Simulation of complex impact problems with implicit time algorithms. Application to crashworthiness problems

in Matériaux et Techniques (2004)

Recently, robust implicit energy and momentum conserving algorithms have been developed in the non-linear range. The authors extended these algorithms to hypoelasticity-based constitutive models and ... [more ▼]

Recently, robust implicit energy and momentum conserving algorithms have been developed in the non-linear range. The authors extended these algorithms to hypoelasticity-based constitutive models and introduced numerical dissipation, opening the way to more complex simulations such as blade-loss in a turbofan. [less ▲]

Simulation of crashworthiness problems with improved contact algorithms for implicit time integration

in International Journal of Impact Engineering (2006), 32(5), 799-825

When studying crashworthiness problems, contact simulation can be the source of a number of problems. A first one is the discontinuities in the normal evolution for a boundary discretized by finite ... [more ▼]

When studying crashworthiness problems, contact simulation can be the source of a number of problems. A first one is the discontinuities in the normal evolution for a boundary discretized by finite elements. Another problem is the treatment of the contact forces that can introduce numerical energy in the system. In this paper, we propose to combine a method of discontinuity smoothing with the energy-momentum consistent scheme that recently appeared in the literature. (c) 2005 Elsevier Ltd. All rights reserved. [less ▲]

Simulation of electronic sensing of biomolecules in translocation through a nanopore in a semiconductor membrane

in Iqbal, S. M.; Bashir, R. (Eds.) Nanopores: sensing and fundamental biological interactions (2010)

Simulation of first and second order scattering by rough surfaces with a sound ray formalism

in Journal of Sound & Vibration (2000), 229(1)

Simulation of glacial-interglacial atmospheric CO2 variations using a comprehensive Earth system model of intermediate complexity

Conference (2010, May 04)

The mechanisms of strong glacial-interglacial variations in the atmospheric CO2 concentration and the role of CO2 in driving glacial cycles still remain debatable. Here using the model of intermediate ... [more ▼]

The mechanisms of strong glacial-interglacial variations in the atmospheric CO2 concentration and the role of CO2 in driving glacial cycles still remain debatable. Here using the model of intermediate complexity CLIMBER-2 which includes all major components of the Earth system – atmosphere, ocean, land surface, ice sheets, terrestrial biota and weathering, aeolian dust and marine biogeochemistry – we performed simulation of the last glacial cycle using variations in the Earth’s orbital parameters as the only prescribed climatic forcing. The model simulates rather realistically temporal and spatial dynamics of the Northern Hemisphere glaciation and temporal dynamics of the atmospheric CO2 concentration. During the glacial inception, the model is able to simulate a decrease in the atmospheric CO2, despite of release of terrestrial biosphere carbon. The drop in CO2 concentration during the first part of the glacial cycle is between 20 and 40 ppmv. It is related primarily to the physical mechanisms – increase of the ocean solubility and relative volume and the age of the Antarctic bottom water masses. The latter is related to increased sea ice formation in the Southern Ocean and lowering of the surface salinity in the northern North Atlantic. During the second part of the glacial cycle, the atmospheric CO2 concentration decreases towards the level of 200 ppmv. A part of this drop is due an increase of biological productivity in the Southern Ocean which is directly related in the CLIMBER-2 model to increase of aeolian dust supply into the Southern Hemisphere via the iron fertilization mechanism. Significant part of the decreasing CO2 trend is also explained by increased weathering on land, especially on the exposed tropical shelves. A decrease in shallow water carbonate sedimentation and shift of CaCO3 sedimentation towards the deep ocean also plays important role in CO2 decrease. With the onset of the glacial termination, initial rise in the atmospheric CO2 concentration is explained by a weakening of the Atlantic thermohaline circulation due to increased freshwater input into the northern North Atlantic. The model is able to simulate the return of CO2 concentration to its interglacial value after termination of the glacial cycle but simulated CO2 concentration still lags considerably behind the ice core reconstructions. [less ▲]

Simulation of Human B-Lymphocyte Proliferation by Agm-1470, a Potent Inhibitor of Angiogenesis

in Journal of the National Cancer Institute (1995), 87(2), 136-9

Simulation of light ion collisions from Intra Nuclear Cascade (INCL-Fermi Breakup) relevant for medical irradiations and radioprotection

in Proceedings to the International Topical Meeting on Nuclear Research Applications and Utilization of Accelerators 2009 (2010)

Simulation of metal forming processes : Numerical aspects of contact and friction

Scientific conference (2003, January)

During this presentation, two numerical methods for managing contact in large stresses/strains problems are described: the Lagrange Multipliers method (available in Cast3M - FE code used in LaCaN) and the ... [more ▼]

During this presentation, two numerical methods for managing contact in large stresses/strains problems are described: the Lagrange Multipliers method (available in Cast3M - FE code used in LaCaN) and the penalty method (available in Metafor - FE code used at LTAS-MCT - University of Liège). Contact algorithms can be divided into three steps. The first one - the contact search - is purely geometric and answers the question: which nodes are currently in contact. Main problems and their solutions are discussed. The computation of the normal force is the second step. Non-penetration conditions are applied on the contact nodes. Finally, during the third step, a tangent force due to friction is applied when the nodes are sticking or sliding. Methods are compared in details in the case of metal forming processes. The penalty method seems to be more efficient when a large number of contact nodes are involved during the simulation. The system to be solved is smaller, the convergence is faster and curved analytical surfaces can be easily used for the tools. However, a good penalty coefficient can sometimes be hard to find. As a conclusion, numerical examples coming from Metafor are presented including skin-pass simulation, hydroforming of a tube and blade loss in a aeronautic engine. [less ▲]

Simulation of Particle Levitation due to Dielectrophoresis

in EuroSimE 2010 (2010)

The aim of the research is to model accurately dielectrophoresis using different numerical tools and compare them to experimental results. The dielectrophoresis phenomenon consists in the creation of ... [more ▼]

The aim of the research is to model accurately dielectrophoresis using different numerical tools and compare them to experimental results. The dielectrophoresis phenomenon consists in the creation of electrostatic forces on nano or micro particles due to a gradient of electric field. The aim of such a setup is to control the motion of micro or nano particles for MEMS applications, for instance, for bioanalysis devices. To validate the numerical results, some prototypes have been fabricated at TU Delft. Using these simulations, a design of microstructure has been chosen to levitate Silica micro-particles. Experimental measurements have been performed and some characteristic behaviours of particle depending on the amplitude and the frequency of the applied voltage have been identified. The measurements are compared to the numerical simulation. [less ▲]

SIMULATION OF PHASE-EQUILIBRIA IN THE CO2-N2 SYSTEM - APPLICATION TO FLUID INCLUSIONS

in Bulletin de Minéralogie (1988), 111(2), 179-182