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Components used in mechanical engineering usually have to bear high mechanical loads. It is, thus, of considerable importance for students of mechanical engineering and materials science to thoroughly study the mechanical behaviour of materials. There are different approaches to this subject: The engineer is mainly interested in design rules to dimension components, whereas materials science usually focuses on the physical processes in the material occurring during mechanical loading. Ultimately, however, both aspects are important in practice. Without a clear understanding of the mechanisms deformation in the material, the engineer might uncritically apply design rules and thus cause ‘unexpected’ failure of components. On the other hand, all theoretical knowledge is practically useless if the gap to practical application not closed.
[...]... with fracture of the tube The strongly differing properties are reflected in the application of engineering materials – you would neither want to build cars of glass nor rubber bridges The multitude of materials enables the engineer to select the best-suited one for any particular component For this, however, it is frequently necessary not only to know the mechanical properties of the materials, but... them The mechanical properties of materials are determined by their atomic structure To understand these properties, some knowledge of the structure of materials is therefore required This is the topic covered in this chapter The structure of materials is investigated by solid state physics, but to understand the mechanical properties, it is not necessary to understand the more arcane aspects of this... short explanation of the basic principles of atomic structure and the nature of the chemical bond Afterwards, the three main groups of materials, metals, ceramics, and polymers, are discussed The most important characteristics of their interatomic bonds are covered, and the microscopic structure of the different groups is also treated For a more thorough introduction into the structure of materials the... picture of the chemical bond, each atom can form as many bonds as there are electrons missing on the outermost shell This type of bond is called covalent and will be described in section 1.3.1 The number of bonds formed by an atom is called its valency So fluorine has a valency of 1, oxygen of 2, and carbon of 4.3 The valency model of the elements can explain many chemical compounds, but not all of them... temperature of metals is usually lower as well The distribution of the electrons over a large region leads to a slow decrease of the interatomic force with the distance of the atoms compared to other types of bonds Because it is thus possible to displace single atoms with a rather small amount of energy, metals can be easily deformed plastically If some metal atoms are replaced by those of another metallic... corresponds to an energy of 1.602 × 10−19 J In chemistry, energies are frequently calculated per mole: 1 eV ≈ 105 kJ/mol 8 1 The structure of materials Fig 1.3 Simple cubic crystal structure Mathematically, a crystal can be considered as a three-dimensional arrangement of points (i e., a lattice of points) that looks identical from each of the points In a real-world crystal each of these points will be... determining the plastic behaviour of metals, they are discussed in detail in chapter 6 1.3 Ceramics All non-metallic, non-organic materials are called ceramics [70].11 Physically, the distinction between ceramics and metals can be based on their bond type – 11 The classification of engineering materials is not unique, and other criteria to distinguish between the classes exist Therefore, some materials are classified... overall binding energy of ceramics and metals is smaller – even in diamond the binding energy of an atom is 7.4 eV, only twice that of copper, a metal with a rather high binding energy In other covalent crystals, typical values are between 3 eV and 5 eV, again approximately twice that of typical metals 18 1 The structure of materials 1.3.2 Ionic bond Many ceramics are compounds of a metal and a non-metal... chemical bond Atoms consist of a positively charged nucleus surrounded by negatively charged electrons Almost the complete mass of the atom is concentrated in the nucleus because it comprises heavy elementary particles, the protons 2 1 The structure of materials (a) s orbital (b) p orbitals (c) d orbitals Fig 1.1 Sketch of selected electron orbitals and neutrons The number of positively charged protons... the unit cell of the cubic lattice is a cube The geometry of the different crystal types will be explained in more detail below Some of the 14 Bravais lattices are very similar The simple cubic and the body-centred cubic lattice differ only in the additional atom that is situated in the centre of the unit cell Such similarities can be described using the symmetries of a crystal A symmetry of an object . y0 w0 h0" alt="" Mechanical Behaviour of Engineering Materials J. Rösler · H. Harders · M. Bäker Mechanical Behaviour of Engineering Materials Metals,. high-temperature materials, the mechanical behaviour of materials, and in m aterials develop- ment. Dr Ing. Harald Harders, born in 1972, studied mechanical engineering, with