Génie physique | EPFL Graph Search

Le génie physique désigne l'application de la physique à l'industrie. Il a pour but l'adaptation de découvertes de la physique à des applications concrètes pour l'industrie, considérant les facteurs économiques. Les ingénieurs physiciens apportent des solutions pratiques à des problèmes divers, souvent complexes et inusités, requérant une connaissance approfondie de la physique. Bien que l'ingénieur physicien soit parfaitement adapté pour le travail en industrie, il peut très bien travailler dans le domaine de la recherche fondamentale ou de la physique théorique. Effectivement, le programme de génie physique offre une base solide dans le domaine de la physique pure. Domaines d'application L'ingénieur physicien est capable de mobiliser des phénomènes physiques ou des matériaux innovants issus de la recherche De nombreuses applications industrielles ont pu bénéficier de développements récents de l'optique (fibres optiques, lasers), de la physique de la matière condensée

Étude des engrenages de microtechnique

Quentin Theurillat-Bonjour

The research presented in this thesis addresses the design of gear drives for micro engineering applications, and was performed in collaboration with a watch manufacturer. Gears have long been found in many fields of mechanical engineering. Their use in watches satisfy specific constraints: small dimensions, little or no lubrication and unusual performance specifications. A literature review allows us to establish a catalogue of existing gear profiles, and a synthesis of profile analysis and generation methods. On the basis of this assessment, we define knowledge gaps which we propose to bridge in the present work by reaching the following objectives: 1. Characterize the behavior of existing gear profiles used in the watchmaking industry (nominal profiles, but also profiles affected by shape errors and axes misalignment errors); determine their kinematic and static performances, and their transmission efficiency. Use these results to compare various profiles on an objective and rigorous basis. 2. Formulate the equations necessary to calculate the tooth profiles using conjugate conditions differing from the tradition-al kinematic conditions ( i.e. imposing the transmission ratio) 3. Work out a design methodology for gear profiles relying on the results obtained while working on the first two objectives To reach those objectives, we develop a computer code allowing us to evaluate the performances of the profiles. The diversity of existing profiles led us to formulate a generic geometrical representation applicable to all profiles, while allowing us to use the same analysis code. The developed tool is then validated by simulating profiles, the behavior of which is known analytically. To calculate conjugate tooth profiles respecting a static criterion, we use the classical theory again, adding a new equation to it, which we derive from a balance of power. We present this equation for the three dimensional case, and the planar case. The resolution method for this equation, valid for static conjugated cams (i.e. a unique pair of teeth), must satisfy a supplementary condition that ensures that the imposed torque ratio leads to an average kinematic ratio compatible with the desired number of teeth. A numerical method was developed for the planar gears case that establishes the range of torque ratios satisfying the imposed average transmission ratio. The lower and upper bounds of the range of solutions are defined in terms of geometric and efficiency considerations, respectively. The proposed approach is illustrated and validated by some profiles computations. In parallel to those theoretical developments, we designed and built a test bench to characterize experimentally the performances of gear profiles, (altered or not by various shape or misalignment errors) under operating conditions similar to those prevailing in a watch. The last part of the thesis provides a critical discussion of these developments places them in a broader context and comments how they could be generalized in future research works.

EPFL2016

3D Printed Acoustically Programmable Soft Microactuators

Amit Yedidia Dolev, Murat Kaynak, Mahmut Selman Sakar

The concept of creating all-mechanical soft microrobotic systems has great potential to address outstanding challenges in biomedical applications, and introduce more sustainable and multifunctional products. To this end, magnetic fields and light have been extensively studied as potential energy sources. On the other hand, coupling the response of materials to pressure waves has been overlooked despite the abundant use of acoustics in nature and engineering solutions. In this study, we show that programmed commands can be contained on 3D nanoprinted polymer systems with the introduction of selectively excited air bubbles and rationally designed compliant mechanisms. A repertoire of micromechanical systems is engineered using experimentally validated computational models that consider the effects of primary and secondary pressure fields on entrapped air bubbles and the surrounding fluid. Coupling the dynamics of bubble oscillators reveals rich acoustofluidic interactions that can be programmed in space and time. We prescribe kinematics by harnessing the forces generated through these interactions to deform structural elements, which can be remotely reconfigured on demand with the incorporation of mechanical switches. These basic actuation and analog control modules will serve as the building blocks for the development of a novel class of micromechanical systems powered and programmed by acoustic signals.

2022

Multiscale methods for wave problems in heterogenous media

Assyr Abdulle, Patrick Henning

In this paper we give a survey on various multiscale methods for the numerical solution of second order hyperbolic equations in highly heterogenous media. We concentrate on the wave equation and distinguish between two classes of applications. First we discuss numerical methods for the wave equation in heterogeneous media without scale separation. Such a setting is for instance encountered in the geosciences, where natural structures often exhibit a continuum of different scales, that all need to be resolved numerically to get meaningful approximations. Approaches tailored for these settings typically involve the construction of generalized finite element spaces, where the basis functions incorporate information about the data variations. In the second part of the paper, we discuss numerical methods for the case of structured media with scale separation. This setting is for instance encountered in engineering sciences, where materials are often artificially designed. If this is the case, the structure and the scale separation can be explicitly exploited to compute appropriate homogenized/upscaled wave models that only exhibit a single coarse scale and that can be hence solved at significantly reduced computational costs.

2017

Étude des engrenages de microtechnique

Quentin Theurillat-Bonjour

EPFL2016