Non-linear modelling of a novel gas strut

2005 ◽  
Vol 219 (10) ◽  
pp. 1153-1164 ◽  
Author(s):  
B Gao ◽  
J Darling ◽  
D G Tilley ◽  
R A Williams ◽  
A Bean ◽  
...  
Keyword(s):  
Vehicle Suspension ◽  
Polytropic Index ◽  
Parametric Modelling ◽  
Nonlinear Characteristics ◽  
Highly Nonlinear ◽  
Linear Modelling ◽  
Non Linear ◽  
Vehicle Suspension System ◽  
Modelling Methods ◽  
Good Agreement

The strut is one of the most important components in a vehicle suspension system; however, it is also one of the most difficult elements to model owing to its highly nonlinear characteristics. In this paper a non-linear gas strut model built in the software package Bath fp is presented. Both analytical and parametric modelling methods were used in the representation of different components in the strut. Simulations at various frequencies showed good agreement with experimental results. A sensitivity analysis of strut performance is presented at the end of the paper. It was found that the damper valve characteristics, the rod diameter, the temperature, and the user-defined polytropic index significantly affect the strut performance.

Influence of Vehicle Suspension System on Ride Comfort

2011 ◽  
Vol 141 ◽  
pp. 319-322
Author(s):  
Jun Zhong Xia ◽  
Zong Po Ma ◽  
Shu Min Li ◽  
Xiang Bi An
Keyword(s):  
Degrees Of Freedom ◽  
Ride Comfort ◽  
Suspension System ◽  
Vehicle Suspension ◽  
Vehicle Model ◽  
Active Suspensions ◽  
Suspension Systems ◽  
Non Linear ◽  
Vehicle Suspension System

This paper focuses on the influence of various vehicle suspension systems on ride comfort. A vehicle model with eight degrees of freedom is introduced. With this model, various types of non-linear suspensions such as active and semi-active suspensions are investigated. From this investigation, we draw the conclusion that the active and semi-active suspensions models are beneficial for ride comfort.

Vibration Control Schemes of Semi- Active Hydro-Pneumatic Dampers for Military Vehicle Suspension

2006 ◽  
Author(s):  
N. Eslaminasab ◽  
M. F. Golnaraghi
Keyword(s):  
Ride Comfort ◽  
Suspension System ◽  
Vehicle Suspension ◽  
Control Methods ◽  
Nonlinear Characteristics ◽  
Suspension Systems ◽  
Car Model ◽  
Military Vehicle ◽  
Highly Nonlinear ◽  
Suspension Control

Hydro-pneumatic dampers are widely used in military and heavy vehicle suspension systems, where large suspension travel (more than 20 inches) is expected. Due to the nonlinear characteristics of these elements, suspension system performance and in particular ride comfort and road handling capabilities of the vehicle are altered. Although these nonlinear characteristics are inherent in nearly all vehicles suspension systems, their effects are dominant in certain maneuvers and especially in off-road conditions where the suspension system experiences rather large displacements. This paper investigates the control of a hydropneumatic damper suspension system, a highly nonlinear system comprised of a pneumatic spring (gas-spring) and a hydraulic damper. First, the hydro-pneumatic damper of a military vehicle is modeled. The model is validated using experiments performed with a dynamometer test machine. Based on the validated model, a 2DOF quarter car model is developed, simulated and analyzed. Secondly, the performance of two well-known semiactive control methods - Skyhook and Rakheja-Sankar (R-S) - are investigated as applied to suspension control in the 2DOF car model. To analyze the performance of these control strategies in the suspension systems where the nonlinear components exist, the method of averaging is deployed. Finally, a new control strategy based on Skyhook and R-S is proposed to address ride comfort and road handling utilizing the variable stiffness gas-spring together with a semiactive damper. The results of this new controller are then compared to that of several well known suspension control methods such as Skyhook to demonstrate the effectiveness of the method.

Laser Oscillation in Aggregates of Ultrasmall Si Nanoparticles

2002 ◽  
Vol 728 ◽  
Author(s):  
Munir H. Nayfeh
Keyword(s):  
Stimulated Emission ◽  
Gaussian Beams ◽  
Single Particles ◽  
Nonlinear Characteristics ◽  
Femtosecond Radiation ◽  
Highly Nonlinear ◽  
Line Narrowing ◽  
Si Nanoparticles ◽  
Speckle Patterns ◽  
Spectral Line Narrowing

AbstractWe dispersed electrochemically etched Si into ultrabright ultrasmall nanoparticles, with brightness higher than fluorescein or rhodamine. The emission from single particles is readily detectable. Aggregates or films of the particles exhibit emission with highly nonlinear characteristics. We observe directed blue beams at ∼ 410 nm between faces of aggregates excited by femtosecond radiation at 780 nm; and at ∼ 610 nm from aggregates of red luminescent Si nanoparticles excited by radiation at 550-570 nm from a mercury lamp. Intense directed Gaussian beams, a pumping threshold, spectral line narrowing, and speckle patterns manifest the emission. The results are analyzed in terms of population inversion and stimulated emission in quantum confinement-induced Si-Si dimer phase, found only on ultrasmall Si nanoparticles. This microlasing constitutes an important step towards the realization of a laser on a chip.

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