Papers by Author: Yuan Qiang Tan

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: An improved method to design equivalent load for multi-stage planetary was introduced in this paper on the basis of methodology for determining the equivalent torque. A multi-stage nominal-load representation of designing equivalent load for load spectrum on each stage was proposed. Compared with traditional single-stage nominal-load method of a gearbox for wind turbine pitch control, it was showed there was an effectiveness and reasonableness of the proposed method in this paper. A testing rig was set up for a pitch drive which it was designed by the multi-stage nominal-load method. A lot of experiments were carried out, and the excellent performances of the pitch drive were showed. From the result, it can be seen that this improved method was feasible.

Abstract: A novel diamond fibers cutter was proposed in this paper for machining of advanced materials. The fibers cutter was prepared by artificially distributing and orientating a large number of diamond fibers, which were prepared by cutting polycrystalline diamond into size of 0.4mm*0.6mm*10mm using Nd:YAG laser, and then lapped on a lapping machine to form sharpened cutting edges. To investigate the machining mechanism of the diamond fibers cutter, an experiment on machining of aluminum alloy reinforced by SiC particles and nano-structured WC/Co coating was conducted in this paper. Based on the surface observation and the cutting force analysis, it could be found that the diamond fibers cutter combined the advantages of conventional wheels and cutting tools, and was fit for machining of both brittle materials and soft materials.

Abstract: Damage and failure of the fiber reinforced composites remain as a challenging research subject in the area of material science and engineering. In this study a novel particle assembly model is developed using two dimensional Discrete Element Method (DEM) for the purpose of simulating the damage and failure process of the single-fiber composite (SFC) under axial tension. Fiber (SiC) and matrix (Epoxy) are represented by particles bonded together through elastic parallel bonds which are calibrated by a series of numerical tests. The contacts between the fiber particles and matrix particles are directly accounted for the fiber/matrix interface which is represented by the contact softening model similar to the cohesive zone model (CZM) in the continuum mechanics. The single-fiber composite tensile test is carried out using the developed DEM model in order to evaluate the interactions between fiber breakage, interfacial debonding and matrix cracking. The numerical results have demonstrated the capability of the developed DEM model in simulating the entire failure process of each individual constituent of the single fiber composite. This study has also confirmed that the DEM model has unique advantages over the conventionally numerical models in terms of dealing with the evolution of microscopic damages in composite materials.

Abstract: 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.

Abstract: 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.

Abstract: The random nature of the abrasive geometries and their distribution in a grinding wheel results in high specific grinding energy and temperature rise, large grinding forces and large deflection in the grinding system. To overcome the shortcomings encountered in grinding, it is necessary to design a new grinding wheel that is structured in controlled abrasive geometries with preferred spatial positioning and orientation. This paper deals with an experimental research of single fibrous-abrasive grinding of a nanostructured WC/12Co Coating. Prepared by the laser cutting of polycrystalline diamond compact (PDC), the single fibrous-abrasive has the dimensions of 0.3×0.6×10mm. The paper reports the research findings on normal and tangential grinding forces in terms of depth of cut and feed rate and discusses the material removal mechanism of nanostructured WC/12Co Coating ground by fibrous abrasive.

Abstract: The objective of this study is to experimentally investigate the effect of reinforced SiC particles on the machining of Aluminum/SiC composite (15% volume ratio of SiC particles with average grain size 15m). Aluminum/SiC composite and aluminum metal were milled by a tungsten carbide endmill in this study. Based on the surface observation and surface roughness inspection, it is found that the machining parameters of Aluminum/SiC composite have optimum values, and that the surface roughness of aluminum/SiC composite is smaller than that of aluminum metal. when feedrate and depth of cut are smaller than limited values, satisfactory surface finish can be attainable, however, as the depth of cut and feedrate increases, the microcracks are first initiated at the interface of SiC particles and aluminum matrix, and then periodically macrocracks are formed on the machined surface, The damage mechanism during the machining of aluminum/SiC are discussed in this paper.