1,721,148 research outputs found
STUDIO DELLE VIBRAZIONI ACUSTICHE NEI CONDOTTI CON UN SEMPLICE METODO A PARAMETRI DISTRIBUITI
No full textControl of Acoustic Vibrations of an Enclosure by means of Multiple Resonators.
No full textA multiple acoustic resonator is a lumped element device composed of a set of volumes connected by means of narrow ducts. It has a finite number of modes of vibration and natural frequencies which can be tuned to the natural frequencies of the lower order modes of an enclosure. This paper is aimed at studying the acoustic behaviour of a system composed of an enclosure connected to a multiple resonator. An analytical model is developed in which the pressure inside the enclosure is expanded in normal modes. The natural frequencies, modes of vibration, damping ratios and forced responses of the coupled system are calculated. Several locations of the resonator and a range of resonator volumes are considered
A Simple Method for the Analysis of Deep Cavity and Long Neck Acoustic Resonators
No full textIn this paper, deep cavity and long neck resonators are considered where one of the axial
lengths is not significantly smaller than the sound wavelength . The axial
motion of the fluid inside a deep cavity and the non-uniform motion of the fluid along
a long neck are taken into account by means of linear or quadratic shape functions. In other
words, the deep cavity or the long neck are represented by a simple one-dimensional finite
element.
Mathematical models of resonators having few degrees of freedom (d.o.f.) are developed
and analytical expressions of the natural frequencies and impedances are derived.
Calculated results are compared with predictions from one-dimensional acoustic theory
and with experimental results
Experimental Modal Analysis of Motorcycle Tires
No full textThe particular problems of modal analysis of motorcycle tires are discussed.
Special equipment developed to test the tire in loaded conditions is presented.
Results in terms of natural frequencies, loss factors and mode shapes of radial-ply
and cross-ply tires are presented. The effect of tire structure on modal properties is
highlighted
Development of a first wall clamp for remote handling
No full textRFX is equipped with a graphite first wall made up of 2016 tiles individually supported from the vacuum vessel. Due to the small dimensions of the ports, human access inside the vacuum vessel is prevented and a robot manipulator has been designed to perform remote operations on the graphite tiles. The clamping system that withstands the applied loads must accomplish the remote handling requirements.
A bayonet clamp has been chosen because it is simple, safe and can be built with clearances and chamfers that, with a proper compliance of the manipulator wrist, allow the compensation of the positioning errors between the parts that have to be matched. To avoid the vacuum welding of the clamp, the surfaces in contact under vacuum are coated with an anti-welding coating.
The paper first describes the main design choices, then deals with the load capability of the clamping system and reports the results of experimental and FE analyses; the last section gives the results of the tests that were performed on anti-welding coatings
Analysis of Motorcycle Slalom ManoeuvresUsing the Mozzi Axis Concept
No full textThe motion of a rigid body is represented in every instant by rotation about, and translation along, an
instantaneous screw axis known as the Mozzi axis. In this paper, the Mozzi axis concept is used to study the
kinematics and handling properties of tilting vehicles. Slalom tests performed on the road with three
vehicles (a super sport motorcycle, a touring motorcycle and a three-wheeled tilting vehicle) are analyzed,
the angle of the Mozzi axis with the road plane and the trace of the Mozzi axis on the road plane are
calculated. The influences of cone spacing and forward speed on these parameters are discussed. The
geometric loci, which are described by the Mozzi trace and turn center when a tilting vehicle moves along a
trajectory, are drawn and compared. The results show that the proposed method of analysis based on the
Mozzi axis concept is effective in highlighting the features of slalom manoeuvres and can also be used to
study other important manoeuvres
The influence of the dynamic response of the rider's body on the open loop stability of a bicycle
No full textThe passive response of the rider's body to bicycle oscillations is experimentally studied by means of laboratory tests. Lumped element models of the rider's body are developed and the relevant stiffness and damping parameters are identified from experimental results. The biomechanical model of the rider is coupled with the benchmark model of the bicycle and open-loop stability analysis is carried out. Results show that the stiffness and damping parameters of the waist do not strongly affect bicycle stability. Uncontrolled arm stiffness has a very detrimental effect on stability and destroys the self-stabilization mechanism. Arm damping has a more complex effect and reduces the self-stability region
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