• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.6 s.99
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• pp.731-737
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• 2005

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.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.10 s.103
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• pp.1202-1210
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• 2005

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.

• Proceedings of the Korea Concrete Institute Conference
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• 1992.10a
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• pp.218-223
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• 1992

Some aspects of the design procedures of reinforced concrete slabs concerning microvibration behavior have to be considered. In this study, a numerical algorithm for the analysis of slabs to withstand the microvibration effects is developed. First, the evaluation criteria for controlling the microvibration of slabs is given from the literature survey. Second, the human-induced load model is developed by the experimental results. Finally, the procedure for the analysis of reinforced concrete slabs, with particular emphasis to the slab subject to human-induced dynamic load, is developed by the finite element method and is then examined by using the slab model tests, In addition, the effects of elastic modulus, mass, shape of slab, and support conditions on the microvibration behavior of reinforced concrete slabs are analyzed. It is concluded that the developed analysis procedure showns in accecptable accuracy compared with the experiments and the analysis procedure cab be easily appkied to the practical microvibration problems.

• Journal of Biosystems Engineering
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• v.24 no.3
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• pp.183-194
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• 1999

Using the dynamic model and simulation program TDA developed in the previous paper, effects of design parameters of an agricultural tractor-trailer system on its vertical seat vibrations were investigated. The tractor-trailer system was excited by traversing over a half-sine bump. The excitation frequencies were determined by traveling velocity of the tractor and a half-sine bump selected appropriately. TDA predicted the autospectra of the vertical seat accelerations with different values of design parameters and compared them to analyze their effects. The design parameters included positions of engine, cab, and seat mountings as well as their dynamic properties. The results of this study suggested guidelines with which an improved structure of tractor may be developed in the early stage of design for a better ride quality.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1718-1723
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• 2003

This paper presents a computational method for deformation modes of a flexible body in multibody system from the experimental modal analysis and an efficient method for flexible multibody dynamic analysis by use of the modes. It is difficult to directly use experimental modal parameters in flexible multibody dynamic analysis. The major reasons are that there are many inconsistencies between experimental and analytical modal data and experimental noises are inherent in the experimental data. So two methods, such as, a method for ortho-normalization of experimental modes and the other one for mode expansion, are suggested to gain deformation modes of a flexible body from the experimental modal parameters. Using the virtual work principle, the equation of motion of a flexible body is derived. The effectiveness of the proposed method will be verified in the numerical example of cab vibration of a truck by comparing analysis and test results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.12
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• pp.1131-1138
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• 2007

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 $100^{\circ}C$ and $150^{\circ}C$. 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 km/h is performed. The real vehicle braking test is carried out at the deceleration rate of 0.2g from a velocity of 90km/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.

• Journal of Biosystems Engineering
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• v.32 no.3
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• pp.153-159
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• 2007

This study was conducted to measure and analyze the noise from a combine head. The combine head, comprised of a cutting knife assembly, pick-up chains, horizontally conveying chains and vertically conveying chains, had an overall sound level of 101 dBA. The sound levels of each component were, respectively, 98.3 dBA for the cutting knife assembly, 88.9 dBA for the pick-up chains, 79.8 dBA for the horizontally conveying chains and 86.3 dBA for the vertically conveying chains, being equivalent to 54.4%, 18.4%, 6.5% and 13.7% of the overall head noise. The main cause of the head noise was considered the impacts that the joint of the cutting knife assembly made with frame when it oscillated. The impact sound was also generated when the chain lug collided with the chain case. To reduce these impact sound, anti-vibration rubbers were installed on the knife assembly joint and the chain cases. It reduced the head noise by 4 dBA but the overall noise level of the combine head was still high. In order to protect the combine operators more effectively from the noise, a safety cab needs to be installed on the combine.

• Journal of Biosystems Engineering
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• v.39 no.1
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• pp.21-33
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• 2014

Background: Significant technological development and changes happened in the tractor industries. Contrariwise, the test procedures of the major standard development organizations (SDO's) remained unchanged or with a little modification over the years, demanding new tractor test standards or improvement of existing ones for tractor performance, safety, and comfort. Purpose: This study focuses on reviewing the research trends regarding performance, safety and comfort evaluation of agricultural tractors. Based on this review, few recommendations were proposed to revise or improve the current test standards. Review: Tractor power take-off power test using the DC electric dynamometer reduced human error in the testing process and increased the accuracy of the test results. GPS signals were used to determine acceleration and converted into torque. High capacity double extended octagonal ring dynamometer has been designed to measure drawbar forces. Numerical optimization methodology has been used to design three-point hitch. Numerous technologies, driving strategies, and transmission characteristics are being considered for reducing emissions of gaseous and particulate pollutants. Engine emission control technology standards need to be revised to meet the exhaust regulations for agricultural tractors. Finite Element Analysis (FEA) program has been used to design Roll-Over Protective Structures (ROPS). Program and methodology has been presented for testing tractor brake systems. Whole-body vibration emission levels have been found to be very dependent upon the nature of field operation performed, and the test track techniques required development/adaptation to improve their suitability during standardized assessment. Emphasizes should be given to improve visibility and thermal environment inside the cab for tractor operator. Tractors need to be evaluated under electromagnetic compatibility test conditions due to large growing of electronic devices. Research trends reviewed in this paper can be considered for possible revision or improvement of tractor performance, safety, and comfort test standards.