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The benefits of using Composite Bearings in Aircraft Shock Absorbers

Trelleborg Sealing Solutions-Brian Bowen, Torben A. Andersen
  • Technical Paper
  • 2019-01-1898
To be published on 2019-09-16 by SAE International in United States
This paper will use actual examples from aircraft recently introduced into service, to describe the main advantages of changing from the currently used metallic bearings, to composite bearings. Abstract: The introduction of composite bearing in a recently introduced twin aisle aircraft has resulted in: • Weight saving, by replacing bronze bearings with plastic bearings • Lowering of the particle count in the shock absorber oil, (Reduced contamination with metal particles) leading to reduced wear on seals and bearings. Qualification testing showed that Composite Bearings are able to provide longer service life than bronze bearings.
 
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Simulation Analysis of a Dual-Purpose Intelligent Mobile Platform for Highway and Railway

Nan Sun
University of Science & Development-Wenming Zhang
Published 2019-06-05 by SAE International in United States
Railways play a huge role in China's transportation industry. In order to ensure intelligence, advanced technology and high efficiency in functions such as railway inspection, rescue and transportation, a dual-purpose intelligent mobile platform for both roads and railways was developed. Due to the height limitation of this platform, resilient wheels and rubber dampers with short stroke are used as the suspension system for the rail chassis. Based on this special suspension form, the dynamic model of the whole platform is derived, and the simulation model of the whole platform is established in the simulation software. The effects of resilient wheels’ axial stiffness, radial stiffness and vertical stiffness, lateral stiffness of rubber dampers on the vertical and lateral stability of the platform were studied. It is found that the increase of the radial stiffness of the resilient wheels will deteriorate the vertical stability and lateral stability of the platform. The increase in the axial stiffness of the resilient wheels will deteriorate the vertical stability of the platform and the lateral stability will be improved. The increase…
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Simulation of Damping Force for a Magneto-Rheological (MR) Damper Featuring Piston Bypass Holes

Li Guojie
Published 2019-06-05 by SAE International in United States
The magneto-rheological (MR) damper featuring piston bypass holes is an MR damper with improved mechanical properties relative to conventional MR dampers. It brings much better ride comfort for occupants by minimizing the harshness component from disturbing the smooth ride of vehicles. However, few studies on this MR damper featuring piston bypass holes are found. This work is aimed to study the principle that this MR damper works on by experiment, modelling and simulation. The MR damper featuring piston bypass holes is tested on MTS system. A mathematical model for the MR damper is established. Head loss and local head loss caused by the viscosity of the MR fluid are both adopted in the mathematical model. The Eyring model is adopted to describe the mechanical behavior of MR fluid. The result of simulation is in good agreement with experimental data. When the local head loss is eliminated from the mathematical model, simulation accuracy decreases. These results indicate that the local head loss due to sudden contraction and sudden expansion at entrance and exit of piston bypass…
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Development of 1D Model of Impact Force in Powertrain Equipment

Denso-Yuma Yoshimaru, Makoto Kondo, Yukie Omuro, Masashi Inaba
Published 2019-06-05 by SAE International in United States
Electromagnetic valves excellent in sealing properties and resistant to sliding are often used in powertrain equipment installed in gasoline- or diesel-engine vehicles. An electromagnetic valve has the function of moving internal valve members by means of electromagnetic force generated by the application of a voltage and thereby changing the flow path. When an electromagnetic valve operates, however, the valve members impact with one another, emitting impact noise caused by it. With the requirement for low noise in electromagnetic valves having become stricter recently from the viewpoint of comfort in the passenger compartment, predicting the noise is needed at the design stage.With this background, this paper describes the development of a 1D model of impact force that will enable the noise and the product performance to be examined simultaneously for a GDI (gasoline direct injection) high pressure pump. In contrast to the conventional model in which a movable member is taken as a mass point with a spring and a damper placed at the impact section, this paper proposes a technique in which a spring-mass model…
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Dynamics of Amphibious All-Terrain Vehicle’s Chassis Having Vibration Energy Harvesting Dampers

Mega Automation, Inc.-Dmytriy Gurevych
Nermar, Ltd.-George Nerubenko
Published 2019-06-05 by SAE International in United States
The rural off-road exploiting of amphibious all-terrain vehicles leads to the intensive vibrations of all parts of a vehicle, and specifically of its chassis. The tested amphibian vehicle’s chassis has the lowest natural frequency of 19.34 Hz. The Vibration Energy Harvesting Damper (VEHD) is used for mitigation of chassis vibrations. VEHD provides the mutually interconnected results: a reduction of undesired vibration levels and a generating of the additional electrical power. Newly patented VEHD consists of two main components: Tuned Mass Damper and Generator of Electricity. The perspective feature of proposed VEHD is the ability of effective vibration damping in a broad range of frequencies due to implementation of a control device, while that device is keeping automatically the changing natural frequency of VEHD equals to current frequency of the external force. The mathematical simulation analysis based on parameters of the amphibious all-terrain vehicle chassis is developed. The experiments arranged on recently designed amphibious all-terrain vehicle illustrate the compliance with theoretical predictions, and efficiency of proposed VEHD operating mainly in low frequency interval. An analysis of…
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Research on Dynamic Load of Belgian Event Based on Virtual Proving Ground

CATARC-Jiansen Yang, Xinyu Wang, Xin Li
Published 2019-04-02 by SAE International in United States
The fatigue load spectrum of the physical proving ground is the necessary input for fatigue life analysis of vehicle parts and components. It is usually obtained by Road Load Data Acquisition (RLDA) and loads decomposition using multi-body dynamics tools. Virtual Proving Ground (VPG) methodology is gradually replacing this technical strategy. The belgian road is the typical event in durability test, in this paper, the flexible body and FTire model are applied to the vehicle multi-body dynamics model in order to improve the simulation accuracy. The result shows that all the wheel center force, shock absorber displacement and axial force acquired by VPG simulation have excellent correlation with real vehicle measured data. It is also proved that the virtual proving ground technology is a reliable and effective method to obtain the fatigue load spectrum in the early stage of development.
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A Study of Triple Skyhook Control for Semi-Active Suspension System

Toyota Motor Corporation-Naoto Shimoya, Etsuo Katsuyama
Published 2019-04-02 by SAE International in United States
The research described in this paper focused on improving occupant ride comfort and road holding by suppressing sprung and unsprung vibration using a semi-active suspension system. It has been reported that occupants tend to perceive vertical vibrations in a frequency range between 4 and 8 Hz as uncomfortable (described below as the “mid-frequency range”). Previous research into semi-active suspension system has focused on reducing vibration in this mid-frequency range, as well as close to the sprung resonance frequency of between 1 and 2 Hz. Skyhook damper (SH) control is a typical ride comfort control used to damp vibration close to the sprung resonance frequency. However, since SH control is not capable of damping vibration in the mid-frequency range, the shock absorbers are configured with a lower damping factor. This helps to achieve a good balance between reducing vibration close to the sprung mass resonance and in the mid-frequency range. In contrast, it has the trade-off effect of increasing unsprung vibration. The triple skyhook (tSH) control, which suspends the vehicle using three virtual elements (i.e., springs,…
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Modelling and Simulation of a Magnetorheological Fluid Damper with Multi-Accumulator during Mode Shifting

Tsinghua University-Cenbo Xiong, Liangyao Yu, Zhenchuan Li, Sheng Zheng
Published 2019-04-02 by SAE International in United States
In a monotube magnetorheological fluid damper (MRFD), there usually exists a compensation chamber with designated initial gas pressure. This enclosed compensation chamber works as an air spring to some degree to provide force to the working piston. In this work, in order to extend the external damping force range and improve the controlling efficiency, a structure of MRFD with three additional accumulators is proposed. These additional accumulators are connected to the atmosphere through an air pump and the compensation chamber with a barometric valve. The external damping force range thus can be rapidly adjusted through mode shifting with this configuration. A mathematical model of this damper with coupled effects between the air and the magnetorheological fluid (MRF) is developed. Comparing the bench tests results with some simulation outcomes, the simulation model of this MRFD is validated. Influences of moving speed of the working piston, air pressure and initial volume of the accumulators on the external performances are simulated. Simulation results tell that the coupled effects between the additional accumulators and the MRF can provide rapid…
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Simulation Research on Engine Speed Fluctuation Suppression Based on Engine Torque Observer by Using a Flywheel ISG

Dongfeng Commercial Vehicle-Weiqun Ren
Tsinghua University-Yaodong Hu, Fuyuan Yang, Lei Du, Minggao Ouyang
Published 2019-04-02 by SAE International in United States
This paper conducts simulation research on engine torque ripple suppression based on the engine torque observer by using a flywheel-ISG (integrated starter generator). Usually, engine torque can be suppressed by using a passive method such as by installing a flywheel or torsional damper. However, failure problems arise in hybrid system because of different mechanical characters of the engine and its co-axial ISG motor. On the prototype test bench, the flywheel of the engine has been removed and replaced by an ISG rotor, namely FISG (flywheel ISG). Besides, the crank and FISG rotor are directly connected, which means no dampers or clutches are installed. If the engine torque ripples can be suppressed by the same level as the flywheel and damper by FISG active torque compensation, the new system can be more compact and economical. Simulation efforts are made to verify its feasibility. Firstly, based on the experimental test bench, which is currently under construction. A mechanical model was built based on LMS AMESim. Secondly, the engine torque observer is built based on the simplified dual-lumped…
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A Study of Vibration Reducing Effect on Vehicle Dynamics by Hydraulic Damper on Body Structure

Honda R&D Co., Ltd.-Katsutoshi Tada, Ken Ito
Published 2019-04-02 by SAE International in United States
This research investigated the mechanism of the effects of hydraulic dampers, which are attached to vehicle body structures and are known by experience to suppress vehicle body vibration and enhance ride comfort and steering stability. In investigating the mechanism, we employed quantitative data from riding tests, and analytical data from simplified vibration models. In our assessment of ride comfort in riding tests using vehicles equipped with hydraulic dampers, we confirmed effects reducing body floor vibration in the low-frequency range. We also confirmed vibration reduction in unsprung suspension parts to be a notable mechanical characteristic which merits close attention in all cases. To investigate the mechanism of the vibration reduction effect in unsprung parts, we considered a simplified vibration model, in which the engine and unsprung parts, which are rigid, are linked to the vehicle body, which is an elastic body equipped with hydraulic dampers. Simulation analysis results revealed that vibration in unsprung parts is reduced by coupling the rigid vibration of the engine and unsprung parts with the elastic vibration of a vehicle body, equipped…
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