Yuan Qiang Tan

Contact Strength of Toroidal Drive with Cylindrical Teeth

The meshing equation of the toroidal drive with cylindrical tooth was established based on space meshing theory, and the formula of contact stress between planet and worm or the toroidal internal gear are derived. Major influence factors were analyzed and forecasted. The contact stress is sensitive to the tooth number of planet center distance and planet radius. Finally, the calculation method of contact strength of toroidal drive was given.

DEM Simulation and Experimental Investigation of Silicon Carbide on Pre-Stressed Machining

In this paper, the technology of pre-stressed machining suitable for ceramic materials was presented. Using the cluster method, the discrete element method (DEM) model of SiC ceramic was established to simulate the crack’s initiation and propagation in cutting processes with different pre-stress value. The scratching tests were carried out to confirm the validity of simulation. Both the DEM simulation and the experimental investigation showed that: with the increasing of pre-stress, the number of radial cracks reduced and the transverse cracks replaced the radial cracks to some extent, and also caused the material removal in the form of smaller fragments. Using pre-stressed machining can decrease the machining damage and improve the surface quality, and further prove that using DEM to simulate the machining process of ceramic materials was feasible.

DEM Simulation of Machining Damage in SiC Pre-Stressing Cutting Process

Based on the theory of metal pre-stressing machining, the method of pre-stressing suitable for ceramic materials machining was presented. Using the cluster method, the discrete element method (DEM) model of ceramic materials machining was established. The DEM simulations of cutting process of SiC ceramic under different machining parameters were carried out by orthogonal test design method, and the effects of machining parameters on the number of surface cracks and maximum crack depth after processing were also analyzed. The results showed that the tool edge radius influenced greatly on the number of surface cracks, while the pre-stress influenced greatly on the maximum crack depth.

DEM Simulation of Ceramic Tool Abrasion in Machining Superalloy

The discrete element method (DEM) model which describes the friction and abrasion behavior of the interface between Sialon ceramic tool and superalloy chip in machining were established, effects of cutting speed and depth of cut on tool abrasion were numerically investigated. The abrasion behaviors of the Sialon ceramic tool mainly appear in terms of abrasive wear, fatigue wear, adhesion wear and diffusion wear. The DEM simulation results show that, within a certain range, the higher cutting speed effectively results in the slighter wear of Sialon ceramic tools, meanwhile the deeper depth of cut leads to more serious tool wear. It is further validated that discrete element method is feasible to simulate the tool wear behavior.

3D Finite Element Analysis of Prestressed Cutting

In order to reveal the adjustment principle of prestressed cutting on the residual stress of hardened bearing steel GCr15, a three-dimensional thermal elastic-viscoplastic finite element model was developed using an Arbitrary Lagrangian Eulerian (ALE) formulation. Several key simulation techniques including the material constitutive model, constitutive damage law and contact with friction were discussed, simulation of chip formation during prestressed cutting was successfully conducted. At the prestresses of 0 MPa, 341 MPa and 568 MPa, distributions of residual stress on machined surface were simulated and experimentally verified. The results indicated that residual compressive stress on machined surface were achieved and actively adjusted by utilizing the prestressed cutting method; meanwhile, within the elastic limit of bearing steel material, the higher applied prestress leads to the more prominent compressive residual stress in the surface layer and subsequently the higher fatigue resistance of the part.

Prediction of Chip Morphology and Cutting Force during Prestressed Cutting of TC4

Chip morphology plays a predominant role in determining machinability and tool wear during the machining of titanium alloys. Chip formation process in prestressed cutting of titanium alloy TC4 was numerically explored via the finite element method. Crack initiation during the chip segmentation was realized by using a ductile fracture criterion which based on the strain energy. Effect of prestress on cutting force and chip formation as well as Mises stress distributions were revealed. The results indicate that chips show the similar characteristic of continuous and regular serrated shape, which is not affected by prestress. Initial stress distribution of workpiece was changed by prestress, which correspondingly leads to the alteration of stress distribution in the subsurface layer. The generated cutting force curves share the same average amplitude and analogous rhythm, which correspond to the chip forming process respectively.

Characteristic Analysis for the Internal Flow Field of CVT Torque Converter Based on FLUENT

According to the issue of CVT torque converter internal flow field such as the complexity and not easy to calculate, the channel model of torque converter is established by UG, the grid of channel model is generated by GAMBIT, the internal flow field of torque converter is simulated based on FLUENT while the pressure and velocity distribution of flow field are calculated under three different conditions. The results show that analyzing the flow field of torque converter by FLUENT has certain guiding significance for the design and optimization of torque converter.

Finite Element Analysis of Tandem Rubber O-Ring Sealing Structure at the End of Shaft

Based on the tandem sealing structure at the end of the shaft,a finite element model of rubber O-rings has been established and the sealing performance of rubber O-ring has been analyzed. There is an un-uniform compression among these O-rings which lead to the sealing failure. Under different friction factors, several groups of the rubber O-rings have been analyzed, finding that the friction factor is the reason of un-uniform compression. The effect of different average compression rate has been investigated, which has been integrated in the sealing criteria for the tandem O-rings, providing a reference for the optimization of tandem sealing structure at the end of the shaft. According to the sealing criteria for a single O-ring, the sealing criteria for the tandem O-rings is built.

Residual Stresses in Prestressed Turning of Nickel-Based Superalloy

Aiming to get appropriate residual compressive stress distribution on machined surface just in the machining process, the technique of prestressed cutting is applied for nickel-based superalloy shafts. This article studies theoretically and experimentally the effect of prestress on the residual stress in the machined surface layer. Prestressed turning tests under the conditions of different prestress, cutting speed, depth of cut and feed rate were carried out, residual stresses were determined via an X-ray diffraction technique. Theoretical result demonstrates that higher prestress leads to more prominent residual compressive stress and validated by experiments, meanwhile measured residual stress profiles indicate that lower cutting speed and lower feed rate lead to more remarkable compressive stress state, contrarily depth of cut shows relatively indistinctive effect.

The Research on the Movement Precision of Globoidal Cam Mechanism Based on Error Modeling

Through analyzing several common errors that have impact on the kinematic accuracy of globoidal cam mechanism, finally a mathematical model of globoidal cam impinged with error was established. By using the differential method, the motion accuracy influence coefficients of the globoid cam mechanism were obtained. The change rule of kinematic accuracy influence coefficient with the change of globoidal cam rotation angle was analysed with practical cases. The analysis result shows: different error factors lead to different influence coefficient; Radius error of the index disc roll has the greatest impact on motion precision, while shaft angle error almost has no influence on the movement precision; The meshing position of the globoidal cam mechanism affects the kinematic accuracy volatile; Moreover, each motion accuracy influence coefficient has a certain relationship with the structure factors of globoidal cam.