Contents of Journal of Mechanical Engineering 53, 6 (2002) 


 

V. ORAVSKY, O. SLIZEK: Contribution to analysis of influence 
of parameters upon solution of multi-parameter systems                    325

J. SLADEK: Description of coordinate measurement accuracy 
on the basis of determination of 3-D point uncertainty                    346

P. MUCKA: Influence of the road profile wavelengths on vehicle 
vibration (in Slovak)                                                     357

Letter to the Editor

C. A. PORK: Praise of biographies of outstanding personalities            379

Abstracts



Contribution to analysis of influence of parameters upon solution of multi-parameter systems

VLADIMIR ORAVSKY, OLDRICH SLIZEK

The paper contributes to not so often tackled problems of elaboration and evaluation of final results obtained by solving a problem, which are in a multi-parameter system very extensive. Short description and classification of the problem elaboration is given. Most attention is paid to so-called secondary analysis of influence of parameters upon the chosen key quantity of the multi-parameter problem. Graphically, it means to find the most representative evaluating diagrams. A criterion for this is the mean width of zone of diagram isopleths, which is taken as a measure of influence and is followed in a special matrix of influence.

For illustration of the above procedure, evaluation of quasi-static efficiency of a symmetric hydrostatic transmission with 5 parameters is presented.

Description of coordinate measurement accuracy on the basis of determination of 3-D point uncertainty

JERZY SLADEK

This article presents a new approach to the issue of coordinate measurement accuracy. The principle of this approach is an assumption that measurement accuracy should be based on the accuracy of identification for each measurement point. Reproducibility error of measured point in a vector form is taken as a basis for the construction of the model. Furthermore, in the course of analysis of random errors participation issue, delineated is the uncertainty area for spatial measurements, and it is established that this area assumes an ellipsoid shape. Its dimensions depend on the work characteristics of the contact head of Coordinate Measuring Machines (CMM). The results of the analysis carried out served as a basis to formulate a conception of methodology for accuracy identification of CMM.

Influence of the road profile wavelengths on vehicle vibration

PETER MUCKA

The paper analyzes the influence of random road-profile wavelength bands on vehicle vibration. The standard ISO 8608: 1995 assumes an equal unevenness intensity in short and long wave bands in the road profile PSD. In reality, differences between intensity of unevenness in wave bands have been observed for about of 40 % of measured roads. For simulation a longitudinal half-car model is used. As the random response the vertical acceleration of sprung mass C.G. and dynamic tyre force are evaluated. Three different cases of waviness parameter values for short waves (kS) and long waves (kL) are investigated: i) kS = kL = 1.5-2.5, ii) kS = 2, kL = 2-2.5, iii) kS = 1.5-2, kL = 2. The results show that the simple usage of profile displacement PSD with constant waviness parameter k = 2 could sometimes significantly affect the predicted vehicle random response. For correct prediction of the vehicle response to the longitudinal road profile all possibilities of the alternative spectra should be taken into account.