Variation Of Lateral Force Research Articles

Analysis on the effect of lateral force variation induced by the lubrication condition between wheel and rail for diagonal wheel load unbalance of railway bogie

Analysis on the effect of lateral force variation induced by the lubrication condition between wheel and rail for diagonal wheel load unbalance of railway bogie

Development of mathematical model for real time estimation and comparison of individual lateral tire force generation

All the forces and torque generated by the powertrain are transmitted through the tires to the ground. Hence intensive study on the generation of longitudinal and lateral forces and its characteristic behavior in real time conditions is paramount. Proper understanding of the change of tire parameters such as slip ratio and slip angle in real time condition will lead to a smart onboard vehicle control system. After extensive study on control systems used in vehicles such as ESC, it is seen that the system relies on driver intended path by monitoring steering angle input and makes decision on basis of difference in intended path and actual path. But this system does not give any idea to the ECU about the rate of change of slip angle which is very important for proper mathematical understanding of behavior of vehicle while cornering since it is the slip angle because of which tire develops lateral force. This project emphasizes on lateral dynamics and aims to determine slip angle and henceforth lateral force of each tire by using two track model in Simulink. The real time data obtained is compared to the existing raw tire data at particular vertical load condition and conclusion is made on the percentage variation of lateral force. Various steady state analysis and response including path curvature and yawing velocity also shows the handling characteristics of the vehicle such as understeering or oversteering while cornering. This way of determination leads to a better approximation and understanding of the behavior of tires in real time. The system along with sophisticated higher degree of freedom models can also be used as a closed loop system along with stability control system to predict the behavior of vehicle and enhance vehicle performance both in straight lines and corners.

Influence of hinge length and distribution number on the camber and cornering properties of a non-pneumatic tire

The camber and cornering properties of the tire directly affect the handling stability of vehicles, especially in emergencies such as high-speed cornering and obstacle avoidance. The structural and load-bearing mode of non-pneumatic mechanical elastic (ME) wheel determine that the mechanical properties of ME wheel will change when different combinations of hinge length and distribution number are adopted. The camber and cornering properties of ME wheel with different hinge lengths and distributions were studied by combining finite element method (FEM) with neural network theory. A ME wheel back propagation (BP) neural network model was established, and the additional momentum method and adaptive learning rate method were utilized to improve BP algorithm. The learning ability and generalization ability of the network model were verified by comparing the output values with the actual input values. The camber and cornering properties of ME wheel were analyzed when the hinge length and distribution changed. The results showed the variation of lateral force and aligning torque of different wheel structures under the combined conditions, and also provided guidance for the matching of wheel and vehicle performance.

Hydrodynamic Forces Measurement in Still Water Tank and Theoretical Validation of a Bio-Dorsal Fin Propulsive System

The simulation level of prototypes mimicking torsional wave propulsion is low at present. A new prototype which uses a combination of crank and rocker mechanisms and pleated-skirt-pattern membrane is presented in this paper. The prototype’s dorsal fin is of high fidelity, the waveform looks pretty smooth and the wave amplitude can reach 85 degrees. In still pool, measurement of thrust and lateral force of dorsal fin were performed with a one-component balance. The experimental results show: 1. the thrust on the dorsal fin has periodic variation, and the frequency of thrust variation is twice the fin frequency. 2. The lateral force on the dorsal fin also has periodic variation, and the frequency of lateral force variation is the same as the fin frequency. 3. The periodic mean thrust on the dorsal fin is proportional to the square of fin frequency, and the influence of fin frequency on dorsal fin is stronger as wave number increases. 4. The computed results of large-amplitude EBT coincide qualitatively with experimental result, but our computed propulsive forces are quantitatively smaller. (This work was supported by the National Natural Science Foundation of China (10572151).)

Ultrasensitive detection of lateral atomic-scale interactions on graphite (0001) via bimodal dynamic force measurements

Enhanced sensitivity to lateral forces on the nominally flat and inert (0001) surface of graphite is demonstrated via room-temperature dynamic force microscopy using simultaneous excitation and FM detection of the lowest flexural and torsional cantilever resonance modes. The site-independent long-range tip-sample interaction causes no significant lateral force variations except near atomic steps but unprecedented sensitivity to short-range forces is achieved on flat terraces in the attractive range. Two-dimensional bimodal force vs distance maps confirm the stronger distance dependence of the torsional frequency shift compared to the flexural resonance shift. This agrees with model calculations based on theoretical expressions. The lateral force gradient is extracted from the measured torsional shift, and a lateral force variation in at most $\ifmmode\pm\else\textpm\fi{}20\text{ }\text{pN}$ is obtained by integrating this gradient parallel to the surface. A further integration reveals a potential-energy variation in the attractive force range of only 3 meV.

Atomic scale study of superlow friction between hydrogenated diamond surfaces

Strong attractive interaction between two clean diamond (001) slabs turns repulsive upon the hydrogenation of surfaces. This repulsive interaction serves as if a boundary lubricant and prevents the sliding surfaces from being closer to each other even under high normal forces. As a result, calculated lateral force variation generated during sliding has small magnitude under high constant loading forces. Superlow friction observed earlier between diamondlike carbon-coated surfaces can be understood by the steady repulsive interaction between sliding surfaces, as well as strong and stiff carbon-carbon and carbon-hydrogen bonds which do not favor energy dissipation. In ambient conditions, the steady repulsive interaction is, however, destroyed by oxygen atoms which chemically modify those stiff surface bonds.

On micro scanning forces under the coupling deformation of atomic force microscope probe

Micro cantilever probe of atomic force microscope (AFM) is a typical micro mechanical component, which is under a coupling deformation during the contact scanning process. Numerical simulations of micro scanning forces and micro topography are presented to investigate the influence of the coupling deformation of AFM probe under the AFM contact mode. It is demonstrated that the normal scan force is actually not constant, which is coupled with the lateral force on an asperity of sample surface, increasing together uphill and decreasing together downhill. The coupling relationship increases with the surface slope, tip height, etc. Coupling deformation of the probe proves to play a minor role on the AFM micro topography image and the perpendicular scan force. However, surface slope plays an important role on the variation of lateral force, and the peak positions of lateral force are not accordant with that of surface topography. These results are in good agreement with those previous AFM experiments.

The Definition of the Tires Limit of Admissible Nonuniformity by Using the Vehicle Vibratory Model

Purpose of this article was to especially emphasize the contribution of tires nonuniformity radial and lateral force variation to vehicles vibrations, within developed nonlinear dynamic model of a vehicle. The tire nonuniformity force variations are introduced in simulations processes by radial and lateral dynamic forces in the area of wheels-road contact. The limits of admissible Peak - to - Peak radial and lateral force variation and Peak - to - Peak first harmonic radial and lateral force variation nonuniformity were defined by using a vehicle vibratory model. The tire nonuniformity parameters were defined from the aspect of vertical seat cushion and the steering wheel rim vibrations using the developed optimization program and the Pentium 90 MHz computer.