Showing papers on "Slip ratio published in 1989"

Simulations of contact-line motion: Slip and the dynamic contact angle

Abstract: Molecular-dynamics simulations of two immiscible fluids confined between solid walls and sheared in a Couette geometry were performed as a function of shear rate for a range of wall and fluid properties. Changes with capillary number in the interface shape and dynamic contact angle were consistent with previous analytic results. Computed velocity fields showed that the usual no-slip boundary condition broke down within \ensuremath{\sim}2 atomic spacings from the contact line. The slip appears to be associated with the breakdown of local hydrodynamic theory at atomic scales.

Slip Effects in Capillary and Parallel Disk Torsional Flows of Highly Filled Suspensions

Abstract: The shear viscosity material function of a highly filled suspension consisting of a Newtonian poly(butadiene acrylonitrile acrylic acid terpolymer) matrix, PBAN, mixed with an ammonium sulfate filler at 60% by volume was studied. Both capillary and parallel disk torsional flows were employed. The rheological characterization revealed strong slip of the suspension at the walls over a broad range of shear stresses in both types of flows. The slip velocity increased approximately linearly with the shear stress. In capillary flows, above a critical shear stress, flow took place in a pluglike manner, owing to slip at the wall. The experimental findings were further elucidated to determine the slip layer thickness and the apparent shear viscosity behavior of highly filled suspensions at high shear stress at the wall values. It was concluded that the slip effects dominate the flow of highly filled suspensions and the true flow and deformation characteristics of the highly filled suspensions may be overshadowed by slip at the walls.

A cohesive zone model for dynamic shear faulting based on experimentally inferred constitutive relation and strong motion source parameters

Abstract: To understand constitutive behavior near the rupture front during an earthquake source shear failure along a preexisting fault in terms of physics, local breakdown processes near the propagating tip of the slipping zone under mode II crack growth condition have been investigated experimentally and theoretically. A physically reasonable constitutive relation between cohesive stress τ and slip displacement D, τ = (τi − τd)[1 + α log (1 + βD)] exp (−ηD) + τd, is put forward to describe dynamic breakdown processes during earthquake source failure in quantitative terms. In the above equation, τi is the initial shear stress on the verge of slip, τd is the dynamic friction stress, and α, β, and η are constants. This relation is based on the constitutive features during slip failure instabilities revealed in the careful laboratory experiments. These experiments show that the shear stress first increases with ongoing slip during the dynamic breakdown process, the peak stress is attained at a very (usually negligibly) small but nonzero value of the slip displacement, and then the slip-weakening instability proceeds. The model leads to bounded slip acceleration and stresses at and near the dynamically propagating tip of the slipping zone along the fault in an elastic continuum. The dynamic behavior near the propagating tip of the slipping zone calculated from the theoretical model agrees with those observed during slip failure along the preexisting fault much larger than the cohesive zone. The model predicts that the maximum slip acceleration be related to the maximum slip velocity and the critical displacement Dc by , where k is a numerical parameter, taking a value ranging from 4.9 to 7.2 according to a value of τi/τp (τp being the peak shear stress) in the present model. The model further predicts that be expressed in terms of and the cut off frequency fmaxs of the power spectral density of the slip acceleration on the fault plane as and that in terms of Dc and fmaxs as . These theoretical relations agree well with the experimental observations and can explain interrelations between strong motion source parameters for earthquakes. The pulse width of slip acceleration on the fault plane is directly proportional to the time Tc required for the crack tip to break down, and fmaxs is inversely proportional to Tc.

Temperature jump and thermal creep slip: Rigid sphere gas

Abstract: The half‐space problems of temprature jump and thermal creep slip are solved for a rigid sphere gas based on the linearized Boltzmann equation The SN method is used, and it is shown that accurate results for the jump/slip coefficients and the temperature, density, and velocity can be obtained in relatively short computational times The previously reported variational results for the jump/slip coefficients are found to be quite good (1%–3% error) It is noted, however, that for rigid sphere molecules the Knudsen layer is somewhat thinner than for the BGK model The creep slip coefficient is in good agreement with the experimental data of Annis [J Chem Phys 57, 2898 (1972)], but for other quantities experimental data are needed

Velocity slip and defect: Hard sphere gas

Abstract: The half‐space problem of rarefied gas flow (the Kramers problem) is considered and use of the SN algorithm is outlined. Accurate numerical results for the velocity slip coefficient and velocity defect are obtained for a hard sphere gas and are compared with previously reported results and experimental data.

Some basic studies on the influence of surface contamination on adhesion force between wheel and rail at higher speeds

Abstract: In order to investigate basically the influence of wheel/rail surface contamination on the adhesion force at higher speeds, traction force and slip ratio were measured with two types of rolling contact testing machines by taking a small amount of liquid paraffin as a contaminating model. And some theoretical analyses were done on the traction-slip relationship as well as the maximum traction coefficient, that is, the adhesion coefficient by taking account of the static and kinetic friction coefficients as well as contact rigidity.

Method for predicting a speed of a vehicle which is equipped with an antilock brake device

Abstract: The present invention is a method for estimating the speed of a vehicle with antilock brake devices by obtaining a vehicle speed as a reference value for determining a slip ratio of a wheel based upon a wheel speed, an acceleration and a deceleration. At least the deceleration is based upon a differentiated value of a highest wheel speed from all wheels. In a vehicle in which the drive wheels are rigidly coupled, at least the deceleration is based upon a differentiated value of a highest value of the lowest wheel speed of the drive wheels and the wheel speeds of the driven wheels.

Slip flow and slip boundary coefficient of a dense fluid via nonequilibrium molecular dynamics

Abstract: The velocity slip of a dense fluid undergoing a plane shear flow is investigated by nonequilibrium molecular dynamics. The flow is driven by moving walls. The particles in the walls are pulled by localized force fields. The resulting velocity profiles exhibit a well-defined velocity slip which depends linearly on the velocity gradient in the bulk.

Slip control device for fluid joint

Abstract: PURPOSE: To produce an acceleration feeling even during the change of a running load by providing a means to detect a running load and a means to receive an output from the detecting means to correct the engaging force of a lockup clutch in response to a detected running load CONSTITUTION: In a step S2, a car speed V, a throttle opening θ, the number NE of revolutions of an engine, the number NT of revolutions of a turbine, and a gear shifting step position G are read from respective sensors to compute a slip ratio NS A car weight W and a car body gradient α are read from respective sensors, and respective correction factors Cw and Ca are read from a map to compute a target slip amount No A deviation ▵N between a present actual slip amount NS and a target slip ratio No is determined, and when it is decided that a present operation area is in a slip control area, control parameters A and B are decided, a feedback amount U is computed, and a duty correction amount ▵dF responding to the feedback amount is determined from a map to determine a present duty ratio D Namely, when a running load is increased, a slip amount is increased COPYRIGHT: (C)1990,JPO&Japio

Hydromagnetic slip flow with heat transfer in an inclined channel

Abstract: The problem of steady two-dimensional laminar flow in slip flow regime of a viscous incompressible and electrically conducting fluid through an inclined channel of rectangular cross-section in presence of a transverse magnetic field has been considered. The walls of the channel are assumed to have prescribed temperatures and finite conductivities. The expressions for the velocity component, induced magnetic field and the temperature are obtained and their numerical results are shown graphically.

Method for controlling forward slip ratio in cold rolling

Abstract: PURPOSE:To control the forward slip ratio in a proper range and to prevent the accuracy of a strip thickness from deteriorating by obtaining the concentration of lubricant making the target forward slip ratio from a predicting formula of friction coefficient and setting the concentration of the lubricant on the inlet side of cold tandem mills. CONSTITUTION:When the strip is rolled in cold tandem mills, the forward slip ratios are obtained from roll speeds at each roll stand 2, 3 and the sheet speeds on the outlet side of each stand, in a rolling time. Friction coefficient predicting formulas are created respectively from an obtained forward slip ratio when the forward slip ratio is in a positive area or in a negative area. The concentration of the lubricant making the target forward slip ratio is obtained from these friction coefficient predicting formulas and the concentration of lubricant on the inlet side of the cold tandem mills is set. The concentration is controlled by a computing element 10 and a pump pressure controller 11 to control the concentration. Consequently, the forward slip ratio can be controlled is a proper range, rolling can be performed by the same roll and a defective shape of a plate can be prevented from being generated.

Control device for vehicle driving force

Abstract: PURPOSE:To make it possible to control the slipping of a wheel without the recurrence of slip by computing the target number of engine revolutions to produce the best suited slip ratio, and restricting fuel supply in the case where the slip ratio of a driving wheel has exceeded the set value established according to throttle valve opening. CONSTITUTION:A car body speed detecting means 1, a driving wheel speed detecting means 2, a detecting means 3 for the number of actual engine revolutions and a throttle opening detecting means 7 are provided, and a computing means 4 for the number of target engine revolutions computes the number of the target engine revolutions to produce the best suited slip ratio on each output signal. A slip ratio commuting means 5 computes a driving wheel slip ratio on the car body speed and the driving wheel speed. In the case where the slip ratio of the driving wheel has exceeded a fixed set slip ratio, a fuel supply controlling means 6 partially or wholly stops supplying fuel to an engine to make the number of the actual engine revolutions coincide with the number of the target engine revolutions. The set slip ratio is established larger as throttle opening becomes larger.

Speed ratio control device for continuously variable transmission for vehicle

Abstract: PURPOSE:To provide an enough drive force during restarting by a method wherein during operation of an antilock brake, the change speed of a speed ratio is controlled in the unstable region of an estimated car speed based on a slip ratio, and in the stable region thereof based on car body deceleration. CONSTITUTION:During operation of an ECU 64 for ABS, it is de cided by an ECU 51 for CVT whether an estimated car body speed estimated from a rotation speed signal, having a lowermost slip ratio, of those from wheel speed sensors 56, 58, 60, and 62 is in a stable region or in an unstable region. During the initial stage of antilock brake operation where no precision is provided for car body deceleration in the unstable region and calculated from the unstable region, based on a slip ratio, the change speed of the speed ratio of a continuously variable transmission 16 is controlled. Meanwhile, in the stable region, the change speed of a speed ratio is controlled based on car body deceleration. Even when, for example, a change from a frozen road surface to a pressure snow road surface having a high road surface friction factor is produced, during the stop of a vehicle, the speed ratio of the continuously variable transmission is returned to the lowermost deceleration side, and a drive force during restarting can be sufficiently provided.

Super high slip ratio motor

Abstract: The utility model discloses a super high slip ratio motor for a beam oil pumping unit. The same class of the present motor is a comb-teeth shape cast-aluminium rotor and needs to adopt the high-voltage casting mode, so the present motor has complicated process, expensive investment and high waste rate. The utility model adopts the squirrel-cage rotor of the copper guiding strip and end ring welding structure, raising the mode of the rotating resistance through reducing the sectional plane of the guiding strip, and the slip ratio of the motor is raised to 15%-25% and even higher. The utility model has simple manufacturing process, low cost and high generalization and standardization degree and is especially suitable for reconstructing the old motor.

Slip patterns in sliding sphere experiments on (110) single crystal Mn-Zn ferrite

Abstract: By sliding a 0.25 mm radius ruby sphere on a (1 1 0) Mn-Zn ferrite crystal grooves have been made at speeds from 0.4 to 400 μm sec−1, at loads from 1 to 7 N and after 1 to 100 passes. The temperature was varied from 20 to 290° C. As in indentations, the slip patterns are found on {1 0 0}, {1 1 1} and {1 1 0} slip systems, due to 〈1 1 0〉 slip along either a vertical Burgers vector or a vector under 60° with the normal. At low loads the inclined slip systems predominate. Cross-slip in the 60° systems is observed in several directions of sliding. Cross-slip occurs at higher loads on the vertical systems as in indentations. The threshold for both primary and secondary slip is speed dependent. At higher temperatures the main slip system is {1 0 0}, on both vertical and inclined systems. The relative importance of nucleation and propagation of slip is discussed. The groove depth varies with the same parameters as the line patterns, but a direct connection between number of lines and depth could not be made. The angular variation of the depth at low load has been related to the resolved shear stress for the slip systems involved. The result is a yield curve for slip along the inclined Burgers vectors.

Slip preventing device for vehicle

Abstract: PURPOSE:To prevent temporary increase of the drive force of drive wheels, by a method wherein gear shifting of a speed change gear is prohibited or gear shifting is effected at a speed slower than usual while a slip state is detected. CONSTITUTION:Signals from an engine rotation speed sensor 20, an airflow meter 22, an output shaft rotation speed sensor 26, and non-drive wheel rotation speed sensors 28a and 28b are inputted to an input interface 30, a central processing unit 32, and an output interface 34, with which an electronic control device 24. The electronic control device 24 calculates a slip ratio, and when the value exceeds a given value, control of lowering of an engine output is effected, and besides the gear ratio of a continuously variable speed change gear 18 is held at a value prevailing when control of lowering of an engine output is started. This constitution, since gear shifting of the continuously variable speed change gear 18 is not effected during lowering of an engine output, prevents a drive force, generated by an inertial change of an engine, from being exerted on front wheels.

General correlations of in situ concentration and slip velocity. Theoretical considerations on the mechanism of slurry flow with the stationary bed in a pipe.

Abstract: In the deposit regime in which a stationary bed of solids appears on the bottom of the pipe, the ratio of the in situ concentration q to the delivered concentration C and the slip velocity are the most important variables govering the mechanism of slurry flow. Many of the empirical and semi-theoretical studies that have produced the correlations for predicting the values of these variables were based upon data on the limited flow conditions. For this reason, serious disagreement among the correlations can be found at comparatively low velocities where the tendency of the particles to settle due to gravitational forces become sufficiently large so that, eventually, the deposit regime may occur.The objective of this paper is to develop general correlations which contain no empirical constants determined from experimental data in pipes.After analysing the force due to particle-particle interactions in liquidsolid fluidised systems, we obtained the relationship between qand C as follows:_??_in which: V=mean velocity of slurry flow;Vt=terminal settling velocity of single particle; Rep=particle Reynolds number;α, β=Swanson's shape factor of particles;n=index of Richardson-Zaki equation for hindered settling of particles.Also, solving the above equation numerically by the method of bisection, it could be shown that the ratio q/C was plotted against the Froude number V2/[gD (δ-1)], with the ratio d/D as a parameter if the area index κ of the particles should be constant: in which: g=gravitational constant;δ=specific gravity of particles; d, D=diameter of particles and pipe respectively.Therefore, assuming q and C to be defined, slip velocity, i. e., the difference Vw-Vs in mean velocity between liquid phase and solid phase, can be determined by:(Vw-Vs)/V=(q-C)/[q (1-q)]Finally, we concluded that the correlations derived theoretically would be applicable in the wide range of slurry flow conditions, since the universality of them was verified with data from the published literature.

System for monitoring vehicular slip angle

Abstract: A slip angle monitoring system directly compares an ab­solute value of a lateral acceleration ( | Y˝ | ) with an ex­perimentarily derived given value which serves as a slip criterion causing a slip angle on a vehicle. Slip angle is set at zero while the absolute value of the lateral accelera­tion is smaller than or equal to the given value. On the other hand, when the absolute value is greater than the given value, the slip angle (ϑ₁ or ϑ₂) is derived by dividing the lateral acceleration by the longitudinal acceleration or by taking minus one power of tangent of quotient dividing the lateral acceleration by the longitudinal acceleration.

Control device of internal combustion engine for vehicle

Abstract: PURPOSE: To eliminate a traction system and to start without the occurrence of a slip during starting by calculating an engine limit based on the slip limit of each drive wheel and limiting a target value during control of an engine output. CONSTITUTION: Torque generated at each drive wheel is calculated by a wheel torque calculating means (a) based on generating torque of an engine, and a dynamic friction factor between each drive wheel and a road surface is calculated by a dynamic friction factor calculating means (e) based on the torque, a rotation angular acceleration (c) and a wheel load (d). Meanwhile, the slip ratio of each driven wheel is calculated by a slip ratio calculating means (g) based on a car body speed (f) and a wheel speed (b) of each drive wheel. The maximum dynamic friction factor of each drive wheel is calculated by a maximum dynamic friction factor calculating means (h) based on the dynamic friction factor (e) and the slip ratio (g), and based on the maximum dynamic friction factor, limit wheel torque, capable of being inputted, at which each drive wheel is moved without a slip is calculated by a limit wheel torque calculating means (i). From a total sum of limit wheel torque of each driven wheel or a value several times as large as that of each drive wheel having a minimum value of limit wheel torque of each drive wheel, limit torque is calculated by limit torque calculating means (j) and j', and by means of the limit torque being an upper limit value, a target value of an engine output is limited by an engine output limit means (k). COPYRIGHT: (C)1991,JPO&Japio

Drive force limiter for vehicle

Abstract: PURPOSE:To restrain smoothly drive wheels from slip irrespective of road surface condition by setting a desired drive force according to the rate of reduction which becomes smaller as the variation of vehicle speed is increased. CONSTITUTION:A throttle valve controlling circuit 34 calculates an actual slip ratio between a tire and road surface from drive wheel speed detected by front wheel rotational frequency sensors 31, 32 and vehicle speed detected by a rear wheel rotational frequency sensor 30. When the actual slip ratio exceeds a set slip ratio, a decrease in a drive force is increased as the actual slip ratio is increased. The larger the variation of vehicle speed calculated from the vehicle speed detected by said sensor 30 is, the smaller decrease ratio sets a desired drive force. Drive force reduction control for causing the actual drive force to coincide with the desired one is carried out by a step motor 35, so that indirect road surface frictional coefficient information is obtained from monitoring the variation of vehicle speed and thus the drive wheel slip can be smoothly restrained irrespective of road surface condition.

Frictional and wear tester

Abstract: PURPOSE:To impart an arbitrary slip ratio and slip angle to a sample, by rotating a cylindrical grinding body by a drive motor and driving a sample shaft for holding an elastic sample by a sample driving means and a sample revolving means. CONSTITUTION:A cylindrical grinding body 3 is rotated by a drive motor 2 and a sample shaft for holding an elastic sample is driven by a sample driving means 8 and a sample revolving means 16. The grinding body 3 and the elastic sample are respectively and independently revolved and driven to impart a slip ratio to the elastic sample while the elastic sample is revolved around a vertical load line 15 by the sample revolving means 16 to impart a slip angle on the grinding surface of the grinding body 3. By this method, the sample shaft 6 and the grinding shaft of the grinding body 3 can be respectively and independently driven with the predetermined number of rotations.

Phase velocity in a gas-liquid bubble flow

Abstract: An experimental method and some results are presented for measurement of gas phase velocity and slip velocity in an ascending gas-liquid flow in a vertical tube.

Cornering limit warning device for vehicle

Abstract: PURPOSE:To warn that the title vehicle is almost in a corner limit state by comparing an actual slip ratio which is calculated from a detected vehicle body speed and a main driving wheel speed and then generating a warning when the ratio exceeds the limit slip ratio. CONSTITUTION:The vehicle body speed detected by a vehicle body detecting means 1 such as right and left front wheel speed sensor and the main driving wheel speed detected by a main driving wheel speed detecting means 2 such as right and left rear driving wheel sensors are supplied to a slip ratio arithmetic means 3, which calculates the actual slip ratio S. This slip ratio S is compared with the set slip ratio Slimit set by a slip ratio setting means 4 corresponding to a value almost in the cornering limit. Then when the ratio S exceeds the ratio Slimit, a warning means 5 generates and sends a warning to inform a driver that the vehicle is almost in the cornering limit, thereby performing safe corner traveling.

Antiskid device for vehicle

Abstract: PURPOSE:To improve the extent of antiskid effect by setting a desired value of engine speed so as to cause a vehicle to become the specified slip ratio when driving wheels slip, and restricting engine output when the engine speed has exceeded the desired value. CONSTITUTION:In this antiskid device, there is provided with a slip detecting device (d) which detects any slip of driving wheels on the basis of output of a wheel speed detecting device (b) detecting respective speeds of both driving and driven wheels. At the time of slip detection, a speed ratio for controlling a slip on the basis of the speed ratio of a torque converter to be detected by a speed ratio detecting device (c) at a point of slip detecting time is operated as a desired speed ratio by a speed ratio operational device (e). A speed desired value for getting the specified slip ratio is set by a desired value setting device (f) on the basis of this desired value and wheel speed. When engine speed has exceeded the desired value, an operating device (h) is controlled via a limit signal outputting device (g), thus engine output is decreased to some extent.

Car body speed presuming method for car with anti-lock brake device

Abstract: PURPOSE: To provide possibility of offering a value close to actual deceleration by determining at least the deceleration on the basis of the hi-select value differentials from the wheel speed of all wheels, and thereby acquiring the car body speed as reference for judging the wheel slip ratio on the basis of the wheel speed and acceleration/deceleration. CONSTITUTION: Control parts 1FL, 1FR, 1RL, 1RR for respective wheels judge that the slip ratio has exceeded the allowable value when appropriate wheel speed has become below the reference wheel speed, and anti-lock brake control for appropriate wheel brake shall be actuated. The car body speed as reference for judging the slip ratio of the wheels is presumed on the basis of the wheel speed and acceleration/deceleration by a front-wheel side and a rear-wheel side car speed presuming means 6F, 6R. Therein the max. wheel speed acquired by a hi-select circuit 5 is fed to a differential circuit 7, and the inner/outer wheel speed difference generated when the car has made transition from straight running to turning is subtracted from the differential value by a subtracting circuit 19, and this resultant shall serve for computation of the deceleration. COPYRIGHT: (C)1990,JPO&Japio

New slip correlation for forced convection two-phase flow

Abstract: Experiments with sodium for the two-phase pressure drop were evaluated in tubes with vertically upwards forced convection. The measurements were carried out at moderate to high mass flow rates (30-4500 kg/m -2 s -1 ) and at moderate pressures (50-300 kPa). By means of these overall pressure drop measurements it is possible to check the applicability of slip correlations to sodium indirectly. The slip correlations known from the literature were not suitable for describing the measurements. A new slip correlation was developed, which is distinguished from the others by the concept of entrainment. This means that starting from a definite vapour velocity, droplets are entrained from the liquid film

Driving wheel slip preventing controller

Abstract: PURPOSE:To restrict a rise of a slip ratio by providing a follow-up controlling means, in which an opening of a first, manually operated throttle valve is followed up by an opening of a second, actuator-driven throttle valve, and operating this means when driving force control for slip prevention is not on operation. CONSTITUTION:A first throttle valve 6, which is operated in likage of depressing of an accelerator pedal 5 and a second throttle valve 3 driven by a motor 2 are provided to a suction pipe. A target opening of the second throttle valve 3 is calculated by TCS (Traction Control System) control unit 8 in order to control the second throttle valve 3. In this case, the TCS control unit 8 is provided with a target value selecting means 21 as a follow-up control means. When the vehicle is on steady traveling, a target value on the B-side is selected, so that the first throttle valve 6 is followed up by the second throttle valve 2. On the other hand, when a driving wheel slip takes place, a target value on the A-side is selected, so that the second throttle valve 2 is controlled according to the target value that is calculated from the output of a wheel-speed sensor 1.