Structural Materials

This introductory chapter shows the conversion between different units of measurement: temperature, length, power, energy, weight, etc. Moreover, several solved exercises are included at the end of the chapter.

This introductory chapter provides a definition of structural and functional materials. The relation between different properties is established. The first part of this chapter discusses the differences between structural and functional properties for natural materials, metals, ceramics, polymers, and composites; the second part is devoted to discussing natural materials (properties and applications).

This chapter is dedicated to metallic structural materials. We review the main properties and applications of metallic materials and provide different exercises that enable the reader’s understanding of the utilization of metals in each application. For that reason, the Ellingham’s diagrams are described at the beginning of the chapter.

This chapter is dedicated to one of the most important structural materials: ceramic materials. For that reason, this chapter is mainly connected with several phase diagrams: CaO–MgO, CaO–SiO₂, SiO₂–Al₂O₃, CaO–Al₂O₃, and CaO–Al₂O₃–SiO₂, which define most ceramic materials. Cement is particularly important in this group of structural materials. The most relevant properties of ceramic materials, i.e., their thermal-shock resistance and their resistance at high temperature, are also described in this chapter.

We can find a wide number of polymeric materials in the nature both organic, as wood, petroleum, rubber, etc., and inorganic, as asbestos and kaolin. This chapter is dedicated to organic polymers, and particularly to artificial organic polymers. Polymers are usually classified in thermoplastics, thermosetting, elastomers, and foams, and in this chapter, we are going to study these four families of polymers.

This chapter is dedicated to composites; the objective of composites is to benefit from the advantageous properties of each family of materials by combining them. The main types of composites are described and classified depending on the family of the matrix material: polymeric matrix composites, metallic matrix composites, and ceramic matrix composites (especially relevant in this last group is steel-concrete).

This chapter introduces the selection of structural materials. Chapter 7 will be the starting point for the following chapters, in which the selection of materials, based on different physical and mechanical properties, will be performed. In this chapter, we include a table listing the properties we will use in the problems and case studies included in subsequent chapters.

This chapter is dedicated to materials used in the manufacture of flat and long products (length > width >> height) and plates. The influence of different sections on the second moment of the area of the cross-section is also described in this section. This way, different geometries are studied to determine the most suitable geometry when stiffness is desired. Different types of beams are described in this section that maximize stiffness, maximize the resistance to plastic deformation (yielding), and minimize the risks of unstable cracking, all while considering minimum cost and weight.

This chapter is dedicated to materials used for struts and columns. We describe in this chapter the selection of materials for columns when considering a design based on resistance to buckling. In the same way, we study the use of struts subjected to tension efforts. Additionally, we include two cases of application: tower cranes and beverage cans.

According to the modern view of fracture mechanics, when we break a structure by tension load, we ought not regard fracture as being caused directly by the action of the applied load pulling on the chemical bonds between the atoms in the material. The direct result of increasing the load on the structure is only to cause more strain energy to be stored within the material. Modern fracture mechanics is therefore less concerned with forces and stresses than with how, why, where, and when strain energy can be turned into fracture energy. In large or complicated structures—such as bridges, ships, or pressure vessels—when they are subjected to a sudden blow, it is possible for this strain energy to be converted into fracture energy so as to create or propagate cracks. The best materials for pressure vessels are studied in this chapter. Three criterions are chosen: rigidity, plasticity, and propagation of cracking as discussed in previous chapters. The theoretical section is complemented with exercises about the selection of materials for a pipe and for a cylindrical vessel.

In this chapter, we consider cost, although cost was used as a factor of selection in several exercises included in previous chapters. Charts for the comparison of materials based on one criterion of selection, apart from cost, are included in this section. They are very useful because we can define regions that comprise materials with the desired requirements. We conclude this chapter with a new concept, that of attributive analysis, which consists of giving weight to each criterion of selection and, in this way, selecting suitable material considering more than one property.

This chapter is entirely dedicated to fatigue resistance as a very important factor for the selection of materials. From the materials resistant to fatigue, steels are one of the best options. The chapter, complemented with exercises, focuses on heat treatments, particularly the quenching and tempering treatments, applied to steels with the purpose of increasing their resistance to fatigue.

This chapter is entirely dedicated to the behaviour of materials at different temperatures both high and low. In the case of polymers, they seem limited to low-temperature applications, whilst ceramic materials can be used in a wide range of temperatures, but they have special interest in high-temperature applications as a result of their properties. In the case of the metals, we can define three temperatures: the melting point; the \(T_{\text{M}} /2\), related with creep problems; and the DBTT (ductile–brittle transition temperature), which is related to the behaviour of materials at low temperatures.

This chapter provides several additional comments that should be considered, along with those mentioned in previous chapters, in relation to structural materials and their properties and selection. The importance of metallic materials is highlighted in this section, although we must not overlook other traditional materials, such as concrete and timber (widely used in construction) and new types of materials such as composites.