The logic behind the choice of body materials in recent years offers a fascinating story when considered in the context of the overall development of the vehicle. This gradually changed to weight reduction with the introduction of CAFE fuel consumption requirements in the 1980s.
OVERVIEW OF CONTENT
While it is important to understand these technologies for the future, the emphasis within the industry is on restoring the economic 'health' of the major car companies by making continuous improvements to the efficiency of existing volume production processes. These materials in various forms are increasingly used to meet safety standards in the form of New Car Assessment Program (NCAP) requirements.
Overview of content 3
However, the structure is becoming increasingly hybridized in terms of materials, to meet emissions and safety regulations, and in the case of electric vehicles to offset weight and increase range. Although there are many reference works in the form of books or conference proceedings on specific aspects of design and related materials, these tend to focus on individual materials, test methods or numerical simulations.
MATERIALS OVERVIEW
This is reflected in the many changes that have occurred in the body materials used for car body structures over 100 years of production. The growing interest in this material is also reflected in the wide coverage given in the following chapters.
Materials overview 5
It is interesting to note that hints were dropped in the corrosion repair manuals of the time4 that poor life was partly due to built-in obsolescence and that the use of zinc coated steel would provide an answer. Huge advances have been made in the protection of the car body over the last 30 years and this is reflected in the design goals of most manufacturers.
Materials overview 7
This resulted in significant improvements in strength, assembly and ease of repair and, as in the case of the Audi A2, a space frame that could easily be mass-produced. Although it was an option in the past for items such as transmission covers, corrosion and ease of design limited its range of use.
Materials overview 9
Aluminum has always been considered an alternative material to steel and there are examples where it was used for models in the early 20th century and for volume production in the 1950s. Polycarbonate, Noryl GTX and carbon fiber composites are all examples of the range of materials used today.
GENERAL FORMAT OF PRESENTATION
Taking into account factors such as suitability for various aspects of manufacturing and likely environmental implications, the effects of various choices on capital investment or meeting emission or disposal regulations can be more comprehensively weighed. This information is presented in Chapter 4 under the heading 'Role of demonstration, concept and competition cars'.
General format of presentation 11
Corrosion resistance is of course of utmost importance in the design of the body structure, and is considered a key issue of consumer concern. The combinations suggested are debatable, but the reasoning is presented for each of the choices.
INTRODUCTION TO BODY ARCHITECTURE AND TERMINOLOGY
In the interim period, it is also possible that solutions to outstanding recycling, plastic rationalization and processing problems will be found. Finally, the lessons learned from small/prestige designs will be introduced once battery/cell stack costs and infrastructure issues are resolved.
Introduction to body architecture and terminology 13
Progress will be evident in the city car and premium car sectors, but changes in volume production will be prolonged. Hybridized structures and related production processes will continue to dominate in the short and medium term.
Refers to all those panels or subassemblies mechanically attached to the main substructure by hinges or other means, hence the synonym 'bolt-on' panels.
CHAPTER
OBJECTIVE
CONTENT
INTRODUCTION
After reviewing the milestones in car body design over the past hundred years, the key considerations of the modern designer are introduced with an example (from BMW) of how these are influenced by material choice. The side effects of these background 'authorization' projects have been adopted in many parallel model programs in recent years and are evident in some of the examples given in this chapter.
HISTORICAL PERSPECTIVE AND EVOLVING MATERIALS TECHNOLOGY
Although it will take some time for alternative fuels to become the norm, interest is increasingly being shown by major car manufacturers and BMW's views are discussed in Chapter 2. Reference is made to wider initiatives such as the flagship Aluminum Experimental Vehicle program composite (ECV), Aluminum Structure Vehicle Technology (ASVT) and Ultra Light Steel Auto Body (ULSAB) which have demonstrated the feasibility of the latest technology.
Historical perspective and evolving materials technology 19
- Body zones and terminology
- Distinction between body-on-chassis and unitary architecture
- Early materials and subsequent changes
The key elements of the main structure are the floor and main loft containing 'A', 'B/C' and 'D' posts or corner pillars and roof/. Bodywork such as that used for the Morris Oxford in the early 1920s featured wood, fabric and metal construction, the most significant change being to an all-steel assembly in 1929 as the influence of the American Budd Company became apparent within Pressed Steel, which provided. the body.
Historical perspective and evolving materials technology 21
Although first introduced in 1948, the Land Rover provides a good example of a modern vehicle with two standard length chassis, serving a host of agricultural and military purposes (see Figure 2.3). Although the chassis was cumbersome, it was and still is ideal for mounting the extensive range of Land Rover Defender body variants.
Historical perspective and evolving materials technology 23
Along with the BMW 328 Roadster (1936e40) and the Dyna Panhard (1954), Rover and Land Rover were among the first aluminum users in Europe, the ubiquitous Defender models using 3xxx series alloys for flat plates with Al-Mg series 5xxx. used in other applications; extensive experience has been gained in pressing, assembly and color pre-treatment and finishing. Still, it's no surprise that with fleet average economy targets being viewed more critically, monocoques are now being considered in more volume-oriented 4x4s such as the Land Rover Freelander.
Historical perspective and evolving materials technology 25
It is debated what exactly constitutes a frameless design, as different forms may incorporate some features of the original frame, e.g. Some claim that the ideal form of chassisless construction emerged in the 1940s with the release of the Austin A304 (see Figure 2.6).
Historical perspective and evolving materials technology 27
Using the powerful FEM analysis programs available today (see Section 2.3), the design can be optimized to maximize the use of properties, thereby reducing the number of prototypes, rework and development time. The more numerical data that can be collected at this stage related to the behavior of the materials, the more effective the modeling will be.
FINITE ELEMENT ANALYSIS
- Materials for Autobodies
However, even with such box sections and subframes, the simply spot-welded and finished bodies provided significant progress in weight reduction while meeting most engineering and manufacturing criteria.
Finite element analysis 29
The figure shows how a matrix can be used to represent the coefficients of the terms of the simultaneous equations. The program can also recalculate the stiffness matrices of the elements after adjusting the node coordinates with the calculated displacements.
Finite element analysis 31
All nodes must be connected to each other and therefore the fifth option shown would be incorrect due to interruptions. An example of car body FEA at Ford was described at one of the recent Boditek conferences, fig.
ONE MANUFACTURER’S APPROACH TO CURRENT DESIGN
- Product requirements
- Structural dynamics
After the first FEA was performed, the resulting deflections and stresses were fed back into PDGS-FAST for post-processing. This allowed the deformation mode to be viewed from any angle with adjustable deflection magnification and the ease of quickly switching between stressed and unstressed states.
One manufacturer’s approach to current design 33
- Design for static stiffness
- Crashworthiness
The researchers considered that over 20,000 nodes are required to predict the overall behavior of the white body. To achieve the target frequencies of 26/29 Hz for the vehicle as a whole, the relevant natural modes of the body must be twice as high and no local modes must occur below these frequencies, e.g.
One manufacturer’s approach to current design 35
- Weight efficiency
In the early 1990s it was also believed that there was still much more potential for weight reduction with steel, albeit in slightly different guises, and perhaps mixed with lighter materials, such as aluminum or plastic sheets, would meet most future goals. . It was with this knowledge that the steel industry's response in the 1990s was a design study undertaken by Porsche Engineering Services on behalf of 32 steel producers (the ULSAB programme, see Chapter 4).
One manufacturer’s approach to current design 37
More specific material-related data was further presented by Ludke7, who referred to the changes in high-strength steel (HSS) used with the. The HSS grades are typical of strengths now included in current designs by European body engineers, using the full range of rephosphorized, IF HSS, high strength low alloy.
One manufacturer’s approach to current design 39
As described earlier, the influence of material properties on impact and collapse characteristics is becoming more apparent with the development of dual-phase and TRIP steels, which offer increased energy absorption due to a unique combination of work hardening and ductility (increased area under the stress-strain curve). Examples of these steels being utilized are given in Chapter 8.) Again, improvement of these properties should be possible by adhesive application, leading to high strength steel utilization of 80 to 90%. An example of a current design that uses 25 grades of mild steel, high-strength steel and ultra-high-strength steel is the Jaguar XF body concept, which also features a vertical pine steel "ring" around the sides of the passenger cell.
PANEL DENT RESISTANCE AND STIFFNESS TESTING
Evaluation of the individual requirements of each part takes place at an early simulation stage. The initial stiffness is given by the slope of the curve in the first region, until the buckling load is reached.
Panel dent resistance and stiffness testing 43
After 'oiling' the panel continues to deflect elastically, before the onset of plastic deformation in the material. Panel stiffness depends on the elastic modulus, the panel thickness, shape and geometry and boundary conditions.
FATIGUE
- Designing against fatigue
Voltage range R is the algebraic difference between the maximum and minimum values of the voltage. A rearrangement and simplification of the formula by Goodman results in the linear relation R¼(su/n) [1eM/su] where.
Fatigue 47
The largest stress amplitude alternating for a given mean stress which can be resisted 'infinitely' is called the fatigue limit. The maximum withstand stress amplitude can be determined from a fatigue limit diagram, (e), for any minimum or mean stress.
ALTERNATIVE BODY ARCHITECTURE
- The unitary aluminum body
- The honda NSX
- The pressed spaceframe (or base unit) concept e steel
Wrinkling and shape control were found to be the main design issues attributed to the lower modulus resulting in higher springiness (compared to steel) and also a lower r-value. Along with relatively lower reshaping limit curves, new disciplines in the form of die setup, crowning and lubrication were found to be essential if the required shapes were to be mass produced.
Alternative body architecture 49
Prior to coating with a four-coat system, a variation of a chromatechrome pretreatment was found to be more suitable than the usual zinc phosphate formulation. The GM Saturn, shown in Figure 2.26, used the same type of pressed steel spaceframe (galvanized undercarriage) for structural integrity and strength, while clad in thermoplastic leather panels (doors, fenders, quarter panels, and fascia ) to increase corrosion resistance and reduce low speed damage.
Alternative body architecture 51
- Pressed aluminum spaceframes and associated designs
The complete vehicle is valid for using extrusions for the suspension struts, door frames, pedal assemblies and dashboard. Referred to as "Versatile Vehicle Architecture" (VVA), the system relies on common material design features, elements of which can be applied to a family of related structures, as illustrated in Figures 2.27 and 2.28 (aec).
Alternative body architecture 53
The Elise technology has the scope to be extended to provide solutions for a wider range of niche cars, which could include 44 MPVs, as well as sports vehicles. The Ferrari supplier produced the plate components and Ferrari supplied the sand castings, including the integral parts of the space frame as the FIGURE 2.27.
Alternative body architecture 55
- The ASF aluminum spaceframe utilizing castings and profiles .1 Audi A8 and A2
The spaceframe structure increased overall body rigidity (42% in bending, 44% in torsion) and safety, while reducing weight by 28% and number of parts by 35% compared to the steel predecessor. This development progressed in 1987 to the Audi ASF (or Audi Spaceframe design) and finally to the production model, the Audi A8 (D2, and later D3 & D4 2010 versions).
Alternative body architecture 57
The resulting A2 body structure was a highly innovative design that took elements of the previous A8 concept but improved them and added technologies. In the 2002 version of the A8 D3, much of the design and manufacturing technology was carried over from the A2.
Alternative body architecture 59
The emphasis on laser and MIG welding as well as mechanical fastening differs from ASVT technology, where adhesive is used to a greater extent on structural joints.
Alternative body architecture 61
- Examples of hybrid material designs .1 Hybrid designs in aluminum and steel
- Hybrid designs with composites
An example of this type of hybridization in passenger cars is the 2003 BMW 5 Series, where the front end featured extensive mixed use of aluminum and steel FIGURE 2.35. Five layers of carbon fiber are used and the maximum properties are developed by precisely aligning the individual fibers, mostly in the same direction as each other.
Alternative body architecture 63
- Aston Martin Vanquish
- Designs based on carbon fiber or CFRP
A steel, aluminum and carbon fiber subframe carried the engine, transmission and front suspension and was bolted directly to the forward bulkhead. The development of carbon fiber structures for bodywork probably began with the launch of the McClaren MP4/1 Formula One car in 1981, in recognition of its lightweight, impact-resistant properties.
Alternative body architecture 65
The Tesla Roadster combines the Lotus Elise-type monocoque chassis, made of resin bonded and riveted extruded aluminum, with a carbon fiber composite skin to achieve a lightweight chassis with a smooth aerodynamic surface. Using RTM and a closed mold configuration, the carbon fiber mat is placed between two polished steel tools and resin is injected to fill the gap.
Alternative body architecture 67
- The influence of alternative drive systems
Electrifying a vehicle means more than just replacing the combustion engine with an electric system. And in the city, the prime hunting ground for an electric vehicle, the driver often has to accelerate due to the volume of traffic.
Alternative body architecture 69
The Drive module is also where you will find the components of the electric drive unit and numerous suspension components. The lower accelerated mass in the event of an accident means that energy-absorbing structures can be scaled down, reducing the weight of the vehicle.
Alternative body architecture 71
Crash-active aluminum structures at the front and rear of the vehicle provide additional safety. The battery, meanwhile, is mounted in the underside of the car to provide it with the best possible protection.
Alternative body architecture 73
- Magnesium
And this allows the combination of materials in the LifeDrive module to provide better levels of safety than a steel monocoque. However, the advantages of the LifeDrive concept do not only lie in the weight savings it allows, the longer range and improved performance characteristics that result, and the increased safety.
INTEGRATION OF MATERIALS INTO DESIGNS
- General
- Other materials used in body design
- Tube hydroforming
Magnesium is now beginning to gain favor as past issues such as corrosion resistance and porosity improve and the push to lighten body structure becomes more important. As evident from the ULSAB program, hydroformed pipe has significant potential in part consolidation, especially for the more robust applications such as 4 4s, which also allow for a bit more freedom of construction.
Integration of materials into designs 75
In this case, the design data for the recently developed Freelander was at hand and could be modified relatively easily to allow an immediate comparison of new and conventional structures. The Land Rover Freelander was selected for this program mainly due to the maturity of the vehicle development program and the design package, which allowed application to either smaller or larger products.
Integration of materials into designs 77
Pre-development stages of ULSAB 40 and attributes of hydroformed sections16: (a) conception stages; and (b) shape comparison with conventional sections. Reprinted with permission from the SAE paper Copyright 1999 Society of Automotive Engineers Inc.). During this progress the advantages of hydroformed sections will be evaluated, firstly to confirm the weight and space saving potential allowed by the shape characteristics (see Figure 2.43(b)) and then for comparison with other possible methods that can produce similar savings (see Figure 2.44).
Integration of materials into designs 79
- Tailor-welded blanks
- Sandwich materials
Comparison of hydroformed with conventional parts and tube manufacturing stages are shown below in Figure 2.46. The 2008 tailored blank concept was introduced with the Citroen C5 for the rear seat interior, where the use of a 0.97mm P220 sheet with a central area of 1.47mm P220 enabled the removal of the reinforcement the central tunnel.
Integration of materials into designs 81
Some of the versions on the market cannot withstand the elevated temperatures during the body structure painting process. Even greater weight savings can be achieved by using an aluminum plate version of the sandwich material.
Integration of materials into designs 83
It is suggested that these sandwich materials are good examples of the new type of hybrid materials that will be used in the future and that make use of the positive advantages of each material type, i.e. a technique used in automotive design is to apply significant amounts of bitumen-based damping materials to critical areas of the body structure and closures.
ENGINEERING REQUIREMENTS FOR PLASTIC AND COMPOSITE COMPONENTS
Both UV resistance and solvent resistance are important performance parameters for exterior panels in particular.
COST ANALYSIS
Cost analysis 85
Producing a large number of heavy duty vehicles in this class may incur a cost penalty and the program manager may decide that the cost penalty of introducing a new material technology will be offset by the final weight positioning of the final vehicle. In conclusion, the main evolutionary stages of the automotive body structure have been reviewed and the role of materials has been introduced with respect to properties, costs and expected performance in use.
Cost analysis 89
Another approach proposed by Dieffenbach18 is to use a stainless steel space frame covered with self-colored composite panels, where potential savings are achieved by deleting different levels of the painting operation. Thus, comparing costs can be an extremely complex process that requires a thorough knowledge of the expected design and production scenario before accurate forecasting can be attempted.
LEARNING POINTS
INTRODUCTION
It is clear that the choice has broadened considerably these days, as material technology has responded to the needs of the automotive engineer. The stage of the strip production process, critical to the development of these parameters, is also identified along with other influencing factors.
96 CHAPTER 3 Materials for consideration and use
MATERIAL CANDIDATES AND SELECTION CRITERIA
- Consistency:a prime req uirement
Not all factors are shown and it is easy to split any of the columns shown. Therefore, it is necessary to strictly monitor the production process of raw materials both in terms of ingredients and process.
STEEL
One of the main differences between Japanese and European body structure design has been the preference for ultimate tensile stress over yield stress as a key design parameter, making it difficult to compare values for the same material. The difference between the available forms, the manufacturing processes associated with each of the coatings, and the corrosion and protection mechanisms are fully described in Chapter 7.
102 CHAPTER 3 Materials for consideration and use
Steel reduction and finishing processes
- Vacuum degassing
- Continuous casting
- Hot- and cold-rolling processes
- Continuous annealing
This is achieved by vacuum degassing the molten steel prior to casting, resulting in the now popular IF steels being used for more complex shaped parts. This was observed in the press shop where for the lower grades of forming steels (DCO-2/3) the "as received" properties did not match the BA ductility levels.
108 CHAPTER 3 Materials for consideration and use
Skin passing
This phenomenon is related to the retention of residual dislocations by the interstitial atoms.6 Before the skin passes, the number of free dislocations is relatively small, as they are locked by cooling from the annealing temperature. The "closing atoms" are mainly carbon, as all nitrogen is combined with aluminum or an alternative addition, and these migrate into the interstices associated with the available dislocations.
110 CHAPTER 3 Materials for consideration and use
Surface topography
Besides imparting a distortion of the order of 1% to the strip to counteract distortion effects, the skin transfer process also determines the final topography of the. The type of finish embossed on the plate surface by the work rolls that come into contact with it is becoming increasingly important as the lubrication properties during pressing and the finish developed during painting can both be optimized according to the final surface shape (see Figure 3.7 ).
112 CHAPTER 3 Materials for consideration and use
The process can be applied to both the last roll of the tandem rolling operation and to the tempering rolls. Some suppliers can now supply a range of surface treatments (eg the 'Sibertex' range) which are combinations of stochastic and deterministic topographies as shown schematically in Figure 3.11.
114 CHAPTER 3 Materials for consideration and use
The texture of the EBT rolls in the tandem and temper mill is generated by a high energy and precisely positioned electron beam. The electron beam applies the homogeneous pattern to the entire surface of the roll, which simultaneously rotates at a constant speed (600 rpm) and translates axially (3 cm/min).
116 CHAPTER 3 Materials for consideration and use
Effects in processing
Higher strength steels
- Ultra high-strength steels
The range of higher strength steels currently available is summarized in Table 3.9, which also defines the hardening mechanism and the appropriate standard for that steel group. Further information on the hardening modes of these steel types is given in Table 3.10, and a more graphical representation is given in Figure 3.12.
118 CHAPTER 3 Materials for consideration and use
The combination of developed high strength associated with relatively high elongation values increases the area under load/. Martensitic steels are hot-rolled with extremely high levels of strength, which are mainly provided by the martensitic phase.
124 CHAPTER 3 Materials for consideration and use
Future developments
It is generally agreed that the next generation of AHSS (including UHSS) will ideally be low carbon (providing weldability), low cost (with a minimum of expensive alloying additions) and straightforward to form, fit and repair using existing facilities. The existing options all have limitations: they represent a growing range of different compositions and surfaces, which complicates the final coating and finishing processes.
Stainless steel
A degree of rationalization and consistency is now needed, and this is probably best achieved by extending the existing family of low carbon steels produced using continuous annealing (CAL) and CAPL (continuous annealing) technology.
126 CHAPTER 3 Materials for consideration and use
ALUMINUM
- Production process
- Alloys for use in body structures
The main concern has been that they are prone to stretcher strain marks or Lu¨ders bands, which can appear as thick bright A-type marks on the sheet surface and coincide with yielding. The 6xxx series alloys are characterized by a higher yield strength than the Al-Mg alloys and are heat treatable, giving a significant degree of annealing hardening at temperatures approaching 200C (see Figure 3.16).
MAGNESIUM
132 CHAPTER 3 Materials for consideration and use
POLYMERS AND COMPOSITES
- Introduction
- Thermoplastics
- Thermosets
The main advantages of the compounds are their relatively high strength and low weight, excellent corrosion resistance, thermal properties and dimensional stability. There is a wide range of different processing techniques that can be used to produce compounds from the above raw materials.
134 CHAPTER 3 Materials for consideration and use
Polymer and composite processing
- Injection molding
- Glass-mat thermoplastic compression molding
Advantages of the process include relatively short production times and the ability to produce complex, precise parts. The low pressures involved in the process allow the use of inexpensive tooling, which is one of the main advantages of the process.
Advanced composites for competition cars
The weight of the cloth and the resin contained within it in the pre-impregnated state are controlled within tight limits. In this state it is workable and the thickness, stiffness and strength of the final structure can be controlled within very good limits.
REPAIR
250 to 3000 parts per year, while still meeting the highest standards demanded by models in the higher segment of the sports car sector. Unless controlled within reasonably tight limits, the effect of further deformation and arbitrarily applied heat treatment during repair can compromise the performance of the repaired part or area.
140 CHAPTER 3 Materials for consideration and use
INTRODUCTION
We have already mentioned major development programs in Chapter 3, where side technology can be traced in broader development programs. As in Chapter 2, although some reference models appear outdated, these technologies can best be understood by assessing their evolution.
THE ECV 3 AND ASVT
The purpose of this chapter, therefore, is to summarize the progress made within each of these initiatives, draw out the essential lessons learned, illustrate technological connections with examples presented in Chapter 3, and, hopefully, provide a reference for future application and further development.
The ECV 3 and ASVT 147
From the beginning it was intended that the system would be suitable for high volume production and the process envisaged for the treatment of the base unit is shown in Figure 4.3. The body weight of the ECV 3 was 138 kg, compared to 247 kg for an equivalent steel structure, and the vehicle weighed.
The ECV 3 and ASVT 149
Using a 5251-0 alloy pre-coated coil, it was shown that the material could be formed using production tooling, although some modification and reworking was required to achieve some of the shapes obtained in steel. The latter's first prototype already used a laser-welded stainless steel fairing with subframes bolted to the front and rear to support the engine, suspension and drivetrain.
The ECV 3 and ASVT 151
It was claimed that the assembled body-in-white (BIW) aluminum alloy base structure, built with ASV technology, required no further finishing to achieve longevity2 and that painting was limited to cosmetic parts, which today would be covered with plastic moldings (see Figure 4.4).3 The feasibility of production was thereby proven, and a full description of the experience and necessary changes is given in subsequent articles by Selwood et al.4 and Kewley et al.2. Improvements in the application of this technology were progressively introduced during the replica program described above, including the selection of series heat treatable alloy plates (6xxx) for more dent resistant exterior panels (see chapter 3), optimization of the pre-treatment/pre-lubrication system applied to the plate surface.
COLLABORATIVE DEVELOPMENT PROGRAMS
- ULSAB and ULSAB 40
Collaborative development programs 153
- FreedomCAR program
The main results of the program have been described many times5,6 and the associated follow-up programs are still ongoing. This program and the widespread dissemination of its findings to car manufacturers and associated initiatives such as 'Great Design in Steel'.
Collaborative development programs 155
- FutureSteelVehicle program
- Overview report
It was formed in early 2002 from the 1993 and 2001 Partnership for a New Generation of Vehicles (PNGV) and works primarily to identify, prioritize and (often) coordinate and encourage collaboration in advanced, pre-competitive automotive research and development (R&D). ) funded by partners and others (namely the National Science Foundation, the American Iron and Steel Institute and the American Chemical Society in the US and similar government organizations in Canada). Fundamental to ensuring reduced greenhouse gas emissions in the life cycle was the measurement of the overall impact on the environment.
Collaborative development programs 157
- Phase 2 report
The FSV program brings even more advanced steel and steel technologies to its portfolio, and consequently to the toolkits of automotive engineers around the world. This includes more than 20 new AHSS grades, representing materials expected to be commercially available in the 2015 and 2020 technology horizon.
Collaborative development programs 159
- Joining technologies
- SuperLIGHT-CAR project
The FSV program brings even more advanced steel and steel technologies to its portfolio than ever before in steel industry projects, and consequently to the toolkits of automotive engineers around the world. Compared to the highly efficient Class A/B production vehicle, whose ICE powertrain weighs almost 100 kg lighter than the BEV, the FSV BEV weighs just 188 kg compared to the production vehicle's 230 kg.
Collaborative development programs 161
- RWTH Aachen University FRP reinforcement program
Most importantly, this 'new lightweight approach work is focused on how continuous fiber-reinforced plastics can be effectively and affordably implemented in high-volume vehicle structures'.8 The goal is to reduce sheet metal thickness on the metal parts and compensate for the weakening of structure by local reinforcement. Due to the stiffness requirements, the rear tunnel supports and the bridge were specified with Carbon Fiber Reinforced Plastic (CFRP) inserts, and for the lightweight floor structure, 1 kg of Fiber Reinforced Plastic e Glass Fiber Reinforced Plastic (GFRP) and CFRPe were used.
CONCEPT CARS
Following the ECV 3 theme, the MG EX-E was a styling exercise to maintain public interest in the MG brand. To quote a chief designer at Volvo, 'concept cars are a great way to give a glimpse of the future without being limited by a specific design.
Concept cars 163
Volvo used the 2001 Detroit Auto Show to present its safety concept car, which was designed to give the driver more control and visibility (see Figure 4.10). Other features include sensors that scan the exact position of the driver's eyes and adjust the seat to allow the best possible visibility, as well as sensors built into the exterior mirrors and rear bumper to alert the driver of approaching traffic in the blind spot towards the rear.
Concept cars 165
Their second-generation fuel cell will be available in 2015 and will be half the weight and size of the current system. The latest concept in the Smart range includes the electric version of the ForTwo, which achieves the equivalent of 300mpg with zero emissions.
Concept cars 167
The Lotus City Car concept has a top speed of 170 km/h and a top speed of 120 km/h on a full charge, all achieved by a powertrain that returns CO2 emissions of 60 g/km on the ECE-R101 test schedule. . Another vehicle in the luxury/sports car category shown at the 2010 Geneva Motor Show was the Lotus Evora 414E High Performance Hybrid Concept.
Concept cars 169
The chassis is designed for scalability so that it can be expanded in width, length and height. As can be seen from the examples above, the aerodynamic styling is also optimized to improve drag coefficients.
COMPETITION CARS
- Introduction
The strength and stiffness of the low-volume VVA chassis can be cost-effectively modified by changing the extrusion wall thickness, without changing the external dimensions. The ability to lengthen or shorten the overhangs with the option to adjust chassis stiffness greatly increases the number of vehicles that can be developed from this vehicle architecture.
Competition cars 171
- F1 car structures d why composites?
- History
O'Rourke confirms that the essential elements of the technology have not changed significantly in the last decade). Carbon fiber hasn't changed much in the last decade, although the availability of higher performance types has improved and prices have dropped slightly.
Competition cars 173
- Extent of use
- Duty d the survival cell structure
- Rule conformity and weight
It is a semi-monocoque shell structure and is variously referred to as a 'chassis', 'tub' or 'monocoque', although it bears a closer resemblance to an aircraft fuselage than anything most people would associate it with. a vehicle. It has been mentioned that the chassis component is of great importance to the performance of the structure.
Competition cars 175
- Structural efficiency
- F1 d A good match for composites
Ideally, any small change in a component stiffness should be felt in the balance of the car. Restrictions are placed on the overall dimensions of the car's bodywork (which includes wings) and the size of the driver's envelope inside the cabin.
Competition cars 177
- Design
- Chassis loading
Load cases are specified for the design of key structural elements and tests are specified to be carried out and passed in the presence of a designated witness. It forms part of the car's aerodynamic envelope and is therefore often complex in shape.
Competition cars 179
- Analysis
- Materials database
The structure resulting from the criteria detailed here weighs roughly half that of the driver it was built to accommodate. A number of different quality assurance techniques are used, but these will only highlight some of the problems.
Competition cars 181
- Testing
- Survival cell proving
- Survival cell crush and penetration
- Survival cell impact
Failure of those deemed to compromise the structural integrity or handling of the car is considered "critical". In addition to the procedure above, the FIA has instituted a series of 12 tests which aim to demonstrate that a minimum level of crash safety has been achieved within the design of the survival cell.
Competition cars 183
- Impact absorber design
- Construction
- Tooling
- Materials
The mass of the impact head is 780 kg, the speed is 12 m se1, which gives an energy of 56 kJ, and the permissible mean deceleration is 35 g. The final, fourth dynamic test case is the steering column, which may incorporate composite materials in its construction.
Competition cars 185
An indisputable fact of component manufacturing is that the quality of a component is greatly influenced by the quality of the tooling used in its manufacture. The model materials used are of an epoxy-based nature, chosen for optimal compatibility with the matrix hardening of epoxy tools.
RALLY CARS
However, they mainly take the form of particle-reinforced types, and their use is largely seen as an extension of the conventional metalworking process. The weight of the body structure itself is reduced by removing most of the clothing.
HYPERCARS
The inner panels have been removed and, like the doors, replaced with carbon fiber, which is also used for the replacement bonnet and tailgate trim.
Hypercars 187
While the concept of the hypercar is thought provoking (and many of the properties of carbon fiber composites highlighted above have been proven in F1 and performance car competitions), criticism was inevitable. Selwood PG, et al. The Evaluation of an Aluminum Bonded Aluminum Structure in an Austin-Rover Metro Vehicle.
STEEL FORMABILITY
- Sheet metal pressworking
The purpose of this chapter is to introduce the key parameters that affect material performance in conversion to component form, and to describe the main manufacturing processes involved. Modern high production pressing operation is introduced and the parameters affecting formability are defined; how to derive test values is explained and the meaning of limit diagramming and its use is summarized; an explanation is given about the influence of different topographies of steel surfaces; main molding and cutting tool materials are introduced along with heat treatment and repair; the different technologies for hydroforming pipes and plates are described; the differences in production practices required for aluminum compared to sheet steel are highlighted; the possibilities for superplastic forming of metals are examined and reference is made to techniques used in plastics.
