Hyun-Seung Jung

Evaluation of Crash Energy Absorption Capacity of a Tearing Tube

This paper deals with the numerical prediction of energy absorption capacity of a tearing tube, which can absorb the crash energy through expanding and axial splitting processes. It is important to consider the dynamic material behavior and fracture characteristics of tube material in order to simulate the deformation behavior of a tearing tube accurately. Uniaxial tensile tests are performed in order to obtain the flow stress curve and the fracture strain of a tube material according to the strain rate. Quasi-static tensile tests were carried out in the range of strain rates from 0.001/sec to 0.01/sec using a static tensile testing machine. Dynamic tensile tests were conducted at strain rates ranged from 0.1/sec to 300/sec using a high speed material testing machine. These dynamic material properties are utilized to finite element analysis through a user material subroutine of ABAQUS/Explicit. Especially, ductile fracture criteria are adopted in order to describe the fracture characteristics of a tube material during axial splitting process. Dynamic tearing cases are simulated and the reliability of numerical results is verified by comparing them with the experimental results in dynamic tearing tests. The simulated results accurately predict the onset of fracture in axial splitting process and the energy absorption capacity has a good agreement with experimental results.

Weight Reduction of an Urban Railway Axle Based on EN Standard

Weight reduction of a railway axle, which is one of heaviest parts in an urban railway vehicle, is discussed in this paper. A wheelset of a railway vehicle is very important with regard to railway safety, and its structural strength should always be considered when attempting to reduce the railway axle weight. In this work, the weight of the axles of a trailer bogie and a motor bogie of the Korean EMU was reduced by replacing solid axles with hollow axles. On the basis of the EN standard for railway axle design, the strength of existing solid axles was analyzed and the required bore size of a hollow axle was determined. It is shown that the weight of the concurrent axle of the Korean EMU can be reduced by up to 20% with a very small decrease in the structural strength. Finite element analyses were also carried out to verify the design result for lightweight hollow axles.

A Study on Design and Dynamic Characteristics of Tearing Tubes Applied in Tram

Abstract : The paper aims to design and verify tearing tube type energy absorption device applied in tram to ensure safety in case of collision accident. Energy capacity of tearing tube is determinated based on EN15227 and Standard Collision Scenarios Criterion in Detail in Republic of Korea. Tearing tube is designed based on theoretical model suggested by X.Huang et al. and assumption by T.Y. Reddy et al. Real scale collision tests are conducted to analyze the energy absorption characteristics and deformation mode. Bending of curl tips is absorbed collision energy when curl tips and tube body are contacted to each other from the tests and we suggest and include the formula on bending of curl tips in theoretical model. Key words :Tram(트램), Tearing tube( 테어링 튜브), EN15227(EN 규격), Collision test( 충돌 시험), Bending of curl tips(컬 끝의 굽힘) 1. 서 론 1) 본 논문은 국내에 새로 도입되는 트램이라는 교통수단의 충돌 사고 시 안전을 확보하기 위한 장치를 설계 및 검증하는 것을 목적으로 한다.Thin-wall 튜브는 에너지흡수부재의 한 종류로 많은 연구가 진행되었다. A. G. Olabi 등 1) 은 thin-wall 튜브의 다양한 에너지 흡수 매커니즘에 대하여 소개하였다. S. R. Reid