Publications de Simon Nessim Henein

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This paper presents innovative mechanisms capable of advantageously providing attitude control for spacecrafts. These new mechanisms, which we have named exure wheels, are the dynamic equivalent of a rotating wheel and can be entirely implemented with exures. A reaction wheel is a well known device for controlling the orientation of spacecrafts [5]. It consists in a motorised y-wheel which is placed within the spacecraft. To set the wheel into angular rotation, a torque is applied to the wheel which in resp

The size-dependent static deflection, pull-in instability and resonant frequency of a circular microplate under capillary force have been studied using modified couple stress elasticity theory. SiZe-dependency is a phenomenon in which the normalized quanti ...

Residual stresses can be advantageously used to permanently preload flexure micro-mechanisms in order to modify their deflection and stiffness. This paper presents a new preloading chevron mechanism (PCM) used to amplify the preloading effect of thin film ...

Mechanical watches are generally regulated by a balance and a spring constituting a harmonic oscillator. This mechanism is intrinsically force-balanced, which makes it essentially insensitive to gravity as well as to the linear accelerations of the watch. ...

The balancing of mechanisms consists in distributing their moving masses, inertias, and elastic components in order to achieve key mechanical properties, such as the elimination of the shaking forces and moments exported onto their supporting structure or ...

The recent adoption of silicon components by the mechanical watch industry has triggered the search for new time bases to advantageously replace the traditional balance and hairspring oscillator. In particular, flexure-based oscillators manufactured in sil ...

Oscillator system (1) comprising:- a substantially planar frame (3);- a first sub-oscillator (5), a second sub-oscillator (7), a third sub-oscillator (9), and a fourth sub-oscillator (11), each sub-oscillator (5, 7, 9, 11) comprising a substantially rigid ...

Statistical shape and appearance models play an important role in reducing the segmentation processing time of a vertebra and in improving results for 3D model development. Here, we describe the different steps in generating a statistical shape model (SSM) ...

Flexure oscillators are promising time bases thanks to their high quality factor and monolithic design compatible with microfabrication. In mechanical watchmaking, they could advantageously replace the traditional balance and hairspring oscillator, leading ...

Flexure-based mechanisms have become state-of-the-art solutions for the design of high-precision mechanisms, free from friction wear, backlash, and lubrication. These properties which are necessary for applications in ultraclean or harsh environments, neve ...

Four-bar linkages can transmit angular motion between two rigid links, but their transmission ratio is generally not constant due to kinematic nonlinearities. When such linkages are implemented with flexures – replacing joints with elastic elements to eliminate friction, backlash, and wear – additional parasitic motions are introduced. This article demonstrates that nonlinearities arising from both rigid-body kinematics and flexure deformations can be harnessed to compensate for one another, leading to opti

Programmable multistable mechanisms exhibit stability behavior whereby the stiffness and the number of stable states can be controlled via programming inputs. In this paper, we report the zero stiffness behavior of a 2-degree of programming (DOP) T-combine ...

In 1851 Léon Foucault created a sensation with his pendulum providing a direct demonstration of the turning of the Earth. This simple device consists of a pendulum which is launched in a purely planar orbit. Following Mach's principle of inertia, the mass ...

A first aspect of the invention relates to a force sensor assembly (1) comprising:- a support (3) adapted to be attached to a frame (5);- a force sensor (9) attached at a proximal end to said support (3) and adapted to deform in response to a force along a measurement axis (2);- an end effector (11) attached at a distal end of said force sensor (9) and adapted to come into contact with a test piece, said end effector (11) having a mass (m);- a compensating system (13) comprising a counterweight (15) having

Classical mechanical watch plain bearing pivots have frictional losses limiting the quality factor of the hairspring-balance wheel oscillator. Replacement by flexure pivots leads to a drastic reduction in friction and an order of magnitude increase in qual ...

Synchrotron‐based X‐ray Tomographic Microscopy (SRXTM) is nowadays a powerful technique for non‐destructive, high‐resolution investigations of a broad kind of materials. High‐brilliance and high‐coherence third generation synchrotron radiation facilities a ...

Perfect elasticity is not achievable in real-life situation, so spring stiffness is not perfectly constant. In this paper, we study the effect of modifying non-linear stiffness terms while keeping the nominal stiffness constant. We introduce three methods ...

Flexure mechanism design is an art, and this book provides the theoretical and practical foundation for scientists and engineers to express their creativity in this field. Flexure mechanisms, also known as compliant mechanisms, rely on the elasticity of matter to provide motion to mechanism linkages. Flexure mechanisms eliminate the disadvantages of classical joints: friction, wear, lubrication and play, while permitting monolithic design. Flexure-based mechanisms have gained prominence in a wide variety of

Classical pivots have frictional losses leading to the limited quality factor of oscillators used as time bases in mechanical watches. Flexure pivots address these issues by greatly reducing friction. However, they have drawbacks such as gravity sensitivity and limited angular stroke. This paper analyses these problems for the cross-spring flexure pivot and presents an improved version addressing these issues. We first show that the cross spring pivot cannot be both insensitive to gravity and have a long st

Buckled beams have become key building blocks in compliant mechanisms to achieve nonlinear behaviors, such as bistability, constant-force and stiffness tuning. However, designing and modeling such components is challenging due to their highly nonlinear cha ...

Simon Nessim Henein

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Flexure wheels for spacecraft attitude control

Investigating The Size-Dependent Static And Dynamic Behavior Of Circular Micro-Plates Subjected To Capillary Force

Residual stress chevron preloading amplifier for large-stroke stiffness reduction of silicon flexure mechanisms

Dynamic balancing of a flexure-based Watt's linkage horological oscillator

Mechanism balancing taxonomy

Optical measurement method for mechanical time base characterization

Two degree of freedom oscillator system

A statistical shape model of the human second cervical vertebra

Design of a Flexure Rotational Time Base with Varying Inertia

Damping of flexure blades based on bi-material additive manufacturing

Optimized design of generalized flexure rotational couplers

Programmable Constant-Force Multistable Mechanisms

Foucault pendulum properties of spherical oscillators

Force and torque sensor assemblies

Gravity-Insensitive Flexure Pivot Oscillators

TOMCAT: A beamline for TOmographic Microscopy and Coherent rAdiology experimenTs

Tuning stiffness nonlinearty: theory and applications

The Art of Flexure Mechanism Design

Gravity insensitive flexure pivots for watch oscillators

Analytical modeling and experimental validation of rotationally actuated pinned–pinned and fixed–pinned buckled beam bistable mechanisms