PSI - Issue 42

Rogério Lopes et al. / Procedia Structural Integrity 42 (2022) 1159–1168 Rogério F. F. Lopes et al./ Structural Integrity Procedia 00 (2019) 000 – 000

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Jongpradist et al. (Jongpradist P., 2015) completed its numerical work by proposing 3 models, so that the vehicle is in accordance with the regulation, using components that start crushing in the deformation zones. Rooppakhun and Bua Ngam (Rooppakhun and Bua-Ngam, 2013) and Cerit et al. (Cerit, 2010) suggested the usage of cylindrical impact attenuators and conical/wavy absorbers to control kinetic energy absorption. There is a need for further study this component (Rooppakhun and Bua-Ngam, 2013), while Cerit et al. (Cerit, 2010) did not observe intrusion resulting from structural reinforcement. Experimentally, Güler et al. (Güler et al., 2020), used an experimental setup without monitoring, to perform tests on a chassis, validating a numerical model. By analyzing the displacement of the steering wheel, it claimed to improve resistance with the addition of energy absorbers. It is expected that the UNECE will create regulations applicable to buses, namely the M3 class. On the market, Mercedes-Benz claims that the Citaro, a urban bus model, complies with the R-29 regulation (Truck, 2022). Therefore, there is an opportunity here to develop new models, creating a family of touring coaches with increased passive safety. The case study in this research is a section of the whole coach structure, including the superstructure and chassis. The coach section under consideration was built and experimentally tested to obtain the strain/time curve during a frontal impact. The deformations and displacements were obtained using experimental cutting-edge monitoring technologies. Numerical assessments were done using FEM formulations using PamCrash based on the geometrical parameters of the coach section. The structural safety evaluation allowed to conclude if the structure has adequate strength to guarantee that the drivers has an adequate residual space for survival, during and after the frontal crash test on the entire vehicle. 1.1. ECE R-29 Regulation The ECE-R29 standard is a regulation on passive safety in the event of a frontal collision that only applies to heavy vehicles with a cabin that is separate from the rest of the vehicle. The well-known trucks are among these vehicles. As a result, no obligation exists at this level for the more specific instance of coaches. Buses from the tourism class, as well as urban buses, are included in this category (Cerit, 2010, ECE-R29, 2010). This certification is designed for use in an experimental test of a coach, a type of tourist transport. This will enable the development of a technological solution based on this standard that allow the study of the bus while also surpassing the specifications of the ECE R 29 regulation. This line of research will allow the manufacturers to provide innovative goods, giving it a competitive advantage in the market. It should also be highlighted that the use of tourist models serves as a motivator, owing to the faster speeds attained. The study relies heavily on these criteria, and the strategy is later extended to additional bus families. The ECE R-29 regulation is subdivided into three sections: Test A (front impact test), Test B (front and rear impact test), and Test C (roof strength test), (ECE-R29, 2010, Raich and DaimlerChrysler, 2003). The emphasis of this work will be on test A. In the frontal impact test, the impactor has a rectangular configuration with a projected dimension of 2500 × 800 . It must weigh more than 1500 and have rounded edges with a radius of 10 ± 5 . In regards of assembly, it must be supported by two bars that are 1000 apart with a length greater than 3500 . It must be upright, with its center of gravity = 50 + 5/– 0 below t he R point of the driver’s seat, as can be seen in Fig. 1.a). The pendulum rotates and strike the front of the vehicle. For N1 or N2 category vehicles, with a gross weight smaller than 7.5 , the impact energy must be 29.4 . The energy must be 55 in the context of a vehicle of category N3 or N2 weighing more than 7.5 . Following this test, the vehicle's cab must have a large enough survival area to accommodate the manikin, shown in Fig. 1.b), on the seat. This component must be in the middle position, and the mannequin must not come into contact with non-resilient components with a Shore-Hardness of 50 or above. Non-resilient parts that can be moved away from the test manikin without the use of tools with less than 100 N of force are not considered (ECE-R29, 2010).