Assesment of Passengers Safety in Emergency Situations, Based on Simulation

Transcription

1 World Applied Sciences Journal 24 (Information Technologies in Modern Industry, Education & Society): 86-90, 2013 ISSN IDOSI Publications, 2013 DOI: /idosi.wasj itmies Assesment of Passengers Safety in Emergency Situations, Based on Simulation Vladimir Vladimirovich Kobishanov, Georgy Sergeevich Mihal'chenko, Viktor Petrovich Tihomirov, Galina Anatolievna Fedyaeva, Dmitry Yakovlevich Antipin and Sergey Gennadievich Shorohov Bryansk State Technical University, Bryansk, Russia Submitted: Aug 5, 2013; Accepted: Sep 15, 2013; Published: Sep 25, 2013 Abstract: We propose a technique to assess the passengers safety in emergency longitudinal collision of passenger trains with obstacles on the railway based on mathematical modeling methods. When analyzing the rolling stock safety in emergency situations we use fleeting and non-linear processes modeling algorithms, as well as mathematical models of anthropometric dummies. Based on the analysis of accidents that have occurred in Russia and abroad, the basic principles for the passengers protection in longitudinal trains collisions with obstacles are given. The technique of injury assessment of passengers and crew in emergency situations is considered, based on the injury determination criteria and comparing their calculated values with the parameters, set by the regulatory documents. On the basis of international experience to ensure rail passenger services safety we propose ways to improve the domestic passengers car bodies passive safety. Technique was successfully tested on the passenger car modern design, produced by the Tver Carriage Works. Key words: Safety Emergency situation Mathematical modeling Dummy Energy-absorbing element The supporting structure Injury criterion Passenger wagon Technique Collision Passive safety system Collision scenario. INTRODUCTION emergency train collisions with obstacles, we propose a two-step procedure, based on the use of anthropometric The current stage of Russian railways development dummies mathematical models [4]: is characterized by the technical means modernization, aimed at increasing the movement speed and The anthropometric dummy computer models transportation comfort while ensuring traffic safety. In line development, designed to assess the passengers with the rail transport development strategy, by 2030 [1] injury level in case of emergency collision and the car production of speed and high-speed rolling stock should model with the cabin internal equipment and interior be mastered, which will significantly improve the Russia detail description. In the developed car dynamic transport system. model, as subsystems, we include dummy dynamic Increasing the new generation passenger rolling models. stock speed can lead to an increased accidents risk, Emergency situation modeling - train collision with an associated with train longitudinal collisions with obstacle on the highway crossing, resulting in a obstacles on the railway. [2] The most probable are determined level of dynamic impacts and acceleration collisions at crossings, reflecting 99% of reported of passenger car body bearing structure elements collision cases on Russian railways [3]. and anthropometric dummies elements. Based on the obtained results, injury criteria are calculated, which Passengers Safety in Emergency Situations Assessing are then compared with the permissible values, Technique: To assess the passengers safety in regulated by standard documentation [5]. On the Corresponding Author: Vladimir Vladimirovich Kobishanov, Bryansk State Technical University, Bryansk, , Russia 86

2 basis of comparison the train passengers injury level their destruction spent a lot of work, requiring a is determined, the most traumatic elements of interior significant amount of energy. These devices are mounted equipment and interior are identified, measures to on the rolling stock bodies in direct contact with the improve the passengers safety and comfort are obstacle and take impact only in emergency shock; in developed. normal use, the safety devices do not take the load and not have an impact on the longitudinal forces The method was tested on the example of assessing transmission processes. the passengers safety in the emergency situation Energy absorption devices main characteristics simulation - a longitudinal passenger train collision with pre-selection is made at the passenger car body a cargo minibus on the highway crossing. bearing structure design stage with the restriction on the impact efforts within collision test scenarios Passenger Cars in the Emergency Situation Safety characterized by the conditions under which there is a Assessment: Passenger cars safety is characterized by rolling stock collision with the obstacle. According with the ability of their bearing structures to resist significant [3] there are two typical collision scenarios: Emergency plastic deformation and to protect passengers and crew passenger train collision with a car at a railroad from serious injury, including death. crossing; emergency passenger train collision with a Passengers protection in emergency situations is cargo wagon. It identifies two main parameters of ensured through the use of active and passive safety. energy-absorbing elements: energy and element motion. Active safety systems, which include systems of alarm, Energy-absorbing devices energy and deformation centralization and blocking, supervisory traffic control, characteristics control is made by full-scale tests. To etc., are intended to prevent accidents. However, the verify compliance of energy-absorbing elements with human factor presence in the movement organization can requirements imposed on them, field tests of the rolling not fully exclude the possibility of accidents, involving stock collision with obstacles are conducted in passengers injury and death. In this regard, the focus of accordance with collision scenarios [8, 9]. However, due the railway rolling stock design is on the passive safety to the high cost of preparing and carrying out similar systems development, aimed at reducing the emergency experiments in Russia a numerical simulation of accidental situations consequences severity without human collision is conducted. intervention [3]. Using the described technique, we developed Domestic passenger cars design can not completely energy-absorbing elements embodiment variants for new exclude the passengers and train staff injury possibility at generation passenger cars body passive safety. We high speed emergency collisions that requires the new propose an original car autocoupling equipment technical solutions development o improve transportation installation structural scheme, allowing to increase the safety [6]. Cars passive safety systems development is a elements stroke by 42%. policy priority direction in the passenger trains safety field. Major work on the such decisions implementation Assessment of Passengers Safety in Emergency are carried out at the rolling stock design stage. Situations: Passengers safety in emergency situations In case of emergency on the passenger car bearing assessment is based on an analysis of their interaction structure is affected by the high intensity load, which can with the cars internal equipment and interior components lead to significant plastic deformation with subsequent and passengers injury levels assessment, by determining derailment. The collision kinetic energy is perceived by the normalized parameters - injury criteria. the car body and diminishes due to its plastic Such studies are possible as with the full-scale deformation, which increases the injury risk to passengers experiments using dummies [10, 11] and with the [7]. mathematical modeling use, which advantage are For the effective impact kinetic energy damping, significant cost savings by eliminating the need for the passenger cars must be equipped with special devices rolling stock destruction in the tests and the expensive that provide controlled deformation character, - energy- dummies use. The practice of using repeatedly proven absorbing elements that are not car bodies bearing anthropometric dummies mathematical models provide structures nodes. The maximum energy absorption occurs results that have a high level of convergence with the during plastic deformation of such devices because on field experiments data [11]. 87

3 In international practice, to assess the vehicles safety When calculating the maximum HIC no account is th dummies Hybrid III 50 Percentile Male [12] are most taken of its value, for which the time interval (t2-t1) greater widely used, whose parameters match the average man than 36 ms. anthropometric characteristics. Dummy performed in a Neck injury criteria NIC is determined by the formula: subsystems set, consisting of individual elements. The interaction elements to one another is fully consistent F M NIC = +, (2) with human body functioning, it is achieved by limiting F k M k the angles of rotation in the dummy hinge joints. where F - axial compression / tensile stress; F k - axial force As part of this methodology we developed dummy is used for the normalization; M - bending moment; Mk - th solid-state computer model Hybrid III 50 Percentile Male, bending moment is used for normalization. which feature is subject to the restrictions on the rotation Thorax injury criteria CTI is determined by the of the joints, joint compounds that mimic the real human formula: joints possibilities. In the simulation dummy was divided into elements: head, neck, chest, shoulder, thigh, etc., Amax D CTI = + max, (3) which were connected by hinges in a single model. For all Ak Dk elements mass-inertial characteristics were designed, where A max - maximum acceleration, A k - acceleration, used depending on the person anthropometric characteristics. for normalization; D max - the maximum deflection of the Modeling of joints (joints) was performed using the chest; generalized force joint with the set of elastic-dissipative characteristics. To set the internal friction in the joints we D k - deformation, used for the normalization. used dissipative component. The limit on the ability to rotate the dummy elements in accordance with the real Thigh injury criteria FFC is determined based on the human joints possibilities was introduced. Pivot joints compression load expressed in kn, transmitted axially on allow to target dummy model elements in space randomly each dummy thigh. to achieve the desired position of the human body in the Tibia injury criteria TCFC is determined by the emergency simulation. formulas: The developed passenger dummy model allows to perform analysis of the nature and dynamic effects levels MR F TCFC = + z, (4) on the dummy elements: linear and angular displacements, ( Mc) ( Fc) R z velocities and accelerations as well as the contact impact forces. On the basis of dynamic forces obtained in the simulation, acting on the dummy elements, we Technique 2 M ( ) ( ) 2 R = Mx + My, (5) of assessing the passengers injury level is based on the calculation of universal indicators - the injury criteria. where M x - bending moment along x-axis; M y - bending In compliance with regulatory guidelines [5, 13] there are moment along Y axis; the following passenger injury criteria: traumatic brain (M ñ) R- critical bending moment; F z- axial compressive injury, injures of neck, chest, thigh and tibia. force in the direction of the axis Z; (F c) z - critical Traumatic brain injury criteria HIC is determined by compressive force along the axis Z. the formula: When calculating the injury criteria, we take into account speed, tensile and compressive axial forces and 2,5 t2 bending moments acting on dummy elements. In addition, 1 HIC = ( t2 t1) adt, (1) for each of the criteria on the basis of the accidents t2 t 1 consequences analysis we set the normalized values t1 (Table 1). where t 1, t 2- time moments, expressed in seconds, defining The described technique of estimating the passenger an interval between the initial and final moments of head cars safety in emergency situations, allows to determine contac with the traumatic subject, for which the value of the car damage nature and the passengers injury degree HIC is a maximum; a - the resultant acceleration, expressed in the longitudinal train collision with an obstacle. in units of gravity g. Obtained results are used as corrective measures in the 88

4 Table 1: The normalized criteria of human injury Normalized criterion value Injury criterion Name Determination method Parameter Value Traumatic brain injury criterion HIC Calculated from the resultant acceleration a, HIC 1000 expressed in units of gravity g; t1 and t2 - time moments, expressed in seconds, defining an interval between the head contact initial and final moments, for which the HIC value is maximized. When calculating the maximum HIC no account is taken of its value, for which the time interval (t2 - t1) greater than 36 ms. The neck injury criterion NIC Determined by the compressive axial force, the axial tensile force, NIC Critical values: 1.4 a shearing force in the rear direction at the junction of - Tension / compression (N) 3600 the head and neck, expressed in kn; bending moment on - Bending moment (N m) 410 the horizontal axis at the junction of head and neck, - Unbend moment (N m) 125 expressed in N m The thorax injury criterion CTI Determined by the acceleration, expressed in units of gravity CTI 1.0 g and the deformation of the chest, which is expressed in mm Chest acceleration (g) 60 Chest deformation (mm) 76 Critical values: - acceleration (g) 85 - deformation (mm) 102 Thigh injury criterion FFC Determined by by the compression load expressed in kn, FFC ( H) 10 transmitted axially on each dummy thigh Tibia injury criterion TCFC Determined based on the compression load expressed in kn, TCFC ( H) 8 transmitted axially to each tibia of the dummy and bending moment, expressed in Nm bearing structures design and modern passenger rolling design of rolling stock units allowed to raise the stock increased safety internal premises design in passenger cars safety overall level by more than 10% collisions. through the use in car interior design and while creating In determining the passenger injury criteria based on premises interior less traumatic materials and equipment the simulation results, we obtained that in result of train items. collision with an obstacle, cars with seats passengers get injured neck and thigh, exceeding the normalized values; REFERENCES open type car passengers have thorax injury exceeded criteria. 1. Strategy for the rail transport development in Russia up to 2030 approved by the Federal Government from CONCLUSION # 877-r. 2. U.S. Government, Safety of Railroad Passenger Proposed method enables the assessment of injury to Vehicle Dynamics: Final Report Summary. General passengers and train stuff in the simulation of any Books LLC, pp: 54. accidents on the railways. Thus resources expenses for 3. Technical requirements for the passenger rolling the preparation and conduct numerical experiments are stock passive safety system for rail track of 1520 mm. minimal. The use of mathematical modeling can even at Approved by the Open Joint Stock Company the passenger cars structures conceptual design stage to "Russian Railways" evaluate the emergency nature and the injury level to 4. Nieder, P. and M. Muser, Trauma Biomechanics: passengers in a critical combination of adverse factors. Accidental Injury in Traffic and Sports. Springer, pp: The above technique has been successfully used in 249. applied research for the benefit of the Tver Carriage 5. Kleinberger, M., E. Sun, R. Eppinger, S. Kuppa, Works. Using the technique, we performed car body R. Saul., Development of Improved Injury bearing parts safety assesment for models , Criteria for the Assessment of Advanced Automotive , The use of these techniques in the Restraint Systems. September 1998, pp:

5 6. Norms for calculation and design of railway cars MPS 10. Commuter Rail Seat Testing and Analysis. Railroad 1520 mm. (non-self). M.: GosNIIV - VNIIZhT, 1996, Systems Safety. DOT/FRA/ORD-01/06, U.S. pp: 319. Department of Transportation, Washington, DC, 7. Goldin, S.L., Foreign experience of December 2002, pp: 203. standardization to ensure the safety of passengers in 11. Commuter Rail Seat Testing and Analysis of Facing a train accident. Railways of the World, 2: Seats. DOT/FRA/ORD-03/06, U.S. Department of 8. Priante, M. and E. Martinez, Crash energy Transportation, Washington, DC, December 2003, pp: management crush zone designs: features, functions 195. and forms. In the Proceedings of the Joint Rail 12. Hybrid III Rail Dummy Specification. Conference & Internal Combustion Engine Spring 13. GOST R Uniform provisions concerning the Technical Conference, pp: approval of vehicles with regard to the protection of 9. Jacobsen, K., D. Tyrell and B. Perlman, Impact the occupants in the event of a frontal collision. tests of crash energy management passenger rail cars: analysis and structural measurements. In the Proceedings of the International Mechanical Engineering Congress, pp: