Conceptual design of automobile engine rubber mounting composite using TRIZ-Morphological chart-analytic network process technique

A.M.Noor Azammi,S.M.Sapuan,M.R.Ishak,Mohame T.H.Sultan

aDepartment of Mechanical and Manufacturing Engineering,University Putra Malaysia,43400,Serdang,Selangor,Malaysia

bAutomotive Engineering Technology Section,UniKL-MFI,43650,B.B.Bangi,Selangor,Malaysia

cLaboratory of Biocomposite Technology,Institute of Tropical Forestry and Forest Products(INTROP),Universiti Putra Malaysia,43400,UPM Serdang,Selangor,Malaysia

dDepartment of Aerospace Engineering,Universiti Putra Malaysia,43400,UPM Serdang,Selangor,Malaysia

Keywords:TRIZ ANP Morphological Automotive composites component Engine rubber composite mounting

A B S T R A C T An engine rubber mounting is one of the important parts of a vehicle.It is a function to isolate or absorb and to reduce vibration to the vehicle body thus to the passenger itself.Due to the engine compartments environment such as heat and massive vibration due to road conditions,the engine rubber mountings lifespan has been reduced.Thus several studies have been conducted to upgrade the material lifespan to make it more reliable and better engine mounting components.This paper presents the conceptual design of kenaf fiber polymer as automotive engine rubber mounting composites using the integration of Theory of Inventive Problem Solving(TRIZ).In this early stage,the solution is generated using 40 inventive principles and TRIZ contradiction method.The solution parameter for the specific design character is the selected using the morphological chart to develop a systematic conceptual design for the component.Four(4)innovative design concepts were produced and Analytic Network Process(ANP)methods were utilized to perform the multi-criteria decision-making process of selecting the best concept design for the polymer composite engine rubber mounting component.

1.Introduction

Conceptual designs are among the most important early stages product development where in general,possible solutions are generated to meet the design goals required for the product[1].Engine rubber mounting has been used since the early stage of the internal combustion engine.The main objective is to absorb and reduce vibration from the engine.An ideal engine mount system isolates vibrations caused by engine dynamic disturbances in various speed ranges and prevents engine bounce originated by shock excitations[2].

Natural rubber is used in mountings because of its combination of properties.Natural rubber provides high strength,outstanding fatigue resistance,high resilience,low sensitivity to strain effects in dynamic applications and good resistance to creep[3].In the real condition of the engine rubber mount beside absorbing vibration,the mounting also exposes to heat and chemical spills.Heat generated from the engine itself,near to exhaust manifold and some time spill from brake fluid,coolant,petrol will tend to reduce its lifespan.The engine operating temperature was above 80°C and can reach over 100°C at the nearest exhaust manifold or catalytic converter.The operation at the high temperature must need to use an expensive silicone rubber for the engine mounting.The temperature of the engine mount can increase if the available space for ventilation was decreased[4].There is some design consideration for engine mounts such as mount configuration and torque axis[5].Others design approach simplify a multidisciplinary optimization problem by reducing the total number of the design objectives based on the natural characteristic of engineering structure[6].

In product design stage,it is important to make the design with proper dimension without sacrifice the strength and reliability of the product component.The rigidity of a mount's supporting structure,along with mount system strength and geometry,are very important considerations[4].Design plays an important rule in producing a good product.An improvement on the product selection or product design with proper thickness will give a good result on its mechanical properties[7].Advantages of properdesign

https://doi.org/10.1016/j.dt.2018.05.009

2214-9147/?2018 Published by Elsevier Ltd.This is an open access article under the CC BY-NC-ND license(http://creativecommons.org/licenses/by-nc-nd/4.0/).selection can reduce up to 73%of weight,freedom to design complex shape with low weight high strength to encourage manufacturer for a polymeric-based composite[8].From the statement above clearly,the issue of durability of engine rubber mount and design needed to be improve.

In this study,a conceptual design of automotive engine rubber mounting composite is developed by using kenaf fiber polymer composites.The conceptual design of engine rubber mounting is developed to replace the existing rubber-based engine rubber mount in order to reduce the component's weight while maintaining the required structural strength for safety and functionality performances.Based on the project requirements,a new concurrent engineering approach using the integration of TRIZ,morphological chart,and ANP methods approach was applied in the development of the conceptual design for the polymer composites automotive engine rubber mount component.Four(4)main stages were involved during the development process which is:idea generation,idea refinement,concept design development and concept design selection using the mentioned methods.Four(4)new concept designs of the component were produced at the end of the development process and the best concept design was selected based on the product design specifications.

2.Applications of TRIZ in concurrent engineering for new product development

The TRIZ technique founded by G.Altshuller in 1946 originating at Russia through which the manner rest on studies of resourceful principles utilized in patents to achieve ideas for the form solutions[9].Among the most characteristics of TRIZ structure is its aim to dispose of any compromise that could rise up in the gap chanced on by specializing in the difficulty seed result in and obviously identifying the point of the subject.There are four(4)particular approaches to the solution that can be selected throughout the TRIZ method looking on the level of involvement of the problem which is 39 engineering parameter and 40 inventive principles[10].The special benefit of TRIZ particularly because the diagnostic medium is it provides a methodical freedom description and modernization method of dealing with the issue various traditional brain-storming innovation program that is repeatedly impromptu and decidedly depending on luck[11].There are many studies related to selection of design and materials for automotive component such as kenaf composite for car spoiler[12],hybrid composite for car anti-roll bar[13][14],material and design selection of car bumper beam[15-19],and spall liners for ballistic protective door panel made from composite[20].In material selection using expert system software also proved to be faster,more interactive and effective in material selection process[21].

The applications of TRIZ in concurrent engineering for product evolution purposes are gaining higher attention as reported by a number of researchers.Among them is the integration of TRIZ with ANP in developing mobile healthcare device product as reported by Shih[22].Based on his studies,he manages to build 3 conceptual design for shock absorbers and finally selecting the suitable design using ANP.Another sample of application of TRIZ integrated with AHP such as design selection of door panel[23].

ANP is a generalization of AHP dealing with dependence and feedback in the entire decision structure[24].One well-known method is the analytic hierarchy process(AHP)to prioritize customers' requirements.According to the review by Ho[25],16 papers combine QFD and AHP,applying the integration to different areas.However,the limitation is the independence among customers' requirements,leading ANP to become an appropriate method instead.

3.Application of TRIZ-Morphological Chart-ANP technique in conceptual design:a new product development case study on automotive composite engine rubber mounting component

Fig.1 shows the automotive part as what we called engine rubber mount which available in most of all moving vehicle which uses internal combustion engine either in the air,land or sea.This product mostly made by using injection moulding technique.The main component of these engine rubber mount is the rubber/elastomers composite which it is the main component that functions as isolator or vibration absorbent.Natural rubber or known as the natural polymer is the most widely used as engine mounting.There are several synthetic polymer composites that are used such as the polyurethane (PU) but it is highly cost and nonenvironmental friendly.

Due to several changes of policy in automotive manufacturer related to the environment protection,automakers worldwide are shifting into green product/material to use in their component.The researcher has been given the task to fulfil the task of producing the green material and friendly to the environment[26].

In this project,natural rubber(NR)with thermoplastic polyurethane blends and kenaf fibers as filler has given the opportunities to develop these new engine rubber mounting composite.Experimental works have been done and all three material is able to be blend together.But in this particular studies,it is focused on the conceptual design of the rubber composites of the engine rubber mounting.There is four(4)design has been prepared and the best designwill be selected using TRIZ principle solution for the early stage.Then a morphological chart will be involved in this study and then use the ANP as the final decision of selecting the design.Fig.2 shows the working framework of the conceptual design studies.

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

In the early paragraph had mentioned and identify the general problem regarding the engine rubber mount.Based on that problem statement,an engineering solution through TRIZ method is applied.The first step is to identify the engineering worsening problem and improvement parameter using contradiction matrix method of TRIZ.The with the contradiction matrix,the 40 principle invention of TRIZ to be filled in Table 1.

The table of contradiction matrix is then simplified to identify the items that need to improve in the worsening features as shown in Table 2.The next step is to identify the suitable TRIZ solution principle to suit the conceptual design of engine rubber composite mount.

In this project,the main design intent is to replace standard engine rubber mount(natural rubber)to the new polymer composite engine rubber mount and subsequently to increase polymer engine mount reliability and its strength.

3.2.Integrating the problem using the 39 engineering parameter and identify the appropriate TRIZ solution principle using the contradiction matrix

The list of improving and worsening features are listed in Table 1 is made to identify the possible contradiction for achieving the design goal are correctly matched with the list of the TRIZ 39 engineering parameters.The target is to form a contradiction matrix between improvement and worsening parameter and thus identify the solution based on TRIZ 40 inventive principle technique,as shown in Table 2.

3.3.Developing solution base on 40 inventive principle method

Based on the result recommended on the contradiction matrix,the outcomes are analyzed and the most suitable principles are selected as a guideline to improve the new engine rubber composite mount concept designs.In order to achieve the new design in the#36 phase transition and changing the degree of flexibility in the#35 parameter changes,the reliability of the engine rubber composites show not be compromised.The summarised design strategy based on identified TRIZ solution is shown in Table 3.

3.4.Refining selected solution principles into relevant alternative design components or system elements

Based on the general design of engine rubber mount available in the market were base on mounting dimension,application,type of engine,location of engine mount,support type and many other features.Fig.3 shows a sample of the common specification of engine rubber mount.Based on this feature,a selection using morphological chart is done to narrow down the criteria the of selection.As shown in Fig.4,the selection is done by the designer's interest or creativity.Thus,by integrating TRIZ solution and morphological chart approach,the designer can instantly transform the general TRIZ solutions within their specific solution of design features in organized approach and order.The use of morphological chart helps the designers to imagine the idea more clearly in order to blend them together to achieve conceptual designs of the product[27].

The integration of the morphological chart with TRIZ solution helps to narrow the design description that we intended or targeted.For example principle solution no(#36)under the parameter changes,the degree of flexibility focuses on the type of material that is used,type of vibration of an absorbent and where is the position that is applied for.Secondly is the principle solution no(#6)which is universality.In these criteria,the capabilities of a composite engine mounting to withstand multi-direction of force,how many supports that are needed and the location of the inner tube.

3.5.Development of NR-TPU blend with kenaf polymer composites engine rubber mounting conceptual designs based on the combination of the identified system elements

The selection of kenaf fiber composite as automotive component has been conducted by many researchers.Using hybrid kenaf/glass fiber polymer composites composition to increase the material strength and stiffness mechanical properties[28][29].The strengthening mechanism is contributed by the stiffer and stronger synthetic glass fiber,and the impermeability property of the glass fiber also reduces moisture absorption of the hybrid composites thus increasing its dimensional stability[30].

Based on the TRIZ solution and morphological chart result,the conceptual design that has been selected as a design strategy in this study is focused on four(4)design.The first main criteria are the inner tube is located in the centre of the mount,second is the number and the size of the support of the mount.Lastly,the position of the support to cater the multi-direction of force.Based on these design criteria the conceptual design is created as shown in Fig.5.All the concept design were modelled in 3-dimensional design using CATIA 3D.In general,all the proposed concept designs comply with the design strategy in Table 3.

3.6.Standard requirement of engine rubber mounting with the finalise selection from both TRIZ solution and morphological chart based on the product design specification(PDS)

Before designing a product,a standard requirement of an engine rubber mounting must have a standard guideline or what we call as product design specification.Whatever the upgrade design strategy requirement needed by the designer must be followed.As shown in Fig.6,the designer has outlined the product design specification.It is then the listed PDS and the design strategy requirement is tabled and will be used in the analytic network process(ANP).

The performance section in Table 4,the strength and deformation is the focus of this studies which determines for its durability and reliability of the engine composite mounting.The selection ofmaterial that is used is important.The material must be a flexible material such as natural rubber,Te flon,Polyurethane(PU)and Silicon.Since Te flon and Silicon is a synthetic polymer non-friendly to the environment and expensive,the combination of natural rubber and PU is selected with kenaf fibers as filler in the composite.The mixing ratio of the new composite will be studied for its flexibility and strength.

Table 1 Contradiction matrix of TRIZ for engine rubber composites mount design.

Based on this design strategy and PDS element it is then compiled and the selection of design is done using the ANP selection process.In the ANP programme,the arrangement of elementsis done as in Fig.7 according to its hierarchy order.

Table 2 The summarised contradiction of TRIZ engine rubber composite mount design.

Table 3 Design strategy based on identified TRIZ solution principles for engine rubber composite mount design.

3.7.Performing the final concept design selection using analytic network process method base on the product design

The selection process is made based on the product design specifications(PDSs)for the engine composite mounting component as shown in Fig.6.From the overall PDS document,three(3)main elements and their subsequent subelements are selected which are performance,weight and cost for the concept design selection purpose.Apart from that,all the initial sub-elements were also translated into the equivalent to the design indicators as listed in Table 4.

A 4-level ANP hierarchy was formulated using the available information as shown in Fig.7.At level-1,the goal of the project was defined and followed by the design selection main criteria and subcriteria at level-2 and level-3 respectively.Finally,all the four design concepts for the polymer composites engine mounting are listed as alternatives at level-4 of the hierarchy.

Table 4 A summary of design strategy and PDS element and their equivalent design indicators for engine rubber composite mounting.

Based on the ANP method,the judgment process between all the concept designs with respect to each selection main criteria and sub-criteria were made using pair-wise comparison technique.The relative importance of each compared information was assigned numerical values based on the visual evaluation of the certain condition.For example,the larger the support surface area or numbers of support is increases,the stiffer or higher strength is able to absorb but will increase the weight and the cost.Based on this evaluation the ANP pair-wise comparison technique is obtained as shown in Fig.8.

From the ANP result,the main objective of the product design selection is the performance of the engine composites rubber mounting.Then it is the cost and lastly is the weight of the product.The result is as shown in Fig.9.In composite engine mounting,performance is categorized as an important element because the component must be able to adapt its natural elements such as heat and vibration despite a weight of an engine.

From the main objective with the respect of conceptual design,Fig.10 shows the concept design no 3 has the highest score with respect to strength in the performance criteria.From the ANP selection method concept design 3 has an overall good result compare to other concept design.The overall synthesized alternative in Table 5 shows concept design 3 has the highest rank.

In the cost and weight are shown in Fig.10(b)and(c),design 3 contribute to high cost and increase in weight.Since the intended material that is used is natural rubber,PU and natural fiber(kenaf)are considered low if compared to Teflon and Silicon.The weight of the composite can be adjusted by verifying the composition of the three material without compromising the strength of the composite material.

4.Conclusion

In conclusion,four(4)new concept design for the NR-TPU blended kenaf fiber composite was developed using the integrated TRIZ-Morphological Chart-ANP method.The solution at conceptual design stage was made possible by using TRIZ method based on the TRIZ 40 inventive principles approach with are parameter changes(#35),phase transition(#36),and composite materials(#40)and the idea generated were further refined into specific design features using the morphological chart.Concept design 3 was selected as the final design concept for the product development at the end of the design selection process using ANP method based on the highest priority vector value compared to the other concept design alternatives.The overall synthesized alternative analysis shows concept design 3 scores and ranked for number1.The combined TRIZ-Morphological Chart-ANP approach demonstrated ability to be practiced hand-in-hand in achieving idea generation,idea refinement,design approach development and concept design selection processes and provides organized as well as comprehensive concurrent engineering method in achieving the specified solution particularly in developing conceptual design of NR-TPU blend kenaf fiber polymer composites automotive engine rubber mounting component.In future,a structural analysis using finite element analysis(FEA)using ANSYS,ABACUS or CATIA can be implemented for further investigation.

Table 5 Overall synthesized for the alternatives.

Acknowledgement

The authors would like to thank Universiti Kuala Lumpur and the Ministry of Higher Education,Malaysia for providing the scholarship award and financially support through UniKL Grant Scheme(STRG 15144)to the principal author in this project and HiCOEgrant(6369107)from Ministry of Higher Education,Malaysia.