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Abstract A finite element model was developed for assessing the efficacy of rugby body padding in reducing the risk of sustaining cuts and abrasions. The model was developed to predict the onset of damage to a soft tissue simulant from concentrated impact loading (i.e., stud impact) and compared against a corresponding experiment. The damage modelling techniques involved defining an element deletion criterion, whereby those on the surface of the surrogate were deleted if their maximum principal stress reached a predefined value. Candidate maximum principal stress values for element deletion criteria were identified independently from puncture test simulations on the soft tissue simulant. Experimental impacts with a stud were carried out at three energies (2, 4 and 6 J), at three angular orientations (0°, 15° and 30°) and compared to corresponding simulations. Suitable maximum principal stress values for element deletion criteria settings were first identified for the 4 J impact, selecting the candidates that best matched the experimental results. The same element deletion settings were then applied in simulations at 2 and 6 J and the validity of the model was further assessed (difference

Human limb surrogates, of varying biofidelity, are used in the performance assessment of sports personal protective equipment (PPE). Such biofidelic surrogates have incorporated soft tissue simulants (silicones) and synthetic bone (short fibre filled epoxy). Testing surrogates incorporating realistic synthetic bone could help to further our knowledge of fracture trauma mechanics, and applications such as the effectiveness of sports PPE. Limb surrogates with embedded synthetic bone are rarely tested to fracture, mainly due to the effort and cost of replacing them. This paper proposes additive manufacturing of synthetic bones, with appropriate bone like fracture characteristics, potentially making them more accessible and cost effective. A Markforged® X7™ printer was used as it prints a base filament (Onyx™) alongside a continuous strand of reinforcement (e.g., carbon fibre). The properties of specimens from this printer vary with the type, volume fraction and position of reinforcement. Bar specimens (10 × 4 × 120 mm) with varying amounts of carbon fibre reinforcement were printed for three-point bend testing to determine the feasibility of achieving mechanical properties close to compact bone (bending modulus of ∼15 GPa, bending strength of ∼180 MPa). Bending strength for the various bar specimens ranged from 32 to 378 MPa, and modulus values ranged from 1.5 to 25.8 GPa. Based on these results, four 140 mm long oval shaped cylindrical specimens of ø14 and ø16 mm were printed to represent a basic radius bone model. Three-point bend testing of these bone models showed similar bending modulus (3.8 to 5.3 GPa vs. 3.66 to 14.8 GPa) to radius bones reported in the literature, but higher bending strength (147 to 200 MPa vs. 80.31 ± 14.55 MPa).

Road-embedded inductive power transfer (IPT) systems have the potential to accelerate the electrification of the transportation sector. For these systems to be economically viable, however, they need to have a similar durability and lifespan to those of asphalt roads. One area that has lacked investigation is thermally induced stresses in a primary IPT pad, which are caused by the increase in the temperature of the pad when it is energized and the differing thermal expansion of the materials within. This paper presents an experimental and a finite element-based methodology for investigating the thermal–mechanical behaviour of a ¼-scale double-D pad, which was energized while suspended in air, as well as energized when embedded in pavement. A focus was placed on the measurement and prediction of strains in the magnetic ferrite cores because of their brittleness. Ferrite strains were measured using a combination of resistive strain gauges and non-metallic fibre Bragg grating (FBG) sensors. Coupled electromagnetic–thermal–structural simulations were conducted to predict temperature and strains in the system, with temperature-dependent properties obtained through physical testing. At an ambient temperature of 50 °C, the temperature in the middle of the copper litz wire coil was predicted to be 100 °C in both the suspended and embedded case. There was an excellent correlation with the experimental results, with a difference of less than 10% for most temperature measurements. When energized, the pad was predicted to experience an upward bow due to its temperature rise, resulting in bending strains in the ferrite cores. At an ambient temperature of 50 °C, the maximum tensile strain in the ferrites of the embedded pad was measured to be 62 microstrains (με), with a root-mean square error that was 18 με across three sensors. The experimental and validated numerical methodology can be applied to full-scale operational IPT pads to analyse and improve their thermal–mechanical performance.

Summary: Objectives: To investigate the effect on the impact response of wrist protectors by incorporating a soft tissue simulant on to a wrist surrogate made of stiff material. The effect of protector strapping condition was also investigated. Design and methods: A compliant and a stiff surrogate were made, based on the wrist geometry specified in ISO 20320:2020 for the “Limitation of wrist extension” test. Two styles of wrist protectors (short, long) were tested on each limb surrogate, subject to a ∼31 ​J impact. Six protectors of each style were tested, with two of each at each strapping condition (loose, moderate, tight) on each surrogate (stiff, compliant) (24 combinations). Example temporal force and wrist angle and force vs. wrist angle plots are presented for comparison between conditions. Results: When protectors were on the compliant surrogate, peak impact force was 55–68% lower (short 3.1 vs. 6.8 ​kN, long 2.7 vs. 8.3 ​kN). The time to reach this peak force was ∼4 ​ms (12%) longer, than for the stiff surrogate. Protector strapping condition had no clear effect for the stiff surrogate, with the wrist extending to its limit for all tests. Strapping protectors tighter on the compliant surrogate tended to decrease the maximum wrist angle and peak force. Conclusions: With results being sensitive to surrogate design and strapping condition, these both need to be clearly reported in future work impact testing wrist protectors, with implications for certification tests within standards.

Objective: Fixed obstacles, such as trees, rocks and posts, are common within recreational ski areas. Collisions with fixed obstacles (CWO) can have severe consequences with significant physical, emotional and economic costs. Despite worldwide use of ski area padding, few studies have focused on padding and CWO. The snowsports safety community is now focusing on this topic to improve safety at recreational ski areas. The objectives of this white paper are to summarize the recent work conducted on ski area padding, to identify unsolved questions about CWOs and opportunities to improve safety. Methods: A review of the current knowledge regarding CWOs and ski area padding was performed, combining scientific studies and experience from the authors and ski area safety professionals. This review covers: (i) the epidemiology of CWOs; (ii) the characteristics of CWOs; (iii) padding type and use; (iv) ski area safety professional practices; and, (v) padding performance and the limits for injury mitigation. Results: Previous studies focused on epidemiology, padding practices and performance and provide motivation for further study in the areas of: (i) prevention of CWOs; (ii) padding practices to improve safety on the slopes; (iii) requirements for padding performance; and, (iv) technological advancement of padding materials and design. Conclusions: There is a need for an international standard for ski area padding, to address the absence of padding performance requirements in most countries. Further research studies should also focus on providing guidance to ski areas on the best practices for choosing, applying, and maintaining ski area padding.

AbstractTransverse Liquid Composite Moulding (LCM) processes for the impregnation of thick parts have been gaining interest recently. Simulations of transverse LCM processes require accurate input of constitutive data to make useful predictions; however, accurate constitutive data are not always available and the magnitudes of deviations due to interpolation and extrapolation errors are not entirely known. The international out-of-plane compressibility and permeability benchmark exercises have shown large variations in both quantities, for each participant, and between different participants. In this work, a simulation model of transverse impregnation and compression for LCM processes is utilised to study the sensitivity of processing predictions to variations in constitutive data resulting from different fitting techniques. It is shown through a case study on saturated permeability measurements that significantly different predictions of the flow rate during permeability measurements arise from relatively small differences in the constitutive data. This study demonstrates the importance of accurate measurement and modelling of the compaction stress gradient and permeability for input into simulations.

This article considers Sean Bonney’s texts Happiness: Poems After Rimbaud (2011), Letters Against the Firmament (2015), Our Death (2019) and antimatter (2019). I write about each of these texts in terms of Bonney’s representation within them of music and noise. Rather than discussing this from a musicological perspective, or in relation to particular musical works, I address the metaphorical use that Bonney makes of figures of music and noise in general. I argue that in each case, the way in which Bonney conceives of music is indicative of a wider perspective on political and social reality and its capacity to be transformed by collective action. The article begins by elaborating the relationship between music and noise as I understand it to exist in Bonney’s writing. Following this, I elaborate the conditions of economic austerity under which Bonney lived during the writing of Happiness and Letters Against the Firmament. The article then aims to elaborate the relationship between a thinking of music and a thinking of community in Happiness before considering how harmony functions as a metaphor for class-domination in Bonney’s prose poetry. The article ends with a consideration of antimatter as a work whose use of rhyme and song-like structures is indicative of a specific ontology of catastrophe developed in Our Death.

Tennis racket design has changed from its conception in 1874. While we know that modern tennis rackets are lighter and have larger heads than their wooden predecessors, it is unknown how their gross shape has changed specifically. It is also unknown how racket shape is related to factors that influence performance, like the Transverse and Polar moments of inertia. The aim of this study was to quantify how tennis racket shape has changed over time, with a view to furthering our understanding of how such developments have influenced the game. Two-dimensional morphometric analysis was applied to silhouettes extracted from photographs of 514 rackets dating from 1874 to 2017. A principal component analysis was conducted on silhouette outlines, to allow racket shape to be summarised. The rackets were grouped by age and material for further analysis. Principal Component 1 accounted for 87% of the variation in racket shape. A pairwise Pearson’s correlation test indicated that head width and length were both strongly correlated to Principal Component 1 (r = 0.916 & r = 0.801, p-values

The sporting goods sector can serve as a proving ground for new technologies. We propose that climbing shoes are an excellent case study for showcasing a systematic approach to bio-inspired design. Foot adaptations to climbing have been described before in some animals and have even been incorporated into bio-inspired products. However, there has not yet been a systematic description of climbing adaptations in mammals, and especially in rock climbing species. We present a description of foot morphology in mammals and compare rock climbing species to those with other locomotion types. Our results show that rock climbing species in our sample had fewer digits and larger anterior pads than arboreal species. Rock climbing species often had hooves or, if they had foot pads, these were relatively smooth. These examples look a bit like current climbing shoe designs, perhaps suggesting convergent evolution. However, there was also variation, with rock climbing species having pads varying in shape, placement and texture. Much of this variation is likely to be dependent on the relatedness of species, with those that are more related having more similar feet. We suggest that incorporation of novel textures and compliant pads might be an interesting focus for future climbing shoe designs.

ACL injuries are among the most severe knee injuries in elite sport, with a high injury burden and re-injury risk. Despite extensive literature on the injury and the higher incidence of injury and re-injury in female athletes, there is limited evidence on the return to sport (RTS) of elite female football players following ACL reconstruction (ACLR). RTS is best viewed on a continuum aligning the recovery and rehabilitation process with the ultimate aim — a return to performance (RTPerf). We outline the RTS and RTPerf of an elite female football player following ACLR and her journey to the FIFA Women’s World Cup, including the gym-based physical preparation and the on-pitch/sports-specific reconditioning. We used the ‘control–chaos continuum’ as a framework for RTS, guiding a return above pre-injury training load demands while considering the qualitative nature of movement in competition. We then implemented the ‘RTPerf pathway’ to facilitate a return to team training, competitive match play and a RTPerf. Objective information, clinical reasoning and shared decision-making contributed to this process and helped the player to reach her goal of representing her country at the FIFA Women’s World Cup.

This study investigates the impact behaviour and post-impact performance of polyamide-6 glass fibre reinforced composites, manufactured by thermoplastic resin transfer moulding. Impact test samples were extracted from quasi-isotropic laminates using two different glass fibre sizings, both with a fibre volume fraction of approximately 52%. A previous study showed that one of these sizings enhanced the interfacial strength and Mode I fracture toughness; however, the effects of the sizing on out-of-plane impact is of greater significance in terms of automotive applications. A drop-weight impact tester was used to determine out-of-plane impact performance for both sizings in terms of impact load-induced and energy returned from the striker. High-speed video of the impact response was simultaneously captured. Testing was carried out at three impact energy levels: two sub-penetration and one full penetration. The impact damage area was observed, and the post-damage compression properties of samples were measured to determine the reduction in their strength and stiffness. Results showed that the use of different sizing technologies had little effect on the post-impact compressive properties and that penetration led to only a 29% drop in compression strength. Overall, the outcomes of this work demonstrate the potential of these materials in automotive applications.

Contact in elite football can result in severe injury such as traumatic fracture. Limited information exists regarding the rehabilitation and return to sport (RTS) of these injuries especially in elite football. We outline the RTS of an elite English Premier League footballer following a tibia-fibula fracture including gym-based physical preparation and the use of ‘control-chaos continuum’ as a framework for on-pitch sport-specific conditioning, development of technical skills while returning the player to pre-injury chronic running loads considering the qualitative nature of movement in competition. Strength and power diagnostics were used to back up clinical reasoning and decision-making throughout rehabilitation and the RTS process. The player returned to full team training after 7.5 months, completed 90 min match-play after 9 months and remains injury-free 11 months post-RTS.

BackgroundFoliar fungicide applications to corn (Zea mays L.) occur at one or more application timings ranging from early vegetative growth stages to mid-reproductive stages. Previous studies indicated that fungicide applications are profitable under high disease pressure when applied during the tasseling to silking growth stages. Few comprehensive studies in corn have examined the impact of fungicide applications at an early vegetative growth stage (V6) compared to late application timings (VT) for yield response and return on fungicide investment (ROI) across multiple locations.ObjectiveCompare yield response of fungicide application timing across multiple fungicide classes and calculate the probability of positive ROI.MethodsData were collected specifically for this analysis using a uniform protocol conducted in 13 states in the United States and one province in Canada from 2014-2015. Data were subjected to a primary mixed-model analysis of variance. Subsequent univariate meta-analyses, with and without moderator variables, were performed using standard meta-analytic procedures. Follow-up power and prediction analyses were performed to aid interpretation and development of management recommendations.ResultsFungicide application resulted in a range of yield responses from -2,683.0 to 3,230.9 kg/ha relative to the non-treated control, with 68.2% of these responses being positive. Evidence suggests that all three moderator variables tested (application timing, fungicide class, and disease base level), had some effect (α = 0.05) on the absolute difference in yield between fungicide treated and non-treated plots ([Formula: see text]). Application timing influenced [Formula: see text], with V6 + VT and the VT application timings resulting in greater yield responses than the V6 application timing alone. Fungicide formulations that combined demethylation inhibitor and quinone outside inhibitor fungicides significantly increased yield response.ConclusionFoliar fungicide applications can increase corn grain yield. To ensure the likelihood of a positive ROI, farmers should focus on applications at VT and use fungicides that include a mix of demethylation inhibitor and quinone outside inhibitor active ingredients.

Auxetic foams have previously been shown to have benefits including higher indentation resistance than their conventional counterparts, due to their negative Poisson’s ratio, making them better at resisting penetration by concentrated loads. The Poisson’s ratio and Young’s modulus of auxetic open cell foams have rarely been measured at the high compressive strain rates typical during impacts of energy absorbing material in sporting protective equipment. Auxetic closed cell foams are less common than their open cell counterparts, and only their quasi-static characteristics have been previously reported. It is, therefore, unclear how the Poisson’s ratio of auxetic foam, and associated benefits such as increased indentation resistance shown at low strain rates, would transfer to the high strain rates expected under impact. The aim of this study was to measure the effect of strain rate on the stiffness and Poisson’s ratio of auxetic and conventional foam. Auxetic open cell and closed cell polymer foams were fabricated, then compression tested to ~80% strain at applied rates up to 200 s−1, with Poisson’s ratios obtained from optical full-field strain mapping. Open cell foam quasi-static Poisson’s ratios ranged from −2.0 to 0.4, with a narrower range of −0.1 to 0.3 for closed cell foam. Poisson’s ratios of auxetic foams approximately halved in magnitude between the minimum and maximum strain rates. Open cell foam quasi-static Young’s moduli were between 0.02 and 0.09 MPa, whereas closed cell foams Young’s moduli were ~1 MPa, which is like foam in protective equipment. The Young’s moduli of the auxetic foams approximately doubled at the highest applied strain rate of 200 s−1.

There is a shortage of young people studying physics and engineering and these professions could benefit from greater diversity. Sports engineering is often used as a tool to change the public perceptions of engineering and sporting examples can be used in physics and engineering classes to engage people. Video analysis is widely used by sports engineers, and this publication showcases how the video analysis of sporting scenarios can be used to teach mechanics. Examples illustrate how the movement of an athlete and equipment can be analysed and linked to basic physics, for sports ranging from sumo to soccer. The examples presented can be used for teaching and outreach, with a view to enthuse students about physics and engineering.

Running is a popular form of exercise, although runners are prone to injury from repeated impact. Running shoes can limit impact forces, but they deteriorate with use. Mechanical ageing typically involves repeatedly compressing the midsole while measuring the energy absorbed within compression cycles to assess degradation. Literature suggests mechanical aging often causes a higher rate of degradation than natural ageing. This work investigated the effect of introducing rest periods into mechanical ageing. Five shoes were mechanically aged using a sine plus dwell waveform (1.25 Hz, max. load 1.5 kN) for seven hours, equating to a simulated distance of 60 km. Three of the shoes were rested for 22 hours every 20 km. The shoes aged with rest periods absorbed more energy than their unrested counterparts for the first 10 km when testing recommenced. This finding has implications for the mechanical ageing, design and recommended lifespan of running shoes.

World Rugby™ permits players to wear padded clothing meeting the requirements of Regulation-12, which limits density, thickness and impact performance. Due to non-uniform geometry, measuring the density of padding can be challenging and provides limited information on mechanical properties. This study investigated how well density could predict the impact performance of rugby padding, whilst reviewing compliance parameters as alternatives. Eleven samples of rugby padding, plus one control material, were tested for compliance, then impacted at energies of 4.9, 9.8 and 14.7 J using the setup as defined in Regulation-12, and finally cut to calculate density. The density and compliance parameters were correlated against peak impact accelerations using a Spearman’s rank test. Density was not significantly correlated with peak acceleration at any energy level, with compliance tests significantly correlated with impact acceleration at only 4.9 J.

Auxetic materials have a negative Poisson’s ratio, meaning they contract laterally during axial compression. Auxetics can also absorb more energy during impacts than conventional materials. Auxetic foam was fabricated by volumetrically compressing open cell foam to buckle cell ribs and impart a re-entrant cell structure, then the imposed structure was fixed by heating and cooling. Passing pins through the foam allowed localised control over compression during fabrication, producing gradient foam with regions with differing Poisson’s ratios and stress vs. strain relationships. Uniform sheets had volumetric compression ratios of three, gradient sheets had volumetric compression ratios of one (unchanged) or three in different regions. One participant jumped barefoot on all foams, cut out to fit pressure sensors; another ran wearing shoes containing uniform converted and unconverted foam insoles. Pressure distribution was measured underneath the foams and foam insoles. Peak pressure was lowest underneath converted foams, warranting further investigation with more participants.

Wrist injuries have been reported to account for 35%–45% of snowboarding injuries. Snowboarding wrist protectors are designed to limit impact forces and prevent wrist hyperextension. The absence of a standard for snowboarding wrist protectors makes it hard to identify models offering an adequate level of protection. Wrist surrogates are well suited for testing and benchmarking wrist protectors. This study investigated the effect of introducing a soft tissue simulant onto an otherwise stiff wrist surrogate on the bending stiffness of snowboarding wrist protectors. A compliant surrogate (stiff core and 3 mm thick silicone layer) and a comparable stiff surrogate were fabricated. Two snowboarding wrist protectors were tested on each surrogate, under three strapping conditions, following a bend test to ~80° wrist extension. The introduction of a compliant layer to the wrist surrogate gave higher torque values for a given wrist extension angle, increasing protector effective stiffness, relative to a rigid surrogate.

The tennis racket has developed since the origins of Lawn Tennis in the 1870s. This study investigated how the tennis racket developed from 1874 to 2017, using measurements and material classifications for 525 samples. Racket measurements covered geometric, inertial and dynamic properties, and the number of strings. Rackets predating 1970 were mainly wooden, and typically characterised by head areas below 0.05 m2, masses over 350 g and natural frequencies below 120 Hz. Rackets from the 1970s were made from wood, metal and fibre−polymer composites, with most postdating 1980 made from fibre−polymer composites with a larger head, lower mass and higher natural frequency than their predecessors. Principal component analysis was used to reduce the dimensionality of the number of variables. Principal component one (PCA1) accounted for 35% of the variance in the measured racket properties, and was found to be significantly affected by material. Head width was best correlated with principal component one (r = 0.897, p < 0.001), followed by head length (r = 0.841, p < 0.001) and natural frequency (r = 0.813, p < 0.001). Early rackets were constrained by the limitations of wood, and the move to composites, which began in the 1970s, allowed this observed increase in head size and natural frequency. As material development has been a major driver of racket design in the past, we propose that new materials and manufacturing techniques, like additively manufactured composites, could further improve the tennis racket. The measurement techniques described here can be used to monitor developments in racket design.

Following high profile, life changing long term mental illnesses and fatalities in sports such as skiing, cricket and American football—sports injuries feature regularly in national and international news. A mismatch between equipment certification tests, user expectations and infield falls and collisions is thought to affect risk perception, increasing the prevalence and severity of injuries. Auxetic foams, structures and textiles have been suggested for application to sporting goods, particularly protective equipment, due to their unique form-fitting deformation and curvature, high energy absorption and high indentation resistance. The purpose of this critical review is to communicate how auxetics could be useful to sports equipment (with a focus on injury prevention), and clearly lay out the steps required to realise their expected benefits. Initial overviews of auxetic materials and sporting protective equipment are followed by a description of common auxetic materials and structures, and how to produce them in foams, textiles and Additively Manufactured structures. Beneficial characteristics, limitations and commercial prospects are discussed, leading to a consideration of possible further work required to realise potential uses (such as in personal protective equipment and highly conformable garments).

Current research of auxetic materials highlights its potential as personal protective equipment for sports apparel with enhanced properties such as conformability, superior energy absorption and reduced thickness. In contrast, commercially available protective materials have proven to be problematic in that they inhibit movement, breathability, wicking and that molded pads are prone to saddling. Foam components are embedded within personal protective equipment for sports apparel, where protective material is positioned at regions of the body frequently exposed to injury of the soft tissue through collision, falls or hard impact. At present, the impact resistance of auxetic open cell polyurethane foam and some additively manufactured auxetic structures have been established, and processes for manufacturing curved auxetic materials as well as molding methods have been developed. Despite this, auxetic materials have not yet been applied as personal protective equipment for sports apparel in current research. This paper argues that there is scope to investigate auxetic materials potential for enhanced wearer functionality through properties of synclastic curvature and biaxial expansion.

Foams are commonly used for cushioning in protective sporting equipment. Volumetrically compressing open-cell polyurethane foam buckles cell ribs creating a re-entrant structure—set by heating then cooling—which can impart auxetic behaviour. Theoretically, auxetic materials improve impact protection by increasing indentation resistance and energy absorption, potentially reducing sporting injuries and burdens on individuals, health services and national economies. In previous work, auxetic foam exhibited ~3 to ~8 times lower peak force (compared to its conventional counterpart) under impacts adopted from tests used to certify protective sporting equipment. Increases to the foam’s density and changes to stress/strain relationships (from fabrication) mean Poisson’s ratio’s contribution to reduced peak forces under impact is unclear. This work presents a simple fabrication method for foam samples with comparable density and linear stress/strain relationship, but different Poisson’s ratios ranging between 0.1 and −0.3, an important step in assessing the Poisson’s ratio’s contribution to impact force attenuation.

Tennis rackets have advanced significantly since the invention of the game in 1874, including innovations in both shape and materials. Advances in these design parameters have implications for racket performance, especially swing speed. This study tested one hundred rackets, spanning brands and eras, using simple, portable instruments in order to pilot protocols and make recommendations for streamlining testing procedures for tennis rackets. A wide range of properties were measured and documented for each racket. We suggest that since Transverse and Lateral Moment of Inertia are well correlated, measuring both is not necessary when processing a large number of rackets. In addition, it is also possible to predict the Transverse Moment of Inertia well from models that use simple dimension and mass measurements, which may be preferable in larger studies. Exploring the use of more complex modelling will allow us to better understand the impact of tennis racket design on performance in the future.

GANDER – for Global Altimeter Network Designed to Evaluate Risk – was anidea that was probably ahead of its time. Conceived at a time when ocean observingsatellites were sometimes 10 years in the planning stage, the concept of affordable fastersampling through the use of altimeter-carrying microsats was primarily advanced as a wayof detecting and tracking storms at sea on a daily basis. But, of course, a radar altimetermonitors changes in sea-level as well as surface wave height and wind speed. Here then is asystem which, flown with more precise missions such as JASON 2, could meet the needs ofocean modellers by providing the greater detail required for tracking mesoscale eddies,whilst servicing forecasting centres and units at sea with near real-time sea state information.A tsunami mode, instantly activated when an undersea earthquake is detected by the globalnetwork of seismic stations, could also be incorporated.