Nonlinear Stability and Tracking of Rail Passenger Trucks

1982 ◽  
Vol 104 (3) ◽  
pp. 256-263 ◽  
Author(s):  
D. Horak ◽  
D. N. Wormley
Keyword(s):  
Critical Speed ◽  
Digital Simulation ◽  
Operating Conditions ◽  
Vehicle Suspension ◽  
Simulation Studies ◽  
Suspension Parameters ◽  
Significant Alignment ◽  
Power Spectral ◽  
Tracking Ability ◽  
Temporal Waveform

An analysis of a rail passenger truck which includes nonlinear wheel/rail geometry and creep forces is formulated for determining truck stability and response to rail alignment irregularities. Digital simulation studies using the analysis have illustrated the large amplitude flange to flange response which occurs in operation of a truck below critical speed on a track with significant alignment irregularity, of a truck near critical speed and excited by irregularities and of a truck operated above critical speed. The variations in temporal waveform, probability density, and power spectral density of vehicle motions for these conditions are described. The influence of vehicle suspension parameters and wheel/rail geometry on truck stability and tracking ability is discussed and related to operating conditions.

Nonlinear Stability of Rail Vehicles Traveling on Vibration-Attenuating Slab Tracks

2020 ◽  
Vol 15 (7) ◽  
Author(s):  
Liang Ling ◽  
Peibin Jiang ◽  
Kaiyun Wang ◽  
Wanming Zhai
Keyword(s):  
Limit Cycle ◽  
Nonlinear Stability ◽  
Critical Speed ◽  
Coupled Model ◽  
Ground Vibration ◽  
Vehicle Suspension ◽  
Lateral Stability ◽  
Hunting Behavior ◽  
Suspension Parameters ◽  
Rail Vehicles

Abstract Various vibration-attenuating slab tracks have been introduced into urban railways to minimize the negative effects of train-induced ground vibration and noise. However, compared with traditional slab tracks, vibration-attenuating slab tracks usually have a lower overall stiffness, which reduces the vehicle lateral stability. This paper presents an investigation of the nonlinear hunting stability of fast metro rail vehicles traveling on vibration-attenuating slab tracks. A three-dimensional vehicle–track coupled model considering different vibration-attenuating slab tracks is developed to investigate the nonlinear hunting behavior of metro vehicles running on different elastic vibration-attenuating tracks. The nonlinear critical speed and wheelset hunting limit cycle of two types of metro vehicles traveling on four typical types of vibration-attenuating tracks are compared in detail. The influences of vehicle–track system parameters, including rail fastener stiffness and vehicle suspension parameters, on the vehicle lateral nonlinear stability are reported. The results show that the flexibility of vibration-attenuating slab tracks leads to a large wheelset limit cycle and lowers the nonlinear critical speed. Increasing track lateral stiffness and designing appropriate vehicle suspension parameters can improve the lateral stability of rail vehicles traveling on vibration-attenuating slab tracks.

Analysis, Design, and Optimization of High Speed Vehicle Suspensions Using State Variable Techniques

1974 ◽  
Vol 96 (2) ◽  
pp. 193-203 ◽  
Author(s):  
J. K. Hedrick ◽  
G. F. Billington ◽  
D. A. Dreesbach
Keyword(s):  
High Speed ◽  
Optimization Problems ◽  
Vertical Plane ◽  
Computer Application ◽  
Vehicle Suspension ◽  
State Variables ◽  
State Variable ◽  
Suspension Parameters ◽  
Suspension Model ◽  
High Speed Vehicle

This article applies state variable techniques to high speed vehicle suspension design. When a reasonably complex suspension model is treated, the greater adaptability of state variable techniques to digital computer application makes it more attractive than the commonly used integral transform method. A vehicle suspension model is developed, state variable techniques are applied, numerical methods are presented, and, finally, an optimization algorithm is chosen to select suspension parameters. A fairly complete bibliography is included in each of these areas. The state variable technique is illustrated in the solution of two suspension optimization problems. First, the vertical plane suspension of a high speed vehicle subject to guideway and aerodynamic inputs will be analyzed. The vehicle model, including primary and secondary suspension systems, and subject to both heave and pitch motions, has thirteen state variables. Second, the horizontal plane suspension of a high speed vehicle subject to guideway and lateral aerodynamic inputs is analyzed. This model also has thirteen state variables. The suspension parameters of both these models are optimized. Numerical results are presented for a representative vehicle, showing time response, mean square values, optimized suspension parameters, system eigenvalues, and acceleration spectral densities.

scholarly journals Research on forest terrain roughness as a source of dynamic action on the vehicle

2017 ◽  
Vol 63 (No. 8) ◽  
pp. 363-369
Author(s):  
Mikleš Milan ◽  
Helexa Milan ◽  
Mikleš Juraj
Keyword(s):  
Correlation Function ◽  
Spectral Density ◽  
Power Spectral Density ◽  
Ground Surface ◽  
Operating Conditions ◽  
Mobile Object ◽  
Object A ◽  
Power Spectral ◽  
Gneiss Granite ◽  
Ground Conditions

The issue of terrain conditions is very complex and its description is approached from different perspectives and with different objectives. Because it consists of the gathering of basic information for a mobile object, a wheeled forestry tractor, the terrain-vehicle approach was taken as the basis. Ground conditions are part of the operating conditions of wheeled forestry tractors. Uneven ground can be regarded as a source of vibration in the vehicle – towing truck. In this respect, given the random shape of the surface roughness, the solution to vibrations leads to a terrain correlation analysis in order to obtain a correlation function and power spectral density of the ground surface. Scanning of the ground micro-profile was performed using a device for quick terrain scanning, which from the mechanical aspect consists of a towing vehicle and a measuring carriage. Correlation function and power spectral density are the evaluation based on ground micro-profile measurements and the results of calculations. Measurements of forest terrain (road) micro-profile were done in the area of Little Fatra and Little Carpathians in Slovakia. In geological terms, the measurements were done in an area with the occurrence of gneiss, granite, limestone and flysch. No measurements were performed in a sandy area.

scholarly journals Simulation Studies on the Effect of Material Characteristics and Runners Layout Geometry on the Filling Imbalance in Geometrically Balanced Injection Molds

Polymers ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 639 ◽  
Author(s):  
Krzysztof Wilczyński ◽  
Przemysław Narowski
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Relaxation Time ◽  
Thermal Diffusivity ◽  
Shear Rate ◽  
Transfer Coefficient ◽  
Operating Conditions ◽  
Optimization Approach ◽  
Simulation Studies ◽  
Layout Geometry

Simulation studies were performed on filling imbalance in geometrically balanced injection molds. A special simulation procedure was applied to simulate properly the phenomenon, including inertia effects and 3D tetrahedron meshing as well as meshing of the nozzle. The phenomenon was investigated by simulation using several different runner systems at various thermo-rheological material parameters and process operating conditions. It has been observed that the Cross-WLF parameters, index flow, critical shear stress (relaxation time), and zero viscosity, as well as thermal diffusivity and heat transfer coefficient strongly affect the filling imbalance. The effect is substantially dependent on the runners’ layout geometry, as well as on the operating conditions, flow rate, and shear rate. The standard layout geometry and the corrected layout with circled element induce positive imbalance which means that inner cavities fills out faster, and it is opposite for the corrected layouts with one/two overturn elements which cause negative imbalance. Generally, for the standard layout geometry and the corrected layout with circled element, an effect of the zero shear rate viscosity η0 is positive (imbalance increases with an increase of viscosity), and an effect of the power law index n and the relaxation time λ is negative (imbalance decreases with an increase of index n and relaxation time λ). An effect of the thermal diffusivity α and heat transfer coefficient h is negative while an effect of the shear rate is positive. For the corrected layouts with one/two overturn elements, the results of simulations indicate opposite relationships. A novel optimization approach solving the filling imbalance problem and a novel concept of global modeling of injection molding process are also discussed.

Parametric Optimization of Structures Under Combined Base Motion Direct Forces and Static Loading

1998 ◽  
Vol 124 (1) ◽  
pp. 132-140 ◽  
Author(s):  
Izhak Bucher
Keyword(s):  
Degrees Of Freedom ◽  
Structural Parameters ◽  
Operating Conditions ◽  
Design Parameters ◽  
Power Spectral ◽  
Loading Patterns ◽  
The Cost ◽  
Selection Of ◽  
Eigenvectors And Eigenvalues

This paper deals with the optimization of vibrating structures as a mean for minimizing unwanted vibration. Presented in this work is a method for automatic determination of a set of preselected design parameters affecting the geometrical layout or shape of the structure. The parameters are selected to minimize the dynamic response to external forcing or base motion. The presented method adjusts the structural parameters by solving an optimization problem in which the constraints are dictated by engineering considerations. Several constraints are defined so that the static deflection, the stress levels and the total weight of the structure are kept within bounds. The dynamic loading acting upon the structure is described in this work by its power spectral density, with this representation the structure can be tailored to specific operating conditions. The uncertain nature of the excitation is overcome by combining all possible spectra into one PSD encompassing all possible loading patterns. An important feature of the presented method is its numerical efficiency. This feature is essential for any reasonably sized problem as such problems are usually described by thousands of degrees of freedom arising from a finite-element idealization of the structure. In this paper, efficient, closed form expressions, for the cost function and its gradients are derived. Those are computed with a partial set of eigenvectors and eigenvalues thus increasing the efficiency further. Several numerical examples are presented where both shape optimization and the selection of discrete components are illustrated.

Control of Maglev Suspension Systems

1996 ◽  
Vol 2 (3) ◽  
pp. 349-368 ◽  
Author(s):  
Y. Cai ◽  
S.S. Chen
Keyword(s):  
Degrees Of Freedom ◽  
Ride Comfort ◽  
Vehicle Suspension ◽  
Semiactive Control ◽  
One Dimensional ◽  
Suspension Systems ◽  
Maglev Vehicle ◽  
Power Spectral ◽  
Power Spectral Densities ◽  
Control Designs

This study investigates alternate designs for control of maglev vehicle suspension systems. Active and semiactive control-law designs are introduced into primary and secondary suspensions of maglev vehi cles. A one-dimensional vehicle with two degrees of freedom, simulating the German Transrapid Magiev System, is used. The transient and frequency responses of suspension systems and power spectral densities of vehicle accelerations are calculated to evaluate different control designs. The results show that both active and semiactive control designs improve vehicle response and provide acceptable ride comfort for maglev systems.

Polymer spur gears behaviors under different loading conditions: A review

2017 ◽  
Vol 232 (2) ◽  
pp. 210-228 ◽  
Author(s):  
Akant Kumar Singh ◽  
Siddhartha ◽  
Prashant Kumar Singh
Keyword(s):  
Modeling And Simulation ◽  
Polymer Composites ◽  
Tribological Properties ◽  
Failure Modes ◽  
Operating Conditions ◽  
Spur Gears ◽  
Simulation Studies ◽  
Loading Conditions ◽  
Comprehensive Review ◽  
Tooth Modification

The significance of polymer gears to transmit power and motion is increasing continuously due to their inherent characteristics. Polymer gears have established themselves as attractive alternatives to traditional metal gears in plethora applications. They are light in weight, have lower inertia, and run noiseless than their metal counterparts. This article presents a comprehensive review of the research on polymer spur gears operating under low (0–8 Nm) and moderate (>8 and ≤17 Nm) loading conditions. Different polymers and polymer composites used till date for the fabrication of such gears are included along with different operating conditions. Various design features of polymer gears and tooth modification techniques for the improvement of the performance and durability of these gears have also been included in this review. The aspects of the modeling and simulation studies of the polymer gears are also emphasized in this paper for completeness of the review. The concept of hybrid gears is discussed along with their tribological properties. Various methods of manufacturing of polymer gears and their failure modes are discussed so as to make the article useful for researchers.

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