Lecture

Relaxation in Traction: Deformation and Hardening

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In course

ME-212: Mechanical Design I: Manufacturing Processes

Application des principales catégories de procédés de production. Modèles physiques élémentaires décrivant le comportement des principaux procédés de production. Compréhension de base des aspects économiques des procédés de production. Méthodologie de ...

Description

This lecture covers the concept of relaxation in traction, where the force returns to zero, leading to permanent deformation. It discusses the real tensile curve, relaxation rate, and the method to calculate strain rate in relaxation. The lecture also explores the anticipation of elastic rebound, calculation of strain, and the transfer equation for work-hardened parts. It delves into the hardening process, work hardening law, and the behavior of hardened parts. Additionally, it explains the relationship between strain rate and hardening, the ultimate tensile stress, and the implications of the transfer equation.

Instructor

Eric Boillat

Contact Microcity Phone: 41 21 69 54456 Teaching & PhD Past EPFL PhD Students as codirector Serguei Kolossov, Cédric André, Jamasp Jhabvala, Christoph Van Gestel, Tatiana Polivnikova, Nikola Kalentics Courses Industrial production processes ME-212 Application windows of the main manufacturing process categories. Implementation of simple models describing the behavior of the main manufacturing processes. Basic understanding of the economic aspects of production processes. Manufacturing proc

Official source

Ontological neighbourhood

Chemical engineering

Materials science: Deformation of materials

Related concepts (32)

Ultimate tensile strength

Ultimate tensile strength (also called UTS, tensile strength, TS, ultimate strength or in notation) is the maximum stress that a material can withstand while being stretched or pulled before breaking. In brittle materials the ultimate tensile strength is close to the yield point, whereas in ductile materials the ultimate tensile strength can be higher. The ultimate tensile strength is usually found by performing a tensile test and recording the engineering stress versus strain.

Tensile testing

Tensile testing, also known as tension testing, is a fundamental materials science and engineering test in which a sample is subjected to a controlled tension until failure. Properties that are directly measured via a tensile test are ultimate tensile strength, breaking strength, maximum elongation and reduction in area. From these measurements the following properties can also be determined: Young's modulus, Poisson's ratio, yield strength, and strain-hardening characteristics.

Work hardening

In materials science, work hardening, also known as strain hardening, is the strengthening of a metal or polymer by plastic deformation. Work hardening may be desirable, undesirable, or inconsequential, depending on the context. This strengthening occurs because of dislocation movements and dislocation generation within the crystal structure of the material. Many non-brittle metals with a reasonably high melting point as well as several polymers can be strengthened in this fashion.

Yield (engineering)

In materials science and engineering, the yield point is the point on a stress-strain curve that indicates the limit of elastic behavior and the beginning of plastic behavior. Below the yield point, a material will deform elastically and will return to its original shape when the applied stress is removed. Once the yield point is passed, some fraction of the deformation will be permanent and non-reversible and is known as plastic deformation.

Deformation (engineering)

In engineering, deformation refers to the change in size or shape of an object. Displacements are the absolute change in position of a point on the object. Deflection is the relative change in external displacements on an object. Strain is the relative internal change in shape of an infinitesimally small cube of material and can be expressed as a non-dimensional change in length or angle of distortion of the cube. Strains are related to the forces acting on the cube, which are known as stress, by a stress-strain curve.

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