Comparative analysis of bio-composites vs conventionalcomposites for technical parts

Technical, Economical and Environmental performances

Vitor Hugo Caetano de Carvalho

hugo.caetano.carvalho@hotmail.com

Instituto Superior Tecnico, Lisboa, Portugal

November 2015

Abstract

The research evaluates the feasibility of natural textile composites as substitute of conventional

materials, on laminated designs. The analysis is asserted from a technical, economic and environ-

mental perspective. The technical performance is studied under a finite element analysis, whereas

the economic and environmental performance of the entire product life is estimated through tool-driver

methods, such as life cycle cost and life cycle assessment, respectively. The models in analysis are a

rocker component and a buggy bonnet, under stress conditions. Essentially, the rocker is a component

of the suspension system of a bicycle and its stiffness is directly associated with the drive manage-

ability. Each technical part is evaluated for two distinct scenarios and five materials. In addition, the

research includes some sensitivity analyses. At last, for a clear knowledge of the possible choices

an integrated methodology, life cycle engineering, is used. The trade-offs are identified and can be

minimized.

Keywords: Natural fiber-reinforced polymer composites, Finite element analysis, Life cycle cost,

Life cycle assessment, Models, Life cycle engineering

1 Introduction

Over the past few decades the market share of

composites has been in continuous growth, thanks

to general economic development and the increased

market penetration. The parts can be designed to

meet the application requirements, providing weight

savings, higher stiffness, higher strength, good vi-

brational damping and low coefficient of thermal

expansion [1]. Therefore, a well-designed part to

be commercially viable must take into account some

key variables such as the material properties, the

part design, cost and end-use or application. The

performance of composites depends on the fiber

(fiber-resin ratio, type, form, orientation), resin and

manufacturing process (MP) [2]. Natural fiber re-

inforced polymer composites (FRC) are emerging

as the replacement to man-made materials, mainly

after the Kyoto agreement. This trend is driven by

changes in the awareness towards green products

by customers; government programs; tax reduction

on renewable; new directives on waste and recy-

cling [3]. Different kinds of natural fibers, due to

their bio renewable nature and inherent eco-friendly

characteristics, offer a number of advantages over

1

other materials.

1.1 Objectives

The main goal of the research is to analyze

the importance of ramie fibers in a design con-

cept by evaluating the technical, economic and en-

vironmental performance. The study concerns the

design and analysis of two case studies, where,

the first is a suspension component of a mountain-

bicycle and the second is a buggy bonnet. The

scope of the work can be divided into specific ob-

jectives, as follows: 1) characterizing mechanical

properties of four laminates (ramie, jute, e-glass

and carbon fiber T300 (CF)); 2) the design stage;

3) finite element analysis (FEA) of a laminated com-

posites, which takes into account the influence of

fiber angle orientation and the stacking sequence;

4) modeling of the product life cycle and related

MP such as hot forging (AHF), wet lay-up (WLU),

blanking and resin transfer molding (RTM). 5) com-

parison of materials from renewable sources; 6)

evaluate the difference of performance between syn-

thetic or man-made and natural FRC; 7) compari-

son between bio-composites (BC) and a conven-

tional material, aluminium alloy (AA).

1.2 Research work approach

The research is developed along the following

points: 1) design of the models, using SolidWorks

2014 (SW) software; 2) before perform a finite ele-

ment method (FEM) analysis, some conditions need

to be defined such as boundary conditions, loading

and mesh element, to illustrate how components

behave in real world; 3) since there are no unidi-

rectional fabrics available commercially for natural

fibers, like ramie and jute, natural and man-made

fabrics present in the research adopt a common

type of weave, a balanced plain weave; 4) identify

and select the interlacing variables. The fiber vol-

ume depends on the MP and the fiber reinforced

form. Also, for comparison purposes the various

kinds of composites can not have the same fiber

volume, due to the variability of the density. If the

fiber volume is constant, the models will have dif-

ferent volumes. To be a fair comparison the com-

posites must have the same dimensions, so the

lamina thickness will be equal in all cases. Which

left another assumption to be made, similar fiber

volume or grammage. The rocker and bonnet com-

posite components are produced from different MP,

and subsequently cannot have the same fiber vol-

ume. From the manufacturing perspective, the rocker

component has at most a typically fiberglass con-

tent up to 25% and the fiber volume of the bonnet

goes up to 40-55%. In this study the maximum fiber

volume content considered for the RTM process is

40%, because it is not a high performance part.

So, based on the market offer, similar fiber vol-

ume and grammage assumptions are applied, re-

spectively, in the rocker and bonnet component. In

other words, for the same lamina thickness, a fiber

with lower density need to have a lower grammage

in order to match similar fiber volume. And if the

grammage is constant, the fiber volume is higher.

5) designing and analyzing of the ply stacking, con-

sidering the influence of the sequence, fiber an-

gle orientation and the deformation; 6) define the

boundaries of the product life cycle; 7) create or

adapt an environment indicator for the ramie fiber.

The SimaPro software libraries, by PRe Consul-

tants, do not contain any environmental indicator

pts/kg for this fiber. Comparison of the available

alternatives based on the production, density and

morphology; 8) input model to depict and analyze

the production processes; 9) LCC and LCA of the

product life cycle; 10) LCE analysis.

2 Composite materials

BC can be classified as either partly ecofriendly,

when one of laminate constituents is non biodegrad-

able or ecofriendly, when both elements result of

2

renewable resources [4].

2.1 Polymeric matrices

In a FRC, the matrix is oblige to: 1) keep the

fibers in place; 2) transfer stresses between the

fibers; 3) provide a barrier against an adverse envi-

ronment, such as moisture and chemicals, and 4)

protect the surface of the fibers from mechanical

degradation [5].

2.2 Natural Fibers

NF, by definition are bio-based fibers from veg-

etable and animal origin. Which includes natural

cellulosic fibers (ramie, jute, etc) and protein based

fibers. Mineral fibers such as asbestos are ex-

cluded, such fibers are not bio-based and contain

products known for health risk [6]. Depending on

the function in the living plant, fibers differ in struc-

tural features and mechanical properties. The fol-

lowing fiber characteristics play an important role

in performance, as referred by [7], the aspect ra-

tio; the cell diameter/cell wall thickness ratio and

the angle oriented cellulose microfibril in the sec-

ondary cell wall layers. However, vegetable fibers

have one crucial concern in terms of end applica-

tion, a large variability of the mechanical properties

from the same specie or even the same plant. Nat-

ural fibers (NF) have some advantages over syn-

thetic fibers such as low density, acceptable mod-

ulus weight ratio, higher acoustic damping, carbon

dioxide sequestration, and biodegradability. NF are

associated with lower costs, depending on the econ-

omy of the countries where such fibers are manu-

factured [4]. Also, NF handling is safer since do

not cause adverse health effects such as allergies,

skin irritation and silicoses, contrary to fiberglass

dusts [8]. Although, there are some disadvantages:

low melting point, high moisture absorption, poor

bonding to polymeric material [9] and relatively low

tensile strength [4] [5]. Enhanced treatments can

be used [9]. BC can be classified as either partly

ecofriendly, when one of laminate constituents is

non biodegradable or ecofriendly, when both ele-

ments result of renewable resources [4].

2.2.1 Ramie

Ramie fibers are obtained from the stem of the

perennial shrub that is also known as Boehmeria

Nivea [10]. The crop can sustain harvesting up to

four times a year. Ramie is propagated through rhi-

zomes for commercial production worldwide. The

stems grow to a height of 2.5 meters. The diameter

of the elementary fiber varies from 4.6 to 126 µm.

Fibers are flat and irregular in shape, with a thick

cell wall and taper to rounded ends. The primary

cell wall is often lignified. It is one of the strongest

natural fibers; when wet, it is even stronger, does

not shrink or lose its shape and dries quickly. Some

experts might not classify ramie as ”natural” for the

reason that, unlike the other bast plants, ramie re-

quires chemical processing to de-gum the fiber. The

solution is far from ideal, it leads to high consump-

tion of chemicals and energy.

2.3 Composite characterization

The theoretically characterization of a compos-

ite is established by a couple of steps. The rule

of mixtures (ROMs) is a method based on a num-

ber of simple and intuitive assumptions, commonly

applied on continuous fibers with elastic behavior.

The properties of the composite are given by math-

ematical expressions, the quantity and arrangement

of its constituents. Fiber-matrix interactions are ex-

plained based on the mechanics of materials ap-

proach. The following requirements must be satis-

fied: a perfect bonding between fibers and matrix,

the distribution of fibers is uniform along the ma-

trix, perfect adhesion, no residual stresses, con-

stituents of the composite behave as linear elastic

up to fracture and the applied load is either parallel

or normal to the fiber direction. Fibers and the resin

have the same longitudinal strain. For approximate

3

values, the fabric layer mechanical properties can

be emulated as two plies separately or together.

When the plies are considered separately, the fab-

ric layer is denoted as being composed by two uni-

directional plies crossed at 90o with each other.

The stiffness layer value is higher than what is ob-

served with a woven fabric, as referred by [11].

Also, the two cross unidirectional plies has lower

tensile strength and higher compressive strength

values. Commonly, the fabric layer is considered

as two plies together. The fabric is replaced by one

single anisotropic layer, x and y being along the

warp and weft direction, respectively. Plain weave

fabric has the same tensile strength value in both

in-plane directions, longitudinal and transversal.

3 Methodology

In a collaboration with the Chemnitz University

of Technology, two models of rocker components

were given, models A and B. Models differ on de-

sign, material and manufacture techniques. In the

manufacturing context, of the dissertation, a pro-

duction volume of 5,000 parts/year [12], is consid-

ered for two technological alternatives, AHF and

WLU. This work also analyzes a bonnet model of a

buggy, which is made by a buggy maker known as

Ancel Reinforced Plastics Lda - Rio Claro, Brazil.

The number of components taken into account is

600 bonnets per year [13], for two methods of fab-

rication, RTM and blanking. Figure 1 shows the

sequence of the analysis.

Figure 1: Stages.

Figures 2 and 3, illustrate the flow chart fol-

lowed in each evaluation.

Figure 2: Technical evaluation.

The scope of the assessment is broken into four

life cycle stages. The production phase takes place

in Lisbon.

Figure 3: Life cycle, cost and environmental impactevaluation.

4 Technical analysis

Several FEA are established to compare data

per FRC. The comparative is obtained by assum-

ing a common setting, same resin properties. Also,

the fabrics are arranged as plain weave, since the

unidirectional form is not available commercially for

natural fibers. In the first instance, the models are

simulated based on the minimum-volume design,

in other words, on a factor of safety basis, similar

or equal to 1. This step helps to narrow down the

number of possible scenarios for the next phase.

While, in the main technical phase, all models must

have a similar deformation as the control material.

If this condition cannot be fulfilled than a lower de-

formation is required. The numerical analysis was

carried out using ABAQUS 6.14 software suite. A

single static load step is defined for the analysis.

Nonlinear effects are not included. In other words,

the material and the geometry are linear. The fail-

ure criteria applied in the composites is Tsai-Hill

criterion. In addition, the model parts in-use needed

to be previously created or reworked on the SW

software. The composite models are composed by

symmetric and balanced laminates. The numerous

fibers in study have different diameters and densi-

ties, so an additional assumption is set up to limit

4

the number of independent variables, equal lamina

thickness as the E-Glass solution. This approach,

allow direct comparison of the solutions, same vol-

ume, the material can be changeable but keep the

same volume (the same number of laminas). Fur-

ther assumptions are case study dependent.

4.1 Theoretical characterization

In the composite industry, thermosetting resins

most often used are the unsaturated polyester and

the vinylester. For high performance use ends the

epoxy and the polyimide [14]. Given the scope

of work, the resin to be used in all candidates is

the unsaturated polyester, Quires 406PA, due to

low cost and fairly good performance. Regarding

the rocker component, the mechanical properties

of the lamina are determined under a similar E-

glass bi-axial fiber volume, based on the market

offer. For the bonnet case study, since RTM pro-

cess has a fiber content up to 40%, it is assumed a

grammage g/m2 similar to E-glass, market-based.

4.2 Case Study: Rocker component

The rocker influences the behavior of the sus-

pension system. The deflecting element consist

in two components, a left and a right component,

pivotally connected to the rear swing arm and the

damper element. This connection ensures trans-

mission of energy while driving, the shock loads on

the rear arm, to the damper element. The element

articulates between two positions: rest suspension

state (35◦) and maximum compression state (65◦)

[15].

4.2.1 Boundary conditions and Loading

Under field tests, the reaction force occurring

was 2250N per component, at a 65◦ angle [16].

As a precaution measure to avoid stress singular-

ities while improving model accuracy and system

safety, a non uniform pressure load is applied, a

cosine pressure distribution. The maximum com-

pression state for both rocker models, A and B,

is simulated by assigning some boundary condi-

tions to the problem. The rocker component has

two holes with pinned constraints and a face roller

support as guidance.

4.2.2 Selecting solid elements

The AA component uses a solid element and

the composite ones a continuum (solid) shell ele-

ment.

4.2.3 Requirements

An aluminum-zinc wrought alloy, 7005, is used

due to be less expensive and stiffener than the

6061. The displacement of model A is used as a

guidance variable on the simulations of model B.

4.2.4 Evaluate

Composite results, based on minimum-volume

design, table 1.

Table 1: Constituent composite comparative

Constituent Thickness [mm] Model [g]

E-glass 11.00 91

CF 6.60 48

Ramie 11.55 81

Jute 13.75 95

Deformation of the ramie composite, figure 4.

Figure 4: Ramie solution, deformation

Results of the main analysis, table 2.

Table 2: Constituent composite comparative

Constituent Thickness [mm] Model [g]

E-glass 19.80 163

CF 12.65 92

Ramie 19.80 136

Jute 24.75 170

5

4.2.5 Sensitivity Analysis

The purpose of this technique is to study the

problem’s response when changing one or two vari-

able values while holding the values of other vari-

ables constant. The weight and the thickness of

the model decreases about of 12.5% and 12.6%,

respectively. In the group analyzed, ramie is the

best natural fiber and the third choice overall, only

lose for the CF and AA.

4.3 Case Study: Bonnet component

The bonnet model was designed as a surface in

the SW software and then imported to the Abaqus

suite.

4.3.1 Boundary conditions and Loading

An uniform load pressure of 800 N is applied

over a circular area of radius 200 mm, simulating a

medium man’s weight, at the center of the bonnet.

The interaction between the bonnet and the vehi-

cle’s main enclosure was assumed as two embed-

ded areas placed symmetrically from the center of

the bonnet, simulating both joints, and a support

base line around the bonnet, figure 5.

Figure 5: Boundary Conditions and Loading.

4.3.2 Selecting shell elements

Since the transverse shear deformation is ne-

glected in thin shell theory, a quadratic shell ele-

ment is used, the triangular shell element STRI65.

4.3.3 Requirements

Bi-axial symmetric composite candidates were

fabricated at room temperature and under constant

pressure by the RTM technique [17]. The original

bonnet model was composed of E-glass continu-

ous filament mat, with 23% of volume fiber, 4mm

thickness, in which the deformation was 23.11mm

[13]. For thesis purposes, a plain weave E-glass

composite is required as the baseline model, in

order to provide direct analysis to the mechanical

properties of the different fibers under the same

assumptions. The composite solution, according

to the Tsai Hill failure criterion (TSAIH), has 4.4

mm of thickness, weights 2.20 kg and the maxi-

mum deformation is about 22.62 mm. The com-

posite mechanical response depends on the lam-

ina’s stacking sequence and orientation angle. As

expected the higher stress occurred in the region at

the border of the two embedded areas. Both val-

ues were identical, due to the not symmetric bon-

net part at y-axis, see bonnet dimensions in annex.

Also, needless to say the deformation decrease

from the composite outside layers to the neutral

line. There are compression stresses (Sxx) and

(Syy) on the upper surface. The final stack lami-

nate sequence is composed with outside layers 45

degree oriented, since the maximum displacement

value is located along the diagonals of the hood.

In other words, the use of laminas (0/90) diminish

the stiffness across the diagonals, which increase

significantly the model’s deformation as the TSAIH

value. The strength of the effect is depend on the

stack sequence, the mid-plane offset distance.

4.3.4 Evaluate

The plain weave E-glass composite maximum

deformation is submitted as design guidance. For

the purpose of these analyses, in order to be as

close as possible of E-glass fabric requirements

and achieve desired results, multiple bonnet candi-

dates are simulated by adding or removing layers,

each layer being 0.55 mm of thickness, arranging

the right layer orientation angle and the specific or-

der in which the plies are stacked. Table 3 illus-

trates some of the results.

6

Table 3: Composite comparative per constituent.

Material Thickness [mm] Weight [kg]

E-glass 4.40 2.20

CF 3.30 1.55

Ramie 4.40 1.94

Jute 4.95 2.12

Remarkably one ply could be saved additionally

in the CF model, which the characteristics would

be 2.75 mm of thickness and 1.30 kg of weight.

The stark performance between composites and

aluminium is a common discussion nowadays. That

said, a bonnet composed of AA is simulated, ac-

cording von Mises criterion, to compare the com-

posite window advantage. The results are 3.13 kg

of weight, with a thickness of 3.40mm. None of the

models match the deformation value of the control

material. If more layers are stacked up, the sec-

ond moment of area increases and subsequently

the deformation decreases even more. The defor-

mation is neglected for comparison purposes since

the solutions have a lower value than the E-glass

composite and the study is done under assump-

tion of elastic material behavior up to fracture. The

worst solution in the weight and thickness contexts

is the AA solution. The CF composite solution sup-

press considerably the competition in the weight

and thickness categories. A similar E-glass defor-

mation is obtained but it has slight lower fiber vol-

ume content. In the natural fiber territory, the jute

is no match for the ramie. From a synthetic versus

natural fibers perspective, CF as first and then the

ramie fiber.

4.3.5 Sensitivity Analysis

As the previous technical part, the bonnet model

is analyzed with the same ramie averaged of [17].

There is clearly a beneficial effect. The mechani-

cal properties of the composite are increased. The

model thickness cut down on one ply, saving weight,

due to a lower second moment of area. The num-

ber of layers has an direct outcome on the model

deformation. Fewer layers, higher deformation.

5 Life cycle

Two individual life cycle approaches, LCC and

LCA. Both multi-step procedures are applied on the

product, based on the system boundaries and the

functional unit. In other words, the process is iter-

ative and depends on the quality and available in-

formation, how far upstream and downstream does

the analysis go. The functional unit stands for the

quantity of the inventory being assigned. Where,

LCIA attempts to establish a linkage between the

product or process and its potential environmen-

tal impacts, classified by potential human health

and environmental impacts of the environmental

resources. LCC stands for the associated costs.

These analyses are attempts to minimize the im-

pacts and expenditures involved [18].

5.1 Determining of key performance indica-tor of ramie fiber

The libraries of SimaPro software do not con-

tain any available indicator for the ramie fiber. Some

fibers are analyzed in some categories to assure

the best approximation to ramie, based on the pro-

duction, chemical and physical properties. Then,

any difference is added in the indicator.

5.2 Methods of fabrication

The cycle time determines the maximum part

production rate and subsequently the number of

parts the capital cost can be spread over. In all

process the building cost is a common denomina-

tor, so it can be neglected. The maintenance cost

is 10% of the machinery initial price. The raw ma-

terial acquisition and the disposal fee are allocated

in the process cost. The fiber is delivered to Valor-

Sul site for incineration, whereas the scrap of the

aluminium is sold.

7

5.3 Use Phase

The cost of assembly is neglected on both cases.

All the concepts are affected in the same way. Rocker

component, does not have any cost or environ-

mental impact associated. Although, in the second

study, the buggy bonnet, the use phase is respon-

sible for most of the environmental impact of a ve-

hicle as result of the fuel consumption.

5.4 End of life (EOL)

EOL refers to the stage when a certain product

reaches the end of its product life cycle. The solid

waste disposal is the same as mentioned earlier.

6 Global evaluation

This section summarizes the results of differ-

ent area analyses. LCE is the art of designing the

product under consideration of the environmental

and economic impacts in conjunction with product

structural analysis. The combination of the data as-

sessed through the different life cycles is a vital key

for the continuous improvement of the product and

to meet customer needs. For a clear knowledge of

the possible choices according to the importance

given to the attributes, the results can be obtained

and viewed through a ternary diagram. Defining

different weight-combinations might change the best

case material for the application.

6.1 Case Study: Rocker component

The various candidates regarding the technical

performance (TP) can be compared according its

stiffness [N/mm] and weight. The rocker compo-

nent stiffness is directly associated with the com-

fort and the stability [12]. Nevertheless, all config-

urations comprehend the same absolute stiffness,

about 1323,53 N/mm. The results of the life cycle

analyses are illustrated in the table 4.

Table 4: Rocker component, LCE.

Material LCC [e] LCA [pt]

E-glass 15.08 0.14007

CF 14.75 0.14624

Ramie 14.37 0.12210

Jute 18.23 0.15193

AA 3.59 0.69196

Figure 6a, illustrates the best material choice,

according the weight of each category. Whereas,

figure 6b, compares the worst of fibers solution with

the AA. The importance given to A and B points,

figure 6a, in the three dimensions: environmental,

economic and technical performance, is (20,30,50)

and (70,20,10), respectively.

(a) CF (blue), Ramie, AA(grey).

(b) Jute (yellow), AA.

Figure 6: Best material choice.

After the ramie solution, the obvious choices

from best to worst are E-glass and jute, as enu-

merated.

6.2 Case Study: Bonnet component

Two attributes of the technical evaluation are

taken into account, such as the mass and the thick-

ness of the models. The deformation is neglected

since the design requirement for comparison pur-

poses of the models is achieved. The deforma-

tion is similar or lower than E-glass baseline model.

Thus, importance-weights need to be assigned for

each attribute. This study assumes a equal distri-

bution of weight for both dimensions in order to be

unbiased. Table 5, summarizes the results of two

life cycle analyses.

8

Table 5: Bonnet component, LCE.

Material LCC [e] LCA [pt]

E-glass 52.28 6.66937

CF 75.96 5.37482

Ramie 44.01 5.80925

Jute 51.19 6.27819

AA 41.97 11.62670

Figure 7a presents the best choices available,

according the importance given to each dimension.

Figure 7b illustrates a comparison between jute and

E-glass candidates.

(a) CF (blue), Ramie(green), AA.

(b) Jute, E-glass (blue).

Figure 7: The best material for a given application,based on the weight of each dimension.

Figures 8a and 8b illustrate the best choice for

two individual scenarios, which the first one is be-

tween jute fiber and AA and the second about the

E-glass fiber and AA.

(a) Jute (yellow), AA. (b) E-glass (blue), AA.

Figure 8: Material choice.

6.3 Fibers Sensitivity Analysis

In a real market context, alternative materials

may not have the same deformation. A sensitive

analysis is done for both case studies, using the

results based on the minimum-volume design.

6.3.1 Case Study: Rocker component

The best material choice is the CF or AA so-

lution, depending on the end-use, figure 9a. The

other fibers solution can be ranked from the best

to the worst, as follows, ramie, E-glass and jute.

In comparison analysis with the AA solution, the

choice depends on the given weights to dimen-

sions. Figure 9b, illustrates the worst fiber solution

in comparison to the AA. Thus, in a identical analy-

sis, the boundaries for E-glass and ramie solutions

appear between the blue and yellow areas.

(a) CF (blue), AA. (b) Jute (yellow), AA.

Figure 9: Best material choice, according to the weightof each category.

6.3.2 Case Study: Bonnet component

All candidates maintain the same properties ex-

cept the CF solution. A ternary diagram is devel-

oped in order to identify possible pattern changes

in comparison with the figure 7a. The CF solution is

reduced in one ply, which results 2.75 mm of nomi-

nal thickness. Figure 10 presents the best solution.

Figure 10: Material selection, regarding the weight ofeach category.

As expected the CF solution is ideal when a

lower and a higher level of importance is given to

the cost and environmental dimensions, respec-

tively. In comparison with the main analysis, fig-

ure 6a, the domain of choice increases. Above the

48.1% of technical importance the CF is the only

solution available.

7 Summary and Conclusions

First phase of rocker component, the ply ori-

entation and the stacking sequence influence the

model deformation, depending on the material and

stacked layers. The first two variables, mention

9

above, with the model geometry play a role in the

variation of the local stress concentration along the

stacked plies. In the minimal-volume assessment,

the ramie fiber cannot compete with the synthetic

fibers, in a thickness context. In a weight context,

the ramie fiber only lose for the CF and AA. CF

solution is the only one that is better than the AA

counterpart, in both contexts. Jute part is clearly

out of its league. Second analysis, the rocker needs

to be as stiff as possible, none of the selected so-

lutions is better than the control material. Bon-

net analysis, the best solution in both scenarios,

is the CF part, followed by the ramie. Stacked

layers has an direct outcome on the part defor-

mation, due to the inertia. A sensitivity analysis

was assessed in both parts, as result there was

weight savings, 13% (rocker) and 14% (bonnet).

This step was done to analyze the effects of the

young modulus and tensile strength. Rocker man-

ufacturing context, approximately 82% of the prod-

uct cost was spent in the workforce, with the excep-

tion of the AA and CF, where is respectively 3.6%

and 58%. The RTM workforce has the following

costs: ramie (11.5%), E-glass and jute (10%) and

CF (6.4%). In the AA is almost non existent. The

major part of the cost is in the use-phase for the

E-glass (47.6%), ramie (49.4%), jute (46.4%) and

AA (83.5%). In the CF case, is in the raw mate-

rial acquisition. Rocker main analysis, the solu-

tion with the lowest cost and the highest environ-

mental impact is the AA. Only when the techni-

cal and economic importance is approximately be-

low 81% and 52%, respectively, the CF or ramie

may be the preferred solution. Ramie fiber is the

best choice, comparing to E-glass and jute. Be-

tween these two, the ideal solution for a high and

low level of technical and economic importance, re-

spectively, is the E-glass. Bonnet study, the best

choice is given between the CF, ramie and AA.

Ramie fiber is the best overall when comparing to

E-glass and jute . Rocker sensitivity analysis, the

best material choices are the CF and the AA. And

then ramie, E-glass and jute, in the fiber context.

LCE method is a decisive consulting tool which al-

lows the business entity to involve a plan of action.

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