Lecture

Force Detection: Nonlinear Effects and Composite Beams

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In course

ME-426: Micro/Nanomechanical devices

In this course we will see an overview of the exciting field of Micro and Nanomechanical systems. We will go over the dfferent scaling laws that dominate the critical parameters, how size affects material properties, how these devices are manufactured, de ...

Description

This lecture covers force detection in beams, discussing nonlinear effects when the force-displacement ratio varies, built-in tension causing stress in beams, and the concept of neutral axis in composite beams. It also explains normal strain and stress, bending moments, and design examples.

Instructor

Luis Guillermo Villanueva Torrijo

Guillermo Villanueva is a Tenure Track Assistant Professor at the Ecole Polytechnique Federale de Lausane (EPFL), Switzerland, in the Mechanical Engineering Institute (IGM). Before joining EPFL he was a Marie Curie post-doctoral scholar at DTU (Denmark) and Caltech (California, US); and before a post-doc at EPFL-LMIS1. He received his M.Sc. in Physics in Zaragoza (Spain) and his PhD from the UAB in Barcelona (Spain). Since the start of his PhD (2002), Prof. Villanueva has been active in the fields of NEMS/MEMS for sensing, having expertise from the design and fabrication to the characterization and applicability. He has co-authored more than 75 papers in peer-reviewed journals (h-index of 24 WoK, 32 GoS) and more than 100 contributions to international conferences. He is serving, or has served, on the program committees of IEEE-NEMS, IEEE-Sensors, MNE, IEEE-FCS and Transducers. He is editor of Microelectronic Engineering. He has co-organized MNE2014 and SNC2015; and he is currently co-organizing the short courses at Transducers 2019 and the 16th International Workshop on Nanomechanical Sensors (NMC2019).

Official source

Related concepts (31)

I-beam

I-beam is a generic lay term for a variety of structural members with an or -shaped cross-section. Technical terms for similar items include H-beam (for universal column, UC), w-beam (for "wide flange"), universal beam (UB), rolled steel joist (RSJ), or double-T (especially in Polish, Bulgarian, Spanish, Italian and German). I-beams are typically made of structural steel and serve a wide variety of construction uses. The horizontal elements of the are called flanges, and the vertical element is known as the "web".

Bending

In applied mechanics, bending (also known as flexure) characterizes the behavior of a slender structural element subjected to an external load applied perpendicularly to a longitudinal axis of the element. The structural element is assumed to be such that at least one of its dimensions is a small fraction, typically 1/10 or less, of the other two. When the length is considerably longer than the width and the thickness, the element is called a beam.

Bending moment

In solid mechanics, a bending moment is the reaction induced in a structural element when an external force or moment is applied to the element, causing the element to bend. The most common or simplest structural element subjected to bending moments is the beam. The diagram shows a beam which is simply supported (free to rotate and therefore lacking bending moments) at both ends; the ends can only react to the shear loads. Other beams can have both ends fixed (known as encastre beam); therefore each end support has both bending moments and shear reaction loads.

Stress–strain curve

In engineering and materials science, a stress–strain curve for a material gives the relationship between stress and strain. It is obtained by gradually applying load to a test coupon and measuring the deformation, from which the stress and strain can be determined (see tensile testing). These curves reveal many of the properties of a material, such as the Young's modulus, the yield strength and the ultimate tensile strength. Generally speaking, curves representing the relationship between stress and strain in any form of deformation can be regarded as stress–strain curves.

Infinitesimal strain theory

In continuum mechanics, the infinitesimal strain theory is a mathematical approach to the description of the deformation of a solid body in which the displacements of the material particles are assumed to be much smaller (indeed, infinitesimally smaller) than any relevant dimension of the body; so that its geometry and the constitutive properties of the material (such as density and stiffness) at each point of space can be assumed to be unchanged by the deformation.

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Introduces internal stress and strain, material properties, and design considerations for axial loads and direct shear.

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Explores moment of inertia in bending beams and stress analysis for beam sections.

Circular Torsion & Bending Beams

Covers stress analysis in circular torsion and bending of straight beams.

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Explores quadratic moment, relative strains in beams, and pure flexion, focusing on neutral axis, curvature, and normal stresses.

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