Papers by Author: Guo Zhong Chai

Abstract: In order to improve the weak mechanical properties of bioceramic HA, composite coatings were prepared by adding the toughening zirconia to HA powder so as to improve the biological and the physical properties but not to reduce the biocompatibility of HA bioceramic coating. The pure HA coating and HA/ZrO2 composite coating containing 30% stabilized zirconia on titanium alloy by employing plasma spraying technology were prepared. The relation curves of load-displacement for the two coatings were obtained with three point bending experiment, and obtained the slope about the straight fitting line. Then the elastic modulus and fracture toughness of the both coatings were calculated. The fracture morphology of the two coatings after their failure was observed using electron microscope.

Abstract: process parameters; surface gloss; Rapid Heat Cycle Molding Abstract: Rapid Heat Cycle Molding is a novel injection molding, which may improve product surface quality effectively. In this paper, one-factor experimental design and Taguchi method were used and the influence of different process parameters (mold heating temperature, melt temperature, injection rate, injection pressure, and packing pressure) on surface gloss of injection product was studied. The results showed that temperature is the significant factor to the surface gloss. Mold heating temperature is principal factor in mold process parameters, while the melt temperature is the secondary factor and injection pressure is the least. The surface gloss increases with increasing mold heating temperature, melt temperature, injection rate through whole processing, while it increases to top then decreases with increasing injecting and packing pressure

Abstract: Many defects such as micro-voids, micro-cracks are introduced during the preparation of particle reinforced composite coating, which significantly change the mechanical properties of the coating. Based on Mori-Tanaka’s concept of average stress in the matrix and Eshelby’s equivalent inclusions microscopic theory, an incremental theory coupled with ABAQUS subroutine UMAT, is developed to study the influence of initial void and void growth on elasto-plastic properties of composite coating. In the composite containing hard spherical particles, debonding of particle-matrix interface is a significant damage process, and the effect of initial void on particle damage is also considered.

Abstract: This paper attempts to use a kind of smart material-magnetorheological fluid and magnetorheological jet polishing method to polish mould. Use self-preparation MR fluid conduct experiments on MR jet polishing setup which developed by ourselves. After polished by MR jet, surface roughness of the mould improved from 812nm to 88nm. The result shows that experiment and its setup are feasible.

Abstract: The subsurface transverse median crack system due to spherical contact in brittle coating-bond -substrate sandwich structure is investigated with an emphasis on stress intensity factor near the crack front using finite element method. This crack system emanates from the lower surface of the brittle layer and extends transversely towards the top of contact surface, resulting in ultimate failure of the structures. In this paper, finite element mesh is designed, and the crack front mesh designing solution for a surface crack subjected to remote tension is validated with Newman and Raju empirical equation. Then the proposed crack front mesh design solution is applied to a typical sandwich structure of various modeling parameters to obtain the SIF with 3D-J integral.

Abstract: Screw thread, as the most basic and widely used mechanic element, has many traditional methods to verify its dimension consistency. Machine vision technology is gradually applied to inspect screw thread in fastener industry because of its fast, precise and repeatable features. Based on analysis of the features and problems of previous vision measurement methods, this paper provides calculation, analysis and simulation of screw thread’s 3D mathematic model, and finally provides corresponding algorithm to correct calculation error resulting from shading effect of backlight projecting.

Abstract: This paper present a cooling simulation method for External Gas-assisted Injection Molding (EGAIM). To simulate the cooling process of EGAIM, a Finite Element Method model with heat transfer processing with isotropic materials containing inner heat source was established, and pressure was loaded on the interface of mold and part as gas packing pressure. The simulation was used to explore the effect of process parameters on the quality of an example with different thickness ribs with ANSYS. The results showed the method is feasible and reliable.

Abstract: To deal with problem of manufacturing system stability caused by uncertain factors in discrete production process, holon was introduced to manufacturing execution system (MES). A distributed manufacturing control architecture based on holon was established. This architecture using cooperation mechanism based stigmergy to realize agility, autonomy and intelligence of system control. Based on the architecture, holon driven agents to visit production elements, acquiring dynamic information of production process. Model design of production factors as order, resource, raw material, product and management factors as optimize, execution was described amply. Finally, workflow of this system was depicted with an example of uncertain order factor.

Abstract: Fluid magnetic abrasive (FMA) is a new precision finishing process. It has the capability of processing free shape surfaces and complex cavities. Due to its strong adjustability and controllability, FMA could be regarded as the final process of machining which could greatly improve the surface quality of workpiece. The paper first introduces the component and machining mechanism of FMA, secondly it describes the model of the material removal in the process, thirdly it presents the devices of FMA polishing. At the end, a grinding head tool based machining mode is proposed for realizing the polishing of internal cavity.

Abstract: In this paper, the main molding process parameters which are relevant to warpage were optimized by orthogonal experiment and finite element software MPI. The result shows that we can get a series of optimized parameters and know how much each process parameter influences the warpage by combining orthogonal experiments with simulation experiments using MPI, while fewer experiments are needed. Verified by MPI, such series of optimized parameters can keep the warpage in a low level and completely meet the standard of the product.