Contents of Journal of Mechanical Engineering 52, 5 (2001) 


 

G. MELTZER: Possibilities and limitations in vibro-acoustic 
diagnostics of machinery                                                 261

Z. VIRAG, M. ZIVIC, I. BUDIC: A numerical method for 
simulation of continuous casting solidification process                  274

J. BAJKOWSKI, M. HAC: Investigation of friction and material 
properties and stress analysis in disk brakes                            289

E. N. AKIMOVA: Parallelization of algorithm for solving 
the three-dimensional problem of elasticity                              299

O. KROPAC, J. SPRINC, M. SPRINC: Variant representation 
of characteristics of random pavement unevenness (in Czech)              309

Abstracts



Possibilities and limitations in vibro-acoustic diagnostics of machinery

G. MELTZER

After a short survey on the object and methods of technical diagnostics, different sources of measured diagnostic signals are explained. The vibro-acoustic signals are more favourable than all the others. Therefore, they are analyzed here in more detail. One of the most important possibilities is to extract diagnostic symptoms with a high content of information by signal processing. Also the so-called diagnostic model (i.e. the formulated relation between condition parameters and diagnostic symptoms) is one of the topics of this paper. Using multivariate diagnostic models (classifiers, artificial neural networks), which can be easily combined with vibro-acoustic diagnostic symptoms, the diagnosis can be made more exact and robust.

A numerical method for simulation of continuous casting solidification process

Z. VIRAG, M. ZIVIC, I. BUDIC

A simple and accurate control volume method has been developed for simulating the solidification process in the continuous procedure of pure metal casting. The method uses a stationary grid, while the released or absorbed latent heat is included in the source term. The melting temperature is maintained in control volumes in which the phase change occurs. The method was tested against the analytical solution for the case of semi-infinite plate cooling, and then applied to the continuous casting process. The obtained results confirm that the method is appropriate for predictions in heat transfer problems involving phase transformation.

Investigation of friction and material properties and stress analysis in disk brakes

J. BAJKOWSKI, M. HAC

In the paper coupled thermal-structural stresses in the steady-state analysis of elements of machines are investigated. This problem is very important in elements under loading, working at high temperatures such as disk brakes or engine turbine blades. The calculations were performed by using the finite element method. The temperature distribution in the cases considered was taken from experimental tests. The data was gathered by complex analysis of materials with regard to physical and chemical properties. This enables to understand better the friction phenomena appearing in machine elements such as disk brakes.

Parallelization of algorithm for solving the three-dimensional problem of elasticity

E. N. AKIMOVA

Parallelization of the algorithm for solving the three-dimensional boundary value problem of elasticity by the boundary integral equations method is considered. Realization of the applied package on the Parallel Computer System MBC-100 is implemented. An analysis of the efficiency of parallelization of the algorithm with different number of i860-processors is carried out.

Variant representation of characteristics of random pavement unevenness

O. KROPAC, J. SPRINC, M. SPRINC

In the article, the full graphical documentation of statistical characteristics of random pavement unevenness is proposed and justified. Its individual components are: measured longitudinal profile of the given road section, longitudinal profile without trend, empirical correlation function, empirical power spectral density (PSD) in several variants. From the last-mentioned empirical characteristics, it is possible to estimate numerical values of free parameters appearing in their analytical models. It follows from measurements conducted in different countries on a number of pavements of different structural realizations and different operational destinations that it is desirable to evaluate the above-mentioned parameters of PSD separately for long and for short wave lengths. In the case of nonhomogeneous unevenness, the variability of unevenness along the trace and the first distribution function are also necessary to be evaluated. When individual greater imperfections are present, their character and frequency are also to be added.