Technology Agency of the Czech Republic, project No TE01020038 "Competence Centre of Railway Vehicles

Vychytil, J.

Špirk, S.

University of West Bohemia Digital Library

Numerical analysis of a passenger safety during a railway vehicle collision: The effect of safety belts

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COMPUTATIONALCHANICSME November 4 - 6, 2019Srníconference with international participation35th2019Numerical analysis of a passenger safety during a railway vehiclecollision: The effect of safety beltsJ. Vychytila, S. ŠpirkaaRegional Technological Institute, University of West Bohemia, Univerzitní 8, 301 00 Plzenˇ, Czech RepublicIn automotive industry, safety belts are with no doubts established and inherent part of passivesafety elements [1]. They keep the occupant at his or her seated position during the impact sce-nario. However, application of such safety elements in railway vehicles is questionable. Thereis an important aspect of the passenger comfort in railway vehicles which might be affected.Also, application of safety belts represents additional cost for manufacturer. Hence, the cru-cial question is related to the potential benefit of safety belts. Would their application increasepassenger safety in a collision scenario of a railway vehicle? The study presented here aims toanswer that question using numerical simulations.As a representative of a passenger, the Virthuman model is used in the Virtual PerformanceSolution (VPS) software. It is based on multi-body structure with deformable segments. Itis easy to position, it requires low computational time and it includes automatic algorithm forinjury criteria evaluation, see e.g. [3]. In this case we evaluate the criteria described in theGMRT2100 regulation for railway vehicles such as HIC15, neck axial force and moment, thoraxdeflection, etc [2]. An important feature of the Virthuman model is the scaling algorithm thatenables to represent any passenger of given age, height, weight and gender. For this particularstudy, 25-year-old male of a 50th percentile is considered, that is, an average male with theheight of 178 cm and the weight of 76 kg.An open coach type interior is considered. Its FE model is developed in the VPS soft-ware. It includes the passenger’s seat and the seat in front of the passenger with folding table.Two-points or three-points belts are fixed to the passenger’s seat in a common sense includingretractors and sliprings. The collision scenario is considered in a configuration with no belt,two-points belt and the three-points belt. Each of these cases is considered in a configurationwith folded and unfolded table at the backrest in front of the passenger. It means, 6 configura-tions of numerical simulations are considered in total. The acceleration pulse is prescribed forthe vehicle interior as defined in GMRT2100 regulation. It corresponds to a frontal collisionscenario of a railway vehicle. The simulation time is 300 ms.The results are evaluated in terms of passenger’s kinematics and injury risk. As an example,kinematics of the passenger at 150 ms for each belting option is provided in Fig. 1. The casewith unfolded table is illustrated here. In case with no belt, knees impact the backrest possiblycausing the injury of both femurs at approximate time of 95 ms. At the approximate time of150 ms, the head hits the headrest causing the possible neck injury. In case with unfolded table,the thorax and abdomen hit the backrest just in the location of the table at approximate time of185 ms. Since the table is made of steel, the impact causes higher injury risk of these two bodyparts. In case of folded table, no impact of the thorax and abdomen with the backseat occurs.231In case with two-points belt, no primary impact of lower limbs and the backrest occur.Hence, no injury risk of the lower limbs is indicated. The body of the passenger is fixed by thetwo-point belt at the abdomen area. However, the torso and lower limbs are thrown against thebackrest. The abdomen is compressed by the belt causing higher injury risk of this body part. Atthe approximate time of 150 ms, the head hits the backrest. In the configuration with unfoldedtable the head hits right the table causing serious risk of head injury. In the configuration withfolded table the had hits the plastic part of the backrest which does not increase the head injuryrisk.In case with three-points belt, whole upper part of the body is fixed with the belt, hence itdoes not impact the backrest in front of the passenger. Slightly increased injury risk of abdomenand thorax only is predicted due to their compression with the belt.Fig. 1. Passenger’s kinematics during collision scenario at 150 ms; configuration with no belt (left), thetwo-points belt (middle) and the three-points belt (right)With respect to the results obtained, following conclusions can be formulated. With noseatbelt, high injury risk of lower limbs is predicted as a result of the impact with steel profiles.The head impact with the headrest leads to increased head injury risk. Injury risk of lowerlimbs is completely reduced in case of a two-point belt. However, this type of belt significantlyincreases the head injury risk in case of unfolded table. Also, significant neck injury risk ispredicted in case of a two-point belt for both folded and unfolded table. Application of a three-point belt minimizes injury risk of both head and neck. Therefore, in case of mounting setabeltsin the railway vehicle interior of an open coach type, three-point belts should be preferred totwo-point belts. In case of a frontal collission scenario as defined by the GMRT2100 regulation,the overall injury risk of a passenger is lower for the three-point belt when compared to a two-point belt.AcknowledgementThis paper was created with the support of Technology Agency of the Czech Republic, projectNo TE01020038 "Competence Centre of Railway Vehicles".References[1] EuroNCAP, Assessment protocol – Adult occupant protection, Version 8.0.2, 2017.[2] RSSB, Requirements for rail vehicle structures, GMRT2100, 2012.[3] Vychytil, J., Manas, J., Cechova, H., Spirk, S., Hyncik, L., Kovar, L., Scalable multi-purposevirtual human model for future safety assessment, SAE Technical Paper 2014-01-0534, 2014, doi:10.4271/2014-01-0534.232

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Numerical analysis of a passenger safety during a railway vehicle collision: The effect of safety belts

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