Contents of the Journal of Mechanical Engineering 51, 2 (2000)

Y. LI: Integrated control of a mechatronic system                           69 

S. JANDA, J. VALENTA: Mathematical model of  the lumbar spine loads         86

T. JIROUT,  F. RIEGER: Influence of blade shape on suspension effect
of three-blade axial turbines (in Czech)                                    92

M. KUPKOVA, M. KUPKA: Calculation of resonance frequencies of non-uniform 
beam and evaluation of related effective elastic moduli                    104

J. PODRUH, L. PESEK: The contribution to vibro-acoustic behavior
of the railway tram wheel (in Czech)                                       115

Integrated control and manipulation of a mechatronic system which is composed of robot and its peripheral equipment is approached in this paper. First the LJ EMU robot is introduced, which is an articulated joint robot for educational purpose. Second a small car controlled by a stepper motor has been designed to carry the robot to enhance its mobility. Since it is not easy to write control program for the EMU robot, a PC computer is employed to replace the original EMU robotic controller. Finally, the EMU robot, two conveyors, and an automatic car have been combined together to form an integrated mechatronic system. The control principle of each component and the relationships among them will be elucidated in this paper. At last a mechatronic system has been set up to demonstrate the control process. The methodology proposed in this paper possesses potential power to be applied in practical field.

The submitted paper deals with a mathematical modelling of loads applied on the lumbar spine. The main objective of this paper is to obtain relationships between external loading forces and moments to which the spine is subjected and the internal forces and moments provided by its structural elements in response. The second goal of this work is to predict the axial compressive force, anterior and lateral shear forces at the intervertebral disc and to determine the forces in muscles on the L₄/L₅ level. The task of reassessment of the role of intra-abdominal pressure (IAP) in the models of the lumbar spinal loads is also important. Finally, clinical relevance and implementation of the results based on the mathematical modelling analyses is discussed.

This paper deals with results of suspension effect measurement. Experiments were carried out with three-blade turbines: pitched blade, fluid foil blade and profiled blade in a cylindrical vessel with dished bottom for mean volumetric of solid phase concentrations equal to 2.5 % and 10 %. In the final part of this paper suspension efficiency of different used agitators is compared. Suspension efficiency is expressed by means of dimensionless power consumption necessary for suspension of solid particles. The most advantageous of the compared impellers is the profiled three-blade turbine and the least effective one is the pitched three-blade turbine.

Effective Young's moduli determined by means of measurements of resonance frequencies of edgewise and flatwise flexural vibrations of prismatic bars with rectangular cross section can sometimes differ from each other. In this paper we present a theoretical manifestation that the shape non-uniformity of the sample tested can serve as one of the reasons for such differences in modulus values. The method used for numerical calculating the effective moduli of interest is briefly sketched. This method is based on employing the principal (or transfer) matrix and its useful properties.

This contribution is aimed at the vibro-acoustics of the railway tram wheel, which has the rim separated from the disk by a rubber cushioning. A numerical 3D FEM model of the wheel was developed by means of specific drawing and dynamic tests on the rubber specimen. The visco-elastic behavior of the rubber was modeled by the proportional damping. The dynamic characteristics of the wheel, such as frequency-modal and damping, were evaluated and analyzed. Furthermore, the time responses of the axisymmetric 2D FEM wheel model at the acoustic environment were calculated and the maxima of the acoustic level were evaluated.