The numerical modelling of multi-physics phenomena: The shape casting process

In this paper a computer simulation tool capable of modelling multi-physics processes in complex geometry has been developed and applied to the casting process. The quest for high-quality complex casting components demanded by the aerospace and automobile industries, requires more precise numerical modelling techniques and one that need to be generic and modular in its approach to modelling multi-processes problems. For such a computer model to be successful in shape casting, the complete casting process needs to be addressed, the major events being:-• Filling of hot liquid metal into a cavity mould • Solidification and latent heat evolution of liquid metal • Convection currents generated in liquid metal by thermal gradients • Deformation of cast and stress development in solidified metal • Macroscopic porosity formation The above phenomena combines the analysis of fluid flow, heat transfer, change of phase and thermal stress development. None of these events can be treated in isolation as they inexorably interact with each other in a complex way. Also conditions such as design of running system, location of feeders and chills, moulding materials and types of boundary conditions can all affect on the final cast quality and must be appropriately represented in the model.

Feature-oriented grid topology design for aerospace configurations

The last few years have seen a substantial increase in the geometric complexity for 3D flow simulation. In this paper we describe the challenges in generating computation grids for 3D aerospace configuations and demonstrate the progress made to eventually achieve a push button technology for CAD to visualized flow. Special emphasis is given to the interfacing from the grid generator to the flow solver by semi-automatic generation of boundary conditions during the grid generation process. In this regard, once a grid has been generated, push button technology of most commercial flow solvers has been achieved. This will be demonstrated by the ad hoc simulation for the Hopper configuration.

Experimental and numerical study of the cold crucible melting process

The cold crucible, or induction skull melting process as is otherwise known, has the potential to produce high purity melts of a range of difficult to melt materials, including Ti–Al and Ti6Al4V alloys for Aerospace, Ti–Ta and other biocompatible materials for surgical implants, silicon for photovoltaic and electronic applications, etc. A water cooled AC coil surrounds the crucible causing induction currents to melt the alloy and partially suspend it against gravity away from water-cooled surfaces. Strong stirring takes place in the melt due to the induced electromagnetic Lorentz forces and very high temperatures are attainable under the right conditions (i.e., provided contact with water cooled walls is minimised). In a joint numerical and experimental research programme, various aspects of the design and operation of this process are investigated to increase our understanding of the physical mechanisms involved and to maximise process efficiency. A combination of FV and Spectral CFD techniques are used at Greenwich to tackle this problem numerically, with the experimental work taking place at Birmingham University. Results of this study, presented here, highlight the influence of turbulence and free surface behaviour on attained superheat and also discuss coil design variations and dual frequency options that may lead to winning crucible designs.

Lifetime assessment of electronic components for high reliability aerospace applications

This paper details a modelling approach for assessing the in-service (field) reliability and thermal fatigue life-time of electronic package interconnects for components used in the assembly of an aerospace system. The Finite Element slice model of a Plastic Ball Grid Array (PBGA) package and suitable energy based damage models for crack length predictions are used in this study. Thermal fatigue damage induced in tin-lead solder joints are investigated by simulating the crack growth process under a set of prescribed field temperature profiles that cover the period of operational life. The overall crack length in the solder joint for all different thermal profiles and number of cycles for each profile is predicted using a superposition technique. The effect of using an underfill is also presented. A procedure for verifying the field lifetime predictions for the electronic package by using reliability assessment under Accelerated Thermal Cycle (ATC) testing is also briefly outlined.

Heavy cultural industries

The present recession has prompted scholarly and journalistic questioning of the contributions of the cultural industries to the economy. The talent-rich metropolitan clusters of London and New York are well-placed to ride out a thoroughgoing shakeup of the media markets if they manage their infrastructure, space and resources strategically, as Richard Florida has recently argued. This seems to be the assumption behind the recent Digital Britain interim report, and Gordon Brown's remarks that a digital revolution "lies at the heart" of Britain's economic recovery and that broadband and the media industry can play a leading role in pulling the UK out of the recession. Focusing on the Digital Britain report and consultation documents, this presentation seeks to unpack some of the fundamental assumptions behind this link between digital infrastructure, creativity and profitability. In particular the implicit notion of an engaged audience of users, generating "content" as well as shaping new media platforms calls into question longheld theoretical constructions of the mass audience of consumers as spectators. [From the Author]

Heavy cultural industries

The present recession has prompted scholarly and journalistic questioning of the contributions of the cultural industries to the economy. The talent-rich metropolitan clusters of London and New York are well-placed to ride out a thoroughgoing shakeup of the media markets if they manage their infrastructure, space and resources strategically, as Richard Florida has recently argued. This seems to be the assumption behind the recent Digital Britain interim report, and the prime minister's remarks that a digital revolution "lies at the heart" of Britain's economic recovery and that broadband and the media industry can play a leading role in pulling the UK out of the recession. Focusing on the Digital Britain interim report, this presentation seeks to clarify some of the fundamental assumptions behind this link between digital infrastructure, creativity and profitability. [From the Author]