Large Wheel Research Articles

Design and Stress Analysis of Nose Landing Gear Barrel (NLGB) of a typical naval trainer aircraft

During the conceptual design phase of aircraft the integration of undercarriage system is very important and it is often difficult to achieve on the first time. The nose wheel landing gear preferred configurations for light naval trainer aircraft. The main objective of this project is to improve the static strength criteria and fatigue life of Nose Landing Gear Barrel considered. The investigations includes preliminary design layout for Nose Landing Gear Barrel and initial sizing has been done. It has been designed and evaluated for strength criteria. A method of analysis for the design of Nose Landing Gear Barrel made up of Al-Cu alloy (BS L 168 T6511) with static loads of axial, bending and normal loads are applied. The geometric modeling of the Nose Landing Gear Barrel was carried out using CAD package CATIA V5 R19 and pre and post processing was done through MSC/PATRAN. The stresses and displacements are obtained with the application of MSC/NASTRAN finite element software. I. INTRODUCTION The Landing gear is the structure that supports an aircraft on the ground and allows it to taxi, take-off and land .The Landing gear system consists of the main landing gear and nose landing gear. Each landing gear includes a shock strut with two and tire assemblies. Tires and the wheel absorbs the original impact on landing and are the principal part of the aircraft involved in the ground control. It allows more forceful application of the brakes without the danger of nosing the aircraft over. Tricycle is the most widely used landing gear configuration. The wheels aft of the aircraft cg is very close to it and carries much of the aircraft weight and load, thus is referred to as the main wheel. Two main gears are in the same distance from the cg in the x-axis and the same distances in y-axis, thus both are carrying the same load. The forward gear is far from cg, hence it carries much smaller load. The share of the main gear from the total load is about 80 to 90 percent of the total load, so the nose gear is carrying about 10 to 20 percent. This arrangement is sometimes called nose-gear. Both main and nose gears have the same height, so the aircraft is level on the ground, although the main gears often tends to have larger wheels. This allows the floor to be flat for passenger and cargo loading. Unlike tail-gear, a nose gear configuration aircraft is directionally stable on the ground as well as during taxing. The reason is that if the aircraft yaws slightly while taxiing, the rolling and skidding resistance of the main gear, acting behind the cg, tends to straighten the aircraft out.

An active-caster add-on drive for manual wheelchairs with a drive mode change function

This paper presents a motorised system for a wheelchair that uses an add-on single-wheel drive system, which is called an active-caster. The active-caster has two electric motors to rotate the wheel shaft and steering shaft independently. This coordinated control provides an arbitrary velocity vector. Despite the single-wheel drive system, the 2DOF motions of the wheelchair can be controlled independently without any constraints. In addition to 2DOF mobility, the proposed system enables wheelchair users to change between rear and front drive modes. The height of the drive wheel equipped on the back of the wheelchair can be vertically adjusted by a linear motor. When all five wheels are in contact with the ground, the wheelchair moves in normal or rear drive mode. Depressing the drive wheel results in the large wheels losing contact with the ground and causes the centre of rotation to shift to the midpoint of the front casters.

Modelling and control of an autonomous articulated mining vehicle navigating a predefined path

This research is conducted on machine dynamics and steering control of an articulated surface mining large wheel loader (LWL) navigating a predefined path. Modelling a LWL based on computational multibody dynamics is achieved by modelling each system of the articulated vehicle separately then merging them to form an overall system of an articulated vehicle navigating a predefined path. This model includes the front and rear frames, articulated hinge, steering actuators, tyre model, steering controller and a predefined path. Fuzzy and PID steering controllers are developed and simulated. Results show that it is possible to model large articulated vehicles as a multibody mechanical system. Both of the developed controllers are able to control the lateral and longitudinal motion of the vehicle and drive the machine over the desired path accurately. The fuzzy logic controller has longer rising time but shorter settling time when compared with the PID controller.

Strong Splitter Theorem

The Splitter Theorem states that, if N is a 3-connected proper minor of a 3-connected matroid M such that, if N is a wheel or whirl then M has no larger wheel or whirl, respectively, then there is a sequence M 0, . . . , M n of 3-connected matroids with \({M_0 \cong N}\), M n = M and for \({i \in \{1, \ldots , n}\}\), M i is a single-element extension or coextension of M i−1. Observe that there is no condition on how many extensions may occur before a coextension must occur. We give a strengthening of the Splitter Theorem, as a result of which we can obtain, up to isomorphism, M starting with N and at each step doing a 3-connected single-element extension or coextension, such that at most two consecutive single-element extensions occur in the sequence (unless the rank of thematroids involved is r(M)). Moreover, if two consecutive single-element extensions by elements {e, f} are followed by a coextension by element g, then {e, f , g} form a triad in the resulting matroid.

Large-Size Wheel Rotary Forging Process Research

For forging process of the large size alloy wheels have several disadvantages, such as using large tonnage presses, high energy consumption, etc.So rotary-forging process route is developed. Forgings forming require 5000-6000T presses by the traditional process, but only require 350T rotary forging presses by new technology. This new process reduces the production costs and energy consumption and extends the life of die. Investigate the effect of several key factors on the forming force. The results show that forming force decreases with the decrease of press amount per turn, and reduce with the die and bars temperature increases. Forging wheel window has small influence on the forming force, but can decrease the forgings cutting weight, improve material utilization. This study plays a guiding role for equipment R & D and determination of the production processes parameters.

High-Accuracy Calibration of the Wheel Spindle Tilt Angle for Grinding Hydrostatic Seal Rings Used in Reactor Coolant Pumps

The hydrostatic seal rings are one of the most important components used in reactor coolant pumps. They are generally made of hard materials such as silicon nitride, alumina, silicon carbide and tungsten carbide. Meanwhile, the form error should be within the length of one to two helium light bands and the surface roughness should be in the scale of nanometers, which make them difficult to machining. In order to solve this problem, a high accuracy grinding method using a large cup wheel had been proposed and the tilt angle of the cup wheel spindle become a crucial factor affecting the ground form errors. This paper addresses a novel method for high-accuracy calibrating the tilt angle of the cup wheel spindle to fit the extremely shallow taper angle of the seal ring conical surface, and the mathematical model is established incorporating a standard optical flat with a high-accuracy laser displacement sensor. The practicability of this method is verified by grinding a seal ring sample with the outer diameter is 200 mm and the taper angle is 700 μrad. It is found that the taper angle error is only 1.72 μrad and the radical profile error of the conical surface is about 0.22 μm.

An Experimental Investigation on Wear of Rail in Different Curve Radius

Among the rail defects, the transverse fatigue crack, which has been the most dangerous damage, is developed near the rail running face and grows perpendicular to the rail surface. Finally, the transverse fatigue crack would result in the failure of railway rail. In this paper, the rolling tests were performed using a JD-1 wheel/rail simulation facility without any lubricant. The tester is composed of a small wheel served as rail and a larger wheel served as wheel. The fatigue behavior of rail rollers with different materials and curve radius were investigated in detail by examining wear volume and wear scar using optical microscopy (OM) and scanning electronic microscopy (SEM). The results indicate that with curve radius decreasing, the wear volume of rail roller increases rapidly and the fatigue damage becomes severe. Furthermore, the cracking propagation angle increases obviously with curve radius decreasing and fatigue wear is dominating during the wear process. There appears distinct plastic deformation on the section of rail roller under small curve radius condition. For the same curve radius, the wear volume of PD3 rail is more than that of PG4 rail and the plastic deformation is more obvious. Moreover, the cracking propagation angle of PD3 rail material is smaller than that of PG4 rail. In conclusion, PG4 rail material is not suitable for the high-speed railway.

Analysis of wheel/rail adhesion under oil contamination with surface roughness

The objective of this study is to investigate the adhesion characteristics of wheel/rail under oil contamination with consideration of surface roughness using a three-dimensional model of wheel/rail in rolling contact. A partial elastohydrodynamic lubrication theory is employed in the model. An under-relaxation revision on the film thickness is used to keep the simulation procedure stable. The dependence of the wheel/rail adhesion coefficient on train speed, surface roughness amplitude, parameter of roughness orientation and axle load is studied under oil contamination. Moreover, the numerical solutions of a two-dimensional model are compared with those of the three-dimensional model. In addition, a good agreement has been found between the numerical results and the experimental results obtained by a JD-1 wheel/rail simulation facility, which consists of a small wheel roller serving as locomotive or rolling stock wheel and a large wheel roller serving as rail.

Research of Element Segregation to Large Wheel Hub Hardness and Mechanical Properties

This paper focused on the Cu alloy elements macro segregation of large squeeze casting wheel hub, analysed element segregation on the wheel axle, wheel arm and wheel rim. Three positions on the hardness and mechanical properties were tested, researched the influence of element segregation on the hardness and mechanical properties.

A Novel Method for Kinematic Optimization of Camshaft Non-Circular Grinding

A novel non-circular grinding technique which utilizes two grinding wheels of different diameters is proposed for the locomotive camshaft with concave curves. The larger grinding wheel is used for rough machining to increase grinding efficiency and the smaller is used for finish machining to form the cam profile accurately. Based on the analysis of motion law of grinding carriage and headstock, the speed and acceleration curves are reconstructed by three different methods to optimize kinematic characteristics of cam non-circular grinding. Simulation and experimental results show that the profile accuracy and surface quality can be improved effectively through kinematic optimization by reconstructing the acceleration curves with cosine curves.

A quasi-static model of wheel–tissue interaction for surgical robotics

Wheel-driven mobile in vivo robotic devices can provide an unconstrained platform for visualization and task performance. Careful understanding of the wheel–tissue interaction is necessary to predict in vivo performance of medical mobility systems. Here, an analytical study of the friction involving rolling contact of a surgical wheel, moving at constant velocities over soft tissue, is presented and verified. A quasi-static frictionless solution is first derived from existing theory, and newly developed theory considering frictional effects is later introduced. In this analysis, the effect of friction on wheel mobility over a viscoelastic substrate is analyzed with wheel velocity as the only changing variable. The analytical model is later verified by experiments and Finite Element Method (FEM) simulations. A simple application of this model to help design a surgical robot is also presented. Additional results indicate that the resistance force, which arises from the tissue viscosity, approaches zero for small and very large wheel velocities.

Lower Cross-Braced Truck and Swing Motion Truck Have Different Effect on Freight Car Dynamics Performance

There are two major types of trucks for freight car in Chinese railroad. One is the lower cross-braced truck; the other is the swing motion truck. To evaluate the different performance, diamond resistant rigidity of the lower cross-braced truck and the lateral stiffness of the swing motion truck are analyzed. To simulate the dynamics performance of the swing motion truck, an equivalent lateral stiffness is calculated. Then it is modeled as a lateral spring between side frames and bolstered to simulate the swing. After that, two typical freight cars’ models which use the two types of trucks are built in SIMPACK. The L/V Ratio and Wheel Load Reduction Ratio are chosen for evaluating running safety of the freight car. The simulation results are compared and they prove that the impact force between wheel and rail when the car passing curve can be reduced effectively as the swing motion truck has a better lateral flexible. Therefore, it has a lower L/V ratio under the same running and loading condition. However, the swing leads a larger lateral displacement of the car-body, so the gravity center of loaded car has a larger lateral displacement than the car with lower cross-braced truck; which results to a larger Wheel Load Reduction Ratio.

Jitter reduction of a reaction wheel by management of angular momentum using magnetic torquers in nano- and micro-satellites

Nowadays, nano- and micro-satellites, which are smaller than conventional large satellites, provide access to space to many satellite developers, and they are attracting interest as an application of space development because development is possible over shorter time period at a lower cost. In most of these nano- and micro-satellite missions, the satellites generally must meet strict attitude requirements for obtaining scientific data under strict constraints of power consumption, space, and weight. In many satellite missions, the jitter of a reaction wheel degrades the performance of the mission detectors and attitude sensors; therefore, jitter should be controlled or isolated to reduce its effect on sensor devices. In conventional standard-sized satellites, tip-tilt mirrors (TTMs) and isolators are used for controlling or isolating the vibrations from reaction wheels; however, it is difficult to use these devices for nano- and micro-satellite missions under the strict power, space, and mass constraints. In this research, the jitter of reaction wheels is reduced by using accurate sensors, small reaction wheels, and slow rotation frequency reaction wheel instead of TTMs and isolators. The objective of a reaction wheel in many satellite missions is the management of the satellite’s angular momentum, which increases because of attitude disturbances. If the magnitude of the disturbance is reduced in orbit or on the ground, the magnitude of the angular momentum that the reaction wheels gain from attitude disturbances in orbit becomes smaller; therefore, satellites can stabilize their attitude using only smaller reaction wheels or slow rotation speed, which cause relatively smaller vibration. In nano- and micro-satellite missions, the dominant attitude disturbance is a magnetic torque, which can be cancelled by using magnetic actuators. With the magnetic compensation, the satellite reduces the angular momentum that the reaction wheels gain, and therefore, satellites do not require large reaction wheels and higher rotation speed, which cause jitter. As a result, the satellite can reduce the effect of jitter without using conventional isolators and TTMs. Hence, the satellites can achieve precise attitude control under low power, space, and mass constraints using this proposed method. Through the example of an astronomical observation mission using nano- and micro-satellites, it is demonstrated that the jitter reduction using small reaction wheels is feasible in nano- and micro-satellites.

FEA Structural Stress of Modalohr System for Semi-trailer Rail Transportation: Weld Root Fatigue Focus

In order to fulfill green requirement (reduction of CO2 emissions given by French “Grenelle”), a great need appears concerning roll-on roll-off efficient technology. Heavy seam welded structures manufacturer has to present an optimized product to fulfill this requirement. In this purpose, the Modalohr system overcomes several challenges: transport 4m height and 38 tons semi- trailer in UIC kinematic gauging with a low floor rail vehicle, use of conventional large wheel bogie with maximum axle load, 9 million kilometers running over 30 years service life. For cost effectiveness, the compact vehicle design uses welded assembly and avoids systematic full penetration welds which may require costly preparation machining. The idea is to develop a one shot FEA which provides both global structural bending and torsional vehicle behaviors and also the fatigue focus on each joint for both weld toe and weld root. The local stress analysis requires too much effort and the structural stress using appropriate inclined shell element in a global system model complies such requirement. A home made tool implements these techniques. LOHR “Seam Sim” development deals with the partial automation of the FEA model generation based on the following key points: solid weld feature are generated in CAD, FEA model automation idealization is achieved without additional manual operation. Postal2 post processing tool has been developed to allows standard FEA code results processing for both static and fatigue assessment. The final display is a scalar stress safety margin map associated for each element to the appropriate criterion over the system depending on the area type; plain metal, sheet metal edges, weld toe, weld root, bolt connection … “Seam Sim” theory [2,3] and Verification & Validation (V&V) has been presented during last fatigue Design conference in 2011 [4], today's aim is to present a highly fatigue demanding industrial application. Loads are applied at a system level to fulfill EN12663-2 standard and additional manufacturer load cases (including longitudinal dynamic fatigue load for 1050m long train and lifting, boarding kinematic load cases). The fatigue results are focused on each detail.

Path planning, modeling and simulation of an autonomous articulated heavy construction machine performing a loading cycle

This research presents path planning and tracking for an articulated large wheel loader during the travel portion of a loading cycle. The study proposes a methodology for path planning, modeling, simulation and control of such vehicles; the analysis focuses on all of these components together and explains the relation among them. The developed methodology for path planning takes into account the dynamics and the performance characteristics of the heavy construction articulated vehicles, it also takes into account the construction working site constraints. The path optimization criterion is based on distance and cusp minimization without neglecting the constraints imposed by the size of the vehicle and its stable turning radius. The proposed path planning methodology is an extension and an improvement for Reeds and Shepp algorithm for a point shortest path calculation. The optimal path is consisted of circular arcs and straight segments, the radius is constant and identical for each arc in the desired path, the radius assumed to be similar to the minimum turning radius of the machine. When optimizing articulated machine path; to best account for machine size and articulation; more than one approach are discussed and compared. The machine is modeled and simulated during tracing the pre-defined planned path. The machine model includes the main frames, tires and a steering controller. The developed PID controller is used to keep machine lateral position within the pre-defined path while traveling with constant speed. The results showed an acceptable optimized path which the machine is able to track closely.

Effects of two different forwarder steering and transmission drive systems on rut dimensions

Impact of two different forwarders, with similar carrying capacities but different transmission drive and steering systems, on rut formation was compared. El-forest F15 with three individual steerable axles without bogies, large wheels (∅164 cm) and an electric hybrid transmission drive system, and a Valmet 860, with conventional transmission drive (∅131 cm wheels, two bogies) were compared. The ruts from the El-forest with or without a load were generally deeper than those produced by the tracked Valmet when driving in a straight line on soft arable land. On an S-shaped or circular course the El-forest and Valmet produced the same rut depths after the first pass, but with an increasing number of passes, the Valmet made deeper ruts. On the intermediate forest land, after driving in a straight line, the El-forest generally produced shallower ruts than the non-tracked Valmet (tracks not used at this site). When driving on a circular course, this difference was also apparent when machines carried a load. The mean rut width created by the El-forest was significantly narrower than from the Valmet at both sites. A transmission drive system with axles and wheels that can be individually steered seems advantageous to reduce rut formation, especially if the wheels have reduced ground pressure on soft soils.

The Effect of Wheel Size on Mobility Performance in Wheelchair Athletes

The purpose of the current study was to investigate the effects of different wheel sizes, with fixed gear ratios, on maximal effort mobility performance in wheelchair athletes. 13 highly trained wheelchair basketball players, grouped by classification level, performed a battery of 3 field tests in an adjustable wheelchair with 3 different wheel sizes (0.59 m, 0.61 m and 0.65 m). Performance was assessed using the time taken to perform drills, with velocity and acceleration data also collected via a wheelchair velocometer. 20 m sprint time improved in the 0.65 m condition (5.58 ± 0.43 s, P=0.029) compared with 0.59 m (5.72 ± 0.40 s). Acceleration performance over the first 2 (P=0.299) and 3 (P=0.145) pushes was not statistically influenced by wheel size. However, the peak velocities reached were greater in the 0.65 m condition (4.77 ± 0.46 m ∙ s(-1), P=0.078, Effect Size [ES]=0.63) compared with 0.59 m (4.61 ± 0.40 m ∙ s(-1)). Impact velocity, calculated as the change in velocity from the onset of a push to the following impact peak, to define coupling performance, was also significantly improved in 0.65 m wheels (0.14 ± 0.14 m ∙ s(-1), P=0.006) than 0.59 m wheels (0.05 ± 0.10 m ∙ s(-1)). The time taken to complete the linear mobility (P=0.630) and the agility drill (P=0.505) were not affected by wheel size. Finally, no significant interactions existed between wheel size, classification and any performance measure. To conclude, larger 0.65 m wheels improved the maximal sprinting performance of highly trained wheelchair basketball players, without any negative effects on acceleration or manoeuvrability. Improvements in sprinting were attributed to a combination of the reduced drag forces experienced and improvements in coupling thought to be due to the lower angular velocities of the wheel/hand-rim when developing high wheelchair velocities in larger wheels.

Hybrid Train Power with Diesel Locomotive and Slug Car–Based Flywheels for NOx and Fuel Reduction

AbstractAn energy-storage flywheel consists of a large inertia wheel sharing a common shaft with a motor generator (MG) set and with magnetic bearings to support the entire rotating assembly. Flywheels mounted on a special slug car are charged from the local utility grid and from regenerative-braking events. Usage of these power sources reduces fuel consumption and the related NOx emission by the locomotive-mounted Diesel generator sets (DGS). The flywheel-supplied power can replace the DGS-supplied power in one or more of the eight fixed power settings (notches), plus idle and reverse, which are common to most locomotives either for line-haul or switchyard service. The slug cars have separate traction motors to be driven by the flywheel systems so that the flywheel power and DGS power are electrically and physically decoupled. A system model is presented that includes the train dynamics coupled with the electromechanical models for the flywheels and traction motors. The modified Davis equation is employe...

Analysis of Intensity and Vibration of 190T Electric Wheel Dump Truck Frame

Through the cracking failure analysis of dump truck frame with large electric wheel, the static and dynamic frame analysis of performance evaluation are conducted by the finite element analysis method. From the strength and stiffness analysis frame structure in the weak links, it is easy to find out crack the parts and the reasons with frame, and through the modal analysis and random vibration and fatigue strength analysis the danger frequency of the frame induced by road encourage is obtained, which can prevent the occurrence of frame cracks and provide a foundation for further optimization of the frame.

A Finite Element Model of Roll-Over Protective Structures for Wheel Loader Frame

ROPS is an effective way to reduce casualty rate in the rolling accident. This paper introduces the design of a cab to strengthen safety-ROPS large wheel loader method. The finite element model, it's a ROPS rear, absorbers and supporting structure frame of the safety-cabs, was created. Force and displacement boundary conditions obtained in accordance with the international standard ISO3471:2008-The large deformation elastic-plastic finite element analysis, horizontal, vertical and ROPS vertical load cases of performance testing and the corresponding lab for investigation. The test results show that the design can meet the requirements of ISO3471 ROPS: 2008. Test results differences and simulation and welded joint of the fracture analysis on the reason.