Kamran Tabeshfar

Materials for Sports

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.

Effect of microstructure on the plain and notched fatigue properties of IMI 550 Ti alloy

Abstract The fatigue crack initiation and propagation in plain and notched specimens of titanium IMI 550 alloy with different percentages of transformed β-phase has been investigated. The S/N curves for plain specimens having a two-phase α/β microstructure were superior to those having a 100% transformed β microstructure. It is thought that this difference is due to easier crack paths in the β-stabilized samples, which contain very large grains. The notched S/N curves, however, were not dependent on microstructure. The overall crack propagation rates were similar for the three microstructures studied.

Mean stress effect in fatigue crack propagation

Abstract Crack propagation rates in three different grades of mild steel and two types of age hardening aluminium alloys have been measured for different stress ratios. The results show a pronounced stress ratio effect for all these materials. A model of fatigue crack propagation is formulated in terms of the size of the cyclic plastic instability zone at the crack tip rather than the zone of plastic yielding. The micro-plastic instability zone is measured by a parameter involving the ratio of the maximum stress intensity and the stress level at which macro-plastic instability occurs in the S N curve of plain fatigue test pieces. Such a parameter provides a means of normalizing crack propagation results obtained for various stress ratios.

Analysis of crack propagation data for a strain ageing and a stabilized mild steel tested under R=0 and R=−1 loading conditions

Abstract Comparative studies of crack propagation in a strain ageing and a stabilized mild steel were carried out under axial loadings of the R = 0 and R = −1 types. The results show the rate of fatigue crack propagation is dependent on both the tensile and the compressive stresses in the fatigue cycles, the compression stresses being less effective than the equivalent tensile stresses in causing crack growth. An equation is presented relating the rate of fatigue crack growth to a stress intensity range which is factored to allow for the variations in fatigue damage associated with the tensile and compressive parts of the stress cycle.

VICARIA: An e-learning tool for risk assessment and management

This paper is based on research carried out as part of the VICARIA project, an interactive tool which was developed from an EC Leonardo grant, to provide distance learning and virtual classrooms in the field of risk management and control. Companies are responsible to provide appropriate training especially in sensitive and critical areas such as risk assessment and management; unfortunately many consider, risk analysis training to be expensive, costly and time consuming. VICARIA allows flexibility in training time, it is cost-effective i.e. reduced travel and subsistence expenses, it enables managers to attend and assist in courses, allowing them to judge the relevancy and quality of training provided and also VICARIA offers specialised and the latest knowledge in the specific field of risk analysis. This system includes accessibility, interoperability, durability and re-usability aspects and uses open standards with respect to platform and content. English, French and Greek are the languages used.

Fracture Characteristics of Iron-Copper Sintered Compacts

A study of fatigue cracking in iron-copper compacts was carried out to compare and analyse the performance of four different types of commercially used iron powders. The compacts were all sintered at above the iron copper peritectic temperature to facilitate liquid phase sintering. Results showed that the powder with a high specific surface had inferior fatigue properties, especially at high stress levels. The other powders, however, had very similar fatigue properties, except that at low stresses the grade with the large average particle diameter resulted in significantly longer fatigue lives. The differences in performance were discussed in terms of the microstructure of the compacts and the powder characteristics.