Andrzej Buchacz

Damping of Mechanical Vibrations Using Piezoelements, Including Influence of Connection Layer’s Properties on the Dynamic Characteristic

The paper presents analysis of flexural vibrating machatronic system. Considered system is compounded of a cantilever bending beam and a strip-like piezoelectric transducer. The transducer is bonded with the beam surface by means of connection layer which has homogeneous properties in whole length. External RC circuit is adjoined to the transducer’s clamps. This mechatronic system is loaded with harmoniousness variable force. Beam’s vibrations affect piezoelectric transducer through the agency of connection layer which generates electric charge and produces additional stiffness. Dynamic equations of considered mechatronic system were determined on the basis of elementary beam and transducer’s section dynamic equilibrium. Transducer’s dynamic equation was assigned using transducer’s piezoelectric properties. Dynamic flexibility of considered mechatronic system was assigned on the basis of approximate Galerkin’s method. Solution of beam’s differential motion’s equation was defined as a product of time and displacement’s eigenfunctions which satisfy defined boundary conditions. Dynamic characteristic of considered mechatronic system, including pure shear of the connection layer was assigned on the end of the beam and illustrated on the chart at the same time taking into account beam and transducer’s geometrical and material parameters.

Study of mechanical properties and computer simulation of composite materials reinforced by metal

In the article, two methods for testing of composite materials reinforced by sheet metal were presented. The first method is based on computer simulation of stresses in the investigated objects. It was carried out in the graphical programme NX. The second method consists in measuring deformations using strain gauge bridges and comparative analysis was carried out. The obtained results show that both methods were applied correctly and the error reaches a few percent.

Development of Mathematical Model of a Mechatronic System

This paper is a continuation of earlier publications of the authors related to the analysis of mechatronic systems including piezoelectric materials used as sensors or actuators for stabilization and damping of mechanical vibration. It was demonstrated that only very accurate mathematical model of the system with the piezoelectric transducers and external electric circuit attached to a mechanical system like a beam or a shaft by a glue layer allows the engineers to design the system with required dynamic parameters. Geometrical and material parameters of all the components have to be taken into account because neglecting the influence of one of them results in erroneous analysis results [1-4]. The paper presents the improved mathematical model of the considered mechatronic system. The assumption of pure shear of the connection layer is rejected during modeling and deformation of the layer is taken into consideration. The purpose of the reported enhancement of the mathematical model of the considered mechatronic system is to improve accuracy of computational results.

Selection of Parameters of External Electric Circuit for Control of Dynamic Flexibility of a Mechatronic System

This paper deals with the analysis of mechatronic systems including piezoelectric materials used as sensors or actuators for stabilization and damping of mechanical vibration. This work presents the analysis of the flexural vibrating one-dimensional mechatronic system – a cantilever beam and the piezoelectric transducer bonded on the beam surface by means of a glue layer. The external RC circuit is connected to the transducer clamps. Dynamic equations of motion of the considered mechatronic system were written down using the discrete-continuous mathematical model, taking into consideration the influence of the connection layer and the external electric circuit. Dynamic flexibility of the mechatronic system was assigned on the basis of the approximate Galerkin method.

Influence of the excitation parameters of the mechanical subsystem on effectiveness of energy harvesting system

Piezoelectric transducers are used more and more often in modern technical devices. The wide range of their possible applications is a result of the possibility to use both direct and reverse piezoelectric effect. Nowadays, application of piezoelectric transducers in energy harvesting systems is getting more and more popular. It is caused by the easy way to convert energy of mechanical vibration to the electric voltage using piezoelectric transducers. This paper presents results of influence analysis of the vibrating mechanical subsystems excitation parameters on the effectiveness of the system designed for energy harvesting. The considered vibrating system is a composite plate with piezoelectric transducer bonded to its surface. Vibrations of the system are excited by means of an actuator with possibility to change the excitation amplitude and frequency. Recovering of electrical energy from mechanical vibrations is possible by using the direct piezoelectric effect - generation of the electric voltage while the transducer is mechanically deformed. In carried out test Macro Fiber Composite (MFC) piezoelectric transducers were used. It was proved that the time that is necessary for switch on the output voltage in analyzed system depends on the frequency of the excitation.

Carbon fiber based composites stress analysis. Experimental and computer comparative studies

Composite materials used nowadays for the production of composites are the result of advanced research. This allows assuming that they are among the most elaborate tech products of our century. That fact is evidenced by the widespread use of them in the most demanding industries like aerospace and space industry. But the heterogeneous materials and their advantages have been known to mankind in ancient times and they have been used by nature for millions of years. Among the fibers used in the industry most commonly used are nylon, polyester, polypropylene, boron, metal, glass, carbon and aramid. Thanks to their physical properties last three fiber types deserve special attention. High strength to weight ratio allow the use of many industrial solutions. Composites based on carbon and glass fibers are widely used in the automotive. Aramid fibers ideal for the fashion industry where the fabric made from the fibers used to produce the protective clothing. In the paper presented issues of stress analysis of composite materials have been presented. The components of composite materials and principles of composition have been discussed. Particular attention was paid to the epoxy resins and the fabrics made from carbon fibers. The article also includes basic information about strain measurements performed on with a resistance strain gauge method. For the purpose of the laboratory tests a series of carbon - epoxy composite samples were made. For this purpose plain carbon textile was used with a weight of 200 g/mm2 and epoxy resin LG730. During laboratory strain tests described in the paper Tenmexs delta type strain gauge rosettes were used. They were arranged in specific locations on the surface of the samples. Data acquisition preceded using HBM measurement equipment, which included measuring amplifier and measuring head. Data acquisition was performed using the Easy Catman. In order to verify the results of laboratory tests numerical studies were carried out in a computing environment, Siemens PLM NX 9.0.For this purpose, samples were modeled composite corresponding to real samples. Tests were made for boundary conditions compatible with the laboratory tests boundary conditions.

The modelling of vibrating bar systems with nonlinear changeable sections of robots by means of hypergraphs and structural numbers

Abstract The modelling of vibrating bar systems with nonlinear changeable sections using hypergraphs, structural numbers of higher rank and complete structural numbers is shown in this paper. The method of determining the dynamic flexibility by means of graphs of the second and third category is also shown.

Comparison of active and semi–active damping in synthesis of various mechatronic discrete systems

Presented research highlights possibility of application of additional active absorbers to mechatronic discrete structures for vibration isolation, in relation to requirements in form of poles and zeros. This new function is defined and compared with semi–active configuration of mechatronic systems that can be obtained by LC or LRC control in external electric network with negative capacitance. Basing on selected examples and types of considered displacement models received from synthesis, respective parameters responsible for damping functions have been investigated. Comparing frequency response functions and dynamical flexibilities, active and semiactive vibration isolation methods have been confronted with regards to damping performance.

Examination of a Cargo Space of a Freight Wagon Modified with Composite Panels

This article presents the method of solving the problem considered with the too fast wearing of a steel sheet paneling of a freight wagon body. The method, described in the work, bases on the use of additional components, which are made of composite materials. The proposed solution is based on the appropriate lining of the inside of a wagon body with composite panels. In order to verify the placing and fixing of composite panels to wagon walls, as well as to verify the behavior of joined composite panels in the given conditions of a wagon work it was used a computer analysis basing on the finite element method. Because of the scale of the analyzed problem it was also created a virtual model of the research stand, which allows experimentally verifying phenomena occurring between the joined composite panels mounted on walls of a freight wagon that is made in a natural size. Carried out researches allowed determining the method of arrangement the composite panels in the inside space of a freight wagon body. It was also determined the method of panels joining and the method of their fixing to the steel paneling of a wagon body. It was also determined the procedure of transferring the results of the experimental analysis of the wagon walls, made in a natural size, on a real object using the matching of a virtual model.

Passive and Active Vibration Isolation Methods in Discrete Mechatronic Systems

Piezoelectric actuators are more and more common in many different technical and precision industries. Mechatronic systems which combine them with mechanical models and steering recently are used in plenty practical applications. In this paper, discrete mechatronic systems have been compared relating to known passive vibration isolation method and active that has been additionally introduced to considered systems. Requirements for the systems have been given in form of poles and zeros. Basing on amplitude response functions and dynamical flexibilities, damping performance in both cases has been investigated.