Roll Plane Analysis of Interconnected Hydro-Pneumatic Suspension Struts

2005 ◽  
Author(s):  
Dongpu Cao ◽  
Subhash Rakheja ◽  
Chun-Yi Su
Keyword(s):  
Heavy Vehicles ◽  
Vertical Stiffness ◽  
Fundamental Properties ◽  
Plane Analysis ◽  
Damping Characteristics ◽  
Pneumatic Suspension ◽  
Parametric Studies ◽  
Suspension Stiffness ◽  
Variable Damping ◽  
Stiffness And Damping

This study presents a compact hydro-pneumatic strut design with enhanced working area to reduce the design pressure requirements for suspension applications. The two struts are interconnected in the roll plane to realize enhanced roll properties of the suspension. The feedback effects of the interconnecting pipes on the suspension stiffness and damping properties are derived and discussed. The influences of fluid compressibility on the effective ride and roll properties are also investigated. Asymmetric and variable damping valves are further introduced to realize adequately damped and soft ride, and high low speed damping in the roll mode. Fundamental properties of the proposed interconnected configurations are derived and compared with those of the unconnected struts with an anti-roll bar, in terms of suspension vertical stiffness, roll stiffness, and vertical and roll mode damping. Parametric studies are also performed to study the role of interconnecting parameters on the essential suspension properties. The results indicate that interconnected suspension with inherent enhanced roll stiffness and damping characteristics offers significant potential to improve the dynamic roll performance of heavy vehicles, while retaining soft vertical ride. The effectiveness of the proposed concept is further illustrated through simulation results attained under two different deterministic excitations.

PROPERTIES OF AN INTERCONNECTED HYDRO-PNEUMATIC SUSPENSION SYSTEM

1995 ◽  
Vol 19 (4) ◽  
pp. 383-396 ◽  
Author(s):  
P.J. Liu ◽  
S. Rakheja ◽  
A.K.W. Ahmed
Keyword(s):  
Dynamic Properties ◽  
The Body ◽  
Ride Quality ◽  
Quality Performance ◽  
Fundamental Properties ◽  
Damping Characteristics ◽  
Load Carrying ◽  
Body Roll ◽  
Pneumatic Suspension ◽  
Stiffness And Damping

The static and dynamic properties of a vehicle suspension comprising hydraulic struts interconnected in the roll plane are investigated. The fundamental properties of the interconnected suspension are investigated and compared to those of the unconnected suspensions with and without the anti-roll bar, in terms of load-carrying capacity, suspension rate, roll stiffness as well as damping characteristics. The anti-roll performance of the interconnected suspension is analyzed for excitations encountered during directional manoeuvres. The ride quality performance is evaluated for excitations occurring at tire-road interface. It is concluded that the interconnected hydro-pneumatic suspension with inherent enhanced roll stiffness and damping characteristics can significantly restrict the body roll motion to achieve improved roll stability of a vehicle.

Investigation on Damping Characteristics of Double Chamber Hydro-Pneumatic Suspension Simulation and Experimental Research

2013 ◽  
Vol 712-715 ◽  
pp. 1662-1667
Author(s):  
Zong Qi Tan ◽  
Hua Ling Zhu ◽  
Dao Feng Zhuo ◽  
Ji Feng Ju
Keyword(s):  
Test Method ◽  
Excitation Signal ◽  
Damping Characteristics ◽  
Model And Simulation ◽  
Orthogonal Test Method ◽  
Pneumatic Suspension ◽  
Variable Damping ◽  
Set Up ◽  
Suspension Performance ◽  
Double Chamber

As to the optimization of double chamber hydro-pneumatic suspension,we researched the influence of excitation signal on the the damping characteristics. First of all, the double chamber hydro-pneumatic suspension nonlinear mathematical model and simulation model were set up to get the damping characteristic curves of different sources.And the influence of different factors was obtained according to the orthogonal test method. The results of the study show that the hydro-pneumatic suspension have nonlinear variable damping characteristics,the excitation signal with higher frequency and larger amplitude have superior damping effect;and the speed of the excitation signal have the biggest influence on its performance.The order of the influence of frequency (f), amplitude (A) and velocity (ν) to suspension performance is: ν>f>A.

Modeling and Analysis of a Self-Steering Axle for Heavy Vehicles

2018 ◽  
Author(s):  
Damon Delorenzis ◽  
Beshah Ayalew
Keyword(s):  
Steering System ◽  
Design Parameters ◽  
Heavy Vehicles ◽  
Vehicle Performance ◽  
Modeling And Analysis ◽  
Damping Characteristics ◽  
Traditional Design ◽  
Steering Mechanism ◽  
Stiffness And Damping ◽  
Market Pressures

Self-steering axles installed on commercial (heavy) vehicles offer important benefits, including improvements to vehicle performance such as off-tracking reduction and improved maneuverability, as well as reduction in pavement wear and damage that otherwise can result from the operation of heavy vehicles on the roadway. Traditional design methods for self-steering axles include empirical and trial-and-error methods to set steering mechanism design parameters based on known design baselines and prior experience. While the design of self-steering axles has not changed very much since their introduction, increasingly regulations and competitive market pressures have promoted the need for new designs to improve the performance of self-steering axles and differentiate new product offerings such as a new integrated steering knuckle concept which provides steering return stiffness and damping using a non-traditional design. This paper introduces models useful in the analysis of the steering return stiffness and damping performance of self-steering axle systems and shows how to identify the steering stiffness and damping characteristics that provide acceptable performance for these systems. The paper offers reduced order models that capture the self-steering axle’s shimmy behavior and discusses how to arrive at acceptable steering and damping characteristics. It presents results of the evaluations of the steering system performance including with comparisons between physical testing and simulations with a self-steering axle installed on a commercial vehicle.

Multidisciplinary Co-Simulation of All-Terrain Crane With the Hydro-Pneumatic Suspension and Multi-Bridges Steering System

2010 ◽  
Author(s):  
Gang Qin ◽  
Jinglai Wu ◽  
Yunqing Zhang ◽  
Liping Chen
Keyword(s):  
Control Strategy ◽  
Ride Comfort ◽  
Control Valve ◽  
Steering System ◽  
Damping Characteristics ◽  
Hydraulic Steering ◽  
Pneumatic Suspension ◽  
Stiffness And Damping ◽  
Multi Body ◽  
And Control

Hydro-pneumatic suspension and multi-bridges steering system, which can meet the demands of ride comfort and steering maneuverability of the crane by their excellent nonlinear stiffness and damping characteristics and innovative control technology in their electro-hydraulic rear axle steering system, is used for construction industry vehicles widely. Such systems have great influences on controllability, steering stability, driving comfort and safety of a vehicle. Such a complex system includes mechanical multi-body, hydraulic, and control components which are influenced each other. However, few previous works concerned the coupling effects from multidisciplinary view, in general just single domain detail model are built and studied. This paper presents a detailed 5 axle all-terrain crane with hydro-pneumatic suspension and multi-bridges steering system consisting of the mechanical parts of suspension and steering multi-body model with ADAMS, suspension and steering hydraulic model that contain cylinder, control valve, and hydraulic pipes, etc., and the control strategy are built with AMESim software. A co-simulation is carried out to study the handling and stability of the vehicle affected by the hydro-pneumatic suspension and electro-hydraulic steering system. Some typical handling maneuvers, such as cornering steering releasing test and pylon slalom course of test are carried out by co-simulation to evaluate the control strategy of the steering and hydro-pneumatic suspension performance numerically. Comparisons between measured data and simulation results validate the correctness of the model.

STUDY ON THE VERTICAL STIFFNESS AND DAMPING COEFFICIENT OF TRACTOR TIRE USING SEMI-EMPIRICAL MODEL

2013 ◽  
Vol 83 (5) ◽  
Author(s):  
Đỗ Minh Cường ◽  
Zhu shi Hong ◽  
Đinh Vương Hùng ◽  
Nguyễn Thị Ngọc
Keyword(s):  
Damping Coefficient ◽  
Inflation Pressure ◽  
Vertical Stiffness ◽  
Damping Characteristics ◽  
Increasing Trend ◽  
Tire Stiffness ◽  
Stiffness And Damping Coefficient ◽  
Stiffness And Damping ◽  
Semi Empirical ◽  
Rear Tire

An experiment was conducted to determine the vertical stiffness and damping characteristics of tractor tires for the aim of simulation and design of the tractor suspension system. Three kinds of tractor tires were selected to measure vertical stiffness and damping coefficient by using Free-Vibration Logarithm Decay Method at five levels of tire inflation pressures and two tire loads. The results show that, for all kinds of tire, the stiffness was linearly increased by increasing tire inflation pressure whereas the damping coefficient decreased when tire inflation pressure increased. The stiffness and damping coefficient of tractor tires also depend on the tire size, the structure of tires as front tire or rear tire. Additionally, the damping coefficient shows the increasing trend while the increase in tire stiffness is not clear by increasing tire load. The results also reveal that the appropriate distribution of tire load, tire inflation pressure and tire size can change significantly the tire stiffness and damping coefficient to control tractor vibration. Keywords: Tire stiffness; Damping coefficient; Tractor tire; Tire inflation pressure.

Double Rail Model and Turnout Simulation

2013 ◽  
Author(s):  
Xinggao Shu ◽  
Nicholas Wilson ◽  
David D. Davis
Keyword(s):  
Contact Point ◽  
Dynamic Performance ◽  
Geometry Optimization ◽  
Simulation Accuracy ◽  
Multibody Dynamic ◽  
Wholly Owned Subsidiary ◽  
Parametric Studies ◽  
Suspension Stiffness ◽  
Simulation Results ◽  
Stiffness And Damping

Transportation Technology Center, Inc., a wholly owned subsidiary of the Association of American Railroads, has developed a double rail model for special trackwork simulation in the NUCARS® vehicle/track interaction multibody dynamic simulation program. The double rail model consists of a primary rail and a secondary rail on each side of the track. it It permits one wheel to contact two rails so that the effects of their relative movements on wheel/rail contact can be investigated. It also allows rail profile and track suspension stiffness and damping to vary on the track. This paper presents simulation results of a freight car running on a No. 20 turnout. Simulation results showed that the double rail model improved the integration stability and simulation accuracy for high frequency wheel/rail (W/R) impacts by capturing the simultaneous multiple W/R contact point situations and transitions under various discontinuous track running surface conditions. Parametric studies of W/R impacts on frog points showed the frog point geometry designs have conflicting requirements for dynamic performance for vehicles equipped with with new wheels and hollow-worn wheels; the NUCARS double rail model provides a useful tool for frog and switch point geometry optimization.

Rotordynamic Performance of a Rotor Supported on Bump Type Foil Gas Bearings: Experiments and Predictions

2006 ◽  
Vol 129 (3) ◽  
pp. 850-857 ◽  
Author(s):  
Luis San Andrés ◽  
Dario Rubio ◽  
Tae Ho Kim
Keyword(s):  
High Speed ◽  
Critical Speed ◽  
Load Capacity ◽  
Test System ◽  
Foil Bearings ◽  
Rotor Imbalance ◽  
Synchronous Motion ◽  
Damping Characteristics ◽  
Rotor Surface ◽  
Stiffness And Damping

Gas foil bearings (GFBs) satisfy the requirements for oil-free turbomachinery, i.e., simple construction and ensuring low drag friction and reliable high speed operation. However, GFBs have a limited load capacity and minimal damping, as well as frequency and amplitude dependent stiffness and damping characteristics. This paper provides experimental results of the rotordynamic performance of a small rotor supported on two bump-type GFBs of length and diameter equal to 38.10mm. Coast down rotor responses from 25krpm to rest are recorded for various imbalance conditions and increasing air feed pressures. The peak amplitudes of rotor synchronous motion at the system critical speed are not proportional to the imbalance introduced. Furthermore, for the largest imbalance, the test system shows subsynchronous motions from 20.5krpm to 15krpm with a whirl frequency at ∼50% of shaft speed. Rotor imbalance exacerbates the severity of subsynchronous motions, thus denoting a forced nonlinearity in the GFBs. The rotor dynamic analysis with calculated GFB force coefficients predicts a critical speed at 8.5krpm, as in the experiments; and importantly enough, unstable operation in the same speed range as the test results for the largest imbalance. Predicted imbalance responses do not agree with the rotor measurements while crossing the critical speed, except for the lowest imbalance case. Gas pressurization through the bearings’ side ameliorates rotor subsynchronous motions and reduces the peak amplitudes at the critical speed. Posttest inspection reveal wear spots on the top foils and rotor surface.

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