Mechanical Behaviour of Materials in Service

Bachelor in Mechanical Engineering or in related areas.

In theoretical lessons the content is presented through the use of both the board and PowerPoint slides. In theoretical-practical classes typical exercises are solved.
The evaluation of this curricular unit is performed through a written exam at the end of the semester. This exam consists of two parts, a theoretical component and a theoretical-practical one, corresponding each to 50% of the final grade.

The main objective of this unit is to understand the concepts and acquire the procedures about the fundamental tools in design and control of mechanical components failure, taking into account their service conditions. The application of these concepts and tools covers a wide area of application, namely, in aerospace, aeronautic and naval industries, in the design of transport vehicles and pressure vessels, and also in several other components and structures subjected to static or dynamic loadings.

1. Main rupture and failure modes in mechanical components.
2. Materials fatigue: high-cycle fatigue; Low-cycle fatigue; behaviour of metals to cyclic plastic deformation; deformation-life curves; life prediction of notched components.
3. Linear elastic fracture mechanics: Griffith’s theory; rupture modes; definition of the stress intensity factor; plastic zone at the crack tip; experimental determination of KIc.
4. Elastic-plastic fracture mechanics: parameters COD and J integral; experimental determination; elasticplastic fracture mechanics applications.
5. Stress corrosion: stress corrosion tests; application of the da/dt-K curves.
6. Application of fracture mechanics to fatigue: da/dN-?K curves; mean stress effect; the crack closure phenomenon; main crack propagation laws; crack growth under variable amplitude loading.
7. Creep and stress relaxation: long duration creep tests; stress relaxation and recovery; elementary problems in creep design.

NAO