• Proceedings of the KSR Conference
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• 2001.10a
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• pp.198-204
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• 2001

Train crashes involve complex interaction between deformable bodies in multiple collisions. The purpose of this study is to suggest the effective analytical procedure using hybrid model for the crashworthiness of motorized trailer of high speed train. The hybrid approach, with very short modeling times and reduced computation times to extract the global behaviour and to perform a pre-optimization of the considered structure. Firstly, various types of crash events are investigated and the conditions for numerical simulation are defined. In this paper, the structural crashwonhiness of Korean High Speed Train trailer was examined through FE analysis. Crash analyses on energy absorbing part and safety zone were carried out to determine each section force. Rollover analysis was performed to observe the amount of intrusion in the passenger's area in case of rollover accident.

• Journal of Ship and Ocean Technology
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• v.5 no.4
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• pp.19-28
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• 2001

A comparative study of the new flexible double hull structure is presented as a collision energy absorbing system, which is constructed with mixed stringers comprising slant and straight stringers for the double hull tanker, The dimension and disposition of this mixed stringers are selected to give the maximum absorbing energy. From the viewpoint of collision energy absorbing efficiency, this structural system is compared with three other types of the double hull constructions with trapezoidal stiffener, stringer type and standard type of VLCC, 310K DWT, Based on the constant hull weight, the proposed double hull structure with mixed stringers shows a improved crashworthiness as the results.

• Journal of the Korean Society for Railway
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• v.10 no.4
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• pp.381-387
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• 2007

In this paper, crashworthiness of the EMU carbody of Incheon Metro is numerically evaluated against two types of overhead line structures (headspan and portal-type). The material of the EMU carbody is stainless steel (SUS301L), and that of the overhead line structures is the structural steel (SS400). The EMU carbody is analyzed under collision conditions, such as upright side-on impact, side-on roof impact and angled roof impact scenarios, to be collided against the headspan type or the portal type at the speed of 64.4km/h, respectively. It is concluded from the numerical results that the overhead line structures will not do so much harm to the EMU carbody of Incheon Metro for various collisions caused by derailment. Furthermore, the overhead line structure of the portal type is superior to that of the headspan type in the crashworthy point of view.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1156-1161
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• 2008

Nonlinear dynamic analysis is generally used in automobile crash analysis and structural optimization considering crashworthiness uses the results of nonlinear dynamic analysis. Automobile crash optimization has high nonlinearity and difficulty in calculating sensitivity. Recently the equivalent static load (ESL) method has been proposed in order to overcome these difficulties. The ESL is the static load set generating the same displacement field as the nonlinear dynamic displacement field at each time step in dynamic analysis. From various researches regarding the ESL method, it has been proved that the ESL method is fairly useful. The ESL method can mathematically optimize a crash optimization problem through nonlinear analysis and well developed static optimization. The ESL is applied to nonlinear dynamic structural optimization of the automobile frontal impact problem. An automobile bumper is optimized. The mass of the structure is minimized while some constraints are satisfied.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.4
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• pp.33-40
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• 2007

Crashworthiness design is of special interest in automotive industry and in the transportation safety field to ensure the vehicle structural integrity and more importantly the occupant safety in the event of the crash. Front side assembly is one of the most important energy absorbing components in relating to the crashworthiness design of vehicle. The structure and shape of the front side assemblies are different depending on auto-makers and size of vehicles. Thus, it is not easy to grab an insight on designer's intention when you glance at a new front side member without experiences. In this paper, we have performed the explicit nonlinear dynamic finite element analysis on the front side assembly of passenger cars to identify the mechanical roles of major parts in relation to collapse modes from the viewpoint of reverse engineering. To do this, we have performed crash FE analysis for the two different assemblies of small car and heavy passenger car and have compared dynamic behaviors of the two.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.1
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• pp.89-98
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• 2007

Crashworthiness design is of special interest in automotive industry and in the transportation safety field to ensure the vehicle structural integrity and more importantly the occupant safety in the event of the crash. Front side assembly is one of the most important energy absorbing components in relating to the crashworthiness design of vehicle. The structure and shape of the front side assemblies are different depending on automakers. Thus, it is not easy to grab an insight on designer's intention when you glance at a new front side member without experiences. In this paper, we have performed the explicit nonlinear dynamic finite element analysis on the front side assembly of a passenger car to identify the mechanical roles of each part of the assembly and to enhance the absorbing energy from the viewpoint of reverse engineering.

• Smart Structures and Systems
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• v.24 no.4
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• pp.427-434
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• 2019

This study investigates the structural integrity of the amphibious tour bus under the rollover condition. The multi-purpose bus called Dual Mode Tour Bus (DMTB) which explores on land and water has been designed on top of a truck platform. Prior to the fabrication of new upper body and sailing equipment of DMTB, computational analysis investigates the rollover protection of the proposed structure including superstructure, wheels, and axles. The Computer-Aided Design (CAD) of the whole vehicle model is meshed and preprocessed under high performance using the Altair HyperMesh to attain the best mesh model suited for finite element analysis (FEA) on the proposed system. Meanwhile, the numerical model is analyzed by employing LS-DYNA to evaluate the superstructure strength. The numerical model includes detail information about the microstructure and considers wheels and axles as rigid bodies but excludes window glasses, seats, and interior parts. Based on the simulation analysis and proper modifications especially on the rear portion of the bus, the local stiffness significantly increased. The vehicle is rotated to the contact point on the ground based on the mathematical method presented in this study to save computational cost. The results show that the proposed method of rollover analysis is highly significant not only in bus rollover tests but in crashworthiness studies for other application. The critical impartments in our suggested dual-purpose bus accepted and passed "Economic Commission for Europe (ECE) R66".

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.10a
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• pp.177-184
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• 2002

The concrete median barriers are the most popular safety appurtenances that can be installed on narrow medians and are effective in keeping uncontrolled vehicles from crossing into opposing lanes of traffic. It is necessary to install and maintain median barriers because it is very difficult to reserve enough room required for medians in KOREA. And concrete median barriers are accepted as the actual alternatives for median barriers, mostly because they require almost no maintenance even after serious collisions. Typical concrete median barriers are 810mm high and have 596mm high glare screens on top of them. But we have experienced a number of “climb” and “roll-over” accidents of heavy vehicles until now, and most of all, there have been some serious accidents caused by the part of broken glare screens. We have performed many computer simulations for the evaluation of the crashworthiness of concrete median barriers, and through the simulations we have tried to find a proper type of concrete median barrier.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1410-1414
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• 2007

In modern automobile body manufacturing, the structural adhesive bonding is recognized to one of new joining techniques for the purpose of light weight body and its application scope in the automobile body has been gradually magnified. Specially, the structural adhesives have the advantages of not only enhancing the design flexibility of automobile body, but also improving automobile performances such as stiffness, crashworthiness and durability. In order to evaluate the performance simulation of the automobile body applied with structural adhesives, it is necessary to develop modeling techniques in the structural adhesives in advance. This paper aims to investigate modeling methodology of structural adhesive junctions for body stiffness simulation. Two main modeling points are the element selection for adhesives and the connectivity between adhesives and adherends. Both of the 1D element used in classical modeling and the 3D element which are more accurate are considered for the adhesives, and the congruent and incongruent mesh models of the adherends are compared for connectivity modeling. By applying the several kinds of modeling methodology to the simple structures, the simulation results are compared and some modeling guidelines are obtained.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.3 s.234
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• pp.395-402
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• 2005

Recently Multidisciplinary Design Optimization Based on Independent Subspaces (MDOIS), an MDO (multidisciplinary design optimization) algorithm, has been proposed. In this research, an MDO problem is defined for design of a belt integrated seat considering crashworthiness, and MDOIS is applied to solve the problem. The crash model consists of an airbag, a belt integrated seat (BIS), an energy absorbing steering system, and a safety belt. It is found that the current design problem has two disciplines - structural nonlin- ear analysis and occupant analysis. The interdisciplinary relationship between the disciplines is identified and is addressed in the system analysis step in MDOIS. Interdisciplinary variables are belt load and stiffness of the seat, which are determined in system analysis step. The belt load is passed to the structural analysis subspace and stiffness of the seat back frame to the occupant analysis subspace. Determined design vari- ables in each subspace are passed to the system analysis step. In this way, the design process iterates until the convergence criterion is satisfied. As a result of the design, the weight of the BIS and Head Injury Crite- rion (HIC) of an occupant are reduced with specified constraints satisfied at the same time. Since the system analysis cannot be formulated in an explicit form in the current example, an optimization problem is formu - lated to solve the system analysis. The results from MDOIS are discussed.