The dynamics of an elastically mounted flat plate in a uniform stream undergoing flow-induced pitching oscillations is studied with the aid of a cyber-physical system which iscapable of simulating arbitrary structural dynamics. The system measures the angularposition and velocity, and combines them with appropriate gains to provide a torque to acomputer-controlled servomotor tha...

Considering the impact of the nonlinear stiffness, a 2 DOF dynamic nonlinear vibration model with cubic terms was established according to the structural feature and nonlinear behavior of the tracked ambulance. In the case of primary resonance and 1: 1 internal resonance, multiple scale method was used to obtain a first-order approximate solution for this model. Taking the parameters of the tra...

The Thirty Meter Telescope has 492 primary mirror segments, each incorporated into a Primary Segment Assembly (PSA), each of which in turn has three actuators that control piston, tip, and tilt, for a total of 1476 actuators. Each actuator has a servo loop that controls small motions (nanometers) and large motions (millimeters). Candidate actuators were designed and tested that fall into the ca...

To determine the stiffness and damping of computer keyboard keys, a computercontrolled test rig that can measure computer key displacement, velocity, and contact force has been designed. The test rig, consisting of a single-axis stage carrying a probe for contacting keys, has been used to collect contact force and motion data as computer keys are depressed and released at constant velocities up...

A design process comprising aspects of modelling and analysis is developed, implemented and verified for a flexible rotor active magnetic bearing system. The system is specified to experience the first three critical frequencies up to an operating speed of 10,000 rpm. Rotor stability at critical frequencies places specific constraints on the equivalent stiffness and damping parameters of the ac...

With the objective of achieving composite material systems that feature high stiffness and high mechanical damping, consideration is given here to unit cell analysis of particulate composites with high volume fraction of inclusions. Effective elastic properties of the composite are computed with computational homogenization based on unit cell analysis. The correspondence principle together with...

In this study the dynamic behaviour of perforated microplates oscillating under the effect of squeeze film damping is analyzed. A numerical approach is adopted to predict the effects of damping and stiffness transferred from the surrounding ambient air to oscillating structures; the effect of hole’s cross section and plate’s extension is observed. Results obtained by F.E.M. models are compared ...

We consider the problem of a rigid body, subject to a unilateral constraint, in the presence of Coulomb friction. We regularize the problem by assuming compliance (with both stiffness and damping) at the point of contact, for a general class of normal reaction forces. Using a rigorous mathematical approach, we recover impact without collision (IWC) in both the inconsistent and the indeterminate...

In this study the dynamic behaviour of perforated microplates oscillating under the effect of squeeze film damping is analyzed. A numerical approach is adopted to predict the effects of damping and stiffness transferred from the surrounding ambient air to oscillating structures; the effect of hole’s cross section and plate’s extension is observed. Results obtained by F.E.M. models are compared ...

A generalised method for the identification of the parameters which describe the dynamic properties of media between coupled substructures using measured FRFs is presented in this paper. The effort is mainly focused on the development of this generalised method and the improvement of its constituent algorithms. The method presented here is more general and more practical in some aspects when co...