An aircraft fuel pump failed just after takeoff, resulting in engine flameout. Investigators discovered that one of the seven pistons broke into several pieces, causing the quill shaft to fracture. An examination of the fracture surfaces revealed severe rubbing on the quill shaft and beach marks on the piston along with a nick on the opposite side of the barrel. In addition, the metal around the corresponding hole in the rotor had plastically deformed and the slipper pad was gone. Based on the investigation, the failure most likely occurred due to a problem with the spring guides or a jammed slipper pad. The chapter provides several recommendations to avoid such failures in the future.

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 reviews the causes and cases associated with the problems originated by tempering of steels. To provide background on this phenomenon, a brief description of the martensite reactions and the steel heat treatment of tempering is given to review the different stages of microstructural transformation. A section describing the types of embrittlement from tempering, along with mechanical tests for the determination of temper embrittlement (TE), is presented. Various factors involved in the interaction of the TE phenomenon with hydrogen embrittlement and liquid-metal embrittlement are also provided. The cases covered are grinding cracks on steel cam shaft and transgranular and intergranular crack path in commercial steels.

This chapter covers the friction and wear behaviors of plastics and elastomers. It begins by describing the molecular differences between the two types of polymers and their typical uses. It then discusses the important attributes of engineering plastics and their suitability for applications involving friction, erosion, and adhesive and abrasive wear. It also discusses the tribology of elastomers and rubber along with their basic differences and the conditions under which they produce Schallamach waves. It includes information on polymer composites as well.

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.

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.

The technology of fabricating composite hardware and structures by filament winding has evolved empirically through the development and manufacturing of specific components. This chapter reviews areas of technology used in building composite parts and discusses the processes from which the current technology was derived. The discussion covers quality control requirements for composite fabrication technology and cleanliness standards in the workplace. It describes technology developed for specific components, including satellites struts, aircraft hydraulic cylinders, drill pipe, drive shafts, couplings, and cryogenic tubing.

Induction heat treating is used in a wide range of applications. Typical uses, as described in this chapter, include the surface hardening of many types of shafts as well as gears and sprockets and the through-hardening of gripping teeth, cutting edges, and impact zones incorporated into various types of tools and track pins manufactured for off-highway equipment.

The load-displacement capabilities of a mechanical press are determined largely by the design of its drive mechanism or, more precisely, the linkage through which the drive motor connects to the slide. This chapter discusses the primary types of linkages used and their effect on force, velocity, and stroke profiles. It begins by describing the simplest drive configuration, a crankshaft that connects directly to the slide, and a variation of it that uses eccentric gears to alter the stroke profile. It then discusses the effect of adding a fixed link, knuckle joint, or toggle to the slider-crank mechanism and how gear ratios, component arrangements, and other design parameters affect slide motion. The chapter also explains how to assess load and energy requirements, time-dependent characteristics, and dimensional accuracy and discusses overload protection, shutheight adjustment, and slide counterbalancing as well.

This chapter identifies the primary causes of service failures and discusses the types of defects from which they stem. It presents more than a dozen examples of failures attributed to such causes as design defects, material defects, and manufacturing or processing defects as well as assembly errors, abnormal operating conditions, and inadequate maintenance. It also describes the precise usage of terms such as defect, flaw, imperfection, and discontinuity.

This chapter discusses the application of high-pressure cold spray to the automotive industry field, with special attention to three applications: additive manufacturing, fabrication methods, and protective coatings. Various studies on the automotive application of cold spray are reviewed. The background and purpose of each application are presented and practical cases are discussed.

This chapter covers the tribological properties of stainless steel and other corrosion-resistant alloys. It describes the metallurgy and microstructure of the basic types of stainless steel and their suitability for friction and wear applications and in environments where they are subjected to liquid, droplet, and solid particle erosion. It also discusses the tribology of nickel- and cobalt-base alloys as well as titanium, zinc, tin, aluminum, magnesium, beryllium, graphite, and different types of wood.

Residual, or locked-in internal, stresses are regions of misfit within a metal part or assembly that can cause distortion and fracture just as can the more obvious applied, or service, stresses. This chapter describes the fundamental facts about residual stresses and discusses the basic mechanisms of residual stress formation: thermal, transformational, mechanical, and chemical.

This chapter is a detailed account of the general characteristics and effects of and the methods for preventing or reducing different categories of wear failures, namely abrasive (erosive, grinding, and gouging), adhesive, and fretting wear.

Prior to forging, it is often necessary to preform billet stock to achieve adequate material distribution. This chapter discusses the equipment used for such operations, including transverse rolling machines, electric upsetters, ring-rolling mills, horizontal presses, and rotary (orbital) and radial forging machines. It describes their basic operating principles as well as advantages and disadvantages.

Because of its speed and ease of control, induction heating can be readily automated and integrated with other processing steps such as forming, quenching, and joining. Completely automated heating/handling/control systems have been developed and are offered by induction equipment manufacturers. This chapter deals with materials handling and automation. First, it summarizes basic considerations such as generic system designs, fixture materials, and special electrical problems to be avoided. Next, it describes and provides examples of materials-handling systems in induction billet heating, bar heating, heat treatment, soldering, brazing, and other induction-based processes. The final section discusses the use of robots for parts handling in induction heating systems.

This chapter summarizes the various kinds of gear wear and failure and how gear life in service is estimated and discusses the kinds of flaws in material that may lead to premature gear fatigue failure. The topics covered are alignment, gear tooth, surface durability and breakage of gear tooth, life determined by contact stress and bending stress, analysis of gear tooth failure by breakage after pitting, and metallurgical flaws that reduce the life of gears. The chapter briefly reviews some components in the design and structure of each gear and/or gear train that must be considered in conjunction with the teeth to enhance fatigue life.

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.

A brittle fracture occurs at stresses below the material's yield strength (i.e., in the elastic range of the stress-strain diagram). This chapter focuses on brittle fracture in metals and, more specifically, ferrous alloys. It lists the factors that must all be present simultaneously in order to cause brittle fracture in a normally ductile steel. The chapter then discusses the macroscale characteristics and microstructural aspects of brittle fracture. A summary of the types of embrittlement experienced by ferrous alloys is presented. The chapter concludes with a brief section providing information on mixed fracture morphology.