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문일동(Il Dong Moon),오석형(Seok Hyung Oh),오재윤(Chae Youn Oh) Korean Society for Precision Engineering 2004 한국정밀공학회지 Vol.21 No.10
This paper presents an analytical modeling technique for representing a hysteretic behavior of a multi-leaf spring used for a large truck. It divides a nonlinear hysteretic curve of the multi-leaf spring into four parts; loading part, unloading part and two transition parts. It provides conditions for branching to a part of the curve corresponding to a current multi-leaf spring status. This paper also presents a computational modeling technique of the multi-leaf spring. It models the multi-leaf spring with three links and a shackle. It assumes those components as rigid bodies. The links are connected by rotational joints, and have rotational springs at the joints. The spring constants of the rotational springs are computed with a force from the analytical model of the hysteretic curve of the multi-leaf spring. Static and dynamic tests are performed to verify the reliability of the presented techniques. The tests are performed with various amplitudes and excitation frequencies. The hysteretic curves from the tests are compared with those from the simulations. Since the presented techniques reproduce the hysteretic characteristic of the multi-leaf spring faithfully, they contribute on improving the reliability of the computational model of a large truck.
대형트럭 프레임의 결합방법에 따른 비틀림 특성이 동적 성능에 미치는 영향
문일동(Moon, Il-Dong),김병삼(Kim, Byoung-Sam) 한국소음진동공학회 2005 한국소음진동공학회 논문집 Vol.15 No.6
This paper evaluates dynamic performance of a cab over type large-sized truck for estimating the effects of frame's torsional characteristics using a computer model. The computer model considers two mounting methods of frame, flange mounting and web mounting. Frame is modeled by finite elements using MSC/NASTRAN In order to consider the flexibility of frame. The torsional test of the frame is conducted In order to validate the modeled finite element model. A load cell is used to measure the load applied to the frame. An angle sensor is used to measure the torsional angle. An actuator is used to apply a load to the frame. To estimate the effects of frame's torsional characteristics on dynamic performance, simulations are performed with the flange mounting and web mounting frame. Simulation results show that the web mounting frame's variations of roll angle, lateral acceleration, and yaw rate are larger than the flange mounting frame's variations, especially in the high velocity and the second part of the double lane course.
문일동(Il Dong Moon),오재윤(ChaeYoun Oh),오석형(Seok Hyung Oh) Korean Society for Precision Engineering 2004 한국정밀공학회지 Vol.21 No.8
This paper develops a computer model of a cab over type large truck for estimating the effects of the mounted method of frame on handling performance. The computer model considers two mounted methods of frame; flange mounted and web mounted. Frame is modeled by finite elements using MSC/NASTRAN in order to consider the flexibility of frame. The reliability of the developed computer model is verified by comparing the actual vehicle test results with the simulation results. The actual vehicle test is performed in a double lane change course, and lateral acceleration, yaw rate, and roll angle are measured. To estimate the effects of the mounted method of frame on handling performance, simulations are performed with the flange mounted and web mounted frame. Simulation results show that the web mounted frame's variations of roll angle, lateral acceleration, and yaw rate are larger than the flange mounted frame's variations, especially in the high test velocity and the second part of the double lane course. Also, simulation results show that the web mounted frame's tendencies of roll angle, lateral acceleration, and yaw rate advance the flange mounted frame's tendencies, especially in the high test velocity and the second part of the double lane course.
범프 로드에서 대형트럭 프레임의 탄성효과를 고려한 컴퓨터 모델 개발
문일동(Moon, Il-Dong),지창헌(Chi, Chang-Hun),김병삼(Kim, Byoung-Sam) 한국소음진동공학회 2005 한국소음진동공학회 논문집 Vol.15 No.10
This paper develops a computer model for estimating the bump characterisitcs of a cat)over type large-sized truck. The truck is composed of front and rear suspension systems, a frame, a cab, and ten tires. The computer model is developed using MSC.ADAMS. A shock absorber, a rubber bush, and a leaf spring affect a lot on the dynamic characteristic of the vehicle. Their stiffness and damping coefficient are measured and used as input data of the computer model. Leaf springs in the front and rear suspension systems are modeled by dividing them three links and joining them with joints. To improve the reliability of the developed computer model, the frame is considered as a flexible body. Thus, the frame is modeled by finite elements using MSC.PATRAN. A mode analysis is performed with the frame model using MSC.NASTRAN in order to link the frame model to the computer model. To verify the reliability of the developed computer model, a double wheel bump test is performed with an actual vehicle. In the double wheel bump, vortical displacement, velocity, acceleration are measured. Those test results are compared with the simulation results.
상용차량의 브레이크 시스템과 차량 시스템 주파수 분석을 통한 브레이크 저더의 실험적 고찰
문일동(Il-Dong Moon),김종대(Jong-Dae Kim),오재윤(Chae-Youn Oh) 대한기계학회 2007 大韓機械學會論文集A Vol.31 No.12
This paper studies experimentally on the building-up process for the amplitude of a commercial truck vibration induced by brake judder. A front axle drum equipped with a drum brake system is utilized for this experiment. A brake dynamo test, a real vehicle ride test and a real vehicle braking test are performed for the analysis of brake judder. The brake dynamo test measures judder by applying brake chamber pressures of 1, 2 and 3 bar at initial brake pad temperatures of 100℃ and 150℃. In order to assess the vertical acceleration at the front axle, the real vehicle ride test on a straight test road with velocities of 20, 40, 60 and 80 ㎞/h is performed. The real vehicle braking test is carried out at the deceleration rate of 0.2g from a velocity of 90㎞/h for evaluating the vertical, lateral and longitudinal accelerations both at the front axle and at the cab floor under the driver's seat. The magnitudes and frequencies of the measured peak accelerations from the brake dynamo test, the real vehicle ride test and the real vehicle braking test are comparatively analyzed. This paper shows that the vibration produced by brake judder is built up due to the brake system's peak acceleration frequency being close to the vehicle ride mode's frequency.
다축 로드 시뮬레이터를 이용한 대형트럭 주요 시스템의 바운스와 롤 및 피치 주파수의 실험적 분석
문일동(Il Dong Moon),오재윤(Chae Youn Oh) Korean Society for Precision Engineering 2005 한국정밀공학회지 Vol.22 No.8
This paper presents a scheme for experimentally analyzing bounce, roll and pitch frequencies of major systems of a large truck using a multi-axial road simulator. The excitation input (amplitude and frequency range) for a frequency response test with the multi-axial road simulator is selected in order that bounce, roll and pitch modes are not coupled each other, the excitation amplitude can be reproduced in a specified excitation frequency range, and tires do not lose contact with posters. Three accelerometers, one gyroscope and four displacement meters are used in the frequency response test using the multi-axial road simulator. The reliability of the presented bounce mode frequency response test scheme is validated by comparing the result from a test using the multi-axial road simulator with the result from a road driving test. The road driving test is performed with velocities of 20㎞/h and 30㎞/h, and in an unladen state. The vertical accelerations at the cab and the front axle are measured in the road driving test. The roll and pitch mode frequency response tests are also performed with the presented frequency response test scheme. Roll and pitch frequencies of major systems of a large truck that are hard to acquire from a road driving test are analyzed as well as bounce frequency.