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In the paper results of simulation of active reduction of vibration of the free-xed beam by piezoelectic actuators made of functionally graded materials are presented. The aim of simmulation was to estimate sensitivity of the process of reduction. The eect of the level of gradation of material properties and amplitude of the applied voltage on eectiveness of the reduction process was analyzed. The analysis was reduced to the case of excited vibrations of the rst mode and was performed by application of the nite element package Ansys.

The model of a mono-tube shock absorber with a bypass is proposed in this paper. It is shown that the application of an additional flow passage (bypass) causes changes to the damping force characteristics when the excitation amplitudes are large. In such cases, the damping force values increase, thereby improving safety of the ride. For small excitation amplitudes, the shock absorber behaves in a similar fashion as shock absorbers without a bypass, ensuring a high comfort level of the ride on roads with smooth surfaces.

In this paper, analysis of a half-car model with linear and nonlinear semi-active dampers is performed. Using Matlab-Simulink software, a response of the system to a harmonic excitation of variable frequency and to an impulse excitation is found. The effect of both the distribution of spring-supported mass and the asymmetry of the support on the frequency characteristics of velocities and displacements at the mounting points of the dampers are analyzed. Additionally, characteristics of forces generated by the semi-active dampers and the response of the system when crossing an obstacle are determined. Keywords

In this paper, an analysis is performed on a quarter-car model of car suspension with semi-active and active damper utilizing the sliding mode (SMC) and linear-quadratic control (LQR). The effect of control parameters and time delays in the transmission of control signal on the factors related to the safety and comfort of driving is investigated. The results obtained from numerical simulations are shown in form of frequency characteristics for several selected performance factors.