Search results for "MECHANICS"
showing 10 items of 9361 documents
Teenage cyclist - Pick up crash by multibody simulation; HIC evaluation and comparison with previous results
2016
The study of the injury caused by Pick-up vehicle-teenage cyclist crash is presented in this paper. The vehicle has high frontal part, in order to compare the results with those obtained previously in the sedan and SUV - teenage cyclist crash. No variation is executed on the model of the teenage cyclist and the bike. Three different positions are analyzed: front, rear and lateral position. The injury on the cyclist head is examined by HIC criterion, in the way indicated in the rules. Correlation HIC – AIS is used to calculate the lethality of the injuries. A comparison is made between the results of the simulations for Pick up, SUV and sedan, concluding that the injury of the head is more d…
Biomechanical comparison between sprint start, sled-pulling and selected squat type exercises
2012
The purpose of the present study was to compare kinetics, kinematics and muscle activity between sprint start, sled-pulling and selected squat type exercises and also to examine how different exercises and variables correlate with the performance time of the block start (10 m). Nine male athletes (4 sprinters, 3 decathlonists, 1 long jumper and 1 triple jumper; mean ± SD; age = 24.9 ± 3.9 yr; height = 180.4 ± 5.9 cm; weight = 80.3 ± 7.5 kg; 100 m record = 11.35 ± 0.29 s) performed measurements and different force-time, electromyographic (EMG) and kinematic variables were compared to sprint start. Most of the comparison was done to the block phase (the phase of force production towards start…
Thermo-Mechanical Behaviour of Flax-Fibre Reinforced Epoxy Laminates for Industrial Applications
2015
The present work describes the experimental mechanical characterisation of a natural flax fibre reinforced epoxy polymer composite. A commercial plain woven quasi-unidirectional flax fabric with spun-twisted yarns is employed in particular, as well as unidirectional composite panels manufactured with three techniques: hand-lay-up, vacuum bagging and resin infusion. The stiffness and strength behaviours are investigated under both monotonic and low-cycle fatigue loadings. The analysed material has, in particular, shown a typical bilinear behaviour under pure traction, with a knee yield point occurring at a rather low stress value, after which the material tensile stiffness is significantly r…
Pressure-Dependent Tuning of Photoluminescence and Size Distribution of Carbon Nanodots for Theranostic Anticancer Applications
2020
Carbon nanodots (CDs) have recently attracted attention in the field of nanomedicine because of the biocompatibility, cost-effective nature, high specific surface, good near infrared (NIR) photothermal conversion into heat and tunable fluorescence properties, which have paved the way toward incorporating use of CDs into innovative anticancer theranostic platforms. However, a reliable synthesis of CDs with established and controlled physiochemical proprieties is precluded owing to the lack of full manipulation of thermodynamic parameters during the synthesis, thus limiting their use in real world medical applications. Herein, we developed a robust solvothermal protocol which allow fine contr…
Fractional viscoelastic transversally isotropic Timoshenko beam
2014
In this paper the viscoelastic behavior of pultruded beams has been examined. Pultruded beams are constituted by a polymer infilled with reinforcement in longitudinal direction, while in the orthogonal direction no fiber are present for technological reasons. As a consequence the material has two different behaviors in longitudinal and in orthogonal directions. It follows that pultruded beams are transversally isotropic, and the shear deformation may not be neglected. Based upon the previous observations and assuming for Creep and/or Relaxation test the power law, the constitutive equations are ruled by fractional operators. From constitutive laws, and assuming the Timoshenko beam theory to…
Modeling the mechanical behavior of carbon nanostructures
2016
Low-dimensional nanostructures are expected to have vast number of applications in the future. Particularly large amount of research has been invested in the atomthick carbon membrane called graphene, which has become popular due to its unique electronic and mechanical properties. This thesis presents studies of the mechanical and electromechanical properties of several different types of graphene nanostructures. In addition, short detours are performed in order to study the elasticity of gold nanostructures and topology effects in graphene nanoribbons. The research is performed by using several different simulation methods. In simulations the system parameters and environment can be chosen…
Longitudinal Gait Analysis of a Transfemoral Amputee Patient: Single-Case Report from Socket-Type to Osseointegrated Prosthesis
2023
The aim of the present case report was to provide a longitudinal functional assessment of a patient with transfemoral amputation from the preoperative status with socket-type prosthesis to one year after the osseointegration surgery. A 44 years-old male patient was scheduled for osseointegration surgery 17 years after transfemoral amputation. Gait analysis was performed through 15 wearable inertial sensors (MTw Awinda, Xsens) before surgery (patient wearing his standard socket-type prosthesis) and at 3-, 6-, and 12-month follow-ups after osseointegration. ANOVA in Statistical Parametric Mapping was used to assess the changes in amputee and sound limb hip and pelvis kinematics. The gait symm…
A Note on the Mechanics of Ancient Gear Systems
2011
This paper deals with the mechanical behavior of the gearwheels of the antiquity, which were generally characterized by triangular shaping of the teeth. The engagement of the conjugate profiles is analyzed in detail, calculating the temporal variation of the speed ratio due to the back and forth shifting of the relative instant center. The admissibility of the points of the theoretical contact path is carefully checked, estimating also the magnitude of the successive tooth collisions and ascertaining the energy losses arising from the particular nature of the coupling. Some very interesting results are that only one couple of teeth turns out to be active at each time instant and that the re…
Parametric sensitivity of a CFD model concerning the hydrodynamics of trickle-bed reactor (TBR)
2016
Abstract The aim of the present study was to investigate the sensitivity of a multiphase Eulerian CFD model with respect to relations defining drag forces between phases. The mean relative error as well as standard deviation of experimental and computed values of pressure gradient and average liquid holdup were used as validation criteria of the model. Comparative basis for simulations was our own data-base obtained in experiments carried out in a TBR operating at a co-current downward gas and liquid flow. Estimated errors showed that the classical equations of Attou et al. (1999) defining the friction factors Fjk approximate experimental values of hydrodynamic parameters with the best agre…
Understanding tungsten erosion during inter/intra-ELM periods in He-dominated JET-ILW plasmas
2021
Tungsten erosion was quantified during inter/intra-ELM periods in He-dominated JET-ILW plasmas by optical emission spectroscopy. The intra-ELM tungsten sputtering in helium plasmas, which dominates the total W source, prevails by a factor of about 4 over inter-ELM sputtering in the investigated ELM frequency range from 90 Hz-120 Hz. He ions are mainly responsible for the W erosion during the ELMs in He plasmas. The strong in/out asymmetry of the ELM-induced W erosion is observed in He plasmas even at high ELM frequencies beyond 100 Hz. In Ohmic/L-mode plasmas and during the H-mode inter-ELM plasma phases both He2+ and Be2+ ionic species are major contributors to the W erosion. Their contrib…