and is selected as the final auto-motive parking brake lever concept design to be constructed usinghybrid kenaf/glass fiber polymer composites based on the requiredproduct design specifications. Further analysis on the accuracy forthe overall subjective judgment process implement in this projectalso revealed that the consistency ratio value is within the recom-mended consistency ratio value of less than 0.10 or 10% [37]. Thisis contributed to the use of numerical values in the majority of thepair-wise comparison situation during the analysis.

Sensitivity analysis using Expert Choice 11.5 software was alsoperformed at the end of the concept design selection process to

further validate the obtained results Sapuan et al. [38]. Apart fromthat, assessment of the stability for the ranking results can also bemade using similar analysis [39]. The analysis was conducted byincreasing the priority vector of all the main criteria defined previ-ously by 20% as shown in Fig. 9. Based on the overall sensitivity re-sults as shown in Table 6, it can be observed that concept design 2emerged with the highest rank in all three (3) simulated scenarios.The findings are consistent with the AHP result previously andvalidated the reported outcome of the selection process.

The highest ranking position for concept design 2 at the end ofthe selection process is mainly contributed to the applied ribbingpattern. Based on design attributes as shown in Table 5, in termof performance, the V-rib pattern incorporated in concept design2 generated the lowest Von Mises stress value to the component,which indicates the selected rib shape and arrangement is ableto withstand the applied load better compared to other ribbing de-sign as shown in Fig. 10. In the other hand, despite moderate stiff-ness performance compared to other concept designs with I, X, I-Vand I-X ribbing patterns, its predicted deformation property is ob-served to be relatively closed to the lowest deformation value withthe difference of only 0.015 mm. Apart from that, except forconcept design 1 which uses I-rib pattern, it is also noticed thatconcept design 2 which uses V-rib pattern possessed good light-weight and low cost attributes compared to other concept designs.Imihezri et al. [40] reported other advantages that can be obtainedby applying V-rib pattern to polymeric based automotive compo-nent design. In term of manufacturing aspect, for polymeric com-ponent manufactured using injection moulding process, V-rib hasshorter fill-time compared to X-rib which reduces production cycletime and subsequently lower production cost. In other finding,they also states that but V-rib offer better lightweight propertycompared to X-rib [31].

4. Conclusions

In conclusions, five (5) new concept designs for the kenaf fiberpolymer composites automotive parking brake lever were

482 M.R. Mansor et al. / Materials and Design 54 (2014) 473–482

developed using the integrated TRIZ–Morphological Chart–AHPmethod. The solution at conceptual design stage was made possi-ble by using TRIZ method based on the TRIZ 40 inventive principlesapproach with are segmentation (#1), local quality (#3) and com-posite materials (#40) and the idea generated were further refinedinto specific design features using the morphological chart. Con-cept design 2 was selected as the final design concept for the prod-uct development at the end of the design selection process usingAHP method based on the highest priority vector value comparedto the other concept design alternatives. The level of consistencyfor the subjective judgments made throughout the analysis wasalso found to be within the recommended consistency ratio valueof less than 0.10. Apart from that, subsequent sensitivity analysisperformed later on further validated the outcome of the designconcept selection process where concept design 2 emerged withthe highest rank in all three simulated scenarios. The integratedTRIZ–Morphological Chart–AHP method proved able to be appliedhand-in-hand in performing idea generation, idea refinement, con-cept design development and concept design selection processesand provides systematic as well as holistic concurrent engineeringapproach in achieving the desired solution especially in developingconceptual design of kenaf fiber polymer composites automotiveparking brake lever component.

Acknowledgments

The authors would like to thank Universiti Putra Malaysia forthe financial support provided through Research University GrantScheme 2007 (vote number 91045) as well as to Universiti Tekni-kal Malaysia Melaka for providing the scholarship award to theprincipal author in this Project.

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