Beams with rectangular cross-section, with large length-to-width ratio, can be excited to torsional vibrations. If the piezoelectric elements are mounted to the beam in pairs at the same cross-section with two separated elements positioned on the same side of the beam, and the voltages applied to them are in the opposite phase, they produce twisting moments which can be applied to reduce the torsional vibrations. Results of FEM simulations are presented and analysed in the paper. All analyses are performed for a steel free-clamped beam. The piezoelectric elements made of PZT material are mounted in pairs on one side of the beam. The analyses are done for separated natural modes.

No abstract

Rational designing of scraper pipe conveyors requires new approach to evaluation of motion resistance. The results of theoretical and experimental investigations of this resistance and final conclusions have been presented in the paper.

What is of particular importance in view of the development and operation of fast railway transport is the overhead system vibration excited by pantograph motion. The problems discussed in the paper are related to continuous system vibration under moving loads. Modelling the catenary-pantograph system is connected with motion of two subsystems, namely: continuous (contact wire) and discrete (pantograph). In the paper, the results of research on dynamical phenomena caused by the interaction between the pantograph and catenary are presented. The stiffness of the catenary wire is taken into account. The dynamical phenomena occurring in the system are described by a set of partial and ordinary differential equations. The solution to these equations has been obtained using approximate numerical methods.

In the paper some results of experiments done on a physical model of a locomotive pantograph co-operating with a supply wire are presented. The concept of model investigations and the description of the testing facility, which has been designed and built at Cracow University of Technology, are introduced. Vibrations and dynamical forces occurring during stationary and non-stationary motion of the system have been measured and analyzed. Experimental data has been applied to model identification and validation of computer simulation results. The procedures of the dimensional analysis theory (criteria numbers) have been utilized to transfer conclusions into natural scale of the real system.