This study introduces the Differential Transform Method (DTM) in the analysis of the free vibration response of a rotating closed section composite, Timoshenko beam, which features material coupling between flapwise bending and torsional vibrations due to ply orientation. The governing differential equations of motion are derived using Hamilton’s principle and solved by applying DTM. The natura...

The coupled lateral–torsional stochastic response of an asymmetric one-storey base isolated building to earthquake excitation is presented. The stochastic model of the 1940 El-Centro earthquake, which preserves the non-stationary evolution of the amplitude and frequency content of the ground acceleration, is used as earthquake excitation. The base isolator consists of an array of elastomeric be...

PURPOSE To describe adaptive changes in torsional alignment that follow sustained cyclovergence in healthy humans. METHODS Eye movements were recorded binocularly from four healthy subjects using dual-coil scleral annuli. Cyclovergence movements were evoked over periods of 30 to 150 seconds using a stereoscopic display, presenting gratings of lines arranged horizontally, vertically, or at 45 ...

Under torsion and beyond the buckling point, multi-walled carbon nanotubes MWCNTs develop a periodic wave-like rippling morphology. Here, we show that torsional rippling deformations can be accurately described by a simple sinusoidal shape function. Combining this observation with the geometry optimization, we develop an effective coarse-grained model that reproduces the complex nonlinear mecha...

This paper studies the dynamical response of a rotary drilling system with a drag bit, using a lumped parameter model that takes into consideration the axial and torsional vibration modes of the bit. These vibrations are coupled through a bit-rock interaction law. At the bit-rock interface, the cutting process introduces a state-dependent delay, while the frictional process is responsible for d...

Vibrations of the Jeffcott rotor are modelled by a three degree of freedom system including coupling between lateral and torsional modes. The crack in a rotating shaft of the rotor is introduced via time dependent stiffness with off diagonal couplings. Applying the external torque to the system allows to observe the effect of crack ”breathing” and gain insight into the system. It is manifested ...

We report the first direct observation of the hydrogen-bond stretching vibration for a water cluster. A perpendicular band of ~D2O!3 was measured by terahertz laser vibration–rotation–tunneling spectroscopy at 142.8 cm in the ‘‘translational band’’ region of the liquid corresponding to the hindered translational motions of water molecules. We have tentatively assigned the spectrum to transition...

A parameter study is presented to determine effects of planet gear design parameters on the global modal behaviour planetary geared rotor systems. The sensitivity analysis conducted using a three-dimensional dynamic model system for number gears, mistuning, mass mesh stiffness and speed. These have varying impacts both natural frequencies mode shapes, therefore vibration modes determined by com...

1. The Tacoma Narrows Bridge. In class we discussed a mathematical model that might expalin the collapse of the Broughton Bridge as a column of soldiers marched across it. It does not explain the collapse of the Tacoma Narrows Bridge, however, as that was caused by torsional, or twisting, oscillations. Consider a roadway of width 2L hanging between two suspended cables, as pictured below. (This...