A vibration absorber for motorcycle handles

This paper describes the application of a vibration absorber to ameliorate the comfort of motorcycle handles. The concept of dynamical absorber is briefly summarised and a frequency response function is expressed as the ratio of vibration amplitudes (transmissibility). Some practical hints on the tuning strategy are also suggested in order to correctly define the absorber and then achieve the most effective vibration reduction. A specifically designed item is presented, with the peculiar characteristic of taking advantage of the damping properties of viscoelastic material undergoing shear deformations. An experimental verification of the good performances of the absorber is eventually given on the basis of both a modal analysis of a motorbike and the testing of its handle on an electrodynamical shaker

Design Of a Spar Buoy for Offshore Wind Turbines

Offshore wind Energy demonstrated to be one of the most promising technologies for growing electric energy demand worldwide. The main objective of this research was to conceive a floating offshore structure for supporting wind turbines. The Mediterranean Sea is characterized by deep water, especially in the western area, from Italy towards Spain, and this makes floating support structures desirable, since in deep water they are cheaper than bottom fixed piles [1]. An aerodynamic, electric and mechanic model was developed and tested against experimental results of laboratory and wind tunnel tests on a small scale wind turbine, demonstrating its reliability, so it was used to determine actions on the floater and a first concept design was performed using commercial software for marine structures analysis. Further steps in this process will include integration of the turbine model with hydrodynamic calculations, as well flume, tank and open sea tests for the designed floate

Performance assessment of a 2 dof gyroscopic wave energy converter

Wave Power is one of the most investigated energy sources today. So far, several devices have been tested and built up to the pre-commercial stage. ISWEC (Inertial Sea Wave Energy Converter) has developed at the Politecnico di Torino, exploiting gyroscopes to extract wave energy. It allows power extraction without using any moving part immersed into water. The previous version of ISWEC presented 1 DOF (Degree Of Freedom), therefore requiring alignment of the device to the incoming wave; this paper describes a novel version of ISWEC, with 2 DOFs and consequently able to absorb power from every wave direction.The kinematics and the dynamics of the device are investigated, in order to compare the 1 DOF and the 2 DOF architectures from the point of view of the extracted power. The resulting simulations show that the 1 DOF prototype is more efficient when aligned with the incoming wave, while the behavior of the 2 DOF device is substantially independent of the wave direction. Such a difference of the performances is quantified and discussed along with considerations on the design and realization of the full-scale prototype

Validation of Two Nonlinear System Identification Techniques Using an Experimental Testbed

The identification of a nonlinear system is performed using experimental data and two different techniques, i.e. a method based on the Wavelet transform and the Restoring Force Surface method. Both techniques exploit the system free response and result in the estimation of linear and nonlinear physical parameters

Stochastic Control of Inertial Sea Wave Energy Converter

The ISWEC (inertial sea wave energy converter) is presented, its control problems are stated, and an optimal control strategy is introduced. As the aim of the device is energy conversion, the mean absorbed power by ISWEC is calculated for a plane 2D irregular sea state. The response of the WEC (wave energy converter) is driven by the sea-surface elevation, which is modeled by a stationary and homogeneous zero mean Gaussian stochastic process. System equations are linearized thus simplifying the numerical model of the device. The resulting response is obtained as the output of the coupled mechanic-hydrodynamic model of the device. A stochastic suboptimal controller, derived from optimal control theory, is defined and applied to ISWEC. Results of this approach have been compared with the ones obtained with a linear spring-damper controller, highlighting the capability to obtain a higher value of mean extracted power despite higher power peaks