Search results for "strength"
showing 10 items of 2415 documents
A numerical approach for the modelling of forming limits in hot incremental forming of AZ31 magnesium alloy
2021
AbstractMagnesium alloys, because of their good specific material strength, can be considered attractive by different industry fields, as the aerospace and the automotive one. However, their use is limited by the poor formability at room temperature. In this research, a numerical approach is proposed in order to determine an analytical expression of material formability in hot incremental forming processes. The numerical model was developed using the commercial software ABAQUS/Explicit. The Johnson-Cook material model was used, and the model was validated through experimental measurements carried out using the ARAMIS system. Different geometries were considered with temperature varying in a…
Mechanical properties of basalt fiber reinforced composites manufactured with different vacuum assisted impregnation techniques
2016
Abstract This work describes an experimental mechanical characterisation campaign on composites made out of a quasi-unidirectional basalt fabric. In order to evaluate the ability of commercial basalt fabrics and their composites to meet the potentials of basalt fibers, the work has used raw materials from commercial catalogs with no further modification. Two common manufacturing techniques for medium performance composites have been adopted: vacuum assisted resin infusion, and hand-impregnated vacuum bagging. Two panels, one for each technique, have been fabricated, able to provide a sufficient number of samples for a comprehensive stiffness and strength characterization through Tensile, Fl…
Interaction of sodium, lithium, caesium, and potassium ions with ascorbyl radicals.
1987
Abstract The influence of the concentration of sodium, lithium , caesium, and potassium ions as well as of the ionic strength of the solutions used on the dismutation rate of ascorbyl radicals has been investigated. While the dismutation rate was not influenced by Li+, it decreased, however, with increasing concentrations of the other ions investigated. The largest effect was obtained with Na+. This change in dismutation rate indicates a stabilizing effect on ascorbyl radical by these ions.
Friction stir consolidation of aluminum machining chips
2017
Friction stir consolidation (FSC) is a solid-phase manufacturing process that consolidates metal powder, chips, or scraps into solid blocks via severe plastic deformation and solid state welding. It has the potential to be a more economical and âgreenâ process to recycle metal waste. In this study, solid discs were made from AA6061 aluminum alloy machining chips by FSC. The progression of the process was revealed by analyzing the motion of the tool, consolidating force, power history, and macro/microstructure of discs produced from a series of partial consolidation experiments. A bowl-shaped recrystallized zone in the vertical cross-sections of the disc products was observed and conside…
Comparison of conventional hamstring/quadriceps ratio between genders in level-matched soccer players
2017
Abstract Objectives: The main goal of our study is to compare the hamstring/quadriceps (H/Q) ratio at different knee angles between level-matched male and female soccer players and to determine whether differences in the H/Q ratio exist between the dominant and the non-dominant leg. Methods: A cross-sectional study design was used to compare an isometric H/Q ratio and functional isokinetic ratio (between hamstring in eccentric contraction and quadriceps in concentric contraction) between males (n = 14) and females (n = 14). These ratios were studied at two different speeds of movement (60° s−1 and 180° s−1) and in five different positions (40°, 50°, 60°, 70° and 80° degrees of knee flexion)…
Integrative Neuromuscular Training Enhances Physical Fitness in 6- to 14-Year-Old Rugby Players.
2021
ABSTRACT Alonso-Aubin, DA, Picon-Martinez, M, Rebullido, TR, Faigenbaum, AD, Cortell-Tormo, JM, and Chulvi-Medrano, I. Integrative neuromuscular training enhances physical fitness in 6- to 14-year-old rugby players. J Strength Cond Res 35(8): 2263-2271, 2021-The purpose of this study was to assess the effects of an 8-week integrative neuromuscular training (INT) program on physical fitness measures in young rugby players. A sample of 138 male rugby players (age range, 6-14 years) was divided into 5 age-related groups: group 1 (G1) (n = 20; age, 7.05 ± 0.58), group 2 (G2) (n = 27; age, 8.57 ± 0.49), group 3 (G3) (n = 31; age, 11.02 ± 0.56), group 4 (G4) (n = 33; age, 13.12 ± 0.58, and group …
''Isokinetic intervention in microtraumatic shoulder instability: an update''
2012
Gremeaux, V. | Croisier, J. L. | Forthomme, B.; International audience; ''Aim. Aim of the present study was to carry out a critical analysis of the use of isokinetic dynamometers for evaluation and rehabilitation in microtraumatic shoulder instability. Methods. A non-systematic literature review was conducted on Medline using the following key words: "isokinetics", "shoulder instability", "evaluation", "rehabilitation". We also analyzed the related articles, and compiled a database of expert opinion. Results. Despite a lack of consensus on testing modalities, lateral and medial rotator muscle strength can be safely and reliably assessed on isokinetic devices in subjects presenting with micr…
Estimation of the emission temperature of an electrodeless discharge lamp and determination of the oscillator strength for the I(2P3/2) 183.038 nm re…
2001
Abstract The 183.038 nm resonance absorption transition of I( 2 P 3/2 ) has been studied using a flash photolysis set-up for gas-phase chemistry and a radio frequency powered electrodeless discharge lamp filled with iodine. The dependence of self-absorption and self-reversal on iodine partial pressure in the discharge volume was measured. The optimum iodine partial pressure, with self-absorption minimized and acceptable intensity, is determined to be approximately 2.5×10 −3 mbar. A method is described to estimate the temperature of the emitting atoms using direct measurements of relative absorption at different absorber concentrations. This yields an emission temperature of 923±50 K. Using …
Solution properties of polyelectrolytes. III. Effect of sodium polystyrene sulfonate concentration on viscometric and size exclusion chromatographic …
1988
The effect of sodium polystyrene sulfonate concentration on the shape of its molecules in aqueous solution at different NaNO3 ionic strengths has been analyzed by viscometry and size-exclusion chromatography (s.e.c). An equation has been developed which predicts the intrinsic viscosity, [η] p.cp.cs, at finite concentration of both polyion (cp) and electrolyte (cs). The experimental results obtained by both techniques can be accounted for in terms of the theory. Several factors involved in the elution mechanism have been considered and the variation of the slopes of s.e.c. calibration curves with cp and cs has been discussed in terms of polyion conformation changes.
Evidence for shared environmental contributions to attention-deficit/hyperactivity traits. A twin study
2019
Background and objectives: Behavior-genetic analyses have shown that measurements of inattention and hyperactivity-impulsivity are genetically-influenced. In view of limited studies on ADHD (Attention deficit hyperactivity disorder) in Spanish samples, this study aims to explore the genetic architecture of ADHD symptoms; inattention and hyperactivity-impulsivity in a Spanish twin schoolchildren sample. Methods: Participants were 258 pairs of adolescent Spanish twins. Symptoms of ADHD, inattention and hyperactivity-impulsivity were assessed by means of a sub-scale of the Strengths and Difficulties Questionnaire. Univariate twin models, according to sex, were run to assess the heritability of…