Current trucks are designed to carry a maximum of payload or a maximum volume of goods. In European Union Regulations, the maximum weight and dimensions of trucks are clearly restricted limiting the flexibility that is needed for safety or aerodynamic issues. This study will analyse the benefits in terms of safety and CO2 emissions that would result from an increase in the maximum semi-trailer tractor combination length (i. e. 40 t-HGV of currently 16.5 m) without changing the maximum load length. Furthermore, the dimensions, layout and design of such an optimised tractor will be determined. Simulations, calculations and illustrations will support the achieved solution and recommendations will be derived. The focus of the research project is to show the impact of a possible change in legislation regarding the cabin length. The task is to develop an integrated cabin concept which is focused on maximising environmental performance through aerodynamic streamlining and optimising safety compared to an appropriate reference cabin. Utility and total cost of ownership aspects set important boundaries. With regard to the internal consistence of the project, the definition of both cabins including material use will be based around consumer preferences. This approach guarantees comparability. In the course of the safety optimisation and with regard to utility implications such as payload requirements, the new cabin’s front structure properties will be designed to optimise impact energy absorption and simultaneously ensure a payload that reflects customer’s requirements. If the larger cabin is found to be heavier than the reference cabin, the report will provide additional general lightweight design strategies for trucks to compensate. In contrast to the APROSYS-project, which is described below in chapter 2.1, a significant advantage in aerodynamic performance at a reasonable cabin length increase is one major task of the study. As a starting point of the optimisations, the generic reference 40 t-HGV will undergo aerodynamic optimisation. The most promising aerodynamic concepts will be set-up in safety simulations, in which optimised passive and active safety performance will be assessed and proven. In the course of the safety optimisation process the fully developed deflecting front shape of the APROSYS-project will serve as a valuable basis. The experiences can be used for the design of an aerodynamic and at the same time safer front structure. The final objective of the project is the concept development of a tractor unit for a 40 t-HGV which is optimised for both safety performance and fuel consumption related to aerodynamics making use of a variable tractor unit length without substantial increase of the empty vehicle weight. The new tractor design will be assessed in a simulation environment and also realised in a 1:18 hardware model for demonstration. The overall aim is to find out how much length increase will prove to be the optimum for the best safety and environmental performance and to create a basis to quantify fuel saving, emission reduction, reduction of fatalities and serious injuries. Also the economic impacts will be analysed. The first step is an overview of the state of the art concerning the body shape of trucks carried out in chapter 3. This also includes the description of close to series and future concept trucks. In addition, the most relevant valid and future regulations are described. On these conditions a generic reference truck has to be defined in chapter 5. As a starting point of the optimisations in chapter 6 the generic reference 40 t-HGV undergoes an aerodynamic optimisation. The most promising aerodynamic concepts is setup in safety simulations in which optimised passive and active safety performance is assessed and proven. In the course of the safety optimisation, and with regard to utility implications such as payload requirements, the new front structure of the truck is designed to optimise impact energy absorption and simultaneously ensure a payload that reflects customer’s requirements. To evaluate the self-protection characteristics of the truck, it is crashed against a semi-trailer block in finite elements (FE) simulation. The partner protection characteristics are evaluated by the FE simulation of truck against passenger car (compatibility) and VRU (vulnerable road users) protection simulations. In addition, the active safety characteristics are evaluated concerning direct and indirect vision. The detailed technical assessment of the optimised front structure is described in chapter 7 of the final report. Therefore the most relevant evaluation parameters are identified at first. Afterwards, a new concept is evaluated for technical aspects. Analogous to that, the environmental and economic impacts are analysed in chapter 8. Reduction of fuel consumption, utility and total cost of ownership aspects set important boundaries. With regard to the internal consistence of this study, the definition of both cabins including material usage is based around consumer preferences. The results from aerodynamic simulation are validated with wind tunnel tests in chapter 6.2. A guideline for new development activities of the industry to introduce an optimised front structure is given in the recommendations of chapter 9. This includes a detailed summary of the effects on passive safety and fuel consumption as well as a priority list for changes of current EU legal standards for cabin lengths. Also the influence on direct and indirect vision is regarded. The study concludes the results with a summary highlighting the main steps and giving an outlook for possible future developments and further research potential. An overview of the work packages of this study is shown in Fig. 2-1. (Author/publisher)
Samenvatting