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Lecture

Thermal Effects: Hyperstatic Systems

In course

MICRO-200: Mechanism Design I

Ce cours introduit les bases de la mécanique des structures : calcul des contraintes et déformations provoquées par les forces extérieures et calcul des déformations. Ces enseignements théoriques sont appliqués à la conception des éléments importants des m ...

Description

This lecture covers the resolution of hyperstatic systems with temperature variation, the effect of temperature on stress and strain in materials, and the concept of hyperstatic problems. It explains how materials expand with temperature, the coefficient of thermal expansion, and the generation of thermal effects. The lecture also discusses relative thermal strain, internal forces due to geometric constraints, and the impact of temperature on structures with different supports. Additionally, it explores indeterminate systems, redundant forces, equilibrium equations, and the compatibility equation in hyperstatic structures.

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Instructors (4)

Born in 1973 and of Egyptian-Swiss nationality, Simon Henein grew up in Cairo. He obtained an engineering degree at the Ecole Polytechnique Fédérale de Lausanne (EPFL) in 1996 and went on to complete his doctorate at the EPFL in 2000. In 2001, he published the book “Conception des guidages flexibles” which has become a reference in precision engineering. He then joined the Centre Suisse d’Electronique et Microtechnique (CSEM), Neuchatel, Switzerland, where he conceived and developed mechanisms for robotic, aerospace, medical and watchmaking applications. He pursued his research career at the Paul Scherrer Institute, Villigen, Switzerland, where he developed instruments for the Swiss Light Source Synchrotron (SLS). Since November 1st, 2012, he is associate professor in microengineering at the EPFL, holder of the Patek Philippe Chair and director of the Micromechanical and horological design laboratory (Instant-Lab).

Danick Briand

Official source

Related concepts (13)

Ring strain

In organic chemistry, ring strain is a type of instability that exists when bonds in a molecule form angles that are abnormal. Strain is most commonly discussed for small rings such as cyclopropanes and cyclobutanes, whose internal angles are substantially smaller than the idealized value of approximately 109°. Because of their high strain, the heat of combustion for these small rings is elevated. Ring strain results from a combination of angle strain, conformational strain or Pitzer strain (torsional eclipsing interactions), and transannular strain, also known as van der Waals strain or Prelog strain.

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.

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.

Finite strain theory

In continuum mechanics, the finite strain theory—also called large strain theory, or large deformation theory—deals with deformations in which strains and/or rotations are large enough to invalidate assumptions inherent in infinitesimal strain theory. In this case, the undeformed and deformed configurations of the continuum are significantly different, requiring a clear distinction between them. This is commonly the case with elastomers, plastically-deforming materials and other fluids and biological soft tissue.

Chemical equilibrium

In a chemical reaction, chemical equilibrium is the state in which both the reactants and products are present in concentrations which have no further tendency to change with time, so that there is no observable change in the properties of the system. This state results when the forward reaction proceeds at the same rate as the reverse reaction. The reaction rates of the forward and backward reactions are generally not zero, but they are equal. Thus, there are no net changes in the concentrations of the reactants and products.

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