Mechanical characterization and numerical modelling of rubber shockpads in 3G artificial turf

Third generation (3G) artificial turf systems use in sporting applications is increasingly prolific. These multi-component systems are comprised of a range of polymeric and elastomeric materials that exhibit non-linear and strain rate dependent behaviours under the complex loads applied from players and equipment. To further study and better understand the behaviours of these systems, the development of a numerical model to accurately predict individual layers’ behaviour as well as the overall system response under different loading conditions is necessary. The purpose of this study was to characterise and model the mechanical behaviour of a rubber shockpad found in 3G artificial surfaces for vertical shock absorption using finite element analysis. A series of uniaxial compression tests were performed to characterise the mechanical behaviour of the shockpad. Compression loading was performed at 0.9 Hz to match human walking speeds. A Microfoam material model was selected from the PolyUMod library and optimised using MCalibration software before being imported into ABAQUS for analysis. A finite element model was created for the shockpad using ABAQUS and a compressive load applied to match that of the experimental data. Friction coefficients were altered to view the effect on the loading response. The accuracy of the model was compared using a series of comparative measures including the energy loss and root mean square error

Mechanical characterisation and modelling of elastomeric shockpads

Third generation artificial turf systems are comprised of a range of polymeric and elastomeric materials that exhibit non-linear and strain rate dependent behaviours under the complex loads applied from players and equipment. An elastomeric shockpad is often included beneath the carpet layer to aid in the absorption of impact forces. The purpose of this study was to characterise the behaviour of two elastomeric shockpads and find a suitable material model to represent them in finite element simulations. To characterise the behaviour of the shockpads an Advanced Artificial Athlete test device was used to gather stress-strain data from different drop heights (15, 35 and 55 mm). The experimental results from both shockpads showed a hyperelastic material response with viscoelasticity. Microfoam material models were found to describe the material behaviour of the shockpads and were calibrated using the 55 mm drop height experimental data. The material model for each shockpad was verified through finite element simulations of the Advanced Artificial Athlete impact from different drop heights (35 and 15 mm). Finite element model accuracy was assessed through the comparison of a series of key variables including shock absorption, energy restitution, vertical deformation and contact time. Both shockpad models produced results with a mean error of less than 10% compared to experimental data

Mechanical characterisation and modelling of elastomeric shockpads

Third generation artificial turf systems are comprised of a range of polymeric and elastomeric materials that exhibit non-linear and strain rate dependent behaviours under the complex loads applied from players and equipment. An elastomeric shockpad is often included beneath the carpet layer to aid in the absorption of impact forces. The purpose of this study was to characterise the behaviour of two elastomeric shockpads and find a suitable material model to represent them in finite element simulations. To characterise the behaviour of the shockpads an Advanced Artificial Athlete test device was used to gather stress-strain data from different drop heights (15, 35 and 55 mm). The experimental results from both shockpads showed a hyperelastic material response with viscoelasticity. Microfoam material models were found to describe the material behaviour of the shockpads and were calibrated using the 55 mm drop height experimental data. The material model for each shockpad was verified through finite element simulations of the Advanced Artificial Athlete impact from different drop heights (35 and 15 mm). Finite element model accuracy was assessed through the comparison of a series of key variables including shock absorption, energy restitution, vertical deformation and contact time. Both shockpad models produced results with a mean error of less than 10% compared to experimental data

Mechanical characterization and numerical modelling of rubber shockpads in 3G artificial turf

Third generation (3G) artificial turf systems use in sporting applications is increasingly prolific. These multi-component systems are comprised of a range of polymeric and elastomeric materials that exhibit non-linear and strain rate dependent behaviours under the complex loads applied from players and equipment. To further study and better understand the behaviours of these systems, the development of a numerical model to accurately predict individual layers’ behaviour as well as the overall system response under different loading conditions is necessary. The purpose of this study was to characterise and model the mechanical behaviour of a rubber shockpad found in 3G artificial surfaces for vertical shock absorption using finite element analysis. A series of uniaxial compression tests were performed to characterise the mechanical behaviour of the shockpad. Compression loading was performed at 0.9 Hz to match human walking speeds. A Microfoam material model was selected from the PolyUMod library and optimised using MCalibration software before being imported into ABAQUS for analysis. A finite element model was created for the shockpad using ABAQUS and a compressive load applied to match that of the experimental data. Friction coefficients were altered to view the effect on the loading response. The accuracy of the model was compared using a series of comparative measures including the energy loss and root mean square error

Spatial measurements for artificial turf systems using hall effect sensors

The purpose of this study was to evaluate a bespoke spatial measurement methodology using Hall Effect Sensors (HES), i.e., utilizing inductance between a permanent magnet and sensor to indirectly measure the magnet position. The aim is to embed the magnet in a boot’s stud and use an array of sensors in the artificial turf. To evaluate the accuracy and applicability of a HES system in sports turf, two studies were carried out. To measure the spatial position vertically, a standard mechanical dynamic impact testing with the magnet embedded, and the sensors below the turf carpet, was compared to the gold standard optical reference measurement system (GOM UK Ltd.: Coventry, UK) . A second study evaluated the horizontal spatial accuracy for sensors in a variable array with a controlled incremental step movement of the magnet on a precise engineering workshop table

Open Chemistry: Realizing Open Data, Open Standards, and Open Source

<p>The Blue Obelisk has brought together the computational chemistry community and those who are passionate about Open Chemistry and realizing the promise of Open Data, Open Standards, and Open Software (ODOSOS); the three pillars the group promotes. We will present current work that has taken place over the past five years, which is inspired by these pillars, and present plans for future work.<br><br>The group is actively engaged in multiple open source projects that rely on and promote open standards and open data including: Avogadro (a powerful 3D molecular editor), OpenQube (a library for quantum mechanics), ChemData (a tool for large-scale chemical data analysis and visualization), Chemkit (a library for cheminformatics), MoleQueue (a HPC queue manager), and VTK (a library for scientific data visualization). The Open Chemistry project benefits greatly from the activities of the Blue Obelisk and makes use of several prominent open-source projects including Qt and MongoDB.</p

Supplementary information files for Comparison of player perceptions to mechanical measurements of third generation synthetic turf football surfaces

Supplementary files for article Comparison of player perceptions to mechanical measurements of third generation synthetic turf football surfacesMechanical testing of synthetic turf football surfaces is considered essential to ensure player performance and safety. However, it remains unknown how well the mechanical outputs reflect player perceptions of these surfaces. The first objective of this study was to investigate the agreement between the outputs from the Rotational Traction Tester and the Advanced Artificial Athlete with player perceptions across a range of controlled third generation turf football surfaces. The second objective was to identify the modifications to the Rotational Traction Tester and the Advanced Artificial Athlete configurations and output variables that give the strongest agreement with player perceptions. An indoor test area containing ten third generation turf surfaces with controlled hardness and traction properties was constructed. Each surface was tested using the Advanced Artificial Athlete and Rotational Traction Tester in their current configuration and in several modified configurations aimed at better replicating the player–surface interaction. Using a trained panel paired comparisons technique, 18 University footballers (11 males and 7 females) identified differences in the surfaces based on four sensory attributes Movement Speed, Slip, Leg Shock and Give. Results indicated strong agreement (correlation coefficients between 0.7 and 1.0) across several Rotational Traction Tester and Advanced Artificial Athlete testing configurations and output variables with player perceptions. It is recommended that the current Rotational Traction Tester is improved through added instrumentation to allow surface stiffness to be evaluated (the rate of generation of traction resistance). It is further recommended that the Advanced Artificial Athlete adopts a new algorithm to improve the accuracy of the surface’s Vertical Deformation and Energy Restitution, and the number of drops is reduced from three to one.</p

Effects of Confinement and Pressure on the Vibrational Behavior of Nano-Confined Propane

Fluids confined in nanopores exhibit significant deviations in their structure and dynamics from the bulk behavior. Although phase, structural, and diffusive behaviors of confined fluids have been investigated and reported extensively, confinement effects on the vibrational properties are less understood. We study the vibrational behavior of propane confined in 1.5 nm nanopores of MCM-41-S using inelastic neutron scattering (INS) and molecular dynamics (MD) simulations. Vibrational spectra have been obtained from INS data as functions of temperature and pressure. At ambient pressure, a strong quasielastic signal observed in the INS spectrum at 80 K suggests that confined propane remains liquid below the bulk phase melting point of 85 K. The quasielastic signal is heavily suppressed when either the pressure is increased to 1 kbar or the temperature is lowered to 30 K, indicating solidification of pore-confined propane. Confinement in MCM-41-S pores results in a glass-like state of propane that exhibits a relatively featureless low-energy vibrational spectrum compared to that of the bulk crystalline propane. Increasing the pressure to 3 kbar results in hardening of the intermolecular and methyl torsional modes. The INS data are used for estimating the isochoric specific heat of confined propane, which is compared with the specific heat of bulk propane reported in literature. Data from MD simulations are used to calculate the vibrational power spectra that agree qualitatively with the experimental data. Simulation data also suggest a reduction of the structural ordering (positional, orientational, and intramolecular) of propane under confinement

Synthesis and SAR Studies of Fused Oxadiazines as γ‑Secretase Modulators for Treatment of Alzheimer's Disease

Fused oxadiazines (<b>3</b>) were discovered as selective and orally bioavailable γ-secretase modulators (GSMs) based on the structural framework of oxadiazoline GSMs. Although structurally related, initial modifications showed that structure–activity relationships (SARs) did not translate from the oxadiazoline to the oxadiazine series. Subsequent SAR studies on modifications at the C3 and C4 positions of the fused oxadiazine core helped to identify GSMs such as compounds <b>8r</b> and <b>8s</b> that were highly efficacious in vitro and in vivo in a number of animal models with highly desirable physical and pharmacological properties. Further improvements of in vitro activity and selectivity were achieved by the preparation of fused morpholine oxadiazines. The shift in specificity of APP cleavage rather than a reduction in overall γ-secretase activity and the lack of changes in substrate accumulation and Notch processing as observed in the animal studies of compound <b>8s</b> confirm that the oxadiazine series of compounds are potent GSMs