S. Ilincic | University of Vienna (original) (raw)

Papers by S. Ilincic

Research paper thumbnail of Special Issue Article Numerical estimation of wear in reciprocating tribological experiments

In order to numerically simulate the contact pressure distribution and area during sliding when w... more In order to numerically simulate the contact pressure distribution and area during sliding when wear occurs, the combined finite element method and boundary element method (FEM–BEM) developed by the authors is extended based on a linear wear law merged with the space- and time-resolved cumulative dissipated frictional energy. In each computed time step, the dissipated frictional energy and the wear rate are determined. Simultaneously, the topography of surfaces in contact are updated after every sliding cycle, providing for each sliding cycle a new input for BEM which is consequently used to redetermine the contact pressure distribution. The numerical results obtained with the proposed FEM–BEM algorithm are found to match qualitatively well with the amount of wear observed in high-frequency reci-procating rig experiments. This demonstrates the suitability of the FEM–BEM contact scheme for wear applications.

Research paper thumbnail of Numerical Modelling of Lubricated Frictional Tribocontacts on the Micro-and Nanoscale

In this article, an overview of the concept of multiscale modelling is given. Two of the mentione... more In this article, an overview of the concept of multiscale modelling is given. Two of the mentioned methods are used as examples how different approaches have to be taken to solve contact mechanical problems at different length and time scales. The first, a coupled finite element -boundary element scheme, describes surface topography changes at the micro-scale. Real specimen topographies are measured with a white light microscope and, together with material parameters, provide the basis for a numerical analysis of the real contact pressure distribution and contact area. It was shown that the contact pressure is mainly determined by the surface roughness and highly irregularly distributed over the surface. The second method, molecular dynamics simulation, is used to atomistically model the behaviour of lubricated sliding contacts at the nano-scale and calculate friction forces via shear simulations. Model substrates consist of Fe and are varied in crystallinity and nano-roughness, while the model lubricants stearic acid, methyl stearate and n-hexadecane are varied in composition and surface density. A conclusion that can be drawn is that once one friction-increasing factor (such as roughness or low additive density) is present, most systems become independent of the other factor.

Research paper thumbnail of The influence of design parameters on contact interlocking caused by material transfer

Electrical Contacts - 2007 Proceedings of the 53rd IEEE Holm Conference on Electrical Contacts, 2007

Contacts, switching DC loads, can create material transfer pip and crater formations which may ca... more Contacts, switching DC loads, can create material transfer pip and crater formations which may cause non opening faults due to interlocking. Both, the material transfer formation and the capability to open the contacts at pronounced material transfer, are affected by the design parameters of the contact system. Since the decoupling of these two phenomena cannot be carried out in experimental investigations, a variation of design parameters without a changed material transfer formation is generally not possible.

Research paper thumbnail of Numerical Modelling of Lubricated Frictional Tribocontacts on the Micro-and Nanoscale

In this article, an overview of the concept of multiscale modelling is given. Two of the mentione... more In this article, an overview of the concept of multiscale modelling is given. Two of the mentioned methods are used as examples how different approaches have to be taken to solve contact mechanical problems at different length and time scales. The first, a coupled finite element -boundary element scheme, describes surface topography changes at the micro-scale. Real specimen topographies are measured with a white light microscope and, together with material parameters, provide the basis for a numerical analysis of the real contact pressure distribution and contact area. It was shown that the contact pressure is mainly determined by the surface roughness and highly irregularly distributed over the surface. The second method, molecular dynamics simulation, is used to atomistically model the behaviour of lubricated sliding contacts at the nano-scale and calculate friction forces via shear simulations. Model substrates consist of Fe and are varied in crystallinity and nano-roughness, while the model lubricants stearic acid, methyl stearate and n-hexadecane are varied in composition and surface density. A conclusion that can be drawn is that once one friction-increasing factor (such as roughness or low additive density) is present, most systems become independent of the other factor.

Research paper thumbnail of Simulation of wear processes using molecular dynamics (MD) simulations

Research paper thumbnail of Wear Quantification by Comparison of Surface Topography Data

Encyclopedia of Tribology, 2013

Research paper thumbnail of Surface Variation in Tribological Processes

Encyclopedia of Tribology, 2013

Research paper thumbnail of Finite and boundary element method contact mechanics on rough, artificial hip joints

Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, 2011

ABSTRACT An extremely small roughness of constant height magnitude is considered on the femoral h... more ABSTRACT An extremely small roughness of constant height magnitude is considered on the femoral head of an artificial hip joint in order to determine the consequences of various regular shapes and clearances on the mechanical performance of this hip prosthesis via a properly coupled finite and boundary element method. In addition, different material combinations typical for widely used hard-on-hard and hard-on-soft hip joint replacements are also taken into account. By analysing the calculated pressure distribution and contact area between the femoral head and the acetabular cup in frictionless dry contact irrespective of material pairings in hip joints, it is shown that both the wavelength of roughness and the clearance significantly affect these mechanical quantities and accordingly too loose or too tight hip implants have to be avoided. Finally, in terms of all numerical findings a suitable optimal design of hip implants is also discussed.

Research paper thumbnail of Combined finite element–boundary element method modelling of elastic multi-asperity contacts

Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, 2009

ABSTRACT A novel formulation of elastic multi-asperity contacts based on the boundary element met... more ABSTRACT A novel formulation of elastic multi-asperity contacts based on the boundary element method (BEM) is presented for the first time, in which the influence coefficients are numerically calculated using a finite element method (FEM). The main advantage of computing the influence coefficients in this manner is that it makes it also possible to consider an arbitrary load direction and multilayer systems of different mechanical properties in each layer. Furthermore, any form of anisotropy can be modelled too, where Green's functions either become very complicated or are not available at all.

Research paper thumbnail of Numerical estimation of wear in reciprocating tribological experiments

Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, 2013

ABSTRACT In order to numerically simulate the contact pressure distribution and area during slidi... more ABSTRACT In order to numerically simulate the contact pressure distribution and area during sliding when wear occurs, the combined finite element method and boundary element method (FEM–BEM) developed by the authors is extended based on a linear wear law merged with the space- and time-resolved cumulative dissipated frictional energy. In each computed time step, the dissipated frictional energy and the wear rate are determined. Simultaneously, the topography of surfaces in contact are updated after every sliding cycle, providing for each sliding cycle a new input for BEM which is consequently used to redetermine the contact pressure distribution. The numerical results obtained with the proposed FEM–BEM algorithm are found to match qualitatively well with the amount of wear observed in high-frequency reciprocating rig experiments. This demonstrates the suitability of the FEM–BEM contact scheme for wear applications.

Research paper thumbnail of Special Issue Article Numerical estimation of wear in reciprocating tribological experiments

In order to numerically simulate the contact pressure distribution and area during sliding when w... more In order to numerically simulate the contact pressure distribution and area during sliding when wear occurs, the combined finite element method and boundary element method (FEM–BEM) developed by the authors is extended based on a linear wear law merged with the space- and time-resolved cumulative dissipated frictional energy. In each computed time step, the dissipated frictional energy and the wear rate are determined. Simultaneously, the topography of surfaces in contact are updated after every sliding cycle, providing for each sliding cycle a new input for BEM which is consequently used to redetermine the contact pressure distribution. The numerical results obtained with the proposed FEM–BEM algorithm are found to match qualitatively well with the amount of wear observed in high-frequency reci-procating rig experiments. This demonstrates the suitability of the FEM–BEM contact scheme for wear applications.

Research paper thumbnail of Numerical Modelling of Lubricated Frictional Tribocontacts on the Micro-and Nanoscale

In this article, an overview of the concept of multiscale modelling is given. Two of the mentione... more In this article, an overview of the concept of multiscale modelling is given. Two of the mentioned methods are used as examples how different approaches have to be taken to solve contact mechanical problems at different length and time scales. The first, a coupled finite element -boundary element scheme, describes surface topography changes at the micro-scale. Real specimen topographies are measured with a white light microscope and, together with material parameters, provide the basis for a numerical analysis of the real contact pressure distribution and contact area. It was shown that the contact pressure is mainly determined by the surface roughness and highly irregularly distributed over the surface. The second method, molecular dynamics simulation, is used to atomistically model the behaviour of lubricated sliding contacts at the nano-scale and calculate friction forces via shear simulations. Model substrates consist of Fe and are varied in crystallinity and nano-roughness, while the model lubricants stearic acid, methyl stearate and n-hexadecane are varied in composition and surface density. A conclusion that can be drawn is that once one friction-increasing factor (such as roughness or low additive density) is present, most systems become independent of the other factor.

Research paper thumbnail of The influence of design parameters on contact interlocking caused by material transfer

Electrical Contacts - 2007 Proceedings of the 53rd IEEE Holm Conference on Electrical Contacts, 2007

Contacts, switching DC loads, can create material transfer pip and crater formations which may ca... more Contacts, switching DC loads, can create material transfer pip and crater formations which may cause non opening faults due to interlocking. Both, the material transfer formation and the capability to open the contacts at pronounced material transfer, are affected by the design parameters of the contact system. Since the decoupling of these two phenomena cannot be carried out in experimental investigations, a variation of design parameters without a changed material transfer formation is generally not possible.

Research paper thumbnail of Numerical Modelling of Lubricated Frictional Tribocontacts on the Micro-and Nanoscale

In this article, an overview of the concept of multiscale modelling is given. Two of the mentione... more In this article, an overview of the concept of multiscale modelling is given. Two of the mentioned methods are used as examples how different approaches have to be taken to solve contact mechanical problems at different length and time scales. The first, a coupled finite element -boundary element scheme, describes surface topography changes at the micro-scale. Real specimen topographies are measured with a white light microscope and, together with material parameters, provide the basis for a numerical analysis of the real contact pressure distribution and contact area. It was shown that the contact pressure is mainly determined by the surface roughness and highly irregularly distributed over the surface. The second method, molecular dynamics simulation, is used to atomistically model the behaviour of lubricated sliding contacts at the nano-scale and calculate friction forces via shear simulations. Model substrates consist of Fe and are varied in crystallinity and nano-roughness, while the model lubricants stearic acid, methyl stearate and n-hexadecane are varied in composition and surface density. A conclusion that can be drawn is that once one friction-increasing factor (such as roughness or low additive density) is present, most systems become independent of the other factor.

Research paper thumbnail of Simulation of wear processes using molecular dynamics (MD) simulations

Research paper thumbnail of Wear Quantification by Comparison of Surface Topography Data

Encyclopedia of Tribology, 2013

Research paper thumbnail of Surface Variation in Tribological Processes

Encyclopedia of Tribology, 2013

Research paper thumbnail of Finite and boundary element method contact mechanics on rough, artificial hip joints

Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, 2011

ABSTRACT An extremely small roughness of constant height magnitude is considered on the femoral h... more ABSTRACT An extremely small roughness of constant height magnitude is considered on the femoral head of an artificial hip joint in order to determine the consequences of various regular shapes and clearances on the mechanical performance of this hip prosthesis via a properly coupled finite and boundary element method. In addition, different material combinations typical for widely used hard-on-hard and hard-on-soft hip joint replacements are also taken into account. By analysing the calculated pressure distribution and contact area between the femoral head and the acetabular cup in frictionless dry contact irrespective of material pairings in hip joints, it is shown that both the wavelength of roughness and the clearance significantly affect these mechanical quantities and accordingly too loose or too tight hip implants have to be avoided. Finally, in terms of all numerical findings a suitable optimal design of hip implants is also discussed.

Research paper thumbnail of Combined finite element–boundary element method modelling of elastic multi-asperity contacts

Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, 2009

ABSTRACT A novel formulation of elastic multi-asperity contacts based on the boundary element met... more ABSTRACT A novel formulation of elastic multi-asperity contacts based on the boundary element method (BEM) is presented for the first time, in which the influence coefficients are numerically calculated using a finite element method (FEM). The main advantage of computing the influence coefficients in this manner is that it makes it also possible to consider an arbitrary load direction and multilayer systems of different mechanical properties in each layer. Furthermore, any form of anisotropy can be modelled too, where Green's functions either become very complicated or are not available at all.

Research paper thumbnail of Numerical estimation of wear in reciprocating tribological experiments

Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, 2013

ABSTRACT In order to numerically simulate the contact pressure distribution and area during slidi... more ABSTRACT In order to numerically simulate the contact pressure distribution and area during sliding when wear occurs, the combined finite element method and boundary element method (FEM–BEM) developed by the authors is extended based on a linear wear law merged with the space- and time-resolved cumulative dissipated frictional energy. In each computed time step, the dissipated frictional energy and the wear rate are determined. Simultaneously, the topography of surfaces in contact are updated after every sliding cycle, providing for each sliding cycle a new input for BEM which is consequently used to redetermine the contact pressure distribution. The numerical results obtained with the proposed FEM–BEM algorithm are found to match qualitatively well with the amount of wear observed in high-frequency reciprocating rig experiments. This demonstrates the suitability of the FEM–BEM contact scheme for wear applications.