Sławomir Zolkiewski

DAMPED VIBRATIONS PROBLEM OF BEAMS FIXED ON THE ROTATIONAL DISK

The problem considered in this paper is one of damped vibrations of the beam in transportation. The dynamical analysis of systems in motion is a very well-known issue, but many detailed cases have not been published yet. The considered case is applied with the double-sided fixed beams placed on a rotational disk. The disk treated as a rigid one is rotated with a constant angular velocity in the stationary reference frame. An application of vibrations of the beam is transformed from a local to global reference frame, damping forces and forces arising from the rotational motion of a local reference center are also taken into consideration. The beam is assumed as a homogenous one with symmetric cross-sections. This work is the dynamical analysis of such a type of vibrations, which is a mathematical one based on considering transient response and dynamical flexibility of this type of systems.

Numerical Application for Dynamical Analysis of Rod and Beam Systems in Transportation

Author’s computer program for dynamical analysis of the systems in transportation is presented in the paper. The presented version of this software is the upgrade of the Modyfit application [7]. The program was developed from the previous one for application that enables to analyze and model damped systems in transportation.

Vibrations of beams with a variable cross-section fixed on rotational rigid disks

The work is focused on the problem of vibrating beams with a variable cross-section fixed on a rotational rigid disk. The beam is loaded by a transversal time varying force orthogonal to an axis of the beam and simultaneously parallel to the disks plane. There are many ways of usage of the technical moveable systems composed of elements with the variable cross-sections. The main applications are used in numerous types of turbines and pumps. The paper is a kind of introduction to the dynamic analysis of above mentioned beam systems. The equations of motion of rotational beams fixed on the rigid disks were derived. After introducing the Coriolis forces and the centrifugal forces, the transportation effect in the mathematical model was considered. This particular project is the first stage research, where there were proposed certain solutions of problems connected with the linear variable cross-sections systems. The further investigation considering the nonlinear systems has been proceeding. The results, analysis and comparison will be presented in the future works.

Robot Control and Online Programming by Human Gestures Using a Kinect Motion Sensor

Monitoring and controlling of robots are key competences for robot producers and many research and development projects are carried out to increase robot performance and add new functionality. The paper presents a concept and implementation of online programming, controlling and monitoring an industrial robot using a Kinect sensor as a HMI part. Presented innovative solution is based on human gestures. A communication interface for gestures analysis performed by the robot operator was created using LabVIEW applications. Communication between the kinetic motion sensor and the robot was carried out through PLC Siemens S7-300 inside a flexible manufacturing system. The connection between the logic controller and the robot controller R30iA was realized in the ProfibusDP network. The connection between the controller and LabVIEW application has been established using the MPI protocol. A hardware communication protocol used by PLC was converted into the OPC protocol. NUI was used to communicate the Kinect with LabVIEW.

Attenuation-Frequency Characteristics of Beam Systems in Spatial Motion

Attenuation-frequency characteristics of the beam systems in spatial motion are presented in this paper. The characteristics enclose mutual relations between particular components of angular velocity and amplitude of vibrations, expressed by the value of dynamical flexibility. Beam systems consisting of homogeneous beams with symmetrical cross-sections undergoing spatial motion are considered. The systems vibrate transversally and beams are considered in spatial motion treated as transportation.

Diagnostics and Transversal Vibrations Control of Rotating Beam by Means of Campbell Diagrams

The paper concerns problem of diagnostics and transversal vibrations control of rotating beamlike system. The considered system is consisted of a simple prismatic beam. The beam is homogeneous and is being rotated round its end. The beam is fixed on the rotational disk. The most common method of analyzing rotational systems is the Campbell diagram. It gives the short and precise information about resonance points and critical angular velocities. In literature it is a very popular method, but used for shaft systems or rotors rather than for beams rotating round the axis of revolution perpendicular to its own axis of symmetry. In this work the exemplary Campbell diagrams for considered systems derived from the dynamic flexibility of beams are presented. In the used mathematical model the Coriolis forces and centrifugal forces were taken into consideration. Also the different types of boundary conditions were applied in this work. The results after proper adaptation can be used in practical applications such as pumps, turbines or wind power plants.

Dynamical Flexibility of Complex Damped Systems Vibrating Transversally in Transportation

The paper deals with the problem of transversal damped vibrations of complex systems in transportation. Many engineering systems are composed of subsystems and there is a need in technical applications to derive the overall model of such systems. Presented model is based on the particular models derived in previous research works of the author.

On force-deflection diagrams of fibre-metal composites connected by means of bolt joints

The fibre–metal laminates made of a steel plate and fibreglass, carbon, or aramid laminate plate were tested in the special laboratory stands. Epoxy resin and polyester resin were used as a matrix to fabricate the composites. The fibre–metal laminates have very good force versus deflection characteristics and overall mechanical properties. They are very popular and widely applied in technical systems. They can be put to use in connecting materials made of various fabrics, connecting high–number layer laminates, and most of all, connecting metals and laminates. In this paper, the chosen results of testing fibrous composite materials connected in bolt joints are shown. Composite materials reinforced with fibreglass, carbon, and aramid fibres are considered. The impact of the number of applied bolts in a joint on strength properties was investigated. The connections by means of four, eight, or 16 bolts were compared. Some exemplary results were presented with diagrams on force versus deflections and charts on strain or force as a time function.

Determination of the Penetration Depth of Eddy Currents in Defectoscopic Tests

In the defectoscopic tests by means of the eddy currents method only a certain superficial layer of the tested element is inspected. The reason of this phenomenon is connected with a very important feature of the eddy currents. The induced eddy currents generate its own magnetic field which obstructs penetration for the primary magnetic field. It is crucial to know the penetration depth of eddy currents. It allows planning successfully the diagnosis process. There are two cases worth mentioning: when the eddy current method is treated as the additional method complementary to the ultrasound method (because it does not detect superficial defects) and when the eddy current method is used as the main method for the thin elements diagnosis. The most frequently used evaluation method of eddy currents penetration depth is connected with determination of the e-folding decrease of electric current. The definition is convenient to use because it is simplified by using in the mathematical formula (allowing determination of the depth) frequency of eddy current and conductivity of the diagnosed elements. However the simplifications are not sufficient in practice. When we change the frequency of eddy currents during the survey or the probe then the depth of penetration is also changed, then we can measure the depth of the defects. While measuring the conductivity of a proper material element it is obligatory to prepare an adequate size of the sample that is free of defects. Knowing the value of penetration depth is then very helpful. On the other hand, when we have a sample of a specified size and we want to measure its conductivity then the knowledge of the depth of penetration of eddy currents helps us to select the proper frequency. In the paper there is described a proposal of a different definition of the penetration depth of eddy current, much more useful and accurate according to the authors. To obtain much more precise results, the new eddy current method was proposed. This method takes into account not only the parameters of the diagnosed sample and the eddy current frequency but the characteristic of the measuring device as well. The above mentioned method is based on the universal mathematical model of impact of conductive thin foil on the measuring coil impedance change. The procedure of calculations is easy to carry out online.

Machining Interface and Adapter for Industrial Robots

Comparing with existing market solutions the low budget solution for milling robots is presented in this work. For robot milling purposes the milling adapter was designed, modelled and manufactured. Some exemplary low cost conceptions of fixing adapter for milling ends were shown. Milling robots can be used for obtaining specific demanded structure by means of carving away material from any type of pattern. Unquestionable advantage of milling robots is easy integration with any type of manufacturing process and strong possibility of automation. Using a different robot made or a manufacturer’s brand it is possible to obtain solutions providing high speeds, high level of automation, easy operation and maximum reliability together with increased performance and productivity.