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logo SMC logo SMC  NLIN logo SMC  NLIN  PROJ5 Surface mechanical properties
   
Contact Peter Berke

Thierry J. Massart

   
Keywords finite element technique, isogeometric approximation, lattice mechanics approach, finite deformation solid mechanics, computational contact mechanics,sliding friction, non linear material models, rate dependent elasticity, thin films modeling, delamination, microscale manipulation by contact, coupled multi-physics numerical models, surface roughness, surface topography effects
   
Collaborations
  • Frankfurt Institute of Advanced Studies, Johann Wolfgang Goethe Univeristy, Germany
  • Chemicals and Materials Department, ULB, Belgium
  • BEAMS Departement, ULB, Belgium
   
Small scale contact Numerical modeling of the surface and the bulk deformation in a small scale contact - Application to the nanoindentation interpretation and to the micro-manipulation

The adaptation of surfaces for specific functions by the use of metallic materials and thin films with advanced mechanical properties can potentially lead to novel applications on the small scales. The conception of nanoscale devices taking advantage of new materials requires the characterization of these materials on the micro– and nanoscales in the first place. One of the frequently used methods of material characterization on small scales is the nanoindentation, being conceptually a nanoscale hardness measurement.

This research work presents a contribution to the interpretation of nanoindentation results, involving a large number of coupled phenomena by using numerical simulations. For this purpose an interdisciplinary approach was chosen, adapted to small scale phenomena combining concepts from physics, mechanics and material science. Numerical models were developed to study the behavior of pure nickel on the atomic scale (discrete description), and on the scale of continuum mechanics (finite element method). This material was chosen for its advanced mechanical and wear properties coupled to bio–compatibility, which can lead to interesting future applications particularly in the biomedical field. Advanced methods of solid mechanics were applied to consider the local finite deformation applied to the material (using a corotational formulation) and to take contact conditions into account in the finite element model (using an augmented Lagrangian treatment of normal and tangential contact).

NL 5 Fig1

The application of the numerical models contributed to the identification of the physics governing the nanoindentation. The rate–dependent plastic behavior of pure nickel in nanoindentation was identified in a coupled experimental–numerical study, and the cumulative effect of surface roughness and friction on the dispersion of nanoindentation results was shown through a numerical study (with results in good agreement with experimental trends). The continuum scale numerical tool was used to model a different application on small scales, the manipulation of objects by contact. The plastic flattening of the surface asperities of the microgripper (made of pure nickel) was identified in a numerical study as source of an important increase of contact adhesion during micromanipulation, which can potentially result in release and accuracy issues, also observed experimentally.

NL 5 Fig2

The results show that physically–based numerical simulations yield results that can potentially explain experimental trends and contribute to the better understanding of the nanoscale world.

     
Support
  • CFWB
  • F.R.S.-FNRS
     
Selected publications
  • [1] P. Berke, M.-P. Delplancke-Ogletree, A. Lyalin, V. V. Semenikhina, A. V. Solov'yov, in Latest Advances in Atomic Cluster Collisions, Structure and Dynamics from the Nuclear to the Biological Scale. Chapter D2: Simulation of the nanoindentation procedure on Nickel on the smallest length scale: a simple atomistic level model, Imperial College Press, London, 205-224, 2008
  • [2] P. Berke, Numerical modeling of the surface and the bulk deformation in a small scale contact - Application to the nanoindentation interpretation and to the micro-manipulation, PhD Thesis, Université Libre de Bruxelles, service BATir, 2008
  • [3] P. Berke, E. Tam, M.-P. Delplancke-Ogletree, T. J. Massart, Study of the rate-dependent behavior of pure nickel in conical nanoindentation through numerical simulation coupled to experiments, Mechanics of Materials, 41, 154-164, 2009
  • [4] P. Berke, F. El Houdaigui, T. J. Massart, Coupled friction and roughness surface effects in shallow spherical nanoindentation, Wear, 268, 223-232, 2010
  • [5] M. Sausse Lhernould, P. Berke, T. J. Massart, S. Régnier, P. Lambert, Variation of the electrostatic adhesion force on a rough surface due to the deformation of roughness asperities during micromanipulation of a spherical rigid body, Journal of Adhesion Science and Technology, 23, 1303–132, 2009