Spinning-punch new technology for aluminum alloy plate-wheels forming
The aluminium alloy plate-wheels are a new kind of wheels with light-weight, energy-saving and environmental protection. Spinning is a conventional technology to form aluminium alloy plate-wheels, but the outline dimension and run-out of rolled lip in end face are difficult to meet the exacting requirements of wheels blueprint. So the new spinning-punch forming technology for aluminium alloy plate-wheels was researched and simulated. 3-D elastic-plastic finite element models were constructed and appropriate boundary conditions were given out. The results show that aluminium alloy plate-wheels with good quality can be formed by spinning-punch forming technology through controlling roller feed rate, roller'diameter, flanging times, and punching stroke, etc. And the relationships between spinning load and roller'diameter, rolled lip forming quality and flanging times are found.
3D FEM numerical simulation and experimental study on symmetric thin-wall tube neck-spinning
A 3D FEM model for symmetric thin-wall tube neck-spinning is established. The spinning process is simulated by means of ANSYS software, and the dynamic boundary and contact problems in simulation are solved. The transient stress distribution of contact area, the transient strain distribution of nodes in typical section and the strain distribution of the whole part at last are attained, and the place and the cause of crack are analyzed. Simulation results show how the strain distribution of typical section, the thickness of some typical nodes, the Z coordinate in typical section and the spinning force of three rollers change with the time. According to study the variation curve, the material flow law along radial, tangential and axial direction is attained and the whole spinning process is studied. The experiment data reflect how the spinning force is influenced by different process parameters, such as feed rate, roundness radius and pass reduction. The simulation and the experiment results supply criteria for optimum design and reasonable parameter selection.
Mechanical behaviour and durability of high volume fly ash cementitious composites
The purpose of this research is to separate different morphological particles of ASTM class F fly ash, and study their effect on mechanical behaviour and durability of high volume cementitious mixtures. In this research wet separation of raw fly ash is carried out, which resulted in three layers of different morphological particles. The first layer of particles float, comprise of about 1-5% of fly ash, is identified as cenospheres or hollow spheres. The second layer of particles is measured to be 55-60% of raw fly ash and consisting of porous spherical and rounded particles rich in Si and Al. The third layer particles is measured to be about 35-40% of raw fly ash. High volume fly ash cementitious composites containing second or third layer particles are tested under compression and bending, highlighting a higher strength and ductility in comparison to cementitious ones containing raw fly ash particles. KEYWORDS. Cementitious matrix; Raw fly ash; Second layer particles; Third layer particles.