• 복합신소재구조학회 논문집
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• 제2권4호
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• pp.11-18
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• 2011

본 논문에서는 컴퓨터 시뮬레이션을 통해 강재-FRP 합성 교량용 방호울타리의 성능을 분석하였다. FRP는 Surface veil, DB 그리고 Roving 섬유로 구성하였다. FRP의 적층을 고려하기 위해 LS-DYNA에서 제공하는 재료모델 MAT58을 사용하였다. 강관과 FRP의 접촉조건을 고려하기 위해 Spot weld 옵션을 사용하였다. 실차충돌 실무 업무편람에 따라 구조적 강도성능, 탑승자 보호성능 및 충돌 후 차량의 거동에 대한 성능평가를 실시하였다. 강재-FRP 합성 방호 울타리는 성능평가를 만족하였다.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2000년도 춘계학술대회 논문집
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• pp.81-88
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• 2000

Unlike structures in the air, the vibration analysis of a submerged or floating structure such as offshore structures or ships is possible only when the fluid-structure interaction is understood, as the whole or part of the structure is in contact with water. Specially, the importance of the added mass is not necessary to say like the submerged vehicle, all of the hull body, is positioned in the water. This paper introduce two method to find natural frequency in consideration of fluid-structure modal coupled vibration analysis. The purpose of this study is to analyze of the vibration characteristic of submerged vehicle to obtain the anti-vibration design data, which could be used in the preliminary design stage data. Underwater pressure hull of submerged vehicle is used as the model of this study. The F.E.M model is meshed by shell and beam element. Also, considering of the inner hull weight, mass element is distributed in the direction of hull length. Numerical calculations are accomplished using the commercial B.E.M code. The characteristics of natural frequency(eigenvalues), mode shape(eigenvectors) and frequency-displacement response are analyzed. The results of this study will be used as the useful design data in preliminary anti-vibration design stage.

• International Journal of Automotive Technology
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• 제6권1호
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• pp.29-35
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• 2005

The structural integrity of either a passenger car or a light truck is one of the basic requirements for a full vehicle engineering and development program. The results of the vehicle product performance are measured in terms of ride and handling, durability, Noise/Vibration/Harshness (NVH), crashworthiness, and occupant safety. The level of performance of a vehicle directly affects the marketability, profitability and, most importantly, the future of the automobile manufacturer. In this study, the Virtual Proving Ground (VPG) approach has been developed to simulate dynamic nonlinear events as applied to automotive ride & handling. The finite element analysis technique provides a unique method to create and analyze vehicle system models, capable of including vehicle suspensions, powertrains, and body structures in a single simulation. Through the development of this methodology, event-based simulations of vehicle performance over a given three-dimensional road surface can be performed. To verify the predicted dynamic results, a single lane change test was performed. The predicted results were compared with the experimental test results, and the feasibility of the integrated CAE analysis methodology was verified.

• Wind and Structures
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• 제15권3호
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• pp.263-283
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• 2012

This paper presents a framework of nonlinear dynamic analysis of a low-speed moving maglev (magnetically levitated) vehicle subjected to cross winds and controlled using a clipped-LQR actuator with time delay compensation. A four degrees-of-freedom (4-DOFs) maglev-vehicle equipped with an onboard PID (Proportional-Integral-Derivative) controller traveling over guideway girders was developed to regulate the electric current and control voltage. With this maglev-vehicle/guideway model, dynamic interaction analysis of a low-speed maglev vehicle with guideway girders was conducted using an iterative approach. Considering the time-delay issue of unsynchronized tuning forces in control process, a clipped-LQR actuator with time-delay compensation is developed to improve control effectiveness of lateral vibration of the running maglev vehicle in cross winds. Numerical simulations demonstrate that although the lateral response of the maglev vehicle moving in cross winds would be amplified significantly, the present clipped-LQR controller exhibits its control performance in suppressing the lateral vibration of the vehicle.

• Smart Structures and Systems
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• 제13권5호
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• pp.797-819
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• 2014

This paper presents a theoretical algorithm for constructing the mode shapes of a bridge from the dynamic responses of a test vehicle moving over the bridge. In comparison with those approaches that utilize a limited number of sensors deployed on the bridge, the present approach can offer much more spatial information, as well as higher resolution in mode shapes, since the test vehicle can receive the vibration characteristics of each point during its passage on the bridge. Basically only one or few sensors are required to be installed on the test vehicle. Factors that affect the accuracy of the present approach for constructing the bridge mode shapes are studied, including the vehicle speed, random traffic, and road surface roughness. Through numerical simulations, the present approach is verified to be feasible under the condition of constant and low vehicle speeds.

• 한국철도학회논문집
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• 제13권4호
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• pp.382-388
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• 2010

본 논문은 샌드위치 복합재가 적용된 철도차량 차체 구조물을 위한 표준유한요소모델을 제시하였다. 최근 샌드위치 복합재는 높은 굽힘 강성 및 강도를 가지며 차체의 경량화와 공간 확보를 통해 에너지 효율을 향상시킬 수 있어 국내의 많은 분야에서 널리 사용되고 있다. 그러므로 복합재 철도 차량의 제작 전에 유한요소법 등을 통해 구조안전성을 검증해야 한다. 본 연구에서는 다양한 철도차량의 실제 구조시험과 같은 수직, 압축, 비틀림 하중 및 고유진동수 해석을 통해 철도차량 구조물의 표준유한요소모델을 검증 제시하였다. 그 결과, 샌드위치 패널의 굽힘 강성을 향상시키기 위한 보강 금속 프레임에는 빔 요소보다는 사각 쉘 요소가 적절하였으며, 샌드위치 패널의 허니콤 코어와 적층복합재의 경우 적층 쉘 요소와 비교하여 적층 쉘 요소와 솔리드 요소를 사용하는 것이 적절하다. 또한, 제안된 표준유한요소모델은 유한요소모델의 수정 없이 충돌모델에 적용할 수 있는 장점을 가지고 있다.

• Wind and Structures
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• 제6권5호
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• pp.325-346
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• 2003

High-sided road vehicles are susceptible to a sharp-edged crosswind gust, which may cause vehicle accidents such as overturning, excessive sideslip, or exaggerated rotation. This paper thus investigates the dynamic behaviour and possible accidents of high-sided road vehicles entering a sharp-edged crosswind gust with road surface roughness and vehicle suspension included. The high-sided road vehicle is modelled as a combination of several rigid bodies connected by a series of springs and dampers in both vertical and lateral directions. The random roughness of road surface is generated from power spectral density functions for various road conditions. The empirical formulae derived from wind tunnel test results are employed to determine aerodynamic forces and moments acting on the vehicle. After the governing equations of motion are established, an extensive computation work is performed to examine the effects of road surface roughness and vehicle suspension on the dynamic behaviour and vehicle accidents. It is demonstrated that for the high-sided road vehicle and wind forces specified in the computation, the accident vehicle speed of the road vehicle running on the road of average condition is relatively smaller than that running on the road of very good condition for a given crosswind gust. The vehicle suspension system should be taken into consideration, and the accident vehicle speed becomes smaller if the vehicle suspension system has softer springs and lighter dampers.

• Wind and Structures
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• 제24권5호
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• pp.405-430
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• 2017

The aerodynamic characteristics of vehicles are critical to assess vehicle safety and passenger comfort for vehicles running on long span bridges in a windy environment. However, in previous wind-vehicle-bridge (WVB) system analysis, the aerodynamic interference between the vehicle and the bridge was seldom considered, which will result in changing aerodynamic coefficients. In this study, the aerodynamic coefficients of a high-sided truck on the ground (ground case) and a typical bridge deck (bridge deck case) are determined in a wind tunnel. The effects of existent structures including the bridge deck and bridge accessories on the high-sided vehicle's aerodynamic characteristics are investigated. A three-dimensional analytical framework of a fully coupled WVB system is then established based on the finite element method. By inputting the aerodynamic coefficients of both cases into the WVB system separately, the vehicle safety and passenger comfort are assessed, and the critical accidental wind speed for the truck on the bridge in a windy environment is derived. The differences in the bridge response between the windward case and the leeward case are also compared. The results show that the bridge deck and the accessories play a positive role in ensuring vehicle safety and improving passenger comfort, and the influence of aerodynamic interference on the response of the bridge is weak.

• 한국자동차공학회논문집
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• 제6권5호
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• pp.146-152
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• 1998

Recently, for the development of vehicle structures and components there is a tendency to increase using numerical simulation methods compared with practical tests for the estimation of the fatigue strength. In this study, an integrated powerful methodology is suggested for fatigue strength evaluation through development of the interface program to integrate dynamic analysis quasi-static stress analysis and fatigue analysis, which were so far used independently. To verify the presented evaluation method, a single and zigzag bump run test, 4-post road load simulation and driving durability test have been performed. The prediction results show a good agreement between analysis and test. This research indicates that the integrated life prediction methodology can be used as a reliable design tool in the pre-prototype and prototype development stage, to reduce the expense and time of design iteration.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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• pp.789-792
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• 1999

Reinforced concrete structures covered creek for road vehicle located in urban areas have been experiencing corrosion of concrete and reinforcing steel caused by $H_2S$ gases generated by anaerobic bacterial. H2S gases react with oxygen and water to form sulfuric acid ($H_2SO_4$). This acid chemically attacks concrete, and sulfate ions penetrate into the concrete, causing rebar corrosion. In this work, to determine the conditions of RC culvert boxes which were constructed in the 1970s, various tests were conducted, including carbonation depth, compressive strength, half-cell potential measurements, and XRD analyses. Results indicated that the concrete deterioration was caused by sulfate attack and rebar corrosion. This paper discusses the evaluation on the durability of reinforced concrete structures covered creek for road vehicle.