Skip to Main content Skip to Navigation
Theses

Stochastic representation and analysis of rough surface topography by random fields and integral geometry – Application to the UHMWPE cup involved in total hip arthroplasty

Abstract : Surface topography is, generally, composed of many length scales starting from its physical geometry, to its microscopic or atomic scales known by roughness. The spatial and geometrical evolution of the roughness topography of engineering surfaces avail comprehensive understanding, and interpretation of many physical and engineering problems such as friction, and wear mechanisms during the mechanical contact between adjoined surfaces. Obviously, the topography of rough surfaces is of random nature. It is composed of irregular hills/valleys being spatially correlated. The relation between their densities and their geometric properties are the fundamental topics that have been developed, in this research study, using the theory of random fields and the integral geometry.An appropriate random field model of a rough surface has been defined by the most significant parameters, whose changes influence the geometry of its excursion. The excursion sets were quantified by functions known as intrinsic volumes. These functions have many physical interpretations, in practice. It is possible by deriving their analytical formula to estimate the parameters of the random field model being applied on the surface, and for statistical analysis investigation of its excursion sets. These subjects have been essentially considered in this thesis. Firstly, the intrinsic volumes of the excursion sets of a class of mixture models defined by the linear combination of Gaussian and t random fields, then for the skew-t random fields are derived analytically. They have been compared and tested on surfaces generated by simulations. In the second stage, these random fields have been applied to real surfaces measured from the UHMWPE component, involved in application of total hip implant, before and after wear simulation process. The primary results showed that the skew-t random field is more adequate, and flexible for modelling the topographic roughness. Following these arguments, a statistical analysis approach, based on the skew-t random field, is then proposed. It aims at estimating, hierarchically, the significant levels including the real hills/valleys among the uncertain measurements. The evolution of the mean area of the hills/valleys and their levels enabled describing the functional behaviour of the UHMWPE surface over wear time, and indicating the predominant wear mechanisms.
Document type :
Theses
Complete list of metadatas

Cited literature [108 references]  Display  Hide  Download

https://tel.archives-ouvertes.fr/tel-00905519
Contributor : Abes Star :  Contact
Submitted on : Monday, November 18, 2013 - 1:12:08 PM
Last modification on : Wednesday, June 24, 2020 - 4:19:07 PM
Long-term archiving on: : Wednesday, February 19, 2014 - 7:45:15 AM

File

AHMAD_Ola_diff.pdf
Version validated by the jury (STAR)

Identifiers

  • HAL Id : tel-00905519, version 1

Citation

Ola Ahmad. Stochastic representation and analysis of rough surface topography by random fields and integral geometry – Application to the UHMWPE cup involved in total hip arthroplasty. Other. Ecole Nationale Supérieure des Mines de Saint-Etienne, 2013. English. ⟨NNT : 2013EMSE0704⟩. ⟨tel-00905519⟩

Share

Metrics

Record views

864

Files downloads

1769