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Surface Constrained Elastic Rods with Application to the Sphere Huynen, Alexandre ; ; Denoël, Vincent in Journal of Elasticity (2016) The unilateral contact between an elastic rod and a rigid surface is encountered in numerous biological and engineering applications. Along continuous contacts, the centerline of the rod reflects the ... [more ▼] The unilateral contact between an elastic rod and a rigid surface is encountered in numerous biological and engineering applications. Along continuous contacts, the centerline of the rod reflects the geometry of the constraining surface. This restriction of the rod axis to surface bound configurations enters its local equilibrium through a reaction pressure which ensures the compatibility between the deformation and the restraint geometry. The classic equations governing the static equilibrium of elastic rods are particularized to surface bound configurations by (i) specifying the location of the rod axis in terms of its coordinates in the parameter space associated with the constraining surface parameterization, and (ii) characterizing the orientation of its material frame through its rotation with respect to the surface normal. This formulation, which emphasizes the relations between the rod configuration and the geometry of the constraint, also leads to an expression for the reaction pressure. This approach is then validated on a spherical surface by comparing with known solutions for elastic curves, i.e., inextensible and twist free rods. [less ▲] Detailed reference viewed: 44 (9 ULg)DE3: Yet another high-order integration scheme for linear structural dynamics ; ; Denoël, Vincent in Proceedings of the 5th ECCOMAS Thematic Conference on Computational Methods in Structural Dynamics and Earthquake Engineering. (2015) Detailed reference viewed: 11 (3 ULg)Numerical simulation of percussive drilling ; Denoël, Vincent ; in International Journal for Numerical and Analytical Methods in Geomechanics (2015), 39(8), 889-912 This paper presents a novel dynamical model to analyze the long-term response of a percussive drilling system. This departs from existing approaches that usually consider a single activation and bit/rock ... [more ▼] This paper presents a novel dynamical model to analyze the long-term response of a percussive drilling system. This departs from existing approaches that usually consider a single activation and bit/rock interaction cycle for the analysis of the process performance. The proposed model integrates the axial dynamics of an elastic piston and an elastic drill bit, a motion-dependent pressure law to drive the piston, and a generalized bit/rock interaction law representative of the dynamic indentation taking place at the bit/rock interface. It applies to down-the-hole percussive drilling as well as top-hole, with minor modifications. The model does not account for the angular motion or the hole cleaning, however. The model is first formulated mathematically; then, a finite-dimensional approximation is proposed for computations. Numerical analyses of the model response, for a low-size down-the-hole percussive system, follow. The period-1 stationary response for the reference configuration is studied in detail, and parametric analyses assessing the influence on the rate of penetration of the bit/rock interaction parameters, the feed force, and the percussive activation parameters are conducted. These analyses reveal that the multiscale nature of the process is well captured by the model and recover expected trends for the influence of the parameters. They also suggest that a significant increase of the penetration rate can be achieved by increasing the percussive frequency. Copyright © 2015 John Wiley & Sons, Ltd [less ▲] Detailed reference viewed: 13 (2 ULg)A Remark on the Poroelastic Center of Dilation Huynen, Alexandre ; in Journal of Elasticity (2014), 116(2), 189-206 In the original derivation due to Dougall (1897), the center of dilation is constructed from the superposition of orthogonal force dipoles. However, it can also be built by combining dislocation dipoles ... [more ▼] In the original derivation due to Dougall (1897), the center of dilation is constructed from the superposition of orthogonal force dipoles. However, it can also be built by combining dislocation dipoles. While the two representations are equivalent in elasticity, the different nature of the force and dislocation dipoles leads to different transient behaviors in poroelasticity, when the response evolves from undrained to drained. Indeed, we show that the poroelastic solution of a center of dilation is obtained by superposing the corresponding elastic solution and either an instantaneous fluid sink or an instantaneous fluid source, depending on whether the center of dilation is treated as a singular stress or displacement discontinuity. A simple explanation to the instantaneous injection or withdrawal of a finite volume of fluid from/to the singularity is given by adopting an exploded view of the poroelastic center of dilation. The exploration of the drained, undrained and transient responses of this singularity also requires to clarify the close relationship between an instantaneous fluid source and a continuous fluid dodecapole, an object constructed by collapsing onto a point three orthogonal pairs of fluid dipoles. [less ▲] Detailed reference viewed: 38 (19 ULg)Aspects of non-smooth dynamics in models of percussion ; ; Denoël, Vincent in Proceedings of the 8th European Nonlinear Dynamics Conference (2014, July 08) Detailed reference viewed: 11 (0 ULg)Event-driven integration of linear structural dynamics models under unilateral elastic constraints Depouhon, Alexandre ; ; Denoël, Vincent in Computer Methods in Applied Mechanics & Engineering (2014), 276 This paper proposes an algorithm for the numerical simulation of linear structural dynamics problems under unilateral elastic constraints, i.e., constraints with a linear force/displacement characteristic ... [more ▼] This paper proposes an algorithm for the numerical simulation of linear structural dynamics problems under unilateral elastic constraints, i.e., constraints with a linear force/displacement characteristic whenever active. The presented procedure relies on an event-driven strategy for the handling of the contact constraints, in combination with one-step schemes dedicated to the time integration of the second-order equations of motion. Efficiency of the procedure follows from the use of cubic Hermite interpolation to continuously extend the normal gap functions that reflect the openings of the contact interfaces. Robustness follows from the proper handling of complex numerical situations, e.g., numerical grazing or discontinuity sticking, through appropriate algorithm structure and numerical implementation. And, integration stability is guaranteed by the very nature of the algorithm and that of the one-step integration scheme. Following a detailed coverage of the integration procedure and the countermeasures to the expected numerical difficulties, three application examples are treated for illustration purposes. A MATLAB implementation of the procedure is provided online; download and usage information are given in the Appendix. [less ▲] Detailed reference viewed: 89 (24 ULg)Eulerian Formulation of the Torque and Drag Problem Huynen, Alexandre ; ; Denoël, Vincent in Detournay, Emmanuel; Denoël, Vincent; van de Wouw, Nathan (Eds.) Third International Colloquium on Nonlinear Dynamics and Control of Deep Drilling Systems (2014, May) Detailed reference viewed: 52 (22 ULg)Multiscale aspects in modeling percussive drilling: from wave propagation to rigid body dynamics Depouhon, Alexandre ; Denoël, Vincent ; in Proceedings of the 3rd International Colloquium on Nonlinear Dynamics and Control of Deep Drilling Systems (2014) Detailed reference viewed: 40 (2 ULg)Accuracy of one-step integration schemes for damped/forced linear structural dynamics Depouhon, Alexandre ; ; Denoël, Vincent in International Journal for Numerical Methods in Engineering (2014) Detailed reference viewed: 27 (2 ULg)Nonlinear Dynamics and Control of Deep Drilling Systems ; Denoël, Vincent ; Book published by College of Science and Engineering (2014) Detailed reference viewed: 75 (2 ULg)An efficient formulation for the simulation of elastic wave propagation in 1-dimensional collinding bodies Depouhon, Alexandre ; ; Denoël, Vincent in Proceedings of the 11th International Conference on Vibration Problems (2013, September 09) Detailed reference viewed: 31 (4 ULg)A drifting impact oscillator with periodic impulsive loading: Application to percussive drilling Depouhon, Alexandre ; Denoël, Vincent ; in Physica D: Nonlinear Phenomena (2013), 258(0), 1--10 Detailed reference viewed: 23 (2 ULg)Eulerian Formulation for an Extensible Elastic Rod Huynen, Alexandre ; ; Denoël, Vincent in Proceedings of the Fifth International Conference on Structural Engineering, Mechanics and Computation (2013, September) This paper reformulates the governing equations of an extensible elastic rod by reference to a given spatial curve. This Eulerian formulation is motivated by the need to solve efficiently the constrained ... [more ▼] This paper reformulates the governing equations of an extensible elastic rod by reference to a given spatial curve. This Eulerian formulation is motivated by the need to solve efficiently the constrained elastica problem encountered in many medical and engineering applications, in which a thin rod is inserted in a tortuous conduit. The Eulerian reformulation of the equations hinges on the restatement of the rod local equilibrium in terms of derivatives with respect to the curvilinear coordinate associated with the reference curve and the description of the rod deflection as a perturbation of this curve. The originality of the proposed formulation lays in the axially unconstrained character of the resulting system such that the determination of the rod configuration between two fixed points reduces to the resolution of a classical boundary value problem. [less ▲] Detailed reference viewed: 102 (44 ULg)On a modified bilinear law to model bit/rock interaction in percussive drilling Depouhon, Alexandre ; Denoël, Vincent ; in Proceedings of the Nonlinear Dynamics in Engineering Conference (2013, August 21) Detailed reference viewed: 45 (2 ULg)Poroelastic Center of Dilation Revisited Huynen, Alexandre ; Conference given outside the academic context (2013) Detailed reference viewed: 5 (3 ULg)Poroelastic Center of Dilation Revisited Huynen, Alexandre ; in Hellmich, Christian; Pichler, Bernhard; Dietmar, Adam (Eds.) Poromechanics V: Proceedings of the Fifth Biot Conference on Poromechanics (2013, July) A comparison of the original elastic solution for the center of dilation with the classic Lame ́ solution reveals an unexpected dependence of the center of dilation solu- tion on Poisson’s ratio. This ... [more ▼] A comparison of the original elastic solution for the center of dilation with the classic Lame ́ solution reveals an unexpected dependence of the center of dilation solu- tion on Poisson’s ratio. This inconsistency is investigated by means of two alternative representations of the singularity which lead to the identification of a compressed zone inside the singularity. The poroelastic equivalent to this nucleus of strain is shown to be the superposition of the elastic one with drained material parameters and an instan- taneous point fluid source associated with a finite volume of fluid that is expelled from the compressed region inside the singularity and is injected in the porous medium. [less ▲] Detailed reference viewed: 23 (10 ULg)Instability regimes and self-excited vibrations in deep drilling systems Depouhon, Alexandre ; in Journal of Sound and Vibration (2013) Detailed reference viewed: 16 (3 ULg)Nonlinear Dynamics Of A Drill Bit Under Percussive Activation Depouhon, Alexandre ; Denoël, Vincent ; in Proceedings of ICTAM 2012, Beijing (2012, August) Detailed reference viewed: 59 (6 ULg)Limit cycling behavior of a hybrid system: Application to percussive drilling Depouhon, Alexandre ; ; Denoël, Vincent in Proceedings of the 2nd International Colloquium on Non-Linear Dynamics and Control of Deep Drilling Systems, Eindhoven, May 2012 (2012, May) Detailed reference viewed: 68 (18 ULg)Recent advances in the modeling of a drillstring inside a curved borehole Denoël, Vincent ; in Proceedings of the 3rd International Colloquim on Nonlinear Dynamics and Control of Deep Drilling Systems (2012) Detailed reference viewed: 11 (1 ULg) |
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