COMPREHENSIVE STUDY OF PARAMETERS FOR CHARACTERIZING 3-DIMENSIONAL SURFACE-TOPOGRAPHY .2. STATISTICAL PROPERTIES OF PARAMETER VARIATION

The main objective of the paper is to understand and interpret statist ical properties of parameter variation on practical engineering surfac es where surface features may be involved and ergodicity or stationari ty or non-stationarity is applied. The understanding of the causes, th e mechanism and the statistical properties of parameter variation of p ractical engineering surfaces is essential for developing an effective approach to describe characteristics and functional performance of th ree-dimensional surface topography. This paper treats parameters as ra ndom variables, and simulates a practical engineering surface with a r andom process. The concepts of stationarity and ergodicity of engineer ing surfaces are presented and quantitative analysis of parameter vari ation for theoretically modelled non-stationary surfaces is carried ou t. In addition statistical properties of parameter variation from thre e kinds of ''typical'' engineering surfaces are discussed, and the inf luences of non-stationarity, surface features and correlation of sampl ed profiles on the properties are specified.