Lecture

Mechanics of Fracture: Introduction and Applications

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In course

CIVIL-526: Steel structures, selected topics

Design and dimensioning of load-bearing structures using structural steel, with emphasis on the specific methods related to steel-concrete composite elements (for buildings and bridges), fatigue (bridges) and fire (buildings). ...

Description

This lecture delves into the mechanics of fracture, exploring concepts such as fracture mechanics, fatigue testing, and material toughness. The instructor discusses the history of fracture mechanics, its applications in real-world scenarios like ship failures, and the importance of understanding factors influencing material resilience. Through examples and calculations, the lecture demonstrates how to determine the critical stress intensity factor for different types of cracks, emphasizing the significance of material toughness in preventing catastrophic failures. The lecture also covers the leak-before-break principle in pressure vessels, the influence of crack geometry on stress intensity, and the role of energy absorption in material failure.

Instructor

Alain Nussbaumer

Expertise Metallic structuresStructural glassFatigue and fracture mechanicsAssessment of existing structuresUltra low cycle Teaching & PhD Past EPFL PhD Students Luís Costa Borges, Claire Acevedo, Nariman Maddah, Farshid Zamiri Akhlaghi, Manuel Santarsiero, Luca D'Angelo, Cláudio Alexandre Pereira Baptista, Albano António Sousa, Jagoda Cupac, Ardalan Hosseini, Martin Garcia, Hossein Heydarinouri, Jian Zhan Past EPFL PhD Students as codirector Marina Rocha Courses Design of steel structures CIVIL-2

Official source

Related concepts (19)

Fracture toughness

In materials science, fracture toughness is the critical stress intensity factor of a sharp crack where propagation of the crack suddenly becomes rapid and unlimited. A component's thickness affects the constraint conditions at the tip of a crack with thin components having plane stress conditions and thick components having plane strain conditions. Plane strain conditions give the lowest fracture toughness value which is a material property.

Fracture

Fracture is the separation of an object or material into two or more pieces under the action of stress. The fracture of a solid usually occurs due to the development of certain displacement discontinuity surfaces within the solid. If a displacement develops perpendicular to the surface, it is called a normal tensile crack or simply a crack; if a displacement develops tangentially, it is called a shear crack, slip band or dislocation. Brittle fractures occur without any apparent deformation before fracture.

Stress concentration

In solid mechanics, a stress concentration (also called a stress raiser or a stress riser or notch sensitivity) is a location in an object where the stress is significantly greater than the surrounding region. Stress concentrations occur when there are irregularities in the geometry or material of a structural component that cause an interruption to the flow of stress. This arises from such details as holes, grooves, notches and fillets. Stress concentrations may also occur from accidental damage such as nicks and scratches.

Materials science

Materials science is an interdisciplinary field of researching and discovering materials. Materials engineering is an engineering field of finding uses for materials in other fields and industries. The intellectual origins of materials science stem from the Age of Enlightenment, when researchers began to use analytical thinking from chemistry, physics, and engineering to understand ancient, phenomenological observations in metallurgy and mineralogy. Materials science still incorporates elements of physics, chemistry, and engineering.

Material

Material is a substance or mixture of substances that constitutes an object. Materials can be pure or impure, living or non-living matter. Materials can be classified on the basis of their physical and chemical properties, or on their geological origin or biological function. Materials science is the study of materials, their properties and their applications. Raw materials can be processed in different ways to influence their properties, by purification, shaping or the introduction of other materials.

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