Enhancement of Surface Integrity in Turning of Particle74 Reinforced Aluminium Matrix Composites by Tool Design

AbstractParticle reinforced aluminium matrix composites (AMCs) are high-strength lightweight materials consisting of a comparatively soft aluminium alloy and hard embedded ceramic particles. The high hardness of the particles results in excellent abrasion resistance. However, this property lends poor machinability involving high tool wear and surface imperfections on the workpieces. For this reason, CVD diamond tipped indexable inserts were used for turning AA2124 with 25% volume proportion of SiC particles. The surface integrity is influenced by the tool geometry, which affects the stress condition in the shear zone. In the research described the influence of modified corner geometries and the width of flank wear land were investigated. The results showed that surface roughness values can be decreased by using tools with a wiper geometry. An increasing flank wear land width of the inserts led to a reduction of the surface imperfections

Phase field analysis of eutectic breakdown.

In this paper an isotropic multi-phase-field model is extended to include the effects of anisotropy and the spontaneous nucleation of an absent phase. This model is derived and compared against a published single phase model. Results from this model are compared against results from other multi-phase models, additionally this model is used to examine the break down of a regular two dimensional eutectic into a single phase dendritic front

Purple Bacteria

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Phase Field Modeling of Fracture and Stress Induced Phase Transitions

We present a continuum theory to describe elastically induced phase transitions between coherent solid phases. In the limit of vanishing elastic constants in one of the phases, the model can be used to describe fracture on the basis of the late stage of the Asaro-Tiller-Grinfeld instability. Starting from a sharp interface formulation we derive the elastic equations and the dissipative interface kinetics. We develop a phase field model to simulate these processes numerically; in the sharp interface limit, it reproduces the desired equations of motion and boundary conditions. We perform large scale simulations of fracture processes to eliminate finite-size effects and compare the results to a recently developed sharp interface method. Details of the numerical simulations are explained, and the generalization to multiphase simulations is presented

Analysis of thermal evolution in textile fabrics using advanced microstructure simulation techniques

Nowadays, membrane structures represent a modern construction element to be used as roof material in modern buildings or as design element in combination with traditional architecture. Membranes are mostly used in an outdoor environment. Therefore they are exposed to wind, radiation (solar and infrared), rain and snow. Specific membranes are three-dimensional fabrics which can be used as energy absorber or as insulation of membrane roofs. The applicability as energy absorber becomes important if the three-dimensional fabrics are designed as a porous flow channel streamed by air and convectively heated up. The transferred energy may be stored in a latent heat storage system. Due to their porous structure, textile fabrics have a large heat-exchanging surface. If they are handled as homogenized porous structures, the heat transfer processes can not be described in a correct way. Therefore a microstructure model locally resolving all filaments of the three-dimensional fabrics has been formulated. By using an advanced meshing tool, a simulation technique has been developed taking into account the local heat conduction properties of the different materials. To analyse the heat transfer processes inside the three-dimensional fabrics, numerical simulations have been performed using the phase-field solver (Pace3D) of the Karlsruhe Institute of Technology and the commercial CFD-Solver StarCCM+. For a better understanding of the thermal behaviour of the fabrics, different thermal loads including thermal conduction in the microstructure (filaments) and convection by the surrounding air have been computed. The results show that the advanced simulation techniques allow to analyse the rate of conductive and convective heat transfer in three-dimensional fabrics. The results of the applied computational methods are compared