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T.Siva Prasad

Associate Professor in Mechanical Engineering, Vignana Bharathi Institute of Technology, Proddatur, Kadapa Dist, A. P., (India)


The fuel efficiency and emission gas regulation of passenger cars are two important issues in present days. The most ideal approach to build the fuel proficiency without giving up security is to utilize fiber reinforced composite materials in the cars. Hood/bonnet is the one of the part having more weight. In this paper we discusses the characteristics of glass fibre reinforced epoxy composites for automobile hood for compensation of existing steel Hood/bonnet . In this work composite Hood/bonnet made up of glass fiber reinforced polymer is carried out by which weight of the Hood/bonnet can be reduced. Modelling of composite Hood/bonnet is carried out by composite workbench layup process by using E- Glass/ Epoxy bidirectional laminates. The present work describes the characterization and cost parameters of new polymer composites consisting of glass fibre reinforcement and followed by analysis of different fabrication process. Comparison of materials is done in all possible ways to accomplish a conclusion regarding weight reduction, strength and many more


The automotive industry is increasingly being pushed by fuel economy and emissions mandates to make cars lighter, „greener‟ and more efficient. This movement has facilitated development of an impressive suite of technology ranging from highly efficient small-displacement forced induction internal combustion engines, to hybrid or purely electric power trains among other technologies. While these technologies and many others are helping automotive manufacturer‟s lower emissions and approach mileage targets, they will not sufficient without supplement; substantial vehicle light weighting is necessary. Generally, this means that traditional material choices are reconsidered. To this end, the use of aluminum alloys, high strength steel alloys, and fiber reinforced polymers (FRPs) is gaining popularity. Fiber reinforced composite parts are used extensively in the aerospace and motorsports industries for structural applications. The automotive industry, however, has not yet seen the same level of composite material integration into structural elements of high production volume vehicles. The author believes this is a function of primarily two factors: a lack of low cost high volume manufacturability, and a lack of understanding of the behavior of the composite materials themselves. The work presented herein has been motivated by an industry collaboration that aims to make improvements to both of the aforementioned factors, with analysis targeted on the latter.


Less fuel consumption, less weight, effective utilization of natural resources is main focus of automobile makers within the present scenario. The on top of is achieved by introducing better design concept, higher material and effective producing method.

Steel hood have many advantages such as good load carrying capacity. Regardless of its preferences, it stays back in low quality to weight proportion. It is accounted for that weight reduction with satisfactory change of mechanical properties has made composites as a suitable substitution material for traditional steel. In the present work, the steel hood utilized as a part of passenger vehicles is replaced with a composite hood made of glass/epoxy composites. The thickness of the composite hood/cap is computed by bending moment equation and different measurements for both steel and composite hood is thought to be the same. The goal was to analyze the weight, stress and cost.

Polymer composite materials have been a part of the automotive industry for several decades but economic and technical barriers have constrained their use. Today, these materials have been utilized for applications with low generation volumes in light of their abbreviated lead times and lower speculation costs in respect to ordinary steel creation. Despite the fact that glass fiber reinforced polymers rule the composite materials utilized as a part of car applications, other polymer composites, for example, carbon fiber-reinforced polymer composites, show awesome guarantee. These choices are attracting on the fact that they offer weight decrease potential twice that of the conventional glass fiber-reinforced polymers utilized today.


Aircraft and spacecraft parts use structural Fibre reinforced plastics widely for manufacturing parts because of their particular mechanical and physical properties such as high specific strength and high specific Stiffness.

Another significant application for fiber strengthened polymeric composites (particularly glass fiber fortified plastics) is in the avionic business, in which they are utilized for creating layer sheets. Composite materials are constituted of two stages: the matrix which is continuous and encompasses the other stage, frequently called as reinforcing phase. Epoxy resigns are generally utilized as framework as a part of numerous fiber reinforced composites; they are a class of materials exceptionally compelling to auxiliary designers attributable to the way that they give a special equalization of concoction and mechanical properties joined with wide handling adaptability. In structural constructions by reinforcing materials glass fibres are mostly used because of their specific strength properties.

Because of orientation in certain direction the strength the Glass fibre-reinforced plastic (GFRP) have great quality such as ratio of strength and ratio of stiffness unlike metal materials and used in many areas. And, it is possible to mould the parts because the flexibility of moulding is wide. The cost of production also can be decreased, because of its high productivity. In this way, the utilization of mould of glass fiber-reinforced plastic is extending to the auxiliary material of planes, cars, sports and something related to energy instead of moulding the press. In spite of the fact that it is normal that the character relies on upon the character of lattice, components of material change contingent upon the fiber introduction, the length of fiber, the condition of tangled fiber, fiber mat structure, the state of embellishment and property of impregnation of matrix and reinforcement, etc. Therefore it is the very important point to be solved to make it clear what effect the fiber content and the fiber orientation have in GFRP when predict the design of material, the best condition of moulding, and the feature of machine.


Fiber orientation can happen by material factor such as intervening power of each fiber according to fiber diameter, the length of fiber, and moulding factor such as closing speed of mould, moulding press, and the temperature of mould. The products press-moulded are not uniform because of fiber orientation and shows anisotropy, so it has a lot of effects on the mechanical properties of moulded products. And it presented a stiffness model to predict a modulus of elasticity of composite materials reinforced with twisted fiber. It studied the intensity and transformation of high strength polymer composite materials for cars, and manufacturing glass fiber-reinforced PET base composite materials by high speed consolidation method.

It is very important to clarity the accuracy of fiber orientation, after establishing the quantity of fiber content and the measuring of fiber orientation angle, in order to get some tips about dynamical feature of shaped products and material design. It studied effect of fiber orientation on the tensile strength in glass fiber-reinforced polymeric composite materials


Today‟s average automobile is about 8% plastics and composites (i.e., about 111.3kgs/vehicle), a small increase from 77.2 kgs during the mid-1970s (Demmler 1998). Small, fuel efficient passenger vehicles generally contain more composites relative to their total weight than do larger vehicles, but larger automobiles such as minivans contain more composites by weight. Composites provide a wide variety of potential automotive applications—

body panels, suspension, steering, brakes, and other accessories—where the demand varies widely by application. The application of composites is still predominantly in non-structural elements of the vehicle today, and is mostly glass fiber-reinforced plastic polymers used in niche-market vehicles with annual production volumes not more than 80,000. Sheet moulding composites (SMC) predominate composites use for semi- structural applications because they are highly competitive for bolt-on exterior panels such as hoods, decklids and fenders, especially in low and mid-volume cars and trucks. In addition to body panels, the current, limited automotive applications of composites include bumper systems, instrument panels, leaf springs, drive shafts, compressed natural gas fuel tanks, intake manifolds, wheel covers, valve covers, fascia supports, and cross vehicle beams. For example, the share of composite drive train elements used in 2000 model year passenger cars was only 6% of total composites used (ACA 2000). There are only a few body-in-white composite applications to date. Fiber-reinforced thermoplastics have the typical advantages of polymer matrix composites such as high weight reduction, high strength, high stiffness, corrosion resistance, parts integration, and energy absorption.


This assessment of the current feasibility of composites in automotive applications is based on the very restricted cost information currently available. The specific cost estimate provided for a given manufacturing technology should not be generalized for that technology. Each cost value is based on many underlying assumptions, both technical and economic; the degree of overall cost sensitivity to these assumptions will vary across different technologies. The use of different sources of information also poses a problem in the consistency of input assumptions made for the cost estimation. The information taken from various sources in the literature and used in this assessment does not allow one-to-one comparison among various manufacturing


technologies for a part application; it does, however, allow one to assess general, qualitative trends and to identify major barriers to the economic feasibility of composite technologies.

Most of the cost studies done to date have examined body-in-white (BIW) designs to demonstrate the economic feasibility of composites in automotive applications. The monocoque BIW design of composites has been found to be less cost only because parts consolidation results in only a small number (~2-20) of relatively large parts.

Figure 1 shows a recent study‟s cost comparison of two composite monocoque BIW designs (i.e., glass fiber- reinforced plastic and carbon fiber-reinforced thermoplastic) against the conventional steel uni body for

an annual production volume of 250,000 parts ( Dieffenbach 1996a). From the cost perspective, these two composite cases provide the two extreme points. Other cases, such as glass fiber reinforced thermoplastics and carbon fiber-reinforced plastic, will lie between them. This study calculates the costs of glass- and carbon fiber- based composite monocoques to be about 62% and 76% higher than conventional steel unibody (Figure 1). The study on which the figure is based assumes the cost of carbon fiber to be $10/lb. Another study has estimated the cost of carbon fiber-reinforced moncoque plastic to be in the range of 41-73% more than the steel unibody, depending on the type of tooling used (Mascarin et al. 1995).

The main factors affecting the economic feasibility for the composite vehicles today are the cycle times of glass- reinforced plastic and the cost of carbon fiber-reinforced thermoplastics material. The cost comparative study of two composite monocoque BIW designs as discussed above indicates that the material cost contributes 60% of the total cost of carbon fiber-reinforced thermoplastics but only 29% for glass fiber-reinforced plastic, as shown in Figure 1. Labor is the second major contributor to cost, accounting for about 35% and 21%, respectively, of the price of carbon fiber-reinforced thermoplastics and glass fiber-reinforced plastic. The lower labor and tooling cost for the carbon fiber-reinforced thermoplastics design considered in that study results from assumed parts consolidation that makes fenders, roof, and quarter panels integral to the upper body shell and not require


additional moulding operations as well as higher moulding rates offered by thermoplastics. The total number of pieces assumed in this study is 76 for carbon fiber-reinforced thermoplastics versus 81 for

Glass fiber reinforced plastic. The glass fiber-reinforced plastic composites use an entire set of SMC panels.

However, lower labor and tooling costs are not sufficient to offset carbon fiber reinforced thermoplastics‟ higher material cost.

Table 1. Cost Component Comparisons of Various BIW Designs ($/lb)

Table 1 compares the costs of various BIW designs considered in the study on a $/lb basis (as opposed to the cost comparison in Figure 1, which are based on a given part). These estimates allow one to make a rough cost comparison of the technologies for any part by applying the appropriate weight reduction that the given part can provide. On the basis of unit weight alone (not considering the weight savings potential that is projected to be 22% and 48% for glass fiber-reinforced thermo-sets and carbon fiber-reinforced thermoplastics, respectively in this study) the cost of a composite monocoque is estimated to be 2-3 times more than the steel unibody. The difference shows primarily from higher material and labor costs. The last column in Table 1 shows the value of weight savings for BIW application, expressed as the ratio of the part‟s cost difference to its weight savings with the steel unibody as the baseline. Because of their higher weight savings potential, carbon-fiber thermoplastic composites look favourable compared to glass-fiber thermo-set composites. The value of weight savings of carbon-fiber thermoplastic composites lies within a range of 60Rs-240/kg, commonly accepted by the automotive industry, where the actual value depends on the application. The value of weight savings is a true measure of the cost effectiveness of a technology, as the range accepted by the industry has been estimated based on life cycle fuel savings resulting from primary and secondary weight savings that lightweight materials provide. The cost of materials always is a long-term major obstacle to additional improvements, as the materials contribute more than 50% of total cost even for a production volume greater than 100,000 parts/year.

Only a few studies have examined the life cycle cost of composites, taking into account the fuel efficiency composites provide during the vehicle operation stage due to light weighting. A life sequence cost comparison between a conventional steel unibody and composite monocoque BIW indicates that composite monocoque has a 12% higher cost than the former (Mascarin and Dieffenbach 1993).The manufacturing cost forms a major share of total life cycle cost, contributing 53% and 63% of total for the steel unibody and composite monocoque, respectively, considered in this study. Even at the level of total life cycle cost, the manufacturing cost of


composites remains an issue of concern for its competitiveness in the automotive marketplace. It has been estimated that the annual production volume at which the composite monocoque becomes competitive is higher on a life cycle basis, i.e., 75,000, but not a substantial increase from a value of 55,000 when considered from the manufacturing cost perspective (Mascarin et al. 1995). The following paragraphs will delve into further details about the various cost components, i.e., raw material, fabrication using various composite moulding processes, and, finally, assembly.


As discussed above, the major backdrop to use composite materials in automotive applications today is the raw materials cost, particularly for carbon fiber-reinforced composites. The plastic resin mixtures cost between 63Rs and 630 per kg, and glass fibers starts around 60 per Kg compared to only Rs25/Kg for steel. Plastic materials are generally half the cost of thermoplastics, 48Rs -58/kg for SMC and BMC compared to 109/kg

for glass-reinforced thermoplastic material. It is calculated that the cost of SMC must approach 30/kg to be competitive with steel for large-scale body panel applications (Behling 1999). It is this high cost of raw material which makes glass fiber polymeric composites‟ price competitive with aluminium or steel only in certain applications such as in complex shapes that are prohibitively expensive to form from metal. The price of the carbon fibers dominates the raw material cost of composites, for example, it accounts for over 80% of the total cost at a fiber loading of 41% by weight for carbon fiber reinforced thermoplastics considered earlier in Figure 1. To be competitive with the conventional steel unibody, it is calculated that the cost of carbon must be 480/kg if used at 16% volume (i.e., a volume 50% less than glass fibers) (Dieffenbach 1996a). If more carbon fibers are needed, i.e., 25% volume (or 20% less than glass fibers), then the carbon fiber price was calculated to be Rs 60/Kg for carbon thermoplastics to be competitive. A sensitivity analysis was undertaken to examine the effect of carbon fiber cost only (keeping original 31 vol% fiber content and other variables unchanged) on the carbon- reinforced thermoplastics monocoque cost (considered in Figure 1). The figure shows what effect R&D that reduces carbon fiber cost can have on the economic viability of the carbon-reinforced thermoplastics monocoque. It is estimated here that for the specific body-in white designs considered here, the carbon fiber cost needs to be 100Rs/kg for the carbon-reinforced thermoplastics monocoque to be competitive with the steel unibody, and 540/kg for it to be competitive with the glass-reinforced plastic monocoque. Achieving the PNGV‟s target cost of 180/Kg of carbon fibers in large scale automotive applications—300rs less than current cost— would significantly reduce the cost differential between the steel unibody and carbon-reinforced

thermoplastics monocoque considered in this study from 76% to 13%. It is projected that a target cost of 180/Kg would make carbon fibers a viable alternative for many large-scale automotive applications.

5.1 Fabrication

The preference of a specific fabrication method depends on the costs and on the technical needs of the component to be produced. In order to guarantee economic production, methods with a high throughput are absolutely necessary. High throughput can be achieved by means of low clock times or by means of high integrative parts.


Table 2 compares the commonly used composite fabrication processes available today, addressing their advantages, disadvantages, and cycle time. The use of prepregs, which are reinforced with carbon or glass in fiber and fabric forms coated with epoxy resins, may be suitable for only limited automotive applications because of lower productivity. One of the chief obstacles in the method for accomplishing higher creation volumes for basic composites is the time at the preforming stage required to place complex, legitimately situated support in the moulding tools. This necessity results in long process durations, high work cost, and low profitability of the trim apparatus speculation. A recent study demonstrates that the expense of preforms contribute around 35% to the aggregate composite BIW expense, contrasted with half to mold and 15% for get together (Mascarin 2000). A portion of the methodologies that are utilized for making preforms are uniquely sew fabric intended to wrap legitimately for a given segment; meshed fortification over formed froth centers;

numerous handle vacuum performing; and mechanically connected chopped fibres known as P4 process

The most broadly accepted reinforced plastic composites in today‟s market include sheet moulding composite (SMC), bulk moulding composite (BMC), reinforced reaction injection moulding (RRIM), and liquid composite moulding processes such as structural reaction injection moulding (SRIM) and resin transfer moulding (RTM).

SMC and RRIM are most commonly used today, contributing to 48% and 40%, respectively to the total plastic components used in the 2000 model year passenger cars (ACA 2000). RTM and SRIM composite moulding processes have been taken into account to provide the best economic balance for the automotive structural products


5.2 Cost

Reducing the cost of manufacturing automotive structural components from lighter weight composite materials so that they are competitive with the component (including life cycle) costs of other materials is the major focus


here. Although cost reduction is a pervasive factor in all composites R&D activities, most of the activities in this area are related to materials, the major factor affecting the viability of composites in automotive applications today


In automotive applications today are steel used mostly in non-structural parts of the vehicle especially for low- and mid-volume cars and trucks. Fiber-reinforced thermoplastics and, especially, glass fiber-reinforced plastic polymers show great potential, the latter having twice the weight reduction potential of steel. Fiber-reinforced thermoplastics share the advantageous properties of polymer matrix composites and are also recyclable, have indefinite shelf life, and feasible for automated, high volume processing with a possible for rapid and low cost fabrication. The cost is the single most major barrier for the limited application of polymer composites in automobiles today.

Most of the cost studies of polymer composites are for body-in-weight (BIW) applications because of the significant weight reduction potential BIWs offer. On a rs/kg basis, the cost of polymer composites is about 2-3 times higher than steel, but a recent study comparing the composite monocoque designs indicates that the cost of glass-fiber-reinforced plastic is about 62% higher than the conventional steel unibody. However, because of the higher weight reduction potential of, the value of glass fiber- reinforced composites‟ weight savings lies in the range of 60Rs-240/kgs. Even on a life cycle basis, the cost of polymer composites is considerably higher than steel unibodies. The major cost-contributing life cycle stage is manufacturing, which includes material costs. To be cost competitive on a part-by-part substitution, cycle time and material utilization must be improved. The material cost plays a key role, particularly at the higher production volume and for glass-fiber-reinforced plastic composites. For the application in structural components where the weight reduction potential is less than for the body-in-white, even larger reduction in the material cost would be necessary. The cost of glass fiber needs to drop by 50% (i.e., to the Rs180-Rs300/Kg range) and smaller cost reductions in other plastic materials are required for the material to be cheaply viable on a life-cycle basis.


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106, No. 12, Dec., pp. 19-22.


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T.Siva Prasad received his M.Tech (Production Engineering) from Sri Venkateswara University,Tirupathi. Presently he is working as Associate Professor in Mechanical Engineering, Vignana Bharathi Institute of Technology, Proddatur, Kadapa dist, A. P., India





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