Hub Material Research Articles

An improved burr size prediction method based on the 1D-ResNet model and transfer learning

Cutting burrs, which are common in the manufacturing process of aluminum alloy wheel hubs, can severely affect the quality of the wheel hub surface and increase the scrap rate. An accurate prediction of the cutting burr size is the basis for solving the burr problem using optimization means. However, wheel hub cutting burrs can be measured only by offline microscopy, which makes acquiring burr size samples challenging, and traditional data fitting and prediction methods perform poorly for limited number of samples. To solve this problem, this paper proposes an improved method for constructing a burr length prediction model. A constitutive model of the wheel hub material A356.2 aluminum alloy is constructed using mechanical tests. This constitutive model is applied to simulate the wheel cutting burr, and the simulation results are verified using cutting experiments. Then, a large amount of simulation is performed, and a one-dimensional residual network (1D-ResNet) is constructed and trained with the simulation data; the results show that the 1D-ResNet model has stronger stability and robustness and improved prediction accuracy compared to the traditional data processing methods. Based on the transfer learning method, the trained 1D-ResNet model is fine-tuned by using the cutting experimental data, and a burr size prediction model fusing the simulation data and the experimental data is constructed. The verification results show that the proposed method can achieve high prediction accuracy with limited number of samples, thus effectively solving the engineering problem of wheel cutting burr size prediction.

Determination of Thermomechanical Stresses in Elements of Vehicles' Braking Systems

The main objective of the study was to develop a model and analyze the thermomechanical behavior of the hub material of the vehicle brake disk. The simulation strategy was based on the solution of the three-dimensional problem of the theory of elasticity for the case of effect of external loads and temperature fields on the metal structure element of the vehicle brakes. To solve this type of task of the theory of elasticity, the differential equations of the second order were used for the first time. Adaptation of the proposed model, completed in the article, has proved the correctness of use of these equations in modeling the thermomechanical processes with determination of stresses and displacements in unevenly heated rotary cylinders of the final length. The proposed method can be applied with high efficiency in stress strain state simulation of individual parts of vehicles.

Topology optimization of an ATV wheel hub

The article is based on the Topology Optimization of an ATV Wheel Hub. So, we use this methodology to reduce the unwanted material of the All-Terrain Vehicle(ATV) Wheel HUB and to reduce the weight. ATV is mainly designed for a competition, where the Hub is used to connect the wheel to chassis via steering knuckles and arm linkages. Hub plays a vital role in the ATV. So, designing of hub should be in proper dimensions. The hub material is designed with a help of SOLIDWORKS. And it was analysed by SolidWorks simulation. The material used for a hub is Aluminium alloy 6063-T6.

Wheel Hub Material Selection through Finite Element Analysis based on Reverse Engineering

This paper aims to analyze the existing wheel hubs and build a three-digit wheel hub model by combining forward and reverse mixing modeling. The Geomagic Wrap and Geomagic Control X software are used to collect the hub’s geometric features, and the construction of the solid model is completed quickly. The precision analysis of the reconstructed solid model was carried out, which verified the method’s effectiveness. The 3D digital model is imported into NX software, and NX software is used to carry out finite element analysis. The best material is selected through the results of the simulation data calculation. Finally, the hub finite element’s static analysis and design strength requirements are compared to verify the reverse design method’s feasibility.

Reverse Modeling and Topological Optimization for Lightweight Design of Automobile Wheel Hubs with Hollow Ribs

Lightweight of wheel hubs is the linchpin for reducing the unsprung mass and improving the vehicle dynamic and braking performance of vehicles, thus, sustaining stability and comfortability. Current experience-based lightweight designs of wheel hubs have been argued to render uneven distribution of materials. This work develops a novel method to combine the reverse modeling technique with the topological optimization method to derive lightweight wheel hubs based on the principles of mechanics. A reverse modeling technique is first adopted to scan and reproduce the prototype 3D geometry of the wheel hub with solid ribs. The finite element method (FEM) is then applied to perform stress analysis to identify the maximum stress and its location of wheel hub under variable potential physical conditions. The finite element model is then divided into optimization region and nonoptimized region: the former is the interior portion of spoke and the latter is the outer surface of the spoke. A topology optimization is then conducted to remove the optimization region which is interior material of the spokes. The hollow wheel hub is then reconstructed with constant wall thickness about 5[Formula: see text]mm via a reverse modeling technique. The results show that the reconstructed model can reduce the mass of 12.7% compared to the pre-optimized model. The present method of this paper can guarantee the optimal distribution of wheel hub material based on mechanics principle. It can be implemented automatically to shorten the time interval for optimal lightweight designs. It is especially preferable for many existing structures and components as it maintains the structural appearance of optimization object.

Experimental investigations on permanent magnet based wheel mechanism for safe navigation of climbing robot

This paper presents excremental studies on permanent magnet based wheel mechanism for safe navigation of climbing robot on ferrous wall surface structures. Three types of wheel mechanism (Wheel 1, Wheel 2 and Wheel 3) are manufactured and compared for their working performance experimentally for climbing robot locomotion trials. The Wheel 1 mechanism with MS hub is very compact, simple in design with easy assemble/dissemble features, and having less manufacturing cost. However, the adhesion force of the prototype wheel is comparable with already reported permanent magnet based adhesion mechanism. Wheel 1 design is further improved by developing Wheel 2 and 3 versions by changing hub material from mild steel to Aluminum. These wheel mechanisms are light in weight and more powerful to achieve maximum adhesion force i.e., 210 N and 251 N with and without rubber grip, respectively, at only 200 gm wheel weight as compared to previously reported permanent magnetic adhesion mechanism. Thus, more payload carrying capacity climbing robot can be developed using these developed mechanisms for field trials of climbing robot. A comprehensive experimental study on the influence of rubber grip thickness, air gap, wheel tilt angle and test surface thickness variation on adhesion force of these developed wheel mechanisms have been reported. The influence of both static and kinetic coefficient of friction (COF) for vertical surface locomotion of climbing robot has also been investigated. These developed wheel mechanisms have been further demonstrated using a four-wheel differential drive prototype-climbing robot for safe navigation testing first on a 2-D framed plane wall structure and next on a 3-D framed wall structure. It is found from the laboratory trials that based on these wheel mechanisms, the climbing robot can safely navigate remotely on even surface for these chosen structures.

Research on Dynamic Behavior of Different Grinding Wheel Hub Material with FEM Method

This paper presented a numerical model of a grinding wheel hub to analyze the dynamic behavior between CFRP hub and steel hub. Natural frequencies of the two different hubs were extracted with the help of finite element software ABAQUS. In addition, the vibration attenuation procedure in the process of free vibration of the hubs was also compared. The numerical results obtained from the model demonstrated that natural frequency of the CFRP hub is much higher than that made of steel owing to the great ratio of elastic modulus to density of carbon fiber. The CFRP hub has a better damping vibration characteristic which allows it to absorb vibration in grinding process to achieve a finer surface roughness.

Spin test of three-dimensional composite rotor for flywheel energy storage system

A rotating disk often undergoes severe vibration at high rotation speeds because of unstable joining between the disk and a drive shaft. As described herein, three connection methods between a driving shaft and an annular rotation disk made of three-dimensionally carbon-fiber reinforced composite were discussed to achieve stable rotation at high rotation speeds by changing the hub material and joining geometry: the connecting device. In two of the three methods, the vibration amplitude increased at a tip speed higher than 500m/s. Key factors that caused the vibration were analyzed. Results show that the third method by which a resin ring (hub) was inserted between the disk and rotation shaft maintained stable joining, even at high-speed rotation.

Numerical Investigation of Knurled Shaft-Hub Connections and Especially of the Joining Process

Faced with increasing cost pressures, manufacturers need to find new solutions for shaft-hub connections. One example is the knurled interference fit, where a shaft with knurls and interference is pressed in a soft hub with a cylindrical bore. At present the potential of the knurled interference fit is not fully used, because there are no general standards available for the design and for the joining process. But the joining process in particular has an important impact on the join strength. A predominantly forming joining process offers some advantages compared to cutting. Forming allows a clearly higher contact pressure over the groove because of the displacement of the hub material, which leads to greater axial reliability. Also, the natural material structure is preserved by the forming, and this, in combination with the hardening of the hub, should allow a higher transmittable torque. The Finite Element Method is used for detailed investigation of the joining process and the transmission behavior in the axial direction. With this method, the local loads, for example the hardening of the hub over the groove due to the formed join, are investigated as well as further parameter variations (e.g., chamfer angle, interference). Hence, an analytical approach for the determination of the necessary joining force was derived.

Failure investigation of wheel gear hub assembly of an aircraft

The failure investigation of an aircraft rear wheel gear hub at hood position was conducted to find the cause of fracture. The stereographs represented river pattern at crack initiation site originating from the preexisting cracks at the inner surface of hood. The metallurgical study showed the overaging of wheel hub material. Stress analysis by finite elemental analysis identified the stress concentration regions nearly at the same positions of wheel hub from where it was failed in reality. The SEM analysis of fracture surface represented that crack propagated by cleavage mode with microvoid coalescence at the eutectic and α-Mg interface. The overloading was a cause of final failure with visible features of chevron marks pointing back in the direction of crack originating site.

An Experimental Study on the Dynamic Behavior of Grinding Wheels in High Efficiency Deep Grinding

The design and material of the grinding wheel hub determine its static and dynamic behaviors which, in turn, play significant roles in grinding performance. This can be of special interest in high efficiency deep grinding (HEDG) process, in which the wheel is subjected to extremely high centrifugal and grinding forces. On the other hand, controlling the dynamic behavior of the grinding wheel through an in-process monitoring and a post-process measurement seems an appropriate approach to optimize the grinding process. This paper addresses the effects of the Carbon fiber-reinforced polymer (CFRP) hub body on the grinding process efficiency through comparing the results of the experiments carried out by two CBN vitrified bonded wheels with different hub materials, CFRP and steel. The experiments were conducted using a new in-process measurement system. It was proved that the dynamic behavior of grinding wheels can affect the chip removal mechanism, and in turn, influences the finished surface roughness. Furthermore, using the CFRP as the hub material leads to a reduction in the wheel radial expansion during the operation and grinding forces. High amplitudes and frequencies have been measured when using the steel grinding wheel, while they can be damped by employing CFRP hub material.

Crack tip displacements of microstructurally small surface cracks in single phase ductile polycrystals

A planar double slip crystal plasticity model is applied to the evaluation of crack tip opening (CTOD) and sliding (CTSD) displacements for microstructurally small stationary cracks under monotonic loading for a material with nominal stress–strain behavior that is representative of a relatively high strength helicopter rotor hub material. Two-dimensional plane strain finite element calculations are presented for CTSD and CTOD of microstructurally small transgranular surface cracks in a polycrystal subjected to monotonic loading. The effects of crack length relative to grain size, orientation distribution of nearest neighbor grains, stress state and stress level are considered for nominal stress levels below the macroscopic yield strength. The CTOD and CTSD are computed for stationary crystallographic surface cracks with various realizations of crystallographic orientations of surrounding grains. It is found that (i) the opening displacement is dominant for remote tension even for crystallographic cracks oriented along the maximum shear plane in the first surface grain, (ii) there is a strong dependence of the CTOD on the proximity to grain boundaries, but lesser dependence of the CTSD, and (iii) that the elastic solutions for CTOD and CTSD are valid below about 30% of the 0.2% offset-defined yield strength.

An Elasto-Plastic Analytical Solution for the Shrink-Fit Problem with a Thin Strain-Hardening Hub and an Elastic Solid Shaft

An analytical solution is obtained in this article for the axisymmetric shrink fit problem with a thin strain hardening hub and an elastic solid shaft. The solution is based on the deformation theory of Hencky, the yield criterion of von Mises, and the assumption of infinitesimal deformations. An elastic power law plastic material model is employed to represent the stressstrain relation of the hub material, with the compressibility of material being included. The solution is derived by using a stress formulation and with the help of a modified Nadai's auxiliary variable method and the extended Michell theorem. All expressions for the stress, strain, and displacement components are derived in explicit forms in terms of an auxiliary variable and four constant parameters that are determined from given boundary conditions by an iterative process. Three specific solutions are presented as limiting cases of the solution. Numerical results are also provided to show quantitatively applications of the solution. This solution, together with the related specific solutions and numerical results, furnishes a new theoretical basis for the mechanical design of shrink-fit sets.

Design and fabrication process for electrostatic side-drive motors

A new process technique has been implemented for the fabrication of electrostatic side-drive micromotors. In the present technique, polyimide has been used as the hub material for fabricating the 4-pole rotor, 8-pole rotor and the wobble micromotors. Process techniques to achieve the micromachining of these structures are discussed in detail.

On the Elastic‐plastic Shrink Fit with Supercritical Interference

AbstractShrink fits with perfectly elastic‐plastic hub material cannot be treated with the help of Tresca's yield criterion, if the ratio of outer and inner diameter as well as the interference exceed certain limits. For linear hardening material, however, a solution exists for all radii ratios. It is shown that, for small hardening, the material in the neighbourhood of the interface undergoes a twofold change of the yield condition.

The shrink fit with elastic-plastic hub exhibiting constant yield stress followed by hardening

The subject of the investigation is the distribution of stress, displacement and plastic strain in a rotating shrink fit, the hub material of which undergoes plastic deformation with constant stress up to a certain plastic strain and linear hardening for larger strain.

無負荷運転時における研削と石の温度分布と熱変形

This paper deals with the temperature distributions and the thermal deformations of the grinding wheels. The investigated wheels are a conventional vitrified bonded alumina wheel and a CBN wheel. The hub material of CBN wheel is an aluminum alloy. From the experimental results measured with the thermographs, it derived that the temperature of aluminum hub is directly affected by the heat flowed from the rotating wheelspindle. However, the influence of heat flow on the vitrified bonded wheel is restricted to the inner abrasive layer of wheel. This difference of temperature distribution between both wheels can be explained by the differences of the thermal conductivity and the air-cooling ability of the wheels. The distance between both peripheries of CBN wheel and wheel spindle remarkably increases with the increase of wheel running time. It can be considered that this large expansion is almost contributed by the thermal expansion of aluminum hub.

The Use of Increased Wheel Flexibility to Improve Chatter Performance in Grinding

The metal removal rates attainable during grinding may often be limited by the onset of an unstable vibration, commonly called regenerative chatter. Chatter is a self-induced vibration which leads to increased power consumption, a poor, generally unacceptable, ***workpiece surface finish, uneven wear of the grinding wheel and, in some cases, actual damage to the wheel. It is known that chatter is more likely to occur when the grinding wheel is hard and for this reason chatter often develops when grinding with diamond or cubic boron nitride (CBN) wheels, whose chief characteristic is that they are very hard-wearing. This paper describes the development of a technique for suppressing chatter which is particularly applicable to the use of diamond and CBN wheels. It has been predicted theoretically and confirmed by experiment that chatter may be suppressed, or even eliminated, by increasing the radial flexibility of a grinding wheel, whilst at the same time maintaining high values of the wheel's natural frequency and damping. It has been shown that the increased flexibility may be achieved by mounting the abrasive rim of the wheel via a flexible coupling, or by manufacturing a wheel by conventional means but with a flexible hub material. Both techniques are successful and diamond and CBN wheels, manufactured to these designs, have performed substantially better than conventional ultra-hard abrasive wheels currently marketed. It is considered that the problem of chatter when using diamond or CBN wheels has been solved. Since this problem has represented one of the major obstacles to the acceptance of CBN wheels by industry, it is anticipated that these wheels will now enjoy a much more widespread usage.

The Development of an Utrahard Abrasive Grinding Wheel which Suppresses Chatter

Previous workers have shown that grinding with ultrahard abrasive wheels may be made substantially more stable by reducing the radial flexibility of the wheel whilst, at the same time, maintaining high values of the wheel natural frequency and damping. Theoretical work has shown that similar beneficial effects may be obtained by merely reducing the contact stiffness of the wheel, and that this could best be achieved by producing a conventionally manufactured wheel with a hub material which was flexible. This possibility was investigated and two wheels were manufactured with “Retimet” as hub material. These wheels had radial static stiffnesses which were an order of magnitude lower than conventional CBN wheels. They both performed well, giving stable grinding, good workpiece surface finish and a complete absence of waves around their periphery after periods of grinding in excess of 12 hours. There were no problems encountered with geometric accuracy of the workpiece or prolonged “spark-out” times.

Rotating Elasto-Plastic Interference Fits

By an elasto-plastic design the transferable torque of an interference fit can be increased significantly. In high-speed applications the initial contact pressure is reduced by the centrifugal body force. A fit having a full shaft and equal elastic constants of shaft and hub material is considered. Using Tresca’s yield criterion an analytical solution determining the dependence of contact pressure on angular velocity is derived. All formulae necessary for design of fits are presented. Numerical results are given and conclusions for practical applications of rotating elasto-plastic interference fits are drawn.