• 한국도로학회논문집
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• 제9권4호
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• pp.215-226
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• 2007

차량방호 안전시설에 대한 성능의 검증은 충돌시험의 가속도와 각속도 데이터를 사용하여 산정한 탑승자 안전지수를 평가하여 이루어진다. 탑승자 안전지수로는 THIV(Theoretical Head Impact Velocity), PHD(Post-impact Head Deceleration), ASI(Acceleration Severity Index), OIV(Occupant Impact Velocity)와 ORA(Occupant Ridedown Acceleration)가 있다. 탑승자 안전지수 계산에 상이한 데이터 처리과정과 수치절차의 적용이 가능하기 때문에 동일한 시험 데이터에 대하여 다양한 탑승자 안전지수값이 결정될 수 있어서 혼란이 초래되고 있는 실정이다. 이러한 문제를 해결하기 위하여 다양한 상세절차와 데이터 처리과정이 탑승자 안전지수에 미치는 영향을 조사하였다. 지침에 제시된 계측시간간격을 사용하여 차량충돌시험이 수행된다면 보간법과 수치적분방법은 THIV와 OIV 값에 영향을 크게 미치지 않았다. 그리고 PHD에 대한 10msec 이동평균방법과 데이터 처리과정의 영점보정은 탑승자 안전지수에 상당한 영향을 미치기 때문에 이에 관한 구체적인 방법이 지침에 규정되어야 한다.

• 한국자동차공학회논문집
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• 제10권4호
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• pp.141-148
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• 2002

Repair were made for front pillar, center pillar and side-step panel for lightweight vehicles with head-on and 40% off-set collision of 15 km/h in a RCAR standard. The salt dilution was sprayed and the compression tests were performed for vehicles with and without anti-corrosional treatment after repair. After 764 hours of salt-dilt sprayed test without using anti-corrosion, the mean penetration depth fur corrosion was shown to be 58% of the thickness. The resulyed decrease in bending stiffness by 10∼20% can cause reduction of the residual life and crash-absorption capability for damaged vehicles. The corrosoin safety tests showed that the anti-corrosional treatment should be made to improve the safety characteristics for a or damaged car.

• 한국자동차공학회논문집
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• 제12권6호
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• pp.135-142
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• 2004

The severe frontal crash tests are NCAP with belted occupant at 35mph and FMVSS 208 with unbelted occupant at 25mph, This paper describes the design process of occupant protection systems, airbag and seat belt, under the two tests. In this study, NCAP simulations are performed by Monte Carlo search method and cluster analysis. The Monte Carlo search method is a global optimization technique and requires execution of a series of deterministic analyses, The procedure is as follows. 1) Define the region of interest 2) Perform Monte Carlo simulation with uniform distribution 3) Transform output to obtain points grouped around the local minima 4) Perform cluster analysis to obtain groups that are close to each other 5) Define the several feasible design ranges. The several feasible designs are acquired and checked under FMVSS 208 simulation with unbelted occupant at 25mph.

• 한국자동차공학회논문집
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• 제16권3호
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• pp.52-59
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• 2008

Most accident reconstruction or analysis depend on the coefficient of friction to estimate the vehicle speeds. Skid mark and coefficient of friction are usually utilized to calculate the velocity and behavior of vehicles. For a critical case such as traffic accident reconstruction, however, the initial velocity of the car should be calculated precisely. In this paper, emergency brake tests on ABS and Non-ABS brake system are conducted on the dry pavement asphalt road on speed 40, 60, 80 and 100 km/h respectively. The SWIFT sensor was established in the front wheel and rear wheel at driver side to measure the forces, moments and speeds of revolution of the tires. These tests results can be available to brake tests and accident reconstruction.

• 한국자동차공학회논문집
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• 제15권1호
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• pp.171-176
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• 2007

An important challenging issue in the automotive industry is the light-weight, safe design and enhancement of crash response of an auto-body structures. These objectives lead to increasing adoption of high strength steel sheet for inner and outer auto-body members. This paper evaluates the dynamic tensile characteristics of high strength steel sheets, HS45R, TRIP60, DP60 and DP100, along the rolling direction and transverse direction. Static tensile tests were carried out at the strain rate of 0.003/sec using the static tensile machine (Instron 5583). Dynamic tensile tests were carried out at the range of strain rate from 0.1/sec to 200/sec using a high speed material testing machine developed. The tensile tests acquire stress-strain relation and strain rate sensitivity of each material. The experimental results show two important aspects for high strength steels: the flow stress increases as strain rate increases; the strain hardening decreases as the tensile stress increases. The experiments also produce interesting results that the elongation does not decrease even when the strain rate increases.

• 한국자동차공학회논문집
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• 제4권1호
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• pp.96-109
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• 1996

The airbag system is known to be extremely efficient for the protection in an automobile crash. The performance of the airbag system is evaluated by real tests. However, the test is very difficult and expensive. Therefore, the computational simulations are carried out with low cost. The airbag analysis is included in the anlysis of the full-car crashworthiness. The behavior of the airbag can be predicted by a thermodynamic analysis. The contact force between the occupant and the airbag is calculated from the contact volume and the pressure in the airbag. The injury rate is evaluated from the contact force and the acceleration of dummies. So far, the contact is defined after the airgag is fully inflated. In many cases, the occupant is seated in the out-of-position and the contact can happen during the inflation process. A new algorithm has been developed for the out-of-position. To describe the inflation process precisely, the airbag is defined by a sphere and a torus. The injury is evaluated for the contact happened at any time. The developed algorithm is coded and interfaced with an existing software in the public domain. The full-car modeling is adopted from the previous study which is tuned for the regular position and real tests. Numerical experimentation have been carried out with a couple of dummies in the out-of-position and the injury processes are analyzed.

• 소성∙가공
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• 제20권4호
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• pp.309-315
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• 2011

The behavior of metallic materials at high strain rates shows different characteristics from those in quasi-static deformation. Therefore, the strain rate should be considered when simulating crash events. The objective of this paper is to evaluate the dynamic tensile characteristics of SPRC440 as a function of the volume fraction of phases. As-received SPRC440 is composed of ferrite and pearlite phases. However, ferrite and martensite phases were observed after heat treatment at $730^{\circ}C$ and $780^{\circ}C$ for 5 minutes, as expected by calculations based on the curves from dilatometry tests. High cross-head speed tensile tests were performed to acquire strain-stress curves at various strain rates ranging from 0.001 to $300\;s^{-1}$, which are typical in real vehicle crashes. It was observed that the flow stress increases with the strain rate and this trend was more pronounced in the as-received specimens consisting of ferrite and pearlite phases. It is speculated that the dislocation density in each phase has an influence on the strain rate sensitivity.

• Tribology and Lubricants
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• 제37권3호
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• pp.112-116
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• 2021

Appropriate friction model usage is important for impact analysis because the relative motions between parts that are in contact for very short durations can vary greatly depending on the friction model. Vehicle seat components that have significant effects on impact analysis are also considered. This paper presents an experimental investigation of various material contact pairs to obtain the friction parameters of the Benson exponential friction model for impact simulation. The Coulomb friction model has limitations for impact analysis because of singularity at zero velocity. Metal/nonmetal materials are prepared, and friction tests are conducted for various sliding speeds, loads, and lubrication conditions. The obtained data are used in the friction model to implement finite element analysis. The parameters of the friction model are obtained by the curve-fitting method. The experimental results show that the friction coefficient with metal/nonmetal contact pairs is stable regardless of the working conditions. The friction model used in this study can also be applied for finite element analysis of the crash conditions, where the friction changes abruptly at the contact interface; the obtained friction parameters are also expected to be more accurate with more precise tests under different working conditions. These results can help improve the accuracy of the finite element analysis.

• 대한토목학회논문집
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• 제40권5호
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• pp.445-454
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• 2020

차량과 충돌 시 분리되지 않는 감충형 슬라이딩 지주는 충돌 초기에 차량과 일체로 되어 강체운동을 한다. 이때 차량의 선형모멘텀이 지주에 전달되면서 차량의 1차 감속을 이루고 이어서 가이드레일 아래에 설치된 Energy-Absorbing Pipe (EAP)가 찌그러지면서 나머지 충돌에너지를 흡수하여 2차 감속을 이룬다. 따라서 EAP는 슬라이딩 지주의 핵심요소이고 그 크기는 지주기초 안에 설치될 수 있어야 한다. 본 논문은 국내 편 지식 표지판에 많이 사용되는 지주와 베이스구조를 합하여 총 507 kg의 무게를 갖는 감충형 슬라이딩 지주에 사용하기 위한 EAP의 개발에 관한 것이다. LS-DYNA프로그램을 이용한 충돌해석을 통하여 EAP구조를 설계하고 실차충돌실험을 통하여 감충성능을 평가하는 과정을 상세히 설명하였다. 본 연구를 통하여 제시된 EAP는 최소 0.9 ton-60 km/h에서 최대 1.3 ton-80 km/h 충돌에 대한 감충성능을 발휘하고 기초길이가 2.7 m 이하로 제약될 때 활용될 수 있다.

• 대한교통학회지
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• 제29권2호
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• pp.59-67
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• 2011

본 연구에서는 충돌사고시 스마트하이웨이의 정시성과 안전성의 손상정도를 최소화 하도록 스마트하이웨이의 종방향 베리어 충돌조건으로 기존의 충돌조건보다 상당히 상향된 충돌조건이 제시된다. 스마트하이웨이 충돌조건을 적용하여 기존 국내 최고 성능등급 베리어에 대한 컴퓨터 시뮬레이션 결과 탑승자 안전도를 만족하지 못하였다. 스마트하이웨이 충돌조건에 만족하는 베리어 개발을 위해서 컴퓨터 시뮬레이션에 의한 설계를 수행하고 실물차량 충돌시험을 통한 성능 검토결과 개발된 N등급 베리어가 탑승자 안전지수와 구조적 적절성을 만족하였다.