• Composites Research
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• v.21 no.1
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• pp.22-29
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• 2008

This paper presents the evaluation of crashworthiness and rollover characteristics of low-floor bus vehicles made of aluminum honeycomb sandwich composites with glass-fabric epoxy laminate facesheets. Crashworthiness and rollover analysis of low-floor bus was carried out using explicit finite element analysis code LS-DYNA3D with the lapse of time. Material testing was conducted to determine the input parameters for the composite laminate facesheet model, and the effective equivalent damage model for the orthotropic honeycomb core material. The crash conditions of low-floor bus were frontal accident with speed of 60km/h. Rollover analysis were conducted according to the safety rules of European standard (ECE-R66). The results showed that the survival space for driver and passengers was secured against frontal crashworthiness and rollover of low-floor bus. Also, The modified Chang-Chang failure criterion is recommended to predict the failure mode of composite structures for crashworthiness and rollover analysis.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.2
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• pp.31-38
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• 2010

Bus manufacturers have tested and studied the dynamic collapse behavior of a bus body structure in rollover since UN ECE established ECE Regulation 66 to provide the requirement for the strength of bus structure. In spite of the costly cycles of practical tests, however, it is still a hard task to meet the rollover regulation by means of local reinforcements in the bus structure. Therefore it is necessary to develop a well designed strategy for the rollover strength implemented in the early stage of vehicle development. In this study, the suitable development method for each design stage from a component to complete body structure was considered to make a well-established development process of a bus body structure for rollover safety. For the efficient approach of the concept design stage, a numerical model based on the plastic hinge theory was used instead of detailed shell models. After setting up the concept design for the component size and geometry, the shell model was used to confirm and optimize the whole structure composition. The process developed in this study was practically used as an effective method to predict the rollover behavior of a new bus body structure.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.7
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• pp.195-201
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• 1999

In Rollover crashes, the development of bus structure to ensure the maintenance of survival space for passengers is very important . So, this paper focuses on understanding the possibility of efficient structural development considering rollover strength through computer simulation using the commercial code, LS-DYNA3D at the initial stage of vehicle development structural members, and impact boundary conditions required by ADR59(Australian Design Rule 59)were applied. In order to confirm the validity of the computational results, the test results. After the usefulness of this method of analysis was confirmed , we have proposed the effective modificationfor rollover strength.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.6
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• pp.28-35
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• 1997

Occupant injuries are always possible in a rollover accident, one of the major accidents in a bus. Thus the structure of body frame should have sufficient strength to protect passengers under accidental loads,. ECE(Economic Commission for Europe) regulation No.66 prescribes that residual space shall be preserved in the passenger compartment during and after the structure has been subjected to the prescribed rollover test. Rollover test on a bus section was completed according to the regulation. The coordinates of body section before and after rollover were measured, and it was checked that the structure still complied with the requirements of residual space. Direct measurement on a bus is difficult because of its large size. Thus photogrammetry by photographing and 3 dimensional digital modeling was introduced, and the coordinates of each point were measured through this method.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.6
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• pp.148-154
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• 1997

The safety problems of buses have been arisen due to the increasing of road traffic. Occupant injuries are always possible in the rollover accident and the frontal impact. Thus the structure of bus should have sufficient strength to protect passengers under accidental loads. ECE(Economic Commission for Europe) regulation No.66 prescribes that the superstructure of the vehicle shall be sufficient strength for passengers' surviving and the residual space shall be preserved in the passenger compartment during and after the standard rollover accident situation. Rollover test and simulation on a large-sized bus was completed according to the regulation. The coordinates of the points on the bus were measured by photogrammetry system. The rollover situation was revived by structural crashes simulation software, PAM-CRASH, and it was checked that the structure still complied with the requirements of residual space during rollover situation. The residual space was preserved during rollover, so it was proved that the structure of the investigated bus had much probability of survival in rollover accidents.

• Journal of Auto-vehicle Safety Association
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• v.13 no.3
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• pp.47-53
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• 2021

This study is a study to estimate the VSL (Value of a Statistical Life) and CBA (Cost-benefit analysis) of the rollover safety standard for hydrogen buses, VSL is an economic value concept used to quantify the benefits of avoiding death. CBA shows the effect of cost-benefit, and if B/C is greater than 1, there is a social effect. In order to estimate the VSL and CBA, the hydrogen bus introduction scenario was assumed to be optimistic (20,000 vehicles in 2030), neutral (15,000 vehicles in 2030), and pessimistic (10,000 vehicles in 2030), and the effect of reducing human casualties was estimated. As a result, except for the pessimistic market situation of introducing hydrogen buses (10,000 vehicles in 2030) and the VSL reduction ratio of 10%, all policies were judged to have high cost-benefit effects. These results indicate that the introduction of the rollover safety standard for hydrogen buses is a socially effective policy.

• Journal of Drive and Control
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• v.19 no.3
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• pp.39-46
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• 2022

In South Korea, to evaluate the rollover safety of domestic vehicles, the maximum slope angle of the vehicle is specified, which is verified by the rollover safety test of driving vehicles. However, the domestic rollover safety test is not suitable for buses, because the small amount of static stability factor (SSF) will invalidate the rollover experimental equation due to the high center of mass position of buses. To solve the above problems, a dynamic model of the bus is prepared with assumptions of mass and suspension spring properties. Subsequently, the maximum slope angle of the model was computed by using the simulation of multi-body dynamics, and the result was compared with actual test results to validate the dynamics model. Also, the rollover Fishhook (roll stability) test was conducted in the simulation for driving model. During the simulation, roll angle and roll rate were calculated to check if a rollover occurred. Through the rollover simulation of buses, the domestically regulated formula for rollover safety and the procedure of rollover test for driving vehicles are evaluated. The conclusion is that the present regulation of rollover test should be reconsidered for buses to ensure to get the valid results for rollover safety.

• Journal of Auto-vehicle Safety Association
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• v.11 no.4
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• pp.63-68
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• 2019

The Korean traffic systems for transportation vulnerable are still under development and their social life are limited even if the traffic environment systems are developed consistently. To secure his/her mobility right, it has been required to set up the particular system for the traffic welfare, for example the express and intercity bus operations for wheelchair users. The express and intercity bus development for wheelchair users based on the original bus model has been performed. This study has investigated the safety tolerance for the bus stiffness, rollover and side impact characteristics to ensure occupant safety using the finite element models. The wheelchair bus model showed the improved crashworthiness according to the partially reinforced structure and better safety tolerance for the wheelchair users.

• Journal of Auto-vehicle Safety Association
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• v.12 no.1
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• pp.39-45
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• 2020

The express/intercity bus models have been developing for wheelchair users to provide the preferable long-distance travels by the Korean government research. In the previous studies, evaluation method was set up for the wheelchair users' safety and the study for wheelchair occupants' safety was performed under various crash loadings mimic to real accidents, frontal crash, side impact and rollover, etc. This study was focused on the evaluation of occupant behaviors and injuries (head and chest) during vehicle impact loading cases in order to ensure the safety of wheelchair passengers in the bus. The occupant response and belt loading data during the sled FE simulation were compared with those of the sled test. The simulation results showed overall safety tolerances of wheelchair occupants under the severe frontal deceleration, side impact loading based on the FMVSS 214 configuration and bus rollover loading.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.373-381
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• 2017

Kyeonggi Provincial Government is considering double decker bus service to solve the problem of heavy rush hour traffic. However, the height-to-width ratio is more than 1.16 times larger than that of a general high-speed single decker bus, and the center of gravity is higher. This could cause driving stability problems, such as turnover and breakaway from the lane, especially under strong side-wind conditions at high speed. In this numerical study, the driving characteristics of a model double decker bus were reviewed under side-wind and superelevation conditions at high driving speed. The rolling, pitching, and yawing moment of the model bus were calculated with CFD numerical simulation, and the results were compared to the recovery angular moments of the model bus to evaluate the dynamic stability under given driving conditions. As the model vehicle moves on a straight level road, it is stable under any side-wind conditions. However, on a curved road under side-wind conditions, it could reach unstable conditions dynamically. There is a chance that the bus will turn over when it moves on a curved road with a radius of gyration less than 100 m under side-wind (15 m/s). However, there is a very small chance of breakaway from the lane under any driving conditions.