Weichao Wu

High response speed microfluidic ice valves with enhanced thermal conductivity and a movable refrigeration source

Due to their ease of fabrication, facile use and low cost, ice valves have great potential for use in microfluidic platforms. For this to be possible, a rapid response speed is key and hence there is still much scope for improvement in current ice valve technology. Therefore, in this study, an ice valve with enhanced thermal conductivity and a movable refrigeration source has been developed. An embedded aluminium cylinder is used to dramatically enhance the heat conduction performance of the microfluidic platform and a movable thermoelectric unit eliminates the thermal inertia, resulting in a faster cooling process. The proposed ice valve achieves very short closing times (0.37 s at 10 μL/min) and also operates at high flow rates (1150 μL/min). Furthermore, the response time of the valve decreased by a factor of 8 when compared to current state of the art technology.

Experimental and numerical analysis of double sided incremental forming

This paper presents a new rapid prototyping process of a thin sheet metal, Double Sided Incremental Forming of a cylindrical part without a die or a clamping device around the periphery of the sheet. The effects of process parameters on part shape, such as gap between two tool heads and feed rate, are examined experimentally with a special device mounted on a general lathe and numerically with a commercial finite element software package, Abaqus. Depending on the process parameter, a truncated cone shape part can be successfully fabricated with two tool heads pressing and moving along the radial direction of the sheet, which is held by lathe spindle at its center. A simple mathematic model to predict the cone angle is proposed and compared well with experimental data.Copyright

Analysis on Filament Winding Sphere Surface Component With Multiple Polar-Holes

This paper presents a new filament winding process for multi-polar holes componet. Some kinds of filament winding components work as connecting piece which has many holes. Traditionally, the hole is usually machined after the fabrication of composite components. This will lead to the fibers around the holes are cut off. In addition, it would also increase the risk of composites delamination and crack around the area of the holes. In order to eliminate these defects, the multi-polar holes filament winding process was proposed. The winding trajectories of a sphere with two non-axial polar holes were designed and tested. Then, by calculating the area of fiber sparse zone and fiber volume fraction of this winding component, it was found that the radiuses of polar holes can significantly influence the area of fiber sparse zone and fiber volume fraction.Copyright

Experimental and Numerical Analysis of Titanium Microtube Elliptical Flaring

Traditional tube flaring processes focuses on expanding one end of the tube without changing its cross-sectional shape. This paper presents a new two-step tube flaring process for expanding one end of a titanium alloy microtube while simultaneously changing its cross-sectional shape from circular to elliptical. Experiments were performed to investigate and verify this process. Furthermore, an analytical model was developed to analyze the forming process and investigate the relationship between punch feed and maximum plastic strain during the flaring process. The analysis shows that the two-step flaring process used is effective in expanding the circular cross section to an elliptical cross section without failure. It is also shown that the developed analytical model can predict the fracture of the tube end during the flaring process approximately. Finally, a FEM simulation was performed to further investigate the two-step flaring process.Copyright

Stress and Strain Analysis on Incremental Sheet Metal Forming With Multiple-Head Tool

A new method of incremental forming was introduced and investigated, which used a tool with multiple heads turning around holding mandrels freely. In order to investigate the advantages of this method, experiment and forming analysis were done. In this process, some truncated components were made from thin Al2024-O Aluminium plate with inward tool path. An analysis model of tool path was created with geometric method. A calculation of strain and stress distribution was developed and compared with experimental results. And an investigation of forming limit was made by experiments with truncated pyramid and strip shape. The results agreed with each other. It has been shown that this method can easily improve the forming efficiency and surface roughness.Copyright