Twin Tube Shock Absorber Thermo-Mechanical Coupling Simulation

2012 ◽  
Vol 566 ◽  
pp. 669-675 ◽  
Author(s):  
Liang Liang ◽  
Liang Tian ◽  
Yun Qing Zhang ◽  
Jie Zhang
Keyword(s):  
Shock Absorber ◽  
Internal Flow ◽  
Ambient Air ◽  
Operating Characteristics ◽  
Working Process ◽  
Damping Force ◽  
Mechanical Coupling ◽  
First Law Of Thermodynamics ◽  
Convection Correlation ◽  
Energy Conservation Law

During the working process, temperature of the oil increases and its viscosity decreases due to the damping force, resulting in changes in operating characteristics of the shock absorber. This paper firstly analyzes the mechanism of themogenesis and heat transfer means of shock absorber in details, and then establishes the thermodynamic model of shock absorber with the energy conservation law and the first law of thermodynamics on this basis. After a comparison between the simulation results and the experimental results, causes of error will be analyzed. The study shows that the more influential correlations are the internal flow convection correlation used between the oil of the different chambers and the tubes of the shock absorber and the external flow convection correlation between the outside tube of the shock absorber and the ambient air.

Feasibility Study on Active Control of Hydraulic Electromagnetic Energy-Regenerative Absorber

2010 ◽  
Vol 139-141 ◽  
pp. 2631-2635 ◽  
Author(s):  
Lin Xu ◽  
Xue Xun Guo ◽  
Jun Yan
Keyword(s):  
Active Control ◽  
Shock Absorber ◽  
Hydraulic Structure ◽  
Electrical Energy ◽  
Vibration Energy ◽  
Working Process ◽  
Damping Force ◽  
Compression Stroke ◽  
New Type ◽  
Test Result

This paper proposes a design of a new shock absorber with combined mechanical- electromagnetic- hydraulic structure, and expounds its working principles. This new type of absorber can recyle the vibration energy and transform it into electrical energy for use. However, in its working process, the damping force in extension stroke is always smaller than that in compression stroke, which is determined by the inner structure, while in traditional absorbers, it is just the opposite. This does not meet the practical demands. Directing at this problem, the paper puts out a way to make real-time adjustment to the damping force by controlling the generator load, and tests the feasibility with a simulation model built with AMESim. The test result reveals that the method is feasible. This contributes a lot to the future further research on active control.

Double Adjustable Shock Absorbers Utilizing Electrorheological and Magnetorheological Fluids

2000 ◽  
Author(s):  
Jason E. Lindler ◽  
Norman M. Wereley
Keyword(s):  
Shock Absorber ◽  
Force Measurements ◽  
Damping Force ◽  
University Of Maryland ◽  
Shock Absorbers ◽  
Piston Head ◽  
Performance Requirements ◽  
Velocity Response ◽  
The University ◽  
Yield Force

Abstract Double adjustable shock absorbers allow for independent adjustment of the yield force and post-yield damping in the force versus velocity response. To emulate the performance of a conventional double adjustable shock absorber, an electrorheological (ER) and magnetorheological (MR) automotive shock absorber were designed and fabricated at the University of Maryland. For the ER shock absorber, an applied electric field between two tubular electrodes, located in the piston head, increases the force required for a given piston rod velocity. For the MR shock absorber, an applied magnetic field between the core and flux return increases the force required for a given piston rod velocity. For each shock absorber, two different shaped gaps meet the controllable performance requirements of a double adjustable shock absorber. A uniform gap allows for control of the yield force of the shock absorber, while a non-uniform gap allows for control of the post-yield damping. Force measurements from sinusoidal displacement cycles, recorded on a mechanical damper dynamometer, validate the performance of uniform and non-uniform gaps for adjustment of the yield force and post-yield damping, respectively.

Electromagnetic Shock Absorbers for Automotive Suspensions: Electromechanical Design

2006 ◽  
Author(s):  
Nicola Amati ◽  
Aldo Canova ◽  
Fabio Cavalli ◽  
Stefano Carabelli ◽  
Andrea Festini ◽  
...  
Keyword(s):  
Shock Absorber ◽  
Dynamic Performance ◽  
Integrated Design ◽  
Design Procedure ◽  
Resistive Load ◽  
Added Resistance ◽  
Damping Force ◽  
Quarter Car Model ◽  
Car Model ◽  
Shock Absorbers

This article illustrates the modeling and design of electromechanical shock absorbers for automotive applications. Relative to the commonly used hydraulic shock absorbers, electromechanical ones are based on the use of linear or rotative electric motors. If electric motor is of the DC-brushless type, the shock absorber can be devised by shunting its electric terminals with a resistive load. The damping force can be modified by acting on the added resistance. An integrated design procedure of the electrical and mechanical parameters is presented in the article. The dynamic performance that can be obtained by a vehicle with electromechanical dampers is verified on a quarter car model.

Design and analysis of an integrated sliding mode control–two-point wheelbase preview strategy for a semi-active air suspension with stepper motor-driven gas-filled adjustable shock absorber

2018 ◽  
Vol 232 (9) ◽  
pp. 1194-1211 ◽  
Author(s):  
Jing Zhao ◽  
Pak Kin Wong ◽  
Xinbo Ma ◽  
Zhengchao Xie
Keyword(s):  
Sliding Mode Control ◽  
Shock Absorber ◽  
Sliding Mode ◽  
Single Point ◽  
Rear Wheel ◽  
Suspension System ◽  
Stepper Motor ◽  
Damping Force ◽  
Mode Control ◽  
Air Suspension

This article proposes an integrated sliding mode control–two-point wheelbase preview strategy for semi-active air suspension system with gas-filled adjustable shock absorber. First of all, a vehicle suspension model with rolling lobe air spring and gas-filled adjustable shock absorber is built, following with a road input model for the front wheel. By describing the detailed structure and working process of the gas-filled adjustable shock absorber, the regulating mechanism between the stepper motor and the designed gas-filled adjustable shock absorber is established. Subsequently, the sliding mode control algorithm is applied to generate the desired damping force with the real-time state of the vehicle. Moreover, to predetermine the road profile for the rear wheel, a two-point wheelbase preview approach is proposed and its superiority is also illustrated as compared with the conventional single-point wheelbase preview approach. To evaluate the performance of the proposed system, numerical analysis is conducted with other three comparative schemes, namely, passive suspension system, active suspension system with H infinity control, and sliding mode control–controlled semi-active air suspension system with adjustable shock absorber. Simulation results show that the integrated sliding mode control–two-point wheelbase preview strategy can be successfully utilized in the semi-active air suspension system with stepper motor-driven gas-filled adjustable shock absorber, and the vehicle performance with the proposed system can be greatly improved.

scholarly journals Evaluation of the accuracy of thermal dissociation CRDS and LIF techniques for atmospheric measurement of reactive nitrogen species

2017 ◽  
Vol 10 (5) ◽  
pp. 1911-1926 ◽  
Author(s):  
Caroline C. Womack ◽  
J. Andrew Neuman ◽  
Patrick R. Veres ◽  
Scott J. Eilerman ◽  
Charles A. Brock ◽  
...  
Keyword(s):  
Conversion Efficiency ◽  
Reactive Nitrogen Species ◽  
Thermal Dissociation ◽  
Ambient Air ◽  
Reactive Nitrogen ◽  
Organic Nitrates ◽  
Nitrogen Species ◽  
Operating Characteristics ◽  
Experimental Conditions ◽  
Standard Additions

Abstract. The sum of all reactive nitrogen species (NOy) includes NOx (NO2 + NO) and all of its oxidized forms, and the accurate detection of NOy is critical to understanding atmospheric nitrogen chemistry. Thermal dissociation (TD) inlets, which convert NOy to NO2 followed by NO2 detection, are frequently used in conjunction with techniques such as laser-induced fluorescence (LIF) and cavity ring-down spectroscopy (CRDS) to measure total NOy when set at > 600 °C or speciated NOy when set at intermediate temperatures. We report the conversion efficiency of known amounts of several representative NOy species to NO2 in our TD-CRDS instrument, under a variety of experimental conditions. We find that the conversion efficiency of HNO3 is highly sensitive to the flow rate and the residence time through the TD inlet as well as the presence of other species that may be present during ambient sampling, such as ozone (O3). Conversion of HNO3 at 400 °C, nominally the set point used to selectively convert organic nitrates, can range from 2 to 6 % and may represent an interference in measurement of organic nitrates under some conditions. The conversion efficiency is strongly dependent on the operating characteristics of individual quartz ovens and should be well calibrated prior to use in field sampling. We demonstrate quantitative conversion of both gas-phase N2O5 and particulate ammonium nitrate in the TD inlet at 650 °C, which is the temperature normally used for conversion of HNO3. N2O5 has two thermal dissociation steps, one at low temperature representing dissociation to NO2 and NO3 and one at high temperature representing dissociation of NO3, which produces exclusively NO2 and not NO. We also find a significant interference from partial conversion (5–10 %) of NH3 to NO at 650 °C in the presence of representative (50 ppbv) levels of O3 in dry zero air. Although this interference appears to be suppressed when sampling ambient air, we nevertheless recommend regular characterization of this interference using standard additions of NH3 to TD instruments that convert reactive nitrogen to NO or NO2.

scholarly journals Numerical simulation of the non-uniform flow in a full-annulus multi-stage axial compressor with the harmonic balance method

2020 ◽  
Vol 12 (3) ◽  
pp. 168781401989721 ◽  
Author(s):  
Haiou Sun ◽  
Meng Wang ◽  
Zhongyi Wang ◽  
Song Wang ◽  
Franco Magagnato
Keyword(s):  
Flow Field ◽  
Harmonic Balance ◽  
Axial Compressor ◽  
Harmonic Balance Method ◽  
Internal Flow ◽  
Uniform Flow ◽  
Experimental Results ◽  
Balance Method ◽  
Operating Characteristics ◽  
Multi Stage

To improve the understanding of unsteady flow in modern advanced axial compressor, unsteady simulations on full-annulus multi-stage axial compressor are carried out with the harmonic balance method. Since the internal flow in turbomachinery is naturally periodic, the harmonic balance method can be used to reduce the computational cost. In order to verify the accuracy of the harmonic balance method, the numerical results are first compared with the experimental results. The results show that the internal flow field and the operating characteristics of the multi-stage axial compressor obtained by the harmonic balance method coincide with the experimental results with the relative error in the range of 3%. Through the analysis of the internal flow field of the axial compressor, it can be found that the airflow in the clearance of adjacent blade rows gradually changes from axisymmetric to non-axisymmetric and then returns to almost completely axisymmetric distribution before the downstream blade inlet, with only a slight non-axisymmetric distribution, which can be ignored. Moreover, the slight non-axisymmetric distribution will continue to accumulate with the development of the flow and, finally, form a distinct circumferential non-uniform flow field in latter stages, which may be the reason why the traditional single-passage numerical method will cause certain errors in multi-stage axial compressor simulations.

Magnitude of Axle Tramp Response to Partially Detreaded Tire Imbalance in Highway-Speed Driving

2012 ◽  
Author(s):  
Paul T. Semones ◽  
David A. Renfroe
Keyword(s):  
High Speed ◽  
Rear Axle ◽  
Shock Absorber ◽  
The United States ◽  
Damping Force ◽  
Shock Absorbers ◽  
Light Trucks ◽  
Single Vehicle ◽  
Frontal Collisions ◽  
Rear Tire

Tire tread separations on light trucks and SUVs have resulted in numerous catastrophic highway accidents over the past two decades in the United States. These accidents frequently involve single-vehicle rollovers or deviations of the impaired vehicle into oncoming traffic, where high speed frontal collisions may ensue. On light trucks and SUVs equipped with a Hotchkiss rear suspension, one explanation for the loss of driver control during an in-process rear tire tread separation is solid axle tramp response to the imbalanced separating tire. This explanation has met with some controversy. The present study will demonstrate that the imbalance forces generated at highway speeds from a partially detreaded tire are sufficient to induce continuous cyclical axle tramp, and can even be sufficient to completely elevate rear-axle tires out of contact with the paved roadway. This imbalance-induced tramping action may be exacerbated during braking and the vehicle’s terminal yaw, when rear traction is crucial to avoiding a catastrophic accident. In addition to test data, several field examples of such events are presented. A key metric of solid axle response to an imbalanced, partially detreaded tire is shock absorber motion. In the present study, shock absorber displacement on the test vehicles, as measured during highway speed tread separation axle tramp events, is found to oscillate through a stroke generally less than one inch (2.5 cm) in length at a frequency in excess of 10 Hz. Peak instantaneous velocities of the shock absorber have been observed as high as 40 in/s (16 cm/s) or more during straight driving under axle tramp conditions. Confirming several previously published findings, the present study shows that increasing shock damping force at the higher operational velocities of the shock absorber reduces the magnitude of axle tramp and assists in keeping the rear axle tires in contact with the ground. Additionally, increasing the distance between the shock absorbers by moving them closer to the wheels provides the same advantage.

scholarly journals Modeling and Analysis of a Hydraulic Energy-Harvesting Shock Absorber

2020 ◽  
Vol 2020 ◽  
pp. 1-11 ◽  
Author(s):  
Zhifei Wu ◽  
Guangzhao Xu
Keyword(s):  
Energy Harvesting ◽  
External Load ◽  
Energy Recovery ◽  
Shock Absorber ◽  
Load Resistance ◽  
Hydraulic Motor ◽  
Damping Force ◽  
Modeling And Analysis ◽  
Unidirectional Flow ◽  
Energy Dissipated

This paper proposes a hydraulic energy-harvesting shock absorber prototype, which realizes energy harvesting of the vibration energy dissipated by the automobile suspension system. The structural design of the proposed shock absorber ensures that the unidirectional flow of oil drives the hydraulic motor to generate electricity while obtaining an asymmetrical extension/compression damping force. A mathematical model of the energy-harvesting shock absorber is established, and the simulation results indicate that the damping force can be controlled by varying the load resistance of the feed module, thus adjusting the required damping force ratio of the compression and recovery strokes. By adjusting the external load, the target indicator performance of the shock absorber is achieved while obtaining the required energy recovery power. A series of experiments are conducted on the prototype to verify the validity of the damping characteristics and the energy recovery efficiency as well as to analyze the effect of external load and excitation speed on these characteristics.

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