| 1. PrefaceAlong with the continuous economic development and rising living standards, there is growing concern about security issues. As a means of daily transport, with the total number of vehicles continues to increase, traffic accidents also occurred more and more frequently. Commercial vehicles occupy a certain status in the transport industry. With the people's security concerns and the increase in frequency of commercial use, people's attention has naturally focused on the commercial vehicle safety issues. Due to their own body structure characteristics, commercial vehicles mostly are "perpetrators" in traffic accidents, and the "victims" mostly are small cars. But it does not mean that their is not a commercial vehicle collision deformation, any collisions are accompanied by deformation energy absorption. Their structural characteristics of commercial vehicles also determine that it will be a fatal car crash in the event of a major accident, causing serious property losses. If the accident is not very serious, it also will have a compression deformation of the cab, and it will cause a life-threatening to the Vehicle occupant. Therefore, the commercial driver's survival space issue became the main concern.At present, commercial vehicle safety problem has attracted widespread attention at home and abroad. European countries concern earlier on the issue of commercial vehicle safety. But now both at home and abroad the laws and regulations regarding to commercial vehicle safety are less and still is not perfect enough. Economic Commission for Europe and regulations " Uniform Provisions Concerning the Approval of Vehicles with Regard to the Protection of the Occupants of the Cab of a Commercial Vehicle, " (ECE R29) is a commercial vehicle driver's safety performance of a unified demands. ECE R29 safety standards describes the cabin crew on the protection of commercial vehicles under a unified certification, Its main objective is to evaluate the cab and suspension of the cab connected devices in the circumstances of front collision, as well as to evaluate the overall strength of the driver's evaluation, aims to reduce the possible harm to the crew in the maximum extent to ensure that the crew's living space. The living space should be able to accommodate the human body model in the requirements.At the same time, in order to ensure the safety of other small vehicles.Regulations stipulated requirements of the FUPDs(FRONT UNDERRUN PROTECTIVE DEVICES) and RUPDs(REAR UNDERRUN PROTECTIVE DEVICES). 2. Main ContentThis paper legislature comes from the actual project basis. Based on ECE R29, there is a positive pendulum impact test on a commercial vehicle, acquiring the dynamic process video and deformation data of main deforming points. The research work is carried out on this basis,at the same time, a virtual test for the RUPDs. The main study as follows:⑴On the basis of reading a lot of literature, the commercial vehicle safety issues have been made brief introduction, and a detailed description of security at home and abroad on commercial research have been given, particularly referred to the survival space of the commercial vehicle cab, which is also the key elements of this paper.⑵A commercial vehicle cab's passive safety virtual test finite element model has been established, which mainly include Pendulum model.A Virtual Test has been made after the completion of finite element model, verify the validity of the model. Virtual test results and the survival space are analyzed and compared with the actual test.⑶For the problem of mounting fracture in the actual test, a careful analysis and research have been made and a virtual test has been taken out. The mounting fracture has been simulated in the virtual test. The mounting fracture will lead to a greater threat for the crew living space. Therefore, this paper has proposed and determined two improvement programs:⑴improving the structure of mounting, ensuring living space and solving the problem of mounting fracture;⑵setting up Energy-absorbing device in front of cab, doing some virtual tests with the basic model of Energy-absorbing device, obtaining the characteristic parameters of Energy-absorbing device. Finally adding improved structure to cab and processing virtual test, obtaining better result, the problem of mounting fracture has been solved. The safety of positive pendulum impact of the commercial vehicle has been improved, ensuring the living space.⑷A virtual test RUPDs finite element model has been set up, processing a virtual test in accordance with the regulations, and conducting a preliminary study of compatibility.3. Significance of This Paper⑴This paper carried out a detailed reading of ECE R29 and a detailed description of an actual pendulum test, and put some of the practical issues in the positive pendulum impact test forward. This will make a reference for the subsequent commercial vehicle safety research, with a certain reference value.⑵This paper established a virtual commercial passive safety test finite element model. In the modeling process, a large number of valuable methods and experience have been accumulated. The finite element model established in this paper can be used as the basis of further research, but also can be further enriched and to be used in other virtual experiments, such as the test B and test C in the ECE R29;the RUPDs virtual test model can be used in further preliminary study of compatibility.⑶For the problem of the mounting fracture in the commercial positive pendulum impact test, this paper have given out the methods to improve the structure, they are:①to improve the mounting structures and materials;②to add the Energy-absorbing devices in front of cab. Processing virtual tests, and obtaining a good result. Although this improved model is a success in the finite element model, but I have processed a feasibility analysis, the program can be achieved in the existing conditions of production process, it also has a reference value for the improvements of the actual structure and has given some improved strategies and ideas to improve the mounting.
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