Search results for "DEFLECTION"
showing 10 items of 101 documents
Load-deflection characteristics of superelastic and thermal nickel-titanium wires
2011
SUMMARY The aim of this study was to investigate the mechanical properties of superelastic and thermal nickel–titanium (NiTi) archwires for correct selection of orthodontic wires. Seven different NiTi wires of two different sizes (0.014 and 0.016 inches), commonly used during the alignment phase, were tested. A three-point bending test was carried out to evaluate the load–deflection characteristics. The archwires were subjected to bending at a constant temperature of 37°C and deflections of 2 and 4 mm. Analysis of variance showed that thermal NiTi wires exerted significantly lower working forces than superelastic wires of the same size in all experimental tests (P < 0.05). Wire size had a s…
From impact refugees to deterritorialized states: Foresighting extreme legal-policy cases in asteroid impact scenarios
2022
Throughout recorded history, humans have crossed national borders to seek safety in nearby countries. The reasons for displacement have been generated by phenomena of terrestrial origin, but exposure to unexpected extra-terrestrial threats poses a different scenario. An asteroid impact warning implies a change of paradigm which would represent a historic precedent. In this regard, the analogies with natural disasters must be considered, along with multiple possible scenarios, and legal aspects related to (a) the legal framework to regulate this situation; (b) the action and responsibility of the states; and (c) the definition of impact refugee and the reconfiguration of traditional concepts…
A multilayer anisotropic plate model with warping functions for the study of vibrations reformulated from Woodcock's work
2013
Abstract In this paper, a suitable model for static and dynamic analysis of inhomogeneous anisotropic multilayered plates is described. This model takes into account the variations of the transverse shear strains through the thickness of the plate by means of warping functions. Warping functions are determined by enforcing kinematic and static assumptions at the interfaces. This model leads to: a 10×10 stiffness matrix coupling to each other the membrane strains, the bending and torsion curvatures, and the x and y-derivatives of the transverse shear strains; and a classical 2×2 transverse shear stiffness matrix. This model has been proven to be very efficient, especially when high ratios be…
Vibration of damaged beams under a moving mass: theory and experimental validation
2004
Abstract A theoretical and experimental study of the response of a damaged Euler–Bernoulli beam traversed by a moving mass is presented. Damage is modelled through rotational springs whose compliance is evaluated using linear elastic fracture mechanics. The analytical solution is based on the series expansion of the unknown deflection in a basis of the beam eigenfunctions. The latter are calculated using the transfer matrix method, taking into account the effective mass distribution of the beam. The convective acceleration terms, often omitted in similar studies, are considered here for a correct evaluation of the beam–moving mass interaction force. The analytical solution is then validated…
Optimization and finite-frequency H ∞ control of active suspensions in in-wheel motor driven electric ground vehicles
2015
Abstract In this paper, the parameter optimization and H ∞ control problem of active suspensions equipped in in-wheel motor driven electric ground vehicles are investigated. In order to better isolate the force transmitted to motor bearing, dynamic vibration absorber (DVA) is installed in the active suspension. Parameters of the vibration isolation modules are also optimized in order to achieve better suspension performances. As the human body is much sensitive to vibrations between 4 and 8 Hz, a finite-frequency state-feedback H ∞ controller is designed to achieve the targeted disturbance attenuation in the concerned frequency range while other performances such as road holding capability …
Material characteristics in the analysis of heated steel beams
1989
Beam fire tests are expensive and complicated. They may be replaced by calculations of the heated beam deflection by means of the method presented in this paper. The following material characteristics in the analysis of the deflection of beams during fire may be taken as fundamental: the steel creep characteristic at elevated temperatures, the modulus of elasticity and the coefficient of thermal expansion. According to the yield hinge theory, the yield stress is the criterion of failure of steel beams in fire. On the other hand, in the analysis of the deflection of the heated steel beams the influence of the yield stress is very small. The influence of the respective material characteristic…
Experimental analysis of the contact pressure distribution in an off-road tyre
2009
In this paper the results of experimental tests are shown, lead by extended method of measurement, on a tire for an off-road vehicle 175/82 R16, inserting Prescale paper at the contact with the ground. The experimental analysis of the pressures is lead, in cross-sectional direction, in 5 zones correspondents to the middle of the single dowels constituting the tread. The results are analyzed by means of software predisposed to the scope so as to go back easily to the value of the pressure. The obtained results are critically analyzed and the result are compared with those obtained by the formulas of Rowland and MacLaurin, and by the nominal pressure at ground, concluding that the expression …
Simplified Procedure for Evaluating the Effects of Creep and Shrinkage on Prestressed Concrete Girder Bridges and the Application of European and Nor…
2013
The effects of time-dependent phenomena on concrete prestressed girder bridges are investigated. The study concerns the case of bridges built directly in their final configuration and that of bridges built by a sequence of stages in which geometry, restraints, and loads vary until the final configuration is achieved. An analytical approach based on the principles of aging linear viscoelasticity and the age-adjusted effective modulus method is followed. The paper has two aims: the first is to provide an efficient and simplified tool for the evaluation of the structural response in the early stages of design; the second is to compare the results of the analyses on actual cases of bridges when…
Modeling and Parameter Identification of Deflections in Planetary Stage of Wind Turbine Gearbox
2012
The main focus of this paper is the experimental and numerical investigation of a 750[kW] wind turbine gearbox. A detailed model of the gearbox with main shaft has been created using MSC.Adams. Special focus has been put on modeling the planet carrier (PLC) in the gearbox. For this purpose experimental data from a drive train test set up has been analyzed using parameter identification to quantify misalignments. Based on the measurements a combination of main shaft misalignment and planet carrier deflection has been identified. A purely numerical model has been developed and it shows good accordance with the experimental data.
Backcalculation of airport pavement moduli and thickness using the Lévy Ant Colony Optimization Algorithm
2016
Interpretation of NDTdata is crucial in any Airport Pavement Management System (APMS), in order to implement strategies to maintain airport pavementssince they allow to estimate their remaining life and related maintenance needs and activities. In this paper, the AntColony Optimization algorithmwasused for backcalculation of pavement moduli from surface deflection data. The algorithm’s performances are illustrated and improvement in prediction quality is demonstrated both in terms of goodness of fitness and computational effort. Moreover, it is proved that the proposed algorithm is also able to predict layer thicknesses, taking into account their variation too.