Deformation and Failure of Materials (FSI-RDF)

The course focuses on methods for securing the structural integrity of mechanical devices and structures from a materials perspective. The approaches consist of two parts: (i) the concept of the approach and strength or integrity calculation, and (ii) the evaluation of material resistance to failure based on mechanical testing. The aim of the course is to explain the principles of evaluating material resistance to failure using basic material characteristics such as yield stress, fracture toughness, or time-to-rupture curves.

The course enables students to gain an overview of the principles, measurement methods, and practical applications of mechanical and fracture mechanical characteristics of engineering materials.

Loss of functionality, component, or structural damage caused by material insufficiency and failure is usually referred to as the limit state. A deformation history precedes the limit state, and, as a result, in addition to loss of machine functionality, material failure occurs. The course is a free continuation of the bachelor course on Limit States of Materials. It focuses on topics such as deformation, fracture initiation, and propagation under different loading conditions. Traditional approaches to evaluating deformation and fracture behaviour are included, for example, plastic deformation under uniaxial loading, fatigue, and creep. Up-to-date methods are also covered, such as those used in low cycle fatigue and, in particular, fracture mechanics. The phenomena are explained with reference to typical families of structural materials; the lectures are therefore especially suitable for branches with limited or no dedicated courses on materials.

The course-unit credit is awarded on condition of meeting the following requirements: participation in all exercises and completion of tasks according to the teacher’s instructions.

In the written part of the exam, the student provides short answers to various questions. An oral question then follows, and complementary questions may arise and/or the student may have to defend their written part.

The exercises are compulsory, and any absence from these exercises must be properly excused. In case of absence, the student is required to submit a protocol to demonstrate understanding of the topic.

1. Limit states and materials design
2. Elastic and inelastic deformation
3. Plastic deformation - dislocations and strain hardening
4. Plastic deformation during uniaxial loading
5. Temperature dependence of plastic deformation; creep deformation
6. Material failures, fracture criteria
7. Parameters of Linear Elastic and Elastic Plastic Fracture Mechanics
8. Fracture toughness determination
9. Brittle fracture of steels - master curve concept
10. Weld joints failures and integrity evaluation methods
11. Fatigue damage and material failures
12. Damage superposition
13. Deformation and fracture of plastics and ceramics

1. Visit to mechanical laboratories, literature, databases
2. Examples from elastic behaviour of materials
3. & 4. Plastic deformation and tensile test - examples
5. & 6. Transition behaviour of steels
7. & 8. Experimental fracture mechanics
9. Steels and steel weldments evaluation
10. & 11. Fatigue - selected examples
12. & 13. Application of knowledge for ceramics and plastics