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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1. Overview The automotive industry is always expanding, due to the increasing number of vehicles that circulate on the road on a daily basis (Lopes et al., 2021). As a result, when statistical data are evaluated, it is undeniable that accident rates have increased (Porcu et al., 2020). Overall, the industry continual improvements have contributed to reduce accident related mortality. This is the result of improved vehicle aesthetics and structural optimization (Europeia, 2016). There are several studies on traffic safety that can be found in the literature. Regardless of whether the vehicle is light or heavy, most manufacturers consider vehicle safety to be a vital factor in vehicle design (UNECE, 2015). The present work focuses on the safety of heavy passenger transport vehicles. Due to the reduced incidence of accidents involving these types of vehicles, the research in the development of new safety measures in these vehicles is reduced (Cafiso et al., 2013). According to the European Road Safety Observatory, buses are one of the safest types of medium and long-distance transportation. Although when accidents involving these vehicles happens might end in death or injured people, (Commission, 2020). Bus accidents accounted for 2.5% , of all traffic related deaths in the EU in 2018, a rate that has been largely stable since 2010. Urban areas account for 47% of all buses related accidents, rural areas for 46% , and highways account for 7% . On other hand, around 55,000 bus accidents occur in the United States each year. An European survey found that the incidence of traffic incidents involving buses has dropped by nearly half since 2005, (Europeia, 2016). By increasing awareness of the issue, the UNECE (Commission for the Union of European Economies) has made a significant contribution. As the attention has gradually shifted to this business, little research has been conducted in this subject. As an outcome, the UNECE has set 11 objectives with the intention of fundamentally changing the trajectory of road safety over the next ten years. The goal of this strategy was to decrease mortality in half by 2020. One of its key goals is to continually enhance the design of these vehicles while also including technological solutions that can greatly reduce the number of deaths. The suggested improvements were primarily performance enhancements, in the bus bodywork (UNECE, 2015). Motor vehicle accidents can exhibit many distinct forms and, as a result, can be classified as having different impact regions. Mátyás Matolcsy (Matolcsy, 2016) dedicated to the classification of bus accidents, amassing data on 560 occurrences over a 12-year period. He categorized bus accidents into two types: frontal collision and combined impact (which includes event areas such as side, rear, and/or rollover). The majority of accidents are caused by frontal collisions (Jongpradist P., 2015). In fact, there are five bus classifications: Class I, Class II, Class III, DD coach, and Small Bus. Another cause of concern in this area is the large number of people involved. A motorbike or automobile accident can harm two or three persons, but a bus accident can injure 50 people (Matolcsy, 2016). Furthermore, bus crashes cause substantial deformations with a strong probability of penetration. These numbers imply that bus components might interact with the passengers, causing them to be forced against other components or pulled apart (Kumar, 2012). These difficulties will need to be addressed thoroughly, with a focus on the passive safety of passengers and the driver. For bus accidents, frontal area collisions account for a considerable percentage of them. This type of accident jeopardizes the driver safety, which is influenced mostly by two factors: the deformation of its compartment measured by the intrusion of materials and structures due to the impact and on the other hand, the driver’s decelerations , which are a result of the collision’s magnitude and duration, (Lopes et al., 2022a). The severity of the injuries is directly related to the speed of the vehicle, with frontal collisions accounting for the bulk of injuries and deaths (Hermann and Olivares, 2005, Olivares, 2008). Several studies using the FEM have been conducted. The obtained results showed the passengers to moving and deaccelerating the trunk, resulting in neck, femur, and chest injuries (Rivero-Urzúa et al., 2019). Manufacturers have been using the ECE-29 Regulation (ECE-R29, 2010) for validating the vehicle's safety in the event of a frontal impact. This regulation is however specific for heavy vehicles with a separate cabin (Cerit, 2010). Matsumoto et al. (Matsumoto, 2012) indicates that driver safety depends on the level of compartment deformation measured by the structural intrusion on impact and the deaccelerations felt. The incorporation of controlled energy absorption solutions during the collision is essential in the optimization of passive safety (Jongpradist P., 2015, Abramowicz, 2003). Currently, buses have insufficient bodywork to absorb all the energy released during a collision, resulting in severe intrusion of the driver's cabin (Jongpradist P., 2015). In an attempt to mitigate this problem, there are several numerical works, whose goal is to discover low resistance zones, signaling the need for geometric optimization, (Youming et al., 2013, Morocho et al., 2022). On the other hand,