This chapter reviews the fundamentals of stress, strain, and deformation and demonstrates some of the tools and techniques used to analyze how materials and structures respond to tension, compression, bending, and shear. It begins with an overview of the behavior of perfectly elastic and plastic materials and viscous substances. It then describes the stress-strain response of two- and three-dimensional solids, explaining how to determine principle stresses and strains using Mohr’s circle and how to derive equivalent stress and strain using the von Mises relationship. It then goes on to analyze the stress state of load-bearing members, pressurized tubes, and pin-loaded lugs, accounting for the effect of geometric discontinuities, such as cutouts, fillets, and holes, as well as cracks. It also explains how finite element methods are used to solve problems involving complex geometric and loading conditions.

This chapter reviews the theories that have emerged from the widespread study of multiaxial fatigue and assesses their validity using data from different sources. It begins by providing background on the studies that the chapter draws on, pointing out differences in methodology and explaining how they influence test results and data. It then discusses the concept of critical planes and how they are used to correlate the effects of uniaxial loading with multiaxial fatigue behaviors. The section that follows covers the various methods used to analyze multiaxial fatigue and identifies one that best treats the general case. The chapter also defines two important factors, the triaxiality factor and the multiaxiality factor, and presents the results of an extensive study to determine how the two factors are related. One of the more interesting findings is that the atomic structure of a material has a significant effect on which theory best describes its fatigue behavior.

In order to understand how various types of single-load fractures are caused, one must understand the forces acting on the metals and also the characteristics of the metals themselves. All fractures are caused by stresses. Stress systems are best studied by examining free-body diagrams, which are simplified models of complex stress systems. Free-body diagrams of shafts in the pure types of loading (tension, torsion, and compression) are the simplest; they then can be related to more complex types of loading. This chapter discusses the principles of these simplest loading systems in ductile and brittle metals.

This chapter describes the mechanical properties of fully pearlitic microstructures and their suitability for wire and rail applications. It begins by describing the ever-increasing demands placed on rail steels and the manufacturing methods that have been developed in response. It then explains how wire drawing, patenting, and the Stelmor process affect microstructure, and describes various fracture mechanisms and how they appear on steel wire fracture surfaces. The chapter concludes by discussing the effects of torsional deformation, delamination, galvanizing, and aging on patented and drawn wires.

This chapter discusses the stress-strain response of materials, how it is measured, and how it used to set performance expectations. It begins by describing the common tensile test and how it sheds light on the elastic design of structures as well as plasticity and fracture behaviors. It explains how engineering and true stress-strain curves differ, how one is used for design and the other for analyzing metal forming operations. It discusses the effect of holes, fillets, and radii on the distribution of stresses and the use of notch tensile testing to detect metallurgical embrittlement. The chapter also covers compression, shear, and torsion testing, the prediction of yielding, residual stress, and hardness.

The relationship of stress and strength gradients must be considered simultaneously in analysis of a particular type of fracture. This chapter discusses the principal elastic stress distribution in members of various shapes under different types of pure loads. A basic understanding of both the stress and strength gradients of metal parts with and without stress concentrations and under different types of loading is provided. The chapter also describes the effect of service conditions on applied stresses.

The mechanical behavior of a material is its response to an applied load or force. Important mechanical properties are strength, hardness, stiffness, and ductility. This chapter discusses three principal ways in which these properties are tested: tension, compression, and shear. Important tensile properties that can be determined by the tensile test include yield strength, ultimate tensile strength, ductility, resilience, and toughness. The chapter describes the effects of stress concentrations on ductile metals under cyclic loads. Other topics covered include combined stresses, yield criteria, and residual stresses of metals.

This chapter addresses the question of how to deal with multiaxial stresses and strains when using the strain-range partitioning method to analyze the effects of creep fatigue. It is divided into three sections: a general discussion on the rationale used in formulating rules for treating multiaxiality, a concise listing of the rules, and an example problem in which axial creep-fatigue data is used to predict the torsional creep-fatigue life of type 304 and 316 stainless steel. The chapter also includes a brief introduction in which the authors outline the challenges presented by multiaxial loading and set practical limits on the problem they intend to treat.

This chapter examines the phenomena of deformation and fracture in metals, providing readers with an understanding of why it occurs and how it can be prevented. It begins with a detailed review of tension and compression stress-strain curves, explaining how they are produced and what they reveal about the load-carrying characteristics of engineering materials. It then discusses the use of failure criteria and the determination of yielding and fracture limits. It goes on to describe the mechanisms and appearances of brittle and ductile fractures and stress rupture, providing detailed images, diagrams, and explanations. It discusses the various factors that influence strength and ductility, including grain size, loading rate, and temperature. It also provides information on the origin of residual stresses, the concept of toughness, and the damage mechanisms associated with creep and stress rupture, stress corrosion, and hydrogen embrittlement.

The water-hardening steels are either essentially plain carbon steels or very low-alloy carbon steels. As a result, the water-hardening tool steels are the least expensive of tool steels and require strict control of processing and heat treatment to achieve good properties and performance. This chapter provides an overview of general processing and performance considerations of water-hardening tool steels. It describes the microstructural characteristics and hardenability of water-hardening tool steels. The chapter discusses the processes involved in the hardening and tempering of water-hardening tool steels.

This chapter begins with a review of some of the terms used in the gear industry to describe the design of gears and gear geometries. It then discusses the types of gears that operate on parallel shafts, intersecting shafts, and nonparallel and nonintersecting shafts. Next, the processes involved in the selection of gear are discussed, followed by information on the basic stresses applied to a gear tooth, the strength of a gear tooth, and the most widely used gear materials. Further, the chapter briefly reviews gear manufacturing methods and the heat treating processing steps including prehardening processes, through hardening, and case hardening processes.

This appendix provides supplemental information on the metallurgical aspects of atomic structure, the use of dislocation theory, heat treatment processes and procedures, important engineering materials and strengthening mechanisms, and the nature of elastic, plastic, and creep strain components. It also provides information on mechanical property and fatigue testing, the use of hysteresis energy to analyze fatigue, a procedure for inverting equations to solve for dependent variables, and a method for dealing with the statistical nature of failure.

This chapter reviews various ways to classify failure categories and summarizes the basic types, causes, and mechanisms of damage, with particular consideration given to whether the likelihood of the types of damage can or cannot be influenced by the heat treating of steel parts. The classical organization for types of damage (failures) is as follows: deformation, fracture, wear, corrosion or other environmental damage, and multiple or complex damage. The chapter also provides some examples of lack of conformance to specification that may at first look like the heat treater did something wrong, but where other contributing factors made it difficult or impossible for the heat treater to meet the specification.

The low-alloy special-purpose tool steels, designated as group L steels in the AISI classification system, are similar to the water-hardening tool steels but have somewhat greater alloy content. This chapter discusses the metallurgy and performance of low-alloy special-purpose tool steels, including those with high carbon content, those with medium carbon content, and those containing nickel.

The objective of mechanical testing of an engineered material is to provide data necessary for the analysis, design, and fabrication of structural components using the material. The testing of filament-wound composite materials offers unique challenges because of the special characteristics of composites. This chapter describes suitable static mechanical test techniques for characterizing laminated composite materials. The approach is to provide recommended techniques, based on consensus opinions of fabricators and users of filament-wound composites, and to survey available techniques that have been used successfully in the field. The chapter describes the effects of various factors on the properties of composite constituents, including fibers, resins, and unidirectional plies. Some aspects of specimen selection are also described. The chapter provides information on pressure bottles and tubular parts that have been developed as standard test specimens for combined load testing of composites.

Fatigue fractures are generally considered the most serious type of fracture in machinery parts simply because fatigue fractures can and do occur in normal service, without excessive overloads, and under normal operating conditions. This chapter first discusses the three stages (initiation, propagation, and final rupture) of fatigue fracture followed by a discussion of its microscopic and macroscopic characteristics. The relationship between stress and strength in fatigue is explained. The next section provides information that may help the uninitiated to appreciate some of the problems of laboratory fatigue testing and of the fatigue process itself. Finally, information on types and statistical aspects of fatigue is provided along with examples.

Ductile fracture results from the application of an excessive stress to a metal that has the ability to deform permanently, or plastically, prior to fracture. Careful examination and knowledge of the metal, its thermal history, and its hardness are important in determining the correct nature of the fracture features. This chapter is a detailed account of the general characteristics and microstructural aspects of ductile fracture with suitable illustrations. It describes some of the complicating factors extraneous to the fracture itself.