Papers by Author: Shou Yan Zhong

Abstract: By Computer finite element analysis, the impact of the interface thickness, the interface module and the short fiber orientation of Al2O3-SiO2(sf)/AZ91D composite on the maximum fiber axial stress and the steady creep rate is studied. Maximum axial stress of the short fiber is in the fiber center, and the axial stress gradually decreases along the direction of the fiber length. When the external stress is constant, the maximum fiber axial stress increases with decreasing of the thickness of the interface, and the steady creep rate increases with the increasing of thickness of the interface. The maximum fiber axial stress increases with the increasing of the interface modulus, the increasing of the interface module improves the load transfer and the creep resistance. Finite element simulation results and experimental results can be well matched to better explain the creep behavior.

Abstract: In this paper, the authors describe a rapid prototyping method to produce vascularized tissue such as liver scaffold for tissue engineering applications. A scaffold with an interconnected channel was designed using a CAD environment. The data were transferred to a Polyjet 3D Printing machine (Eden 250, Object, Israel) to generate the models. Based on the 3D Printing model, a PDMS (polydimethyl-silicone) mould was created which can be used to cast the biodegradable material. The advantages and limitations of Rapid Prototyping (RP) techniques as well as the future direction of RP development in tissue engineering scaffold fabrication were reviewed.

Abstract: In this papers, the authors described a rapid prototyping method to produce vascularized tissue such liver scaffold for tissue engineering applications. A scaffold with interconnected channel was designed using CAD environment. The data were transferred to a Polyjet 3D Printing machine (Eden 250, Object, Israel) to generate the models. Based on the 3D Printing model, a PDMS (polydimethyl-silicone) mould was created which can be used to cast the biodegradable poly (L-lactic-co-glycolic acid) (PLGA )material. The advantages and limitations of Rapid Prototyping (RP) techniques as well as the future direction of RP development in tissue engineering scaffold fabrication were reviewed.

Abstract: Constant stress tensile creep tests were conducted on an AZ 91–25 vol.% Al₂O₃-SiO₂ short fiber composite and on an unreinforced AZ 91 matrix alloy. The creep resistance of the reinforced material is shown to be considerably improved compared with the matrix alloy. The creep strengthening arises mainly from the effective load transfer between plastic flow in the matrix and the fibers. Microstructural investigations by SEM revealed good fiber–matrix interface bonding during creep exposure. Short fibers have a great function in load bearing and load transfer, and greatly hinder the dislocation movement, thus enhancing the creep resistance of the composite. Damage and multiple rupture of aluminum silicate short fiber, quality of the interface combination between aluminum silicate short fiber reinforcement and the matrix, are two important factors of the creep deformation microstructure process control of Al₂O₃-SiO_2(sf)/AZ91 composite. The creep mechanism of the composite is dislocation and grain boundary sliding control.

Abstract: The enterprise clusters are many enterprises in the same region, which are centralized to produce the same mass products. In the context of globalization, the enterprise clusters are becoming an important force of the leading world economy. Based on investigating and analyzing for the enterprise clusters in south China, the local area networks of the enterprise clusters can be built by using multi-level distributed computer system. The CAD and MIS systems are integrated into the local area networks of the enterprise clusters so that the flexible manufacturing systems can gain manufacturing data from the integrated systems. So, the integrated systems greatly improve the productivity of the enterprise clusters. The CAD and MIS system integration model of intelligentization has been dwelt on in this paper.

Abstract: We present an approach that combines Computer Tomography (CT), reverse engineering (RE) and rapid prototyping (RP) for individual implant production in maxillofacial surgery. 3D acquisition of the patient’s skull is performed, after acquisition of data; an individual computer-based 3D model of the bony defect is generated. These data are transferred into RE software to create the implant using a computer-aided design (CAD) model, which is directed into the RP machine for the production of the physical model. The implant is then directly used in investment casting such as “Quick Cast” pattern to produce the titanium model. In the clinical reports presented here, reconstructions of one patient with mandible bone defects were performed using this method. The custom prostheses perfectly fit the defects during the operations, and surgery time was reduced.

Abstract: In this paper, frictional behaviors of tool, workpiece and chip in turning particulate reinforced iron-based composites were investigated. Experimental results reveal that in frictional process, the frictional coefficient decreases with the normal force increasing or with the reinforcement content decreasing. In turning process, the variation rule of such parameter is just similar to that of frictional process, but frictional force and average frictional coefficient on rake face are more than that of frictional process. Meanwhile, the frictional mechanism of cutting tool and material is also studied. It indicates that adhesion occurs on tool-chip interface. The intense scratching of reinforcing particulates blocks the formation of adhesion layer and makes the frictional coefficient decrease, on the other hand, it increases the sliding resistance of chip, which makes the frictional coefficient increase. Since the latter is dominant, the tool-chip frictional coefficient increases with the increase in reinforcing particulates.

Abstract: To improve the maxillofacial surgery outcome, modern manufacturing methods such as rapid prototyping (RP), reverse engineering (RE) and medical imaging data have been utilised to manufacture custom-made prostheses after previous failed reconstructive surgery. After acquisition of data, an individual computer-based 3D model of the bony defect was generated and transferred into RE software to create the prosthesis CAD model. Then the physical model of the prosthesis was fabricated by RP technique. The precise fit of the prosthesis was evaluated using the prosthesis and skull models. The prosthesis was then directly used in investment casting such as “Quick Cast” pattern to produce the titanium model. In the clinical reports presented here, reconstructions of one patient with large mandible bone defects were performed using this method. The custom prostheses perfectly fit the defects during the operations, and surgery time was reduced. These cases showed that the prefabrication of a prosthesis using modern manufacturing technology is an effective method for maxillofacial defect reconstruction.

Abstract: AZ91 magnesium matrix composite was fabricated by squeeze infiltration process. The aluminum silicate short fibers were used as reinforcement, and aluminum phosphate was adopted as binder, fabricating process was improved as well as reducing fabricating cost effectively. The optimum technique of squeeze casting, that was, preform-body temperature of 6600C, mould temperature of 5600C, pouring temperature of 7600C and pressure of 30~50MPa. The reaction products were investigated by optical microscopic, XRD and SEM. The results show that an ideal stronger interface is formed by the chemical reaction between magnesium alloy matrix and aluminum phosphate binder due to the produce of MgO particles and a little MgAl2O4 particles in the interface. AZ91 magnesium matrix composite is well-organized, and its grain size is significantly smaller than that of the matrix. The structure of AZ91 magnesium matrix composite is uniform without casting defects such as shrinkages and inclusions.