Leon Foster

Quasi-static characterisation and impact testing of auxetic foam for sports safety applications

This study compared low strain rate material properties and impact force attenuation of auxetic foam and the conventional open-cell polyurethane counterpart. This furthers our knowledge with regards to how best to apply these highly conformable and breathable auxetic foams to protective sports equipment. Cubes of auxetic foam measuring 150 × 150 × 150 mm were fabricated using a thermo–mechanical conversion process. Quasi-static compression confirmed the converted foam to be auxetic, prior to being sliced into 20 mm thick cuboid samples for further testing. Density, Poissons ratio and the stress–strain curve were all found to be dependent on the position of each cuboid from within the cube. Impact tests with a hemispherical drop hammer were performed for energies up to 6 J, on foams covered with a polypropylene sheet between 1 and 2 mm thick. Auxetic samples reduced peak force by ~10 times in comparison to the conventional foam. This work has shown further potential for auxetic foam to be applied to protective equipment, while identifying that improved fabrication methods are required.

An improvement index to quantify the evolution of performance in running

Abstract Improvements in track and field sports have been attributed to factors such as population increase, drugs and new technologies, but previous research has found it difficult to distinguish the contributions from specific influences. Here it is shown how this is possible by means of a performance improvement index based on useful work done combined with modelling of the annual top 25 performances. The index was set to 100 in 1948 and showed that, by 2012, it had increased in running events to between 110.5 and 146.7 (men’s 100 m and marathon). Underlying global effects accounted for the majority of all improvements (16.2 to 46.7) with smaller influences attributable to an influx of African runners (3.6 to 9.3), and a 4 -year oscillation that arose from staging of the Olympic Games (±0.2 to ±0.6). Performance decreased with the introduction of compulsory random drug testing (−0.9 to −3.9) the World Anti-Doping Agency (WADA; −0.5 to −2.5) and fully automated timing (−0.6 to −2.5). Changes in elite sporting performance since the 1890s are attributable to societal changes caused by the industrial revolution and globalisation superimposed on millennia of human evolution.

Auxetic Foam for Snow-Sport Safety Devices

Skiing and snowboarding are popular snow-sports with inherent risk of injury. There is potential to reduce the prevalence of injuries by improving and implementing snow-sport safety devices with the application of advanced materials. This chapter investigates the application of auxetic foam to snow-sport safety devices. Composite pads—consisting of foam covered with a semi-rigid shell—were investigated as a simple model of body armour and a large 70 × 355 × 355 mm auxetic foam sample was fabricated as an example crash barrier. The thermo-mechanical conversion process was applied to convert open-cell polyurethane foam to auxetic foam. The composite pad with auxetic foam absorbed around three times more energy than the conventional equivalent under quasi-static compression with a concentrated load, indicating potential for body armour applications. An adapted thermo-mechanical process—utilising through-thickness rods to control in-plane compression—was applied to fabricate the large sample with relatively consistent properties throughout, indicating further potential for fabrication of a full size auxetic crash barrier. Further work will create full size prototypes of snow-sport safety devices with comparative testing against current products.

An improvement index to quantify the evolution of performance in field events

Abstract The mean of the top 25 performances in 8 men’s and 5 women’s field events since the 1890s showed that performances increased dramatically after the Second World War II and subsequently plateaued during the late twentieth century. A performance improvement index, developed on the basis of work done, was set to 100% in 1948. The underlying rise found in all events was modelled using an exponential function with a superposition of steps and linear changes to account for the introduction of rule changes, drugs testing and the introduction of new technologies. The performance improvement index in throwing events increased to 140.9% compared with 125.8% in jumping events, and women’s performance improvement always exceeded that of men’s. Around half of all events were shown to have reached 99.9% of their predicted limit with a majority reaching it within the next 25 years. It was concluded that performance will only change in the future if an intervention takes place: this could be the emergence of a new technology, a rule change or a new athlete population.

Real-Time Monitoring of User Physical Activity and Position in an Outdoor Public Space

A primary aim of the ProFit FieldLab project is to encourage physical activity through innovations in products, services and ICT systems. User interactions with newly installed prototype play and exercise equipment within a FieldLab needs to be monitored so that its value and effectiveness can be assessed. Real-time feedback of activity level and location is important to associate user activity with specific pieces of equipment and video capture data. However, there is no current off-the-shelf solution for this. The aim of this study was to create a low-cost, real-time activity and location monitoring system based around a smartphone. The system incorporates accelerometer, heart rate, GPS and Wi-Fi RSSI values. Initial testing of the system has shown that user activity level and movement on a specific item of play equipment in the Delft FieldLab can be recorded alongside targeted video capture.

Development of smart inner city recreational facilities to encourage active living

Lowfield Park in Sheffield, UK is a green recreational space maintained by the City Council. Lowfield Park was selected as the primary Sheffield FieldLab for the ProFit project which ended in 2015. The ProFit project was European Interreg IVbNWE funded with the aim of encouraging physical activity through innovations in products, services and ICT systems. In 2014 the Sheffield Hallam University City Athletics Stadium (SHUCAS) was introduced as a secondary FieldLab. A number of innovative systems have been installed into the FieldLabs, these include: Pan Tilt Zoom cameras, automatically timed sprint and running tracks, outdoor displays/touchscreen and a gait analyser. This paper describes the hardware, software and cloud infrastructure created to enable these systems. Pilot testing has been carried out over the last year and has found a positive effect on both sites. The systems created will be taken forward to Sheffield’s Olympic Legacy Park, which is currently under development.