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The purpose of this work is to validate a nonlinear mathematical model (finite element method) for dynamic simulation of Stockbridge dampers of electric transmission line cables. To obtain the mathematical model, a nonlinear cantilever beam with a tip mass was used. The mathematical model incorporates a nonlinear stiffness matrix of the element due to the nonlinear curvature effect of the beam. To validate the mathematical model, the numerical results were compared with experimental data obtained on a machine adapted from cam test. Five different circular cam profiles with eccentricities of 0.25, 0.5, 0.75,1.25, and 1.5 mm were used. Vibration data were collected through three accelerometers arranged along the sample. A good concordance was found between the numerical and experimental data. The same behavior was observed in tests of another Stockbridge damper excited by a shaker. The nonlinear behavior of the system was evidenced. Key words: Stockbridge, cam machine, shaker, finite element method (FEM), nonlinear model. Le but de cette recherche est de valider un modele mathematique non lineaire (methode des elements finis) pour la simulation dynamique d'amortisseurs de vibration Stockbridge pour cables de ligne de transport electrique. Pour obtenir le modele mathematique, on a utilise une poutre en porte-a-faux non lineaire avec une masse de pointe. Le modele mathematique integre une matrice de rigidite non lineaire de l'element en raison de l'effet de courbure non lineaire de la poutre. Pour valider le modele mathematique, les resultats numeriques ont ete compares aux donnees experimentales obtenues sur une machine adaptee de l'essai a came. Cinq profils de cames circulaires differents avec des excentricites de 0,25, 0,5, 0,75,1,25 et 1,5 mm ont ete utilises. Les donnees sur les vibrations ont ete recueillies au moyen de trois accelerometres disposes le long de l'echantillon. Une bonne concordance a ete constatee entre les donnees numeriques et experimentales. Le meme comportement a ete observe dans les essais d'un autre stock bridge excite par un agitateur (<>). Le comportement non lineaire du systeme a ete mis en evidence. [Traduit par la Redaction] Mots-cles: Stockbridge, appareil galet de cam (<>), agitateur (<>), methode des elements finis (<>), modele non lineaire., Introduction Stockbridge damper (Stockbridge 1928) (Fig. 1) is currently the most common type of damper use in transmission lines. Generally, the damper consists of two masses (dead weight) attached at [...]

HDPE pipes are frequently laid in buried or submerged conditions and are often subjected to considerable internal pressure. This context requires the consideration of HDPE as a structural material and demands constitutive models to predict failure possibilities in short and long terms. This article presents an approximate procedure to simulate the viscoelastoplastic nature of HDPE's material behavior under creep conditions. While a generalized Kelvin-Voigt model based on Prony series is used to model viscoelasticity, the power law of Zapas-Crissman is adopted to account for viscoplastic effects. The associated material parameters are obtained from experimental creep-recovery tests evaluated at different stress levels and constant temperature. As this type of test allows an uncoupled procedure for identifying the viscoelastic and viscoplastic material parameters, this task is divided into two stages: (i) a constrained nonsmooth optimization problem is defined and solved for the viscoelastic parameters, and (ii) the viscoplastic parameters are determined by linear regression. Thereafter, the viscoelastic and viscopiastic parameters obtained for each experimental stress level are interpolated linearly for intermediate stress conditions. Finally, a numerical-experimental example is presented, showing that the proposed procedure is able to reproduce adequately more complex loading conditions., INTRODUCTION Motivated by ever more challenging industrial requirements, technological advancements have thrusted the development of nontraditional structural materials, which frequently show improved multifunctional properties with respect to those of conventional [...]

The mixed-metal cluster compound, (Me2NH2)6((SCN)9W3S4SnCl3).0.5H2O is prepared by the reaction between W3S4(4+) and SnCl2.2H2O from 2M aqueous HCl solution in the presence of NaSCN and Me2NH2Cl. The chloride ligand selectively bonded to the Sn and the thiocyanate to the W centers through N coordination. X-ray crystal structure analysis shows the presence of cubane-type W3S4Sn core. The 119Sn Mossbauer spectrum gives information about the environment and bonding at the tin atom.

Ce(super 3+), Tb(super 3+), Dy(super 3+), Ho(super 3+), Er(super 3+), Tm(super 3+), Yb(super 3+) in the C-terminal site of calbindin D(sub 9k) is evaluated that provide 1H-15N residual dipolar coupling (rdc) used for solution structure determination. Paramagnetic lanthanides are capable of orienting the protein in high magnetic fields to an extent similar to orienting devices, and each lanthanide orients according to its magnetic susceptibility tensor.