This paper studies dynamic stability of functionally graded beams with piezoelectric layers subjected to periodic axial compressive load that is simply supported at both ends lies on a continuous elastic foundation. The Young’s modulus of beam is assumed to be graded continuously across the beam thickness. Applying the Hamilton’s principle, the governing dynamic equation is established. The eff...

A possibility to suppress beam-beam interaction in a circular collider by means of introducing a plasma at the interaction point of the colliding beams is considered. It is shown that for TeV proton and muon colliders, the overdense plasma can easily suppress the beam-beam tune-shift parameter several times without degrading the beam lifetimes. In this paper we study a possibility to overcome a...

crack identification is a very important issue in mechanical systems, because it is a damage that if develops may cause catastrophic failure. in the first part of this research, modal analysis of a multi-cracked variable cross-section beam is done using finite element method. then, the obtained results are validated usingthe results of experimental modal analysis tests. in the next part, a nove...

In this paper, the mechanical behavior of three-phase inhomogeneous materials is modeled using the meso-scale model with lattice beams for static and dynamic analyses. The Timoshenko beam theory is applied instead of the classical Euler-Bernoulli beam theory and the mechanical properties of lattice beam connection are derived based on the continuum medium using the non-local continuum theory. T...

In this paper we present a study of beam halo based on a three-dimensional particle-core model of an ellipsoidal bunched beam in a constant focusing channel. For an initially mismatched beam, three linear envelope modes – a high frequency mode, a low frequency mode and a quadrupole mode – are identified. Stroboscopic plots are obtained for particle motion in the three modes. With higher focusin...

nowadays, tunneling in urban areas is a common activity for a variety of transportations such as subways, water supply, lifelines andsewers that may require blast operations. the characteristics of stress waves of the blast are quite different from earthquake waves. the blast waves are usually of high frequency content, short duration, equality of amplitudes in horizontal and vertical direction...

nowadays, tunneling in urban areas is a common activity for a variety of transportations such as subways, water supply, lifelines andsewers that may require blast operations. the characteristics of stress waves of the blast are quite different from earthquake waves. the blast waves are usually of high frequency content, short duration, equality of amplitudes in horizontal and vertical direction...

Wiggler insertions are expected to occupy a significant portion of the lattice of the Next Linear Collider (NLC) Main Damping Rings (MDR) and have a noticeable impact on the single-particle beam dynamics. Starting from a realistic 3D representation of the magnetic fields we calculate the transfer maps for the wigglers, accounting for linear and nonlinear effects, and we study the beam dynamics ...

An investigation of the beam-beam interaction as a function of transverse separation of colliding proton and antiproton bunches is presented. A mathematical model describing resonant excitation of separated beams is examined. Beam-beam experiments in the Fermilab collider measure beam-beam resonant excitation ~particle losses! at different transverse beam separations in the storage ring. The ex...

The forced vibration behaviors are examined for nonlocal strain gradient nanobeams with surface effects subjected to a moving harmonic load travelling with a constant velocity in terms of three beam models namely, the Euler-Bernoulli, Timoshenko and modified Timoshenko beam models. The modification for nonlocal strain gradient Timoshenko nanobeams is exerted to the constitutive equations by exc...