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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)Integrated dynamical models of down-the-hole percussive drilling Depouhon, Alexandre Doctoral thesis (2014) Due to the overall process complexity, studies about percussive drilling usually focus on a limited set of the subprocesses underlying it, e.g., the hammer thermodynamics or the interaction between the ... [more ▼] Due to the overall process complexity, studies about percussive drilling usually focus on a limited set of the subprocesses underlying it, e.g., the hammer thermodynamics or the interaction between the bit and the rock. Following this paradigm, the assessment of the process performance is typically performed by considering a single percussive activation and a single interaction cycle between the bit and the rock, from arbitrary initial conditions. The need for an integrated approach to evaluate drilling performance, based on the dynamical interaction of the subprocesses underlying drilling, is evident. Such an approach requires simplified models, however, as the computational cost associated with full scale models is simply unbearable. In this thesis, three dynamical integrated models are proposed and a preliminary analysis is conducted for a reference configuration and around it. The models couple three modules that represent: (i) the dynamics of the mechanical system, (ii) the interaction between the bit and the rock, and (iii) the activation of the mechanical system. For each module, simple representations are considered; of particular importance is the bit/rock interaction model which is a generalization to repeated interactions of experimental evidence observed for a single interaction. In the first model, the dynamics of a rigid bit is cast into a drifting oscillator and the activation modeled as a periodic impulsive force. The second and third models account for the dynamics of the piston and the activation results from the impact of the piston on the bit. They are respectively based on elastic and rigid representations of the two bodies. In the rigid model, analytical results of wave propagation in thin rods are used to represent the contact interaction between the piston and the bit. In the elastic model, wave propagation is resolved. Their preliminary analysis has revealed the occurrence of complex dynamical responses in the space of parameters. Expected trends are recovered around a reference configuration corresponding to a low-size hammer, with an increase of the rate of penetration with the feed force and the percussive frequency. The latter is seen to have a strong influence on the rate of penetration. Interestingly, our analyses show that when the activation period has the same order of magnitude as the timescale associated with the bit/rock interaction, a lower power consumption is observed, indicating a possible resonance phenomenon in the drilling system. Also, the predictions of the rigid model are shown to be in good agreement with the ones of the elastic model, in the explored range of parameters. Given the piecewise linear nature of the proposed models, dedicated numerical tools have been developed to conduct their analysis. As such, the thesis proposes a high-order time integration scheme for structural dynamics as well as a novel framework to evaluate the accuracy of such schemes, and a root-solving module to perform event-detection for coupling with event-driven integration strategies. Specific to the framework is the account for both structural damping and external forcing in the evaluation of the scheme order of accuracy. Specific to the root-solving module is the forcing of event occurrence in the localization procedure. [less ▲] Detailed reference viewed: 250 (16 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: 42 (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)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: 25 (2 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)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)Apparent Coexistence of Multiple Regimes of Self-Excited Vibrations in Drilling Systems Depouhon, Alexandre ; in Proceedings of the 1st International Colloquium on Non-Linear Dynamics and Control of Deep Drilling Systems, Liège, March 2009 (2009, March) Detailed reference viewed: 26 (5 ULg)Digimat Material eXpert – From the Material Lab to the Efficient and Optimal Design of Reinforced Plastic Parts Depouhon, Alexandre ; ; in Proceedings of EnginSoft International Conference 2009, CAE Technologies for Industry (2009) Detailed reference viewed: 60 (7 ULg)Multi-Scale Modeling of Crash & Failure of Reinforced Plastics Parts with Digimat to LS-DYNA interface ; Depouhon, Alexandre ; in Proceedings of the 7th European LS-DYNA Conference (2009) Detailed reference viewed: 41 (5 ULg)Predictive Design of Honeycomb Sandwich Panels ; Depouhon, Alexandre ; in Proceedings of Sampe Benelux professional meetings (2008, November) Detailed reference viewed: 19 (2 ULg)Apparent Coexistence of Multiple Regimes of Self-Excited Vibrations in Deep Drilling Systems Depouhon, Alexandre ; in Proceedings of ICTAM 2008, Adelaide (2008) Detailed reference viewed: 22 (6 ULg)Stability of TAZ apparatus: a drilling equivalent Depouhon, Alexandre Master's dissertation (2007) Detailed reference viewed: 18 (3 ULg)Optimal Control Strategies for a Ducted RUAV Hendrick, Patrick ; Depouhon, Alexandre ; in Proceedings of Platform Innovations and System Integration for Unmanned Air, Land and Sea Vehicles (AVT-SCI Joint Symposium) (2007) Detailed reference viewed: 8 (2 ULg)Modélisation et contrôle d'un mini-drone de type rotor caréné Depouhon, Alexandre Master's dissertation (2006) Detailed reference viewed: 68 (3 ULg) |
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