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Optimized Structural components and add-ons to improve passive safety in new Electric Light Trucks and Vans (ELTVs)

Final Report Summary - OPTIBODY (Optimized Structural components and add-ons to improve passive safety in new Electric Light Trucks and Vans (ELTVs))

Executive Summary:
Electric Vehicles (EVs) have a completely different distribution of internal components with less architectural constrains. For instance, the use of in-wheel motors implies that the front of the vehicle, typically used to accommodate the thermal engine, now becomes a free space where other components can be located.
Safety levels of occupants, pedestrians, cyclists and urban infrastructure in crashes mainly depend on the structural behavior of the front and rear of the vehicle, in combination with the rest of the frame: front/rear bumpers, hood, sides, floor panels, pillars, etc.
This project called OPTIBODY, takes advantage of the new distribution of internal components in EVs to develop a new concept of modular structural architecture for electric light trucks or vans (ELTVs) focusing on the improvement of passive safety.
This new structural concept is composed of a chassis, a cabin and a number of add-ons bringing specific self protection against impacts and also providing partner protection (crash compatibility) while interacting with other vehicles or vulnerable users.
OPTIBODY is innovative in several fields:
• Modularity. Module-based design implies easier assembly and improved reparability for new ELTVs. OPTIBODY presents a pilot demonstrator where every module or component can be individually optimized in terms of manufacturing processes, weight optimization, crash energy absorption, etc. All these components must be compliant with some specific characteristics required to fit in the global concept of electric vehicle called OPTIBODY.
• Definition of the basic vehicle concept. As previously stated, this new structural concept of ELTVs is composed of a chassis, a cabin and a number of specific add-ons. The chassis is required to act as a key structural supporting element for the other components in the vehicle. The cabin brings occupant protection and is attached to the chassis. Finally, the add-ons and energy absorbing elements bring specific self-protection in case of impacts. Additionally, the add-ons also provide partner protection in case of interaction with other vehicles or vulnerable users (pedestrian, cyclists and motorcyclists).
• Definition of the market. As a modular vehicle, OPTIBODY represents a market opportunity for SME capable to manufacture any of the individual modules present in the OPTIBODY concept. These companies can make use of their specialized knowledge to optimize the components in terms of functionality, cost, shape or design. In this way, small and medium sized manufacturers can offer their own component proposals to LTV assemblers.
At the end of the project a demonstrator shows how it performs under crash-test conditions and, after the test is performed, how the damaged modules can be individually repaired.
Project Context and Objectives:
PROJECT CONTEXT
OPTIBODY is a new concept of modular structural architecture for electric light trucks or vans (ELTV’s) focusing on the improvement of passive safety.
Latest trends in electric vehicles design, show the increasing importance of dedicated vehicles instead of the classical general purpose concepts. Thus, manufacturers develop specific vehicles for urban logistics, vehicles for urban mobility, utility vehicles for municipalities, etc. They can be denoted as electric light trucks or vans (ELTV), worldwide homologated as N1 or even N2 vehicles. In Europe, they are also classified under L7e category (Directive 2002/24/CE).
The current status of electric traction technology imposes very light vehicles to optimize energy consumption, as the operational autonomy is still one of the drawbacks of EV’s. Most of present and near-future EV’s will still run in urban areas, in consequence at low-to-medium speed in short range displacements.
In addition, newly-designed EV’s have a completely different distribution of internal components with less architectural constrains. For instance, the use of in-wheel motors implies that the front of the vehicle, typically used to accommodate the thermal engine, now becomes a free space where other components can be located.
Safety levels of occupants, pedestrians, cyclists and urban infrastructure in crashes mainly depend on the structural behaviour of the front and rear of the vehicle, in combination with the rest of the frame: front/rear bumpers, hood, sides, floor panels, pillars, etc.
The use of in-wheel motors in substitution of other classic powertrain architectures is a key factor to enable the design of innovative vehicle structures for optimized passive safety,by freeing up the space traditionally occupied by the engine, transmission, and all of a drivetrain’s associated accessories. In this context, and taking into account the potential significant impact on the basic vehicle concept if the electrification of road vehicles is brought to extreme consequences, is where the project OPTIBODY was bornt.

OPTIBODY Consortium has developed a new concept of modular structural architecture for electric light trucks and vans implementing new concepts entirely acceptable by the automotive industry.
Thus, OPTIBODY, given the new distribution of internal components in EVs represents a unique opportunity to implement innovative solutions for passive safety in ELTVs.
These novelties can be grouped in several fields:

OPTIBODY’s Innovations in modularity for ELTV’s
-Module-based design implies easier assembly and improved repairability for new ELTVs.
-Each module/component is subject of individual optimization in terms of manufacturing processes, weight optimization, crash energy absorption, etc.

OPTIBODY’s Innovations in the basic vehicle concept of ELTVs:
This new structural concept of ELTVs is composed of a chassis, a cabin and a number of specific add-ons:
-A chassis is required to act as a key structural supporting element for any other components in the vehicle.
-A cabin improving current levels of comfort in EVs, occupant protection and ergonomics is attached to the chassis.
-A number of add-ons bring specific self protection in case of front, rear and side impacts, as well as in case of rollover. Additionally, these add-ons will also provide partner protection in case of interaction with other vehicles or vulnerable users (pedestrian, cyclists and motorcyclists).

OPTIBODY’s Innovation in the market:
Modular ELTVs represent a market opportunity not only for vehicle manufacturers, but also for component manufacturers. Components are designed to play specific roles within the global electric vehicle concept called OPTIBODY. These components can be optimized (functionality, cost, shape, design…) and manufactured by independent companies and installed by different car makers. This characteristic configures a new ELTV market where, in addition to big manufacturers, small and medium sized manufacturers can offer their own component proposals to LTV assemblers.

OPTIBODY has been developed by a very complementary Consortium formed by partners from four different countries (Spain, Poland, Italy and Sweden) and different profiles:
-Vehicle manufacturers and transformers: MONDRAUTO and AMZ.
-Vehicle parts and raw materials suppliers: BELLA and SSAB.
-Vehicle homologation institution: IDIADA
-Vehicle crash-test and performance laboratory: PIMOT
-Research institutions specialized in vehicle design: UNIZAR (Univ. of Zaragoza), POLITO (Univ. of Torino)
-Research company specialized in vehicle repairability: CENTRO ZARAGOZA
-Company specialized in vehicle designing: ITALDESIGN

S&T Objectives
Two main kinds of objectives have been distinguished. On one hand, as scientific objectives, a general theoretical improvement of passive safety will be achieved for electric vehicles under category L7e. On the other hand, as technological objectives, theoretical concepts have been shaped as a pilot demonstrator. The consequence of the achievement of these two objectives is that end users will take benefit of a better protection and manufacturers, trough the concept of modularity; will be able to join a new market with new opportunities.
As a general practise, the project has been developed by establishing theoretical conceptions that have been subjected to a further industrial adaptation.

As remarked above, in classic cars, the front is the natural location of the main power train components and auxiliaries: the thermal engine, clutch, gear box, air conditioning compressor, battery, heat exchangers, etc. while in new EVs, with or without in-wheel motors, most of the power train components are located at different spots in the vehicle. In consequence it is feasible the introduction of innovative front parts, made of optimized materials able to provide a higher level of protection for occupants and pedestrian, as well as improved protection in case of collisions against elements of urban furniture. Topics such as controlled deformability and enhanced energy absorption can now be more easily addressed. Fronts and rears can also be designed to achieve optimized levels of repairability and maintainability, given the frequency of small crashes in urban driving.
This is what defines OPTIBODY: a new modular concept for electric light trucks or vans (ELTV’s) focusing on the improvement of passive safety that represents a step-forward in passive safety levels.

The concept OPTIBODY has been achieved because the following objectives have been reached:
• Enhanced crash compatibility for ELTVs: new free spaces in electric vehicles bring an opportunity to implement new load paths and energy absorbers. Typically, ELTVs bodies/cabins are made of very light materials. As crash-safety regulations are less restrictive than for passenger cars, crashes with other vehicle categories result in very high fatality ratios.
• Enhanced passive safety by the introduction of add-on components: as it was analysed in previous projects (i.e. FP6-PLT-506503 APROSYS), the introduction of specific add-on components ensure the enhanced pedestrians, cyclist protection and road/urban infrastructure protection. OPTIBODY is the first time that the components suggested in those previous projects are specifically designed to be implemented in a concept of modular vehicle much less restrictive than conventional vehicles provided with thermal engines.
• Optimized repairability in low severity crashes: the introduction of repairability criteria in the design of the add-ons represents an innovation, not previously explored, in terms of damaged parts reparation/substitution cost.
• Optimized ergonomics and space distribution for passengers and main components accessibility: the redesign of the whole vehicle architecture, given the higher flexibility in component distribution associated to electric traction (innovative vehicle concepts), enables the introduction of demanding ergonomic and accessibility criteria.
• Better maintainability along the use phase of these urban vehicles: optimized repairability and component accessibility result in a better maintainability along the use phase of the vehicle.
• Establishment of the requirements for impact-safe ELTVs and definition of new safety paradigms: the technical requirements for an “OPTIBODY” quality marking have been defined in the project.

A very important issue in OPTIBODY is modularity. Modularity is a general systems concept, typically defined as a continuum describing the degree to which a system’s components may be separated and recombined. In industrial design, modularity refers to an engineering technique that builds larger systems by combining smaller subsystems.

Unlike a tightly integrated product whereby each component is designed to work specifically (and often exclusively) with other particular components in a tightly coupled system, modular products are systems of components that are “loosely coupled.”

Aspects of modular design can be seen in cars or other vehicles to the extent of there being certain parts to the car that can be added or removed without altering the rest of the car.

In consequence, the concept of modularity affects the totality of the vehicle design. Each vehicle subsystem has been designed in a way that it is able to perform its function in the total vehicle by itself, with a minimum of contribution from the other subsystems. Modularity also opens new possibilities for the automotive sector: parts complete exchangeability, independent testing, homologation or certification of components, easy vehicle modification or adaptation during its lifetime, better reuse and recycling of parts at the end of the vehicle life, better maintainability and repairability, etc.

Modularity is widely used in other technological domains, like the electronics appliances, computers, etc. It is however completely new in the field of passenger cars and partially considered in trucks or vans.

In consequence, the modular design of ELTVs’ structure has some important implications for the OEMs. The manufacturing and use of critical parts, such as safety add-ons or vehicle frames, will not be exclusive of a determined car maker or a determined vehicle category. Standardized parts (with verified performance) can now be produced by independent companies and mounted by any vehicle manufacturer. Although the personalization of parts is natural in this market, the basic performance of parts is guaranteed if integration procedures are followed. Cost reduction, better maintainability and repairability and increased average vehicle safety are direct consequences of modularity.

During the project, the following milestones have been reached, in accordance with the project work-programme:
-Analysis of standards, existing solutions and research projects results in the field of safety systems for vehicle occupants, pedestrian, cyclist and environment.
-Analysis of the requirements of new electric light trucks and vans.
-Design and test of optimized vehicle fronts/rears/chassis.
-Test and validation of components and integrated systems.
-Definition of recommendations for the introduction of optimized safety systems in new electric light trucks and vans.
Project Results:
The first results of the project refers to a compendium of conclusions about the accidentology of light vans.
The data analyzed showed that the trend was to reduce the number of fatalities in road accidents. During the last decade (2000 - 2009), IRTAD data showed a general decrease on all countries, except in countries like Cambodia (+17.5) or Malaysia (+1.2). In Europe, the number of accidents has been reduced in most countries, except Romania, where the number has increased. Germany remains the country with greater number of accidents followed by Italy, UK, Spain and France.
A review of the Piemonte Region database, in Italy, showed that only one person died in accidents involving quadricycles. The small number of fatalities and injuries in accidents involving this category of vehicles might me due to: safety measurements integrated in the vehicles, small mass, low speed, they mostly circulate in urban areas and/or the number of vehicles in this category is very small. Frontal-side impact (Frontal with offset) and rear impact are by far the most frequent types of accidents. However, frontal impact and pedestrian accidents are much more severe causing more casualties and injuries than the other types of prevailing accidents.
The number truck accidents and the number of fatalities associated with those accidents are significantly higher than for quadricycles. Especial effort need to be done to reduce the number of pedestrian accidents in both quadricycle and truck cases.
Analyzing the CARE database, in 2009 a total of 19,910 people were killed in the countries of the EU14 group. Italy was the country with greater number of deaths in traffic accidents, a total of 4,731 deaths. Accidents in urban areas represent a high number of deaths and they require especial attention due to the urban use that the OPTIBODY vehicle will have. Into the EU19 group 153,780 people died during the period between 2000 from 2009. According to CARE database, the number of deaths in lorries under 3.5 tons, was of 893 for the EU19 in 2009, 5.2% less compared to 2008. A total of 155 of those deaths occurred in urban areas.
Accidents trends in U.S. showed a decrease in the number of deaths over the last years (2000-2007). In 2007, 41,059 people died in the U.S. roadways and the total number of accidents exceeds 6 million. The number of injured people was 2,491,000. In the U.S. 3.6 times as many passenger car occupants were killed as LTV occupants in car-to-LTV collisions. When LTVs were struck in the side by a passenger car, 1.6 times as many LTV occupants were killed as passenger car occupants. On the other hand, when passenger cars were struck in the side by LTVs they were killed 18 times more than LTV occupants.
Japan has more than 90 million registered vehicles, of which more than 16 million are trucks. The number of accident documented in the Traffic Bureau and the National Police Agency database was 832,000, in which a total of 5744 died during 2007. If only trucks are considered, there were 153,746 accidents and 1650 of them were fatal. The higher number of accidents occurred in drivers with 10 or more years of experience.
A review of the VC/ COMPAT and FIMCAR projects as well as a review of the existing literature was performed to evaluate the state of the art of the accidentology and the existing and future test procedures to evaluate car-car and car-truck crash compatibility.

Considering the fact that the OPTIBODY vehicle category does not require any mandatory crash test for certification, it was necessary for the project to establish a minimum of safety requirements for the OPTIBODY vehicle that ensured the safety of its passengers. These crash tests did not need to be as demanding as for conventional vehicles due to the nature of the L7e and low speed vehicles.

Another preliminary task referred to the elaboration of a study of damageability and reparability applicable to electrical light vans
RCAR crash test procedures were used to evaluate damageability and reparability. These crash tests were used to analyse the vehicle performance and quantify its damage and reparability in low-speed crashes to encourage vehicle designers to limit unnecessary damage to the structure in low speed front and rear crashes. Cars are catalogued as “good” or “poor” reparability vehicles. The test procedure was reviewed in 2006 to change the impact angle from 0º to 10º and the rear impact barrier weight from 1000kg to 1400kg.
Low-speed structural crash tests are used to evaluate vehicle’s damageability and reparability (RCAR). The evaluation includes an assessment of the vehicle’s damage in two impacts:
• A 15 km/h frontal impact into a rigid barrier
• A rigid-faced mobile barrier, striking at 15 km/h the rear of the stationary vehicle
RCAR tests procedures for reparability assessment were summarized. Then, the reparability assessment of an electrical vehicle was studied. As the vehicles CITROËN C-Zéro, PEUGEOT iOn and MITSHUBISHI I-Miev share the same structure, the results obtained from the front and rear crash tests, shown in a technical presentation done by PSA PEUGEOT CITROËN in November 2010, are applicable to the three vehicles. These results were been extensively described.
Probably the most important conclusion from these results was that there were not significant differences in damages respect conventional (fuel engine) models. In fact, even in rear crash test, no damage was done to any of different electrical devices, despite these devices were located in the rear part of the vehicle (motor, inverter, chargers).
This conclusion should be taken into account for OPTIBODY concept, it will be important if no electrical component is damaged when vehicle will be tested under RCAR procedures to assess its damageability.
Finally, some recommendations to take into account when repairing/operating electric vehicles and some considerations for rescue operations were given. These recommendations include the precautions that need to be taken when repairing electric vehicles such as the use of protective equipment, the order to be followed in the operations and some mechanical and bodywork repairing procedures. The rescue recommendations include the identification of the electric vehicle, the location of the electric components, the preparation of the required tools and the rescue procedures such as the vehicle immobilization, the High Voltage (HV) system shut-down and the precautions in case of water submersion or fire.

In addition to the previous preliminary tasks, a report on design guidelines for new concepts of ELTVs was elaborated.
The first stages in the development of the OPTIBODY project generated a great amount of relevant technical knowledge. Then, a compendium of the most important results, conclusions was elaborated.
The information collected was divided into a number of specific areas of knowledge:
• Issues related to the vehicle battery pack. Requirements according to the vehicle homologation category were detailed. Different battery technologies were described and compared. The battery pack positioning in the vehicle was also analysed, from the safety point of view. Finally, the most relevant applicable standards were listed.
• Powertrain, in particular traction motors. OPTIBODY contemplated the use of in-wheel motors. A detailed study of the specific performance of EVs with in-wheel motors, compared to traditional architectures, was performed. The impact of the motors mass on the tire vertical dynamics was also analysed. Corrective measures were proposed.
• Vehicle weight reduction as a key design objective. Vehicle weight influence in fuel consumption was studied. Vehicle weight evolution was presented and the possible means to achieve substantial weight reductions were also described.
• ELTVs crashworthiness. Basic technical issues were described. Crash compatibility for ELTVs was analysed in detail.
• Enhanced passive safety concept based on deformable layers with modulated energy absorption capacity. The most external layer, considered as an add-on to the vehicle, was described, characterised and analysed in detail.
• Maintainability as an innovative aspect of the new EVs. Although there aren’t many data up to date, some conclusion and recommendation could be extracted from the existing information.

Related to proposal of solutions to meet safety requirements, the vehicle can be divided mainly in four different parts: FRONT, SIDE, and REAR part and the ADD ON.
• FRONT part. The aim of the front part is to manage and absorb the energy in case of a front overlapped impact against a barrier or a full impact against a rigid structure, both in high speed and insurance tests.
Three main elements are present in the front part: crash beam, crash box and front rail.
The main function of the crash beam is to absorb energy in case of impact at low speed (insurance test) in order to protect the equipment inside the engine compartment. It is also necessary to manage the energy in case of impact against the leg of the pedestrian. The contribution of this component in the energy absorption and the deformation at the end of the impacts at low speed and high speed, was analyzed. It was interesting to observe that the contribution of the crash beam strictly depends not only on the properties same beam, but also on the properties of all absorbing system (crash box, front rail).
The crash box is a boxed beam made of two C-shaped shells, joined together by welding along their longitudinal flanges. The main goal of the crash box is to absorb the energy in case of impact at low speed. For this reason the crash box is welded in the front part with the crash beam, and in the rear part with a plate. This sub assembly is fixed to the rear structure by means of bolts and nuts, applied on the rear plate. This solution is used to reduce the reparability costs in case of impact at low speed. With a correct design of this component, all the energy of a low speed impact is absorbed by these two components in order to avoid deformations in the remaining frame. The reparability costs are limited to the substitution of the assembly made of the crash box and of the crash beam. The main goal of the front rail is to absorb the energy of an impact at high speed. The front rail has the same geometry of the main rail but it is welded to two plates, joined in the front and rear part to the remaining body structure with bolts and nuts. This solution was adopted for two main reasons: first, it is possible to reduce the reparability costs as discussed before for the crash beam and crash box; then, this solution allows adopting different materials for the front rail and the vehicle body.

• SIDE part. The side structure is characterized by a series of crash boxes. Each crash box is fixed, at one end, to a plate by welding: these assemblies are fixed to the longitudinal main rail of the chassis with bolts and nuts. At the opposite end, the crash boxes are welded to a crash beam. For the geometry and the material of the crash beam, the two different solutions examined before for the front structure, can be taken into consideration. The side crash boxes are made of two C-shaped shells in this case also, welded together along the longitudinal flanges to make a boxed beam. For the material adopted, the same consideration made for the front structure was considered valid. In this case the crash boxes were longer, and their section decreased from the plate to the crash beam like a frustum, in order to control the correct stable crushing process.
• REAR part. The rear part aims to absorb energy in case of rear impact at low speed. It is made of two crash boxes, connected by a transverse crash beam. The considerations about geometries and materials are the same illustrated before for the equivalent components in the front part of the vehicle.
• Joining between front and rear chassis. To ensure the modularity of the vehicle, the chassis must be designed in two main parts:
• Front part: cabin, main fastening points for the powertrain devices, sub-components aimed to absorb the energy in case of front impact
• Rear part: aimed to carry the goods and in particular to bring different types of exchangeable superstructures.
These two main parts are joined together with plates and a series of bolts and nuts. The plates are welded to the main longitudinal rails of the front and rear chassis. During the design phase, in particular after examination of the front impact behaviour, the connections between these two parts appeared to be possible weak points. In fact, after the first phase of the impact where both the front structure of the vehicle and the barrier deform themselves absorbing energy, the rear part of the vehicle moves up. During this motion the two parts did not appear aligned and with some plastic deformation. For this reason the plate used to join the two chassis parts needed to be carefully designed.
• Add-ons. The automotive industry has been working on improving the protection of vulnerable road users (VRU) for years. It seemed reasonable to extend this research to the improvement of industrial vehicles as well. Since most trucks are designed to maximize the loading space within the maximum dimensions legally accepted, the front part approximates a planar and vertical surface.

Related to manufacturing issues, the structural design activity required assistance from other tasks to define the optimum features related to damageability and reparability based on the analysis of repairing/replacement procedures for every module of the OPTIBODY concept. Features given three different analysis were performed:
• Analysis of most frequently damaged parts.
• Analysis of damageability and reparability.
• Analysis of joints.
As a result of these analysis, the optimum features related to damageability and reparability to be achieved for every module were be given.

Moreover, the development of a new vehicle concept includes the use of some materials for it, whether existing or new, and which must meet the requirements of safety and reparability seen in previous tasks. Additionally, it is important that these materials meet certain minimum requirements regarding their reuse, recycle and recovery.
The European directive 2000/53/EC set the minimum percentages by an average weight per vehicle, in order to ensure its reuse, recyclability or recovery. Following this Directive as a reference, the different processes of reuse, recycling and recovering for vehicles at the end of its life were analyzed, in order to know what processes were applied and how effective they were, for each group of materials planned to build the OPTIBODY concept, mainly steel, aluminium, plastics (thermoplastics) and composites.

All the knowledge generated lead to the definition of a specific OPTIBODY demonstrator. The combination of the structural requirements together with reparability considerations established the final definition of the demonstrator.
• High strength steel frame. The frame of the OPTIBODY vehicle is composed by a cabin and a basis frame, and the profiles have a circular section. The frame basically consists of two longitudinal beams connected with several transversal beams welded to them. The section of these longitudinal profiles has a 50 mm diameter, and these profiles are 1.50 mm thick. The rest of the profiles of the structure have a 38.1 mm section diameter and are 1.60 mm thick.
In order to favour the modularity and reparability characteristics, the junction of the different parts that compose the vehicle is made through the use of steel sheets. One is welded to one part of the vehicle (e.g. the longitudinal profile), another sheet is welded to the part that is wanted to be joined (e.g. one end of a composite crash structure), and both sheets are joined together by screwing them.
The cabin consists of a set of longitudinal and transversal beams making a compartment for the driver. It has been mounted at the front of the frame and has been adjusted to the optimum position and ergonomics of the driver.
Concerning the position of the batteries, the set of batteries has been installed in the rear zone behind the cabin at approximately the same height as the longitudinal beams. A composite floor is fixed on top of the battery set.
The maximum whole vehicle mass of 550 kg must include the chassis with the frame and the cabin, the add-ons, and all the elements necessary to complete the vehicle such as floor panels, doors, etc. As a consequence, the chassis mass must be inferior to 550 kg and the selection of the materials used involved a key factor in order to achieve a significant mass reduction at the same time that an appropriate stiffness and an optimum behaviour against impact is obtained. In this way, Aluminium alloys, high strength steels and composites were the main materials considered for developing the chassis.

Firstly it was decided to use aluminium to make the chassis. However, it was finally made of high strength steel because, in spite of having a higher density, their Young’s Modulus is also higher. This enables the chassis to use profiles with a smaller section, which reduces the weight of this part. The steel used to make the tubes is DOCOL 800 DP.
Some of the advantages of using high strength steel are:
- Weight reduction
- Simplified manufacturing
- Increased safety
- Improved environment protection
- Longer lifecycle
- Increased payload
- Increased load capacity
- Reduced total cost
• Energy absorbing elements. The elements added for this purpose are: composite crash structures, hole triggered crash-boxes, crashbeam and frontal add-on.
The composite crash structure is placed between the steel crash-box and the longitudinal member, so it is designed to be more resistant than the crash-box but softer than the longitudinal member in case of an impact. It is necessary that both, the crash-box and the longitudinal beam, have a sheet welded at one of their sides.
At the both ends of the composite crash structure there are also screwed sheets. They are based on a semi-hexagonal geometry. This way, a modular component, which will be able to fulfil the requirements for different kind of vehicles and which will be adapted to the available space, was made.
Definitions of specifications were carried out using numerical tools.

• Crashbeam. The bumper is crucial as it must be capable of absorbing a certain amount of energy preventing the frame from major damages. It has a profile with a rectangular section of 52x96 mm and it is 2 mm thick. As it is a straight profile, it is necessary to use an element that eases the junction in the lower part between the structure and the frontal add-on.
Firstly, a curved sheet that adapted its shape to the add-on was going to be used. This sheet was welded to the crashbeam in the exterior edges of the ends of the crashbeam and screwed to the frontal add-on. However, this element made the whole structure more rigid. Therefore, this sheet was cut, remaining only its ends.

• Frontal add-on. In case of accidents in which pedestrians are involved, the fact that the head of the pedestrian does not crash into the windscreen is bore in mind when designing the geometry of the frontal add-on. The movement of the pedestrian is another factor to keep in mind. It is also important that the frontal add-on dissipates part of the energy produced during the impact. Furthermore, the driver must have good visibility of the road.
In the beginning, the model was composed of five elements. From the inner to the outer layer, they were:
1. A 1.75 mm layer of GLASS MAT-FABRIC (650 g/m2)
2. A 20 mm foam core made of PVC 60
3. A 1.75 mm layer of GLASS MAT-FABRIC (650 g/m2)
4. A 0.8 mm layer of CSM EMULSION FIBERGLASS MAT (300 g/m2)
5. A 0.7 mm layer of GELCOAT
A process for optimizing the properties of the frontal add-on was later carried out. Different configurations of composite materials were modelled and their behaviours were analysed. After studying and comparing the values of the deceleration in x-direction, the displacement in x-direction and the HPC15 value ('Head Performance Criterion (HPC)' ), a configuration for the frontal add-on was chosen.
1. A 0.8 mm layer of CSM EMULSION FIBERGLASS MAT (300 g/m2)
2. A 10 mm foam core made of PVC 60
3. A 0.8 mm layer of CSM EMULSION FIBERGLASS MAT (300 g/m2)
4. A 0.5 mm layer of GELCOAT
This option offers a less rigid behaviour. Therefore, it absorbed more energy and the crash should have a less severe effect on occupants and pedestrians.
The “modularity” and “reparability” terms are also kept in mind in order to join the frontal add-on to the structure.
- Frontal add-on adaptation to the cabin. The frontal add-on is joined to the cabin both upper and lower sides.
- Replacement. One of the objectives of the OPTIBODY vehicle is replacing parts that compose it with ease. In the case of the frontal add-on, the upper part can be removed by unscrewing it from the sheets welded to the structure. The lower part is separated by means of the crashbeam, which is unscrewed from the composite crash structures.
- Divided frontal add-on. In order to facilitate and reduce repairing costs, a front add-on divided into four parts was proposed. Due to the joint between the different parts could lead to a stiffer joint area, being a critical issue from the point of view of the protection of vulnerable road users, adhesive bonding was proposed as a solution.
To get the adhesive that could be the most suitable for the intended requirements, a comparative analysis was done by means of point impact tests.
At the end of the project, the pilot demonstrator of the vehicle was manufactured and integrated. Four main elements formed the vehicle: the chassis, the cabin, the frontal add-on and the two front rails.
It was the moment to assess the performance of the passive safety elements installed in the pilot demonstrator against vehicle impacts and the repairability of the frontal add-on after one of these collisions.

Three full vehicle tests were carried out: an RCAR test was carried out to mainly assess the repairability of the frontal add-on of the vehicle. The results showed a good performance both in time investment in repairability tasks and in costs of new materials or parts replaced. On the other hand, in terms of crashworthiness, crash boxes were too stiff, so they did not dissipate part of the impact energy and the front rails were detached from the crash box base before they started to be deformed. The crash boxes were drilled to make them weaker.
Two full frontal additional tests were performed to assess the capacity of the crash boxes and the front rails of dissipating the impact energy. In the first test, at 25 km/h, although the crash boxes dissipated impact energy, the front rails were detached as well before they started to be deformed. As a consequence, the front rail bases were reinforced and they were attached to the vehicle frame, the most rigid part of the vehicle. Finally, in the test at 40 km/h, both crash boxes and front rails dissipated the whole impact energy in a coordinated way.
Two lower legform impact tests were performed under the European Standard. The results showed that the frontal add-on located before the bumper beam did not jeopardize the pedestrian safety in case of run over.
Two of the most important aims of the OPTIBODY project were achieved. A frontal add-on made of composite materials had been designed, developed and manufactured in previous phases; in this stage of the project, it was tested and its repairability and safety was assessed showing the expected results, that is, repairing tasks after a collision are viable and, in case of impact, the frontal add-on does not cause more severe injuries either in vehicle occupants or in pedestrians.
The frontal passive safety elements as the bumper beam, crash boxes and front rails were tested. After several modifications based on the test results, a complete system that performed as one ensemble was achieved. The whole energy of a 40 km/h frontal impact (one of the most severe accidents in urban environment) was dissipated.
Potential Impact:
It has already been explained that the most relevant characteristics of OPTIBODY derive from two basic factors. On one hand, OPTIBODY, as an electrical vehicle concept, takes advantage of the availability of new frontal spaces to improve, in case of collision, not just its crashworthiness, but also its crash compatibility. On the other hand, modularity is an extra advantage in terms of repairability and also -in case of successful introduction in the market- in terms of new business opportunities for not only big sized vehicle manufacturers, but also for small and medium sized companies able to manufacture the modules required by the concept OPTIBODY (even, not necessarily vehicles manufacturers).

The different impacts that launching a concept as OPTIBODY can be divided in these two big fields.
The first of them is related to the fact that the concept OPTIBODY represenst a high level of safety (self-protection and partner- protection) for ELTVs. Then, the concept OPTIBODY could be the starting point to define a standard of “safe electric vehicle” and all the EU citizens should benefit of this.
The second one corresponds to the market opportunities that the modularity brings. Finding new market possibilities for SMEs is extremely important in a crisis context as the current one, moreover if we know that these small and medium sized companies are the economic motor of Europe and the main employment contributor.

To have an idea of the impact (social and economic) that the improvement in currents levels of pasive safety may have, we should first consider to which kind of problem we face up.
General Introduction on Traffic Accidents and Consequences
Related to traffic accidents, the EU underlines that saving lives is a shared responsibility. Achieving high levels of safety will be the contribution of OPTIBODY.
Road accidents are the greatest source of accidental death throughout the European Union.
A general overview of size and evolution of the problem can be obtained from an analysis of the evolution of fatalities, injured and accidents in the EU. In the period 1991-2008 fatalities evolved from 75.346 to 38.875; injured were reduced from 1.907.125 to 1.631.345; finally, accidents were reduced from 1.444.623 to 1.233.754. The evolution of these data is shown in the next Figure.

Although the evolution of fatalities, injured and accidents is constantly decreasing, the problem is big enough and expected results are not being achieved, so special efforts to fight this problem have still to be made.
Related to urban areas, in 2005, 8.579 persons were killed in urban road traffic accidents in the EU-14 (EU- 15 without Germany). This is 32,9% of all traffic accident fatalities in 2005. In the last decade, urban road fatalities have reduced by more than one quarter (27,1%), while the total number of fatalities has reduced slightly less (25,3%).
OPTIBODY, as a safer concept of electric vehicle, brings new opportunities for innovative designs and technical concepts that can directly contribute to the reduction of fatalities and injuries, which also means a direct social benefit for citizens.

OPTIBODY improvements in VRU protection
Pedestrian and other vulnerable users related fatalities represent a significant amount of fatalities and injuries. ELTVs are expected to have relevant presence in urban environments, which implies more intensive coexistence with pedestrian and other vulnerable users. OPTIBODY implement dedicated add-ons for pedestrian and vulnerable users protection.
The proportion of pedestrian fatalities is about 17% and the proportion of cyclist fatalities is about 6%. Age groups that have the highest percentage of pedestrian fatalities are children younger than 10 years of age and adults aged 65 years or older. Cyclist fatalities have the highest share among children between 6 and 14 years of age. The percentages for these age groups are about twice as high as the average percentages for all age groups.
Most fatalities, severe and slight injuries to pedestrians and cyclists occur in urban areas. Motor vehicles (cars, lorries, and buses) account for over 80% of vehicles striking pedestrians and cyclists. Crashes involving pedestrians and cyclists occur frequently at facilities designed for pedestrians and cyclists such as pedestrian crossings, cycle tracks, and cycle lanes. This means that these facilities are not necessarily good enough to prevent crashes.
Factors that have been identified as contributory factors in the causation of pedestrian and cyclist crashes and injuries are the speed of motorised vehicles, the weight and design of motor vehicles, the lack of protection of pedestrians and cyclists, their visibility and vehicle control, and alcohol consumption.
These figures suggested the adoption of mandatory regulations and countermeasures oriented to the different groups of vulnerable users. For instance, regulations and directives related to helmets, pedestrian protection in passenger cars, road restraint systems for motorcyclists and cyclists, etc. are some of the initiatives directly oriented to protect vulnerable users. In addition, some scientific and technical works show the expected benefit of new countermeasures to improve safety of pedestrian and other vulnerable users.
The project PROMISING (Promotion of mobility and safety of vulnerable road users, Contract No. RO-97- RS.2112 Final Report. July, 2001) presents some expected benefits derived from development and installation of front, rear and side underrun guard rails on trucks. This project establishes that protecting all sides of trucks by means of energy absorbing devices with a low ground clearance is expected to reduce the number of fatal injuries by about 12%. If it is assumed that the cost of accidents is reduced 10% per year, these costs easily exceeds the cost of providing protection against underriding. Benefits would exceed costs even if the safety effect was as small as 5%. It would therefore seem to be a good idea to provide trucks with protection against underriding.
Another work, carried out by Goudswaard, A.P. & Janssen, E.G. (1990) “Passive safety of commercial vehicles; a literature study” (In Dutch, TNO-report 754080030, TNO Road-Vehicles Research Institute IW- TNO, Delft) establishes that lorries could be made much safer for third parties by the application of adequate protection around the vehicle. Such protection prevents the dangerous underrun of, for instance, cyclists and other two-wheeled vehicles. In 35-50% of the crashes between heavy goods vehicles and two- wheelers, injury severity can be limited by side-underrun protection. Moreover, this facility prevents a road user involved in the collision still being run over. The number of traffic fatalities in urban areas due to crashes of this type could be reduced by 10%.
A third work carried out by Kampen, L.T.B. van & Schoon, C.C. (1999) “The safety of lorries; An accident and measures analysis commissioned by the Dutch Transport Operators Association” (In Dutch, R-99-31, SWOV Institute for Road Safety Research, Leidschendam) establishes that for moped riders, cyclists and pedestrians, closed side-underrun protection on lorries is more effective than open protection. Both open and closed side-underrun protection appear in the top ten of relevant and cost-effective measures to reduce the number of casualties as a result of crashes involving lorries.
Finally, the project APROSYS (FP6-PLT-506503) shows some impressive data, specifically in deliverables D2.1.2A “Development of strategies for enhanced pedestrian and cyclist friendly design (including front and side structures) including overrun prevention systems for new Heavy vehicle concepts based on the existing standards defined in 89/297/EWG” and D2.1.2B “Suggestions for design changes by means of add on parts for existing HV designs (special topic on HV from CEE countries) for front and side structures”. These data state that, for vulnerable road users (VRU) (pedestrian and cyclist), statistics indicate that more than 1.400 unprotected road users in the current EU member states lose their lives every year due to accidents with heavy vehicles. For opponent vehicles, yearly statistics show approximately 500 occupants that suffer fatal injuries due to impacts with the side of trucks and trailers.
These APROSYS documents also state that due to improved new design concepts, test methods and development guidelines resulting from this sub-project, the fatality and serious injury rate of the 3 victim groups (pedestrian, cyclists and car occupants) can be reduced by approximately 30%. This is nearly equivalent to 600 saved lives within the EU each year and a significant reduction in suffering and societal cost through the reduction in injuries and injury severity.
As a conclusion, lateral and frontal underrun protection is widely considered as a key factor to reduce the number of fatalities related to pedestrian and other vulnerable users. OPTIBODY is an electric vehicle concept expected to be adopted in the development of new future electric urban vehicles, so high level of coexistence with cyclists, motorcyclists and pedestrian is expected and, therefore, specific protection for these vulnerable users must be provided.
At this point, OPTIBODY will take advantage from the concept of modularity to allow the implementation of specific side and front add-ons that can always be under continuous development to increase the level of protection. In this sense, it is important to remark that these add-ons are not a unique solution. OPTIBODY is a concept, and several manufacturers can develop their own technical solutions for vehicles matching the concept of OPTIBODY. Moreover, this modularity also brings opportunities to new research lines, specifically oriented to improve de design and mechanical performance of dedicated side add-ons, or dedicated frontal add-ons.

From a social point of view, OPTIBODY allows an easier coexistence of ELTVs and vulnerable users. For instance, very small ELTVs can move in ancient urban areas where traffic calming techniques apply to allow a coexistence of vehicles and pedestrian.

OPTIBODY improvements in passive safety and compatibility of light trucks and vans:
LTVs involved in traffic accidents have proved to be highly aggressive with other involved vehicles. To avoid this problem, OPTIBODY, as a concept, will be provided with optimized self-protection and partner- protection. Both, occupants of LTVs and occupants of other vehicles struck by a LTV will take benefit of this.

OPTIBODY will take advantage of modularity and reduction of structural constraints to offer high levels of self-protection and partner-protection. Again, the concept of modularity brings to scientists a chance to develop research lines specifically oriented to improve the mechanical performance of specific modules under different critical situations. And, the availability of new free spaces, will allow implementing new and innovative energy absorbers with optimized response in case of accident.
In addition, occupants of LTVs involved in traffic accidents as well as occupants of vehicles struck by LTVs will benefit of the concept OPTIBODY trough a reduction of the risk to be death or injured in these accidents.

OPTIBODY improvements in Reparability
A significant proportion of costs during the lifetime of a vehicle, specially a urban vehicle, comes from maintenance and repairing of crash damages. OPTIBODY, as a modular and electric concept, with less constraints, will establish the basis for new repairability techniques, with better results and lower costs.
After a collision, returning a vehicle to its pre-accident condition as well as maintenance operations represent a costly and time consuming business in today’s vehicles. Costs are directly related to today’s vehicles architecture that descends from the presence of an internal combustion engine on board.
Development of new vehicle concepts (electrical powered) without the constraints derived from the internal combustion engine will allow to define optimum features in order to guarantee a good performance regarding damageability, repairability and maintenance, in a physical sense and in terms of costs.
The unique characteristics of OPTIBODY allow the definition of new repairing and maintenance procedures derived from modularity and new vehicle’s architecture, making them easier and more cost effective compared to today’s vehicles, reducing overall crash repair and maintenance costs without compromising safety. These new procedures will have influence not only in electric vehicle’s manufacturers but also in workshops and insurance sectors.
As a consequence, reduction in repairing and maintenance costs for new vehicles will mean not only an economic saving for users but also an important reason to buy new electric vehicles, helping these new vehicles to be implemented in a short/middle term. Lower costs in repairing could have a big influence in Insurance sector when these new electric vehicles will be extended, probably causing a reduction in insurance policies.

List of Websites:
Project website address:http://optibody.unizar.es/