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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: 64 (7 ULg)Stochastic Modal Analysis of Structures with Random Shape Using X-FEM ; Van Miegroet, Laurent ; Duysinx, Pierre Conference (2008, July) Detailed reference viewed: 44 (2 ULg)Stochastic Finite Element Analysis of Thermoelastic Effects in Micro-Resonators ; Golinval, Jean-Claude Conference (2006, July 17) In the design of micro-electromechanical systems (MEMS) such as micro-resonators, dissipation mechanisms may have detrimental effects on the quality factor. One of the major dissipation phenomena to ... [more ▼] In the design of micro-electromechanical systems (MEMS) such as micro-resonators, dissipation mechanisms may have detrimental effects on the quality factor. One of the major dissipation phenomena to consider in such systems is thermoelastic damping. Hence, the performance of such MEMS is directly related to their thermoelastic quality factor which has to be predicted accurately. Moreover, the performance of MEMS can vary because manufacturing processes may leave substantial uncertainty in the geometry and in the material properties of the device. The reliability of MEMS devices is affected by the inability to accurately predict the stochastic behavior of the system due to the presence of these uncertainties. The aim of this paper is to provide a framework to account for uncertainties in the finite element analysis of the thermoelastic quality factor. The present work focuses on second moment approaches, in which the first two statistical moments, i.e. the mean and the variance, are estimated. The perturbation stochastic finite element method is used in order to determine the mean and the variance of the thermoelastic quality factor of MEMS. The perturbation SFEM [1] consists in a deterministic analysis complemented by a sensitivity analysis with respect to the random parameters. This enables the development of a Taylor series expansion of the response, from which the mean and variance of the response can be derived knowing the mean and variance of the random parameters. The perturbation SFEM is applied on the analysis of the thermoelastic quality factor of a micro-beam whose elastic modulus is considered as a random variable. Due to the nature of the thermoelastic problem, this study involves the calculation of eigenvalue sensitivities of a non-symmetric damped system [2]. The mean and variance of the quality factor are compared to the results obtained by Monte-Carlo simulations. References: [1] Kleiber, M., Hien, T.D., The stochastic finite element method: basic perturbation technique and computer implementation. Wiley & Sons, Chichester, 1992. [2] Choi, K.M., Jo, H.K., Kim, W.H., Lee, I.W., Sensitivity analysis of non-conservative eigensystems, Journal of Sound and Vibration, v. 274, p. 997-1011, 2004. [less ▲] Detailed reference viewed: 53 (3 ULg)Modeling and Uncertainty Quantification of Thermoelastic Damping in Micro-Resonators ; Golinval, Jean-Claude Conference given outside the academic context (2006) In the design of micro-electromechanical systems (MEMS) such as micro-resonators, dissipation mechanisms may have detrimental effects on the quality factor, which is directly related to the response ... [more ▼] In the design of micro-electromechanical systems (MEMS) such as micro-resonators, dissipation mechanisms may have detrimental effects on the quality factor, which is directly related to the response amplitude of the system that is excited at its natural frequency. One of the major dissipation phenomena to be considered in such micro-systems is thermoelastic damping. Hence, the performance of such MEMS is directly related to their thermoelastic quality factor which has to be predicted accurately. Moreover, the performance of MEMS depends on manufacturing processes which may cause substantial uncertainty in the geometry and in the material properties of the device. The reliability of MEMS devices is affected by the inability to accurately predict the behavior of the system due to the presence of these uncertainties. The aim of this paper is to provide a framework to account for uncertainties in the finite element analysis. Particularly, the influence of uncertainties on the performance of a micro-beam is studied using Monte- Carlo simulations. A random field approach is used to characterize the variation of the material as well as the geometric properties. Their effects on the thermoelastic quality factor of a micro-beam are studied. [less ▲] Detailed reference viewed: 61 (2 ULg)THERMOELASTIC DAMPING IN VIBRATING BEAM ACCELEROMETER: A NEW THERMOELASTIC FINITE ELEMENT APPROACH ; ; et al Conference given outside the academic context (2006) In order to respond to the demand of accurate miniature inertial navigation systems, ONERA has been working on the design of a vibrating beam accelerometer called the Vibrating Inertial Accelerometer (VIA ... [more ▼] In order to respond to the demand of accurate miniature inertial navigation systems, ONERA has been working on the design of a vibrating beam accelerometer called the Vibrating Inertial Accelerometer (VIA). The accuracy of the VIA is directly related to the thermoelastic quality factor of its sensitive element, which is a beam made of quartz. In this work, thermopiezoelectric finite element analyses of the beam are carried out in order to determine the thermoelastic quality factor. These finite element results are compared to the analytical and experimental quality factors. Due to their inherent restrictive assumptions, analytical models overestimate the quality factor while the finite element results are in good agreement with the experimental values. As the finite element model allows to take into account the real geometry of the beam and the piezoelectricity of the material, it allows to quantify more precisely the thermoelastic quality factor. [less ▲] Detailed reference viewed: 119 (2 ULg)Modélisation par éléments finis du couplage thermo-élastique dans les structures vibrantes ; Golinval, Jean-Claude Conference given outside the academic context (2005) Micro-accelerometers and micro-gyrometers are being developed in order to respond to the demand of accurate miniature inertial navigation systems. In the design of such accurate systems, which require a ... [more ▼] Micro-accelerometers and micro-gyrometers are being developed in order to respond to the demand of accurate miniature inertial navigation systems. In the design of such accurate systems, which require a high quality factor, the dissipation mechanisms such as the thermoelastic damping have to be considered. In order to assess the thermoelastic influence on the behavior of vibrating structures, analytical models may be used for simple configurations under very restrictive assumptions. In order to investigate more complex structures, the finite element method may be used. An oscillating clamped-clamped beam is modelled using thermoelastic finite elements. The analytical and finite element analyses show that the thermoelastic coupling implies a natural frequency shift, an amplitude attenuation, a difference of phase between the thermal and mechanical degrees of freedom and influences the quality factor of the resonating system. [less ▲] Detailed reference viewed: 80 (4 ULg)F.E. modelling of electro-mechanical and thermo-elastic couplings in micro-system ; ; Rochus, Véronique et al Scientific conference (2004) Detailed reference viewed: 20 (2 ULg) |
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