Contents of Journal of Mechanical Engineering 54, 2 (2003) 


 

LI, Y., LEONG, S. H.: A CMAC neural network approach to redundant manipulator 
kinematics control                                                             65

ROBBE, M.-F., SARDAIN, P.: Comparison of several simplified models and 
scenarios to simulate a steam explosion in a tank                              82

MATSUDA, T., SATO, M.: Development of torsional damper with crowd of solid 
balls for engine crankshaft                                                   101

PLESEK, J., HOSCHL, C.: Consistent explanation of an apparent paradox in 
thermo-elasticity theory (in Czech)                                           111

KUDLICKA, J.: Energy flow of elastic waves in a composite (in Slovak)         119

Abstracts



A CMAC neural network approach to redundant manipulator kinematics control

YANGMIN LI, SIO HONG LEONG

This paper studies the inverse kinematics issue of redundant manipulators using the neural network method. The conventional method of solving this problem analytically is by applying the Jacobian Pseudoinverse Algorithm. It is effective and able to resolve the redundancy for additional constraints. However, its demand for computational effort makes it not suitable for real-time control. Recently, neural networks have been widely used in robotic control because they are fast, fault-tolerant and able to learn. In this paper, the CMAC (Cerebellar Model Articulation Controller) neural network for solving the inverse kinematics problems in real time is presented. Simulations have shown that the CMAC neural network has good performance in tackling the inverse kinematics control of redundant manipulators.

Comparison of several simplified models and scenarios to simulate a steam explosion in a tank

MARIE-FRANCE ROBBE, PIERRE SARDAIN

A fuel-coolant interaction is one of the phenomena to be considered in the frame of the safety analysis of experiments involving a molten metal and a cold fluid. The interaction between a hot molten metal and a cold liquid contained into a tank can lead to a short and high over-pressurisation which can challenge the integrity of the tank. As the over-pressurisation depends much on the accident conditions, it is essential to compare the influence of different scenarios envisaged for this kind of accident. Simplified one-dimensional numerical tools were used to have the opportunity to compute several accident scenarios in a limited computation time.

Development of torsional damper with crowd of solid balls for engine crankshaft

TAKASHI MATSUDA, MOTOHIRO SATO

In this paper, new torsional damper is developed in order to improve the defects of known dampers such as rubber dampers, oil dampers and solid frictional dampers, which are used for vibration reduction of crankshafts in most of reciprocating engines for automobiles. The damper is designed and manufactured, and the experiments on the vibration reduction are carried out. As a result, it is suggested that those defects can be improved by this experimental damper, and that the effective damping is achieved by the new damping mechanism, that is, the fluctuation of the natural frequency of testing crankshaft system caused by alternating between the angular sliding and the coupling of damper mass to the damper casing in every period of the torsional vibration of the crankshaft.

Consistent explanation of an apparent paradox in thermoelasticity theory

JIRI PLESEK, CYRIL HOSCHL

A paradox involving a thermoelastic helical spring device was discussed in literature. The spring is heated then loaded with the aid of the heat and mechanical energy supply. Subsequently, the spring is cooled to the initial temperature and unloaded, which brings the device back to its initial thermodynamic state. The energy balance performed on the closed cycle seemingly reveals a leftover of mechanical energy gained by the dilatation during the cooling stage.

This paper shows that the explanation suggested in the cited reference is unsatisfactory since it disregards the effect of thermoelastic coupling - a simplifying assumption often made in engineering practice. Instead, a new solution is proposed in which the coupling term plays a crucial role.

Energy flow of elastic waves in a composite

JAN KUDLICKA

Energy flow of elastic waves in an epoxy matrix composite reinforced by continual boron fibres is investigated. For this anisotropic material, mean values of the energy flow densities for axisymmetric elastic waves in a hollow cylinder as functions of the radial co-ordinate and the wave number are determined. The results for selected wave numbers and phase velocities from the basic dispersion curve are compared with those obtained for an isotropic epoxy cylinder.