Michael Schulz

Smoothed particle hydrodynamics simulation of shear-induced powder migration in injection moulding

We present the application of the smoothed particle hydrodynamics (SPH) discretization scheme to Phillips’ model for shear-induced particle migration in concentrated suspensions. This model provides an evolution equation for the scalar mean volume fraction of idealized spherical solid particles of equal diameter which is discretized by the SPH formalism. In order to obtain a discrete evolution equation with exact conservation properties we treat in fact the occupied volume of the solid particles as the degree of freedom for the fluid particles. We present simulation results in two- and three-dimensional channel flow. The two-dimensional results serve as a verification by a comparison to analytic solutions. The three-dimensional results are used for a comparison with experimental measurements obtained from computer tomography of injection moulded ceramic microparts. We observe the best agreement of measurements with snapshots of the transient simulation for a ratio Dc/Dη=0.1 of the two model parameters.

Polyester-styrene/ceramic nanocomposites for antenna applications

Polyester-styrene polymer composites of high permittivity ceramic nano powders (barium titanate) are fabricated and electrically measured for antenna applications. It is shown that the usage of high permittivity ceramic contents can increase the relative permittivity of the composites to around 10 at microwave frequencies. The Polyester-styrene composite material preparation technique is described. The materials are used to fabricate various dielectric resonator antenna elements. Details of the antenna fabrication techniques are discussed. Results show fabricated antenna elements and arrays with large impedance bandwidth. The presented techniques provide a precise method for fabrication of complicated or multi-segment dielectric resonator antennas.