Dual Wheel Research Articles

Effect of temperature gradients on the behaviour of jointed plain concrete pavements

Abstract In many countries of Latin America, Jointed Plain Concrete Pavements (JPCP) are designed using the American Association of State Highway and Transportation Officials (AASHTO) or the Portland Cement Association (PCA) methods, none of which take explicitly into account the environmental conditions of the specific region where a JPCP will be built. It is well known that temperature gradients across the thickness of concrete slabs produce curling which can cause slabs to lose support at its corners and its center depending on the time of the day. This situation, in combination with vehicle loading, generates tensile stresses which can be significant enough to cause initial cracking and the subsequent failure of the pavement. In this research, the Finite Element (FE) package EverFE2.25 was used to study the impact of temperature gradients (calibrated to account for humidity gradients) in combination with a vehicle load (a dual wheel tandem axle of 180 kN) on the performance of a typical JPCP highway section. For the JPCP under study, the apparent increase of the tensile stresses attributable to negative local (ΔT = -18.5°C) Equivalent Temperature Gradients (ETGs) was as 5.5 times larger than the one induced by the axle when it was placed at the border of the slab and up to 8.8 times larger when it was placed at the corner of the slab. Although the apparent increase was not as high when the positive local ETGs (ΔT = +18.5°C) were used, the absolute magnitude of the stresses in combination with the vehicle load were still high enough for the pavement to fail under fatigue. Thus, local temperature gradients should be studied regionally and considered in the design of JPCP using more suitable design procedures such as the Mechanistic-Empirical design procedure.

Design and analysis of a dual reaction wheel with ultrasonic motor for nano-satellites

Design and analysis of a dual reaction wheel with ultrasonic motor for nano-satellites

Evolution of the Deflection According to Truck Overloading—Comparison between Benkelman Beam Method and FEM of Lateritic Pavements

The study of the deflection due to the passage of an axle on a pavement structure has the advantage to make possible to pronounce on the portance, the rigidity and the homogeneity of this one. In the case where the allowed axle load is not respected, surface deflection leads to premature deterioration of the roadway. In order to study the evolution of these deformations, deflection measurements were made by using the Benkelman method in the Fatick-Kaolack road in Senegal by varying the axle load with the following values: 10, 13 and 16 tons on three different zones. The results show a linear evolution of the deflection as a function of the axle load. Also, the impact of truck overloading was studied by considering different values of the axle load with comparison to the allowed axle load by using frequent types of vehicle. A numerical simulation of the Cast3M pavement was done first, in the case of an isolated single wheel with a radius of 12.5 cm, then in the case of an equivalent dual wheel with a radius of 18.1 cm for loads of 10 to 19 tons. In the same way, the pavement design software (ALIZE) is used to analyse the variation of the axle load. The results show a linear evolution of the deflection, which corroborates the measurements made in the field and those obtained by Samb (2014) with a slope coefficient equal to 1.7. Nevertheless, the case of an isolated single wheel of 12.5 cm radius is closest to the measurements with a straight line of slope coefficient equal to 1.9.

Assessment of cracks detection in pavement by a distributed fiber optic sensing technology

This paper presents the feasibility of damage detection in asphalt pavements by embedded fiber optics as a new non-destructive inspection technique. The distributed fiber optic sensing technology based on the Rayleigh scattering was used in this study. The main advantage of this technique is that it allows to measure strains over a long length of fiber optic with a high spatial resolution, less than 1 cm. By comparing strain profiles measured at different times, an attempt was made to link strain changes with the appearance of damage (cracking) in the pavement. This non-destructive method was evaluated on accelerated pavement testing facility, in a bituminous pavement. In our experimentation, the optical fibers were placed near the bottom of the asphalt layer. The application of 728,000 heavy vehicle loads (65 kN dual wheel loads) was simulated in the experiment. Optical fiber measurements were made at regular intervals and surface cracking of the pavement was surveyed. After some traffic, a significant increase of strains was detected by the optical fibers at different points in the pavement structure, before any damage was visible. Later, cracking developed in the zones where the strain profiles were modified, thus indicating a clear relationship between the increased strains and crack initiation. These first tests demonstrate that distributed fiber optic sensors based on Rayleigh scattering can be used to detect crack initiation and propagation in pavements, by monitoring strain profiles in the bituminous layers.

Wheel Attachment Failures in Light-Duty Vehicles

The frequency of vehicle accidents attributable to wheel attachment failures on light-duty (non-dual rear wheel) vehicles was extremely low prior to the advent of cast and forged aluminum alloy and forged “styled steel” wheels in the early 1970s. The sharp increase in such accidents which accompanied the rapid increase in the popularity of the more attractive solid wheels was attributable to a widespread failure among many after-market (and some OEM) suppliers and service organizations to recognize that the stiffer cast and forged wheels required more stringent installation and maintenance standards than did the more “forgiving” stamped steel predecessors. Coincident with, but not in response to, the increased frequency of wheel attachment failures on light-duty vehicles, hub-piloted wheels were introduced on heavier (dual rear wheel) vehicles as a means of reducing the long-standing higher frequency of attachment failures on vehicles equipped with the heavy-gage forged steel wheels. This reduction was accomplished by increasing the portion of the installation torque converted to wheel clamp force through a reduction in the portion lost to nut-to-wheel friction. Failure on the part of some investigators to recognize the factors responsible for the increased incidence of wheel separations on light-duty vehicles and the unique features of hub-piloted wheels gave rise to the formulation and propagation of myths and misconceptions regarding the causes and cures for such separations. It is the purpose of this article to identify critical features of wheel and wheel attachment designs and of their installation and maintenance requirements that relate directly to attachment failures and to dispel some of those myths and misconceptions.

A comparative study of conventional and controlled traffic in irrigated cotton: I. Heavy machinery impact on the soil resource

To increase in-field efficiency of mechanical operations, machines have increased in size and capacity, which has resulted in cotton pickers approaching 40Mg in mass. Such mass presents concern for soil compaction and subsequent crop performance. Controlled traffic farming (CTF) is a useful means to reduce machine impact, but is not highly adopted globally. This investigation was designed to compare a standard cotton picker side-by-side to a CTF converted cotton picker in terms of soil resource impact. A replicated, side-by-side, commercial scale experiment was instigated with a 1.5m row-spacing CTF system compared against a 1.0m row-spacing standard cotton system. Soil moisture, bulk density, and strength were measured immediately prior and post harvest, along with crop yield, for two cotton seasons and one wheat season. In depth cotton quality, water use efficiency and economic analysis are undertaken in a companion paper. Both machines were shown to induce comparable soil compaction, effects detectable to 0.8m soil depth, with the main difference being a 17% reduction in furrow traffic for the CTF system. The inner and outer dual wheel of the standard picking system had similar impact, effectively creating a horizontal compaction pan at ≈0.35–0.40m depth, perpendicular to the direction of machine travel. Bio-ripping of this compaction pan by wheat was demonstrated as ineffectual. The CTF system grew less cotton plants per hectare, but outperformed the standard system. Bio-ripping more effectively accessed water in the CTF system and out yielded the conventional system by ≈60%.

Static Analysis of Flexible Pavements over Expansive Soils

To study and predict the behavior of flexible pavement over expansive soils, a pavement structure was subjected to different laboratory and fieldwork experiments. The existing pavement was replaced and designed based on California Bearing Ratio (CBR) method, with a new one, and subjected to the traffic from various number of load cycles from 12.1 up to 155.52 kcycles of standard axle load (80 kN) through dual wheel assembly over a 6-month period. As the preliminary step, the deflection measurements were taken at the asphalt surface layer, using a Total station at different distances as function of truckload applications. The numerical analysis is carried out with the Finite Element software package PLAXIS version 2012. In the new model, the calculation of the transferred pressure to the pavement through contact area of tires is 3D it was turned into a 2D problem, and the pavement was subjected to a static loading using a ratio factor of dynamic additional charge. The materials’ behavior was simulated with nonlinear models: Mohr–Coulomb (MC) for pavement layers and soft-soil model (SSM) for the expansive subgrade, in saturated drained and undrained conditions. The results indicate that displacements under static loading in saturated drained conditions and when non-linear materials are present are the closest to field measured deflections.

Design and Test of Dual Actuator Nose Wheel Steering System for Large Civil Aircraft

In order to improve aircraft ground handling characteristics and airport working efficiency, large handling angle and torque are requested for the nose wheel steering system of large civil aircraft. A following swivel selector valve is firstly designed to meet the demand for the hydraulic pressure commutating as soon as the dual actuator nose wheel steering mechanism passes through its dead center position. Considering the multiple objective functions of nose wheel steering mechanisms, those core design parameters are multiobjective optimized. A nose wheel steering electrohydraulic servo system with handling and antishimmy functions is designed for the steering mechanism. Then the prototypes of the steering mechanism and electrohydraulic servo system are researched to validate the design. Using the swing actuator to provide the load torque and ground excitation, the steering test bench is prepared to test the system working. The steering test and the antishimmy test are conducted to verify the functions of the system. The test results, such as steer angle, steer torque hydraulic pressure, and antishimmy torque, are analyzed in detail and compared with the theoretical results. The results show that the property of the prototype achieves the design objectives, such as work mode, steer angle, and steer torque.

Design Charts for Flexible Airfield Pavement Based on Analytical Study

In this paper, an attempt has been made to develop design charts for flexible airfield pavements without or with geosynthetic reinforcements considering 20-years pavement life. The analytical study comprises Federal Aviation Administration method (1996) and Barenberg's design method (1975) to interpret the design charts. It concerns different types of aircrafts such as single wheel gear, dual wheel gear, dual tandem wheel gear, DC 10-10, 10CF, A300-B2/ B4, B747-100,SR,200B,C,F and B 747 SP with their different gross weights and annual departures. The required pavement thickness over a layer depends on several influencing factors such as California bearing ratio (C.B.R.) of the pavement layer, gross weight of aircraft and its annual departure. For a particular aircraft, the required pavement thickness is lesser over a layer with higher California Bearing Ratio (C.B.R.). The required thickness is more under the higher gross weights of an aircraft with same annual departure. As the annual departures of an aircraft increases, the required pavement thickness also increases over a particular layer. Results indicate appreciable reduction in the required aggregate thickness due to the inclusion of geosynthetic reinforcement.

Microstructure and mechanical properties of economical dual phase wheel steels based on CSP line with later ultra fast cooling

To attain the economical wheel steels with high strength, the microstructure and properties of steel with microstructure consisting of ferrite and martensite were studied. The transformation behaviour of the economical wheel steels under continuous cooling condition and stepped cooling condition were researched and the 11·0-mm thickness wheel steel strips with simple chemical composition were developed on compact strip production (CSP) line with later ultra fast cooling (UFC) system. The results indicate that the dynamic continuous cooling transformation (CCT) curves of low carbon Mn–Cr steel is characterised by a large ferrite region, and the stepped cooling pattern is more beneficial to achieve ferrite–martensite microstructure than continuous cooling pattern. In order to obtain adequate polygonal ferrite matrix during stepped cooling process, the early cooling temperature should be controlled in the range of 700–660°C and the isothermal holding time should be ensured. The 11·0-mm thickness dual phase (DP) wheel steel strips are achieved on CSP line via control cooling technology based on later UFC system. Tensile strength increment of C–Mn–Cr steels can reach 130–170 MPa when the F-P microstucture is replaced by F-M microstucture. The wheel steel strips with tensile strength above 590 MPa, yield ratio under 0·62 and elongation above 28% have been used for wheel discs, whose weight achieve reduction of 16–22%.

A model for equivalent axle load factors

Most design methods for road pavements require the design traffic, based on the transformation of the traffic spectrum, to be calculated into a number of equivalent passages of a standard axle using the equivalent axle load factors (EALFs). In general, these factors only consider the type of axle (i.e. single, tandem or tridem), but they do not consider the type of wheel on the axles, i.e. single or dual wheel. The type of wheel has an important influence on the calculation of the design traffic. The existing design methods assume that the EALFs are valid for all pavement structures and do not consider the thickness and stiffness of the pavement layers. This paper presents the results of the development of a model for the calculation of the EALFs considering the type of axle, the type of wheel and the constitution of the pavement. The model was developed based on the tensile strain at the bottom of the asphalt layer that is responsible for bottom-up cracking in asphalt pavement, which is the most widely considered distress mode for flexible road pavements. The work developed in this study also presents the influence of the type of wheel (single and dual) on pavement performance. The results of this work allowed the conclusion that the EALFs for single wheels are approximately 10 times greater than those for a dual wheel. This work also proposes average values for the EALFs. An artificial neural network was developed to calculate the EALFs.

Effect of Dowel Looseness on Response of Jointed Concrete Pavements Using Three-Dimensional Finite Element Analysis

This paper evaluated an effect of dowel looseness on response of jointed concrete pavement using 3D finite-element analyses of rigid pavement systems that relies on an embedded formulation of a beam element. This embedded element allows the efficient modelling of dowel looseness using nodal contact approach and permits the dowels to be exactly located irrespective of the slab mesh lines. These studies indicate that significant reduction in load transfer efficiency and increase in both slab and base course stresses can be expected due to small gaps varies from 0.25 to 1.25mm between the dowels and the slabs. For the worst case the LTE were reduced to 11.3% and 11.6% respectively for single wheel loading and odd dual wheel loading case while there were voids present at the base course layer for 1.25 cases 4.

Mechanical Response of Asphalt Pavement under Overloading

This paper examines theoretically the possible mechanical response changes on both bituminous pavement structure using linear elastic method, the change regulation of deflection,stress on the bottom of base and subbase and compress strain on the top of subgrades between semi-rigid base and flexible pavement pavement. In the load application procedure, a dual wheel with the a series of pressure was chosen.The results have shown that the deflection tensile stress and subgrade compressive strain on the surface increase with the increase of axle load and they would result in serious effect of overloading on the earlier damage of asphalt pavement.

Research on the Electronic Differential Control Strategy of Electric Vehicle

According to the electric vehicle driven by dual wheel hub motors, the article analysed the principle of mechanical differential. And the article used the principle of differential under the same force of mechanical differential, put forward a new adaptive control strategy of electronic differential based on torque control. According to torque control£¬the controller controls the speed of the drive motors on both sides, which achieves the aim of the adaptive electronic differential.

Validation of the Performance of Pervious Concrete in a Field Application with Finite Element Analysis

Abstract Pervious concrete is a paving material that has a number of stormwater and other environmental benefits. Most current applications of pervious concrete are in residential streets, parking lots, driveways, and sidewalks, and it is being considered for shoulders and more high volume applications. Characterizations of stress distribution and deflection patterns in pervious concrete systems may be useful parameters in the structural design of these high volume uses. Pervious concrete panels with tandem axle dual wheel loads were analyzed using finite element analysis. The wheel position was considered in the corner, center, and edge of the pavement. The critical stresses obtained from the analyses were compared against experimental tensile and compressive strengths obtained from samples from a field application for various pervious concrete layer thicknesses, and additional experimental data. It was found that pervious concrete panels of sufficient thickness have adequate strength to support the applied wheel loads. To compare the long term performance when subjected to cyclic loading, the critical tensile stresses for various pavement thicknesses were compared with pavement condition index (PCI) rating data obtained from a field application reflecting pavement performance of approximately 131,000 cycles of an 80 kN single-axle load. For this particular field application, it was found that, for cyclic loading, the required thickness of the pervious concrete layer was approximately 40 %–80 % higher compared with that for the static loading condition.

Design of the WIYN High Resolution Infrared Camera (WHIRC)

ABSTRACTThe WIYN High Resolution Infrared Camera (WHIRC) is a high-resolution near-infrared imager (0.8–2.5 μm) designed to produce superb images over a moderate (3.3′ × 3.4′) field of view on the WIYN 3.5 m telescope at Kitt Peak National Observatory. It takes scientific advantage of the excellent image quality produced by the telescope and its image stabilization subsystem, the WIYN Tip-Tilt Module (WTTM), which is located on one of two Nasmyth ports. WHIRC mounts to WTTM and reimages the WTTM focal plane to a plate scale of 0.1″ pixel-1 at the WHIRC detector. Its straight-through optical path makes for a compact, very low mass, instrument—a necessity, given the stringent moment-loading requirement at the WTTM interface. The WHIRC optical path consists of a vacuum window, a five-element collimator, a dual filter wheel, a five-element achromatic camera, and a 2k2 Raytheon VIRGO mercury cadmium telluride (HgCdTe) detector. A novel all-aluminum lens cell design is used to achieve 13 μm lens centering tolerances between ambient and the 77 K operating temperature. A suite of 13 filters facilitates broadband (J, H, and Ks) imaging, as well as narrowband imaging tailored to a variety of astronomical investigations. The imaging performance of WHIRC is excellent. Irrespective of seeing, the telescope, and WTTM, WHIRC delivers 0.13″, 0.11″, and 0.08″ FWHM images in J, H, and Ks, respectively. On sky, the imaging is equally impressive yielding images as good as ∼0.25 FWHM in Ks. In this article we describe the WHIRC design in detail and present the predicted and measured instrument performance.

Characterisation of surfacing materials for orthotropic steel deck bridges. Part 2: numerical work

The lifespan of surfacing course materials like mastic asphalt on orthotropic steel deck bridges is quite short when compared with that of ordinary road pavements. Several problems including cracking and rutting of the surfacing materials have been reported in many countries. This is the second part of the two papers on characterisation of the behaviour of typical surface course materials for orthotropic steel deck bridges. In this paper, details of the constitutive model and its numerical implementation are presented. An important component of the model is an unconditionally stable, implicit Euler backward algorithm for the integration of the constitutive equations. Comparisons of model predictions and laboratory measurements at different temperatures, deformation rates and confining stresses are shown. Utilisation of the model in finite element analyses has enabled the investigation of the inelastic response of a 3D orthotropic steel deck bridge subjected to dual wheel loads.

Design of the Dual Offset Active Caster Wheel for Holonomic Omni-Directional Mobile Robots

It is shown how a holonomic and omni-directional mobile robot is designed towards indoor public services. Dual offset steerable wheels with orthogonal velocity components are proposed. The proposed wheel provides precise positioning and reliable navigation performance as well as durability. A fabricated prototype is introduced, then, an experiment is carried out.

2B25 Motion Analysis and Control of Dual Wheel Vehicle as Human-Machine System

A prototype of dual-wheel inverted-pendulum vehicle (DIPY) was developed. DIPV have become popular in crowded area because of their compact size and maneuverability. However, no technical report has been published on the control of such a vehicle with its rider on, in spite of the fact that rider's inertia and maneuver skill has strong effect on the vehicle performance. This study tried to simulate the DIPV-rider system movement using a simple dynamical model. The actual DIPV and rider movements were measured using LabView and motion capture system. From the time domain analyses, the effects of rider's maneuvering skill and experience, the control gains were observed.

THREE-DIMENSIONAL ANALYSIS OF FLEXIBLE PAVEMENTS SUBJECTED TO TRAFFIC LOADS USING FINITE ELEMENT TECHNIQUE

To predict pavement responses and performance due to external working loads, it is necessary to estimate stresses and deformations through pavement. When the induced strains are relatively small, they are usually evaluated using the theory of elasticity. Boussinesq's theory is used for this estimation through homogeneous soil. These responses in case of layered pavement system are less than those obtained for the ideal homogeneous case depending upon the stiffness of the layers. Semianalytical solutions are available to analyze the behaviour of elastic layered soil deposits subjected to surface loads. For more complex cases of soil deposits or loading conditions, it is necessary to perform numerical analysis using finite element technique. In addition, most of pavement materials do not linearly perform under the action of traffic loading. In this paper, the ANSYS version-8 program is used to analyze in three dimensions the behaviour of a layered pavement system under static loads indicating load transmission issues for a wide variety of materials stiffness, tire pressures and axle loads with dual wheels. Also linear and non linear analyses were preformed for different previously mentioned items. In this research, the pavement is modeled as a multilayered elastic system composed of a subgrade assumed to be an infinite medium upon which layers of finite thickness infinitely extended horizontally are laid. Furthermore, it is assumed that vertical loading, such as dual wheel loads are simultaneously applied to obtain stresses and deflections through the road pavement. On the basis of this research, remarkable conclusions are drawn out.