Solid State Phenomena Vol. 198

Abstract: Work presents a proposal of an analysis method of the piezoelectric transducer. The considered system is a longitudinally vibrating single PZT plate. The main aim of this work is to designate characteristics of the considered PZT plate. Using constitutive equations of piezoelectric materials and an equation of the plates motion a matrix of characteristics of the system was obtained. Relations between mechanical and electrical parameters (forces, displacements, electric current and voltage) that describe behaviour of the system are included in the matrix of characteristics. A dynamic flexibility relation between the plates deformation and a force applied to the system is considered. A structural damping of the plates material was being taken into consideration and its influence on the plates dynamic flexibility is analysed. This work is an introduction to a task of analysis of complex systems. In future work the developed model and proposed mathematical algorithm will be used to analyse piezoelectric stacks. Non-classical methods will be used. It is a part of research works of Gliwice research centre related with an analysis and synthesis of mechanical and mechatronic systems [4-7,9,10,16-18]. Passive and active mechanical and mechatronic systems with piezoelectric transducers were analysed [1-3]. Works were also supported by computer-aided methods [8]. Both classical and non-classical methods were being considered. The discussed subject is important due to increasing number of applications of both simple and reverse piezoelectric phenomena in various modern technical devices.

Abstract: This paper presents the application of the Self-exited Acoustical System (SAS) for monitoring stress changes in steel. The change of the speed of wave propagation, which is associated with the change of the resonance frequency in the system is caused by the deformation of the examined material. The SAS system is based on this phenomenon and can be used for an indirectly measurement of the stresses changes in the steel. Preliminary calculations such as static analysis and dynamic simulation of the system were carried out. The results of calculations were compared with the experimental data of the steel beam.

Abstract: By analyzing underwater flexible object motion, new challenges facing mechanical and engineering industry can be seen. One of typical examples is the need to solve the complex task of elastomeric (e.g. rubber or silicone) robotic objects interaction with the water boundary. Current work is an attempt to launch an investigation on elastomer dynamics of experimental and theoretical research in two directions. Experimental studies have been conducted with a sample loading on the tensile and compression machine. Theoretical research investigation proposes a new model with internal interactions inside elastomers. Model is based on common lateral and diagonal interaction links between cross-sections of a material. Results of the work are applied for vibration systems motion modeling. Additionally, a new dynamical material model may be applied for the imitation of muscle dynamics and thus to provide basis for further applications in biomechanics such as development of artificial muscles.

Abstract: The paper considers the dynamics of ball bearings with defects. A mathematical model of a ball bearing with defects is offered. The performed theoretical and experimental investigations of ball bearings with defects are described. Five cases of various defects are investigated, including the defective outer race, the defective inner race, the defective rolling element, the defective inner and outer races, the rolling element and a separator, the worn-out ball bearing.

Abstract: The main objective of this work is to present a reverse task of the dynamics of discrete vibratory mechanical systems. This task is reverse to analysis and is called structural and parametric synthesis. As a result of performing the synthesis one obtains a structure and values of individual parameters of the system of required properties. Such properties refer to the determination of individual frequencies of the system vibration. Synthesis is divided into two stages. The first stage consists in definition of the structure as well as the values of parameters of a passive system without vibration reduction. In the second phase, one selects a method of vibration reduction as well as system structure and parameters with vibration-reducing elements. In case of already-existing systems, the first stage consists in the identification of the system and its analysis. There are no changes in the second stage (Figure 1) [. Another objective of this work is to use mechanical elements in the form of kinematic excitations as the implementation of active reduction of vibration as well as to check the influence of this subsystem on the basic system. The application of the synthesis presented in this work enables the correction of the already-existing machines and devices as well as the modification of newly-created systems with the view of their future functioning.

Abstract: The harvesting of ambient energy has become more important over the last years. This paper will investigate an analytical effort to predict the Duffing parameters for a magnetoelastic cantilever structure. The modeling is compared to a nonlinear harvester with point dipoles. The system consists of a harmonic excited cantilever structure with a magnetic tip mass. The beam is firmly clamped to the host structure. A second oppositely poled permanent magnet is located near the free end of the beam. The system is a bistable nonlinear oscillator with two equilibrium positions. Several studies show the better performance of the setup. The approach is not limited for energy harvesting techniques. The setup is suitable for broadband oscillations and also to tune the resonant frequency closer to the excitation frequency.

Abstract: In this paper the method of modelling a speed-varying geared rotor system is presented. The proposed approach enables us to obtain an accurate low-order lumped parameter representation of the investigated system. The final model consists of reduced modal models of an undamped beam/torsional shaft system as well as a spatially lumped model of other linear and nonlinear phenomena including gear mesh interaction.

Abstract: The aim of this paper is to create a method for reduction of constructive weights of system of cross-beams (grillages) optimizing its elements. The study has practical application and aimed primarily to companies who design civil and industrial buildings, different types of mechanical constructions, vehicle industry, etc.

Abstract: In given article the nut drivers electric power consumption studies depending on the corresponding fixed threaded joints assembly time are made. So far there are no recommendations from the tool manufactures for nut drivers optimal operating modes (the conclusion is made based on the attached instructions which provide instrument manufacturers), when evaluating this aspect taking into account the electrical power consumption and assembly time for different types of fixed threaded joints (wood, metal, plastic, etc.) and also taking into account obtainable tightening moments. In the examined literature sources which deal with the opportunities concerning the optimization of the automated assembly processes of fixed threaded joints, not enough attention is paid to the reduction of the instruments energy consumption which is one of the main tasks in the industrial process because it directly impacts production costs.

Abstract: The milling process considered in the paper is a finishing milling of ship bow thruster. It is really challenging task because this kind of object can be prone to vibration, and due to certain conditions, the self-excited chatter vibration may appear [. One of the methods of the chatter reduction depends upon the selection of the spindle speed by matching it to the optimal phase shift between subsequent passes of the tool cutting edges [. However, in case of complex-shaped objects there may be different values of optimal spindle speeds for various points of the workpiece surface. The paper presents an example of implementation of the procedure of building the optimal spindle speed map [. In order to create the map for specific surface points, optimal spindle speed is obtained with the use of various modal analysis techniques. The map seems to be effective way for eliminating chatter in case of the process of milling flexible details.