Contents lists available at ScienceDirect Safety Science journal homepage: www.elsevier.com/locate/safety Design and injury analysis of the seated occupant protection posture in train collision Weilin Yang a,b , Suchao Xie a, ⁎ , Haihong Li a , Zengtao Chen b a Key Laboratory of Traffic Safety on Track, Ministry of Education, Central South University, Changsha, Hunan 410075, PR China b Department of Mechanical Engineering, University of Albera, Edmonton, AB T6G 2G9, Canada ARTICLE INFO Keywords: Frontal collision Dynamic response Injury Occupant’s protective posture ABSTRACT In order to minimize injuries and protect safety of seated occupants in train collision, this study proposed a self- protective posture with hands laced behind head and body curled up for occupants. Through the local sled simulation test, the effectiveness of hands laced behind head posture was verified. In order to obtain the optimal protective posture with body curled up, First, the waist angle A, leg angle B and backward rotation angle C around the hip-point H of a dummy were selected as factors to design orthogonal test with different factor levels. Then, by using the direct analysis method, the influence laws of each factor on dynamic response and injury of occupants were analyzed. Furthermore, synthesized each kind of critical injury value of human body, the radial basis function surrogate model was constructed. Combining with NSGA-II multi-objective genetic algorithm, the parameters of curled-up body posture of occupants were optimized. The balance optimal protective posture of occupants was at 40-0-08 (A-B-C). Finally, the optimal scheme was verified in the simulation system for standard collision of train at the speed of 48 km/h. The results show that after optimization, head injury of occupants reduces by 88% and axial force and bending moment of neck separately decrease by nearly 50% and 80%. Moreover, stresses on thigh bone and tibia bone decline by 53% and 56%, respectively. 1. Introduction It is an important issue to protect the safety of seated occupants in the train collision. At present, passive protection is one of the important ways to minimize impact injuries that occupants may suffer from (Zhang et al., 2018; Chen et al., 2018; Luo and Fan, 2018; Praveen et al., 2018). The structural crashworthiness of railway vehicles is one of research focuses (Lu, 2002; Xue et al., 2005; Hosseini and Bayat, 2011; Hosseini and Nankali, 2010; Gao and Tian, 2007; Xie et al., 2017a, 2017b). In the early 20th century, European Union successively carried out large- scale collision projects of real vehicles, such as TrainCol (Wei et al., 2012), SafeTrain (European Union Contract, 2001) and SafeTram (Hecht, 2004) and proposed the basic requirements of energy adsorp- tion and crushing distance for energy-absorbing components in the front end and middle of vehicles (EN15227:2008, 2009). Jacobsen et al. (2004) designed the crushable components by using crash energy management (CEM) method. The method was usefully to crush the end of the car in a controlled manner and limit the structural damage from intruding into the passenger compartment. Based on characteristic curve of energy-absorbing structures, Zhang et al. (2016) changed the plastic platform forces of main energy-absorbing structures in the ends of a vehicle and combined with genetic algorithm to realize maximum ordered deformation length of energy-absorbing components. Xie et al. (2017a, 2017b, 2017c, 2018), Liu et al. (2018), Peng et al. (2015, 2017) and Gao et al. (2017) proposed different energy-absorbing structures to improve the crashworthiness performances. By considering that collision force hurls occupants against interior parts of the compartment, scholars conducted a lot of studies on interior structure of the trains (Kirkpatrick et al., 2001; Simons and Kirkpatrick 1999; Tyrell, 2002; Parent et al., 2004; Severson et al., 2006, 2004). Rail Safety and Standards Board (RSSB) carried out a series of re- searches on secondary collision of structure of passenger compartment and occupants in trains and issued a series of standards in view of in- terior structure, such as train materials, safety belt and seat structure (AV/ST9001, 2002; GM/RT2100, 2010). Tyrell et al. (1995) and Anton et al. (2017) focused on the influences of seat stiffness and occupant restraint pulse on fatalities resulting from secondary collision. Seat stiffness variation studies had showed positive effects of plastic de- formation in the seat structure which can decrease concentrated forces on the occupant’s abdomen. Besides, lap and shoulder belts can help the seated occupants survive in all the collision scenarios. Wei and Zhang https://doi.org/10.1016/j.ssci.2019.04.028 Received 31 October 2018; Received in revised form 18 March 2019; Accepted 19 April 2019 ⁎ Corresponding author. E-mail address: xsc0407@csu.edu.cn (S. Xie). Safety Science 117 (2019) 263–275 0925-7535/ © 2019 Elsevier Ltd. All rights reserved. T