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This paper describes a detailed study of tube extrusion by simulation using finite element method (FEM). The finite element model used one-sixth of symmetry. The extrusion load, temperature evolution and metal flow were predicted. Innovative methods, combining both grid and surface tools, were used to define in detail the flow of material. These showed clearly the inner and outer surface formation mechanisms of the tube extrusion. The seam weld, an important quality indicator, was also evaluated by selecting an appropriate criterion.

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In this paper, both direct and indirect extrusions are simulated using a viscoplastic constitutive model. The simulated velocity fields for both direct and indirect extrusions are discussed and compared with experimental results. Advanced numerical techniques are used to trace backward and forward discrete particles of the billet. The effect of friction on the material flow is discussed. Back-end defects are simulated and practical methodologies are derived to minimise such defects using finite element modelling (FEM). Peak loads, temperatures and strain rate distribution are also compared between direct and indirect extrusions. Numerical subroutines have been developed and integrated into the FEM software in order to introduce the possibility of prediction of microstructural evolution. The results of such numerical simulations to increase productivity within the extrusion industry are currently limited only by the lack of sufficient physical metallurgical detail and by obstacles preventing the FEM simulation to be directly applied. This aspect is discussed in some detail.

Strength-improved Zr-based metallic glass/porous tungsten phase composite by hydrostatic extrusion Appl. Phys. Lett. 90, 081901 (2007); Abstract. It is widely recognized that subgrain size has significant influence on the strength and ductility of metals. Modelling of subgrain size evolution is essential for the detailed understanding and control of mechanical properties. In the present paper, the evolutions of subgrain size during hot extrusion of various aluminum alloys are first predicted. A nearly constant distribution of subgrain size is pursued by iso-subgrain extrusion processes. Substructural strengthening coupled with microstructural evolution is also studied in addition to the normal thermal-mechanical coupled analysis.

The interplay between materials science and sports equipment takes many forms. Certainly a broad cross section of materials is used in sporting equipment to improve performance and safety, and to reduce cost. The new materials used in sports equipment originate from a long history of innovation, drawing from and contributing to other technologies. Amateurs and professionals play sports, so rules on the use of new technology vary immensely. This allows for a short circuit of new technology into the market-place in some cases and restriction or prohibition of opportunities in others. Also materials selection and development for sports equipment must stretch beyond consideration of the object itself to include the human interface and design of a system that best makes use of the materials. Sports after all are about human capability and interaction. The equipment is just a facilitator. Certainly more efficient ways exist of placing a ball into a hole than hitting it with a long metal stick from hundreds of yards away. This is perhaps the most unique element of materials development for sports. The rules governing materials development are not just laws of science and of government but rules put into place just for “sport.” Because of the connection of sports to the lives of so many people, either as participants or spectators, materials science of sporting equipment is also a great platform for educating students about materials selection and behavior.