After several failed attempts to lower their starboard wheels for landing, pilots engaged the help of gravity through g-force maneuvers and managed to coax the wheels into place. An inspection following the incident revealed a broken universal joint in one of the linkages that opens and closes the doors to the undercarriage compartment. The failed component was removed from the aircraft and examined using optical and electron microscopes. Under low magnification, the fracture surface appeared jagged except for one corner that was relatively smooth. SEM fractography revealed the presence of fatigue striations in the smooth region and dimpling elsewhere. Based on their findings, investigators concluded that fatigue loading initiated a crack in the universal joint that progressed with time and that the final fracture occurred due to bending tensile overload.

This article addresses critical aspects in bond testing of thermal spray coatings and provides step-by-step guidance for obtaining representative and reproducible test results based on ASTM C633 and other applicable industry standards. It clarifies details of ASTM C633 requirements and provides examples of the best practice confirmed by hundreds of tests performed worldwide, adopted by numerous industrial standards, and requested to comply with international technical standardization and certification organizations such ISO, AS, SAE, and Nadcap.

This chapter briefly reviews the history of brazing from ancient times to the early 20th century.

This article is intended to help engineers understand why the fatigue behavior of weldments can be such a confusing and seemingly contradictory topic and hopefully to clarify this complex subject. It first reexamines the factors influencing the fatigue behavior of an individual weldment using extensive experimental data and a computer model that simulates the fatigue resistance of weldments. Next, the process of fatigue in weldments is discussed in general terms, and the service conditions that favor long crack growth and the conditions that favor crack nucleation are contrasted. The article then presents experimental data that show the effect of weldment geometry on fatigue resistance. Several useful geometry classification systems are compared. Finally, a computer model is employed to investigate the behavior of two hypothetical weldments: a discontinuity-containing ("Nominal") weldment and a discontinuity-free ("Ideal") weldment.

This chapter discusses the fatigue behavior of bolted, riveted, and welded joints. It describes the relative strength of machined and rolled threads and the effect of thread design, preload, and clamping force on the fatigue strength of bolts made from different steels. It explains where fatigue failures are likely to occur in cold-driven rivet and friction joints, and why the fatigue strength of welded joints can be much lower than that of the parent metal, depending on weld shape, joint geometry, discontinuities, and residual stresses. The chapter also explains how to improve the fatigue life of welded joints and discusses the factors that can reduce the fracture toughness of weld metals.

This chapter describes joining by forming processes including riveting, clinching, crimping, and dieless joining techniques. It also discusses the fatigue behavior of clinched joints and the results of fatigue tests that compare clinched and spot welded joints.

The chapter covers various aspects of biotribology in the context of dental care, orthopedic implants, haptics, eyewear, and stents and fixation devices. It also addresses the issue of biocompatibility and the effects of friction and contact pressure on skin.

This chapter presents a comprehensive coverage of mechanical fastening methods. It begins with a discussion on the advantages and disadvantages of mechanical fastening followed by sections providing information on mechanically fastened joints and the selection of the correct fastener system. The chapter then describes important structural fasteners, namely bolts, screws, pins, collar fasteners, rivets, blind fasteners, machine pins, and spring clip fasteners. The following sections describe the process involved in presses, shrink fits, hole generation, and fastener installation. The chapter ends with information on miscellaneous mechanical fastening methods.

Brazing and soldering jointly represent one of several methods for joining solid materials. This chapter summarizes the principal characteristics of the various joining methods. It then discusses key parameters of brazing including surface energy and tension, wetting and contact angle, fluid flow, filler spreading characteristics, surface roughness of components, dissolution of parent materials, new phase formations, significance of the joint gap, and the strength of metals. The chapter also describes issues in processing aspects that must be considered when designing a joint, and the health, safety, and environmental aspects of brazing.

This chapter considers the role of materials in brazing operations and the manner in which they impact on the choice of processing conditions and their optimization. The concepts covered are metallurgical and mechanical constraints, and constraints imposed by the components and their solutions as well as service environment considerations.

Soldering and brazing represent one of several types of methods for joining solid materials. These methods may be classified as mechanical fastening, adhesive bonding, soldering and brazing, welding, and solid-state joining. This chapter summarizes the principal characteristics of these joining methods. It presents a comparison between solders and brazes. Further details on pressure welding and diffusion bonding are also provided. Key parameters of soldering are discussed, including surface energy and surface tension, wetting and contact angle, fluid flow, filler spreading characteristics, surface roughness of components, dissolution of parent materials and intermetallic growth, significance of the joint gap, and the strength of metals. The chapter also examines the principal aspects related to the design and application of soldering processes.

This chapter focuses on tensile testing of three types of engineering components that undergo significant loading in tension, namely, threaded fasteners and bolted joints; adhesive joints; and welded joints. It describes the standardized tensile test for externally threaded fasteners and provides a brief background on relationships among torque, angle-of-turn, tension, and friction. The chapter also describes the test methods covered in the ASTM F 606M standard, namely, product hardness; proof load by length measurement, yield strength, or uniform hardness; axial tension testing of full-sized products; wedge tension testing of full-sized products; tension testing of machined test specimens; and total extension at fracture testing. Finally, the chapter covers tensile testing of adhesive and welded joints.

This chapter considers the materials and processing aspects of soldering and the manner in which these interrelate in the development of joining processes. It discusses the processes involved in eliminating or suppressing metallurgical and mechanical constraints as well as constraints imposed by the components.

This article discusses the various options for controlling fatigue and fracture in welded steel structures, the factors that influence them the most, and some of the leading codes and standards for designing against these failure mechanisms. The two most widely used approaches discussed for fatigue control in welded joints are the S-N curve approach and the fracture mechanics assessment methods.

Materials used in joining, whether solders, fluxes, or atmospheres, are becoming increasingly subjected to restrictions on the grounds of health, safety, and pollution concerns. These regulations can limit the choice of materials and processes that are deemed acceptable for industrial use. The chapter addresses this issue with a focus on soldering fluxes. The chapter also describes factors related to soldering under a protective atmosphere, provides information on chemical fluxes for soldering of various metals, and discusses the processes involved in fluxless soldering processes.

This chapter discusses the various methods used to join titanium alloy assemblies, focusing on welding processes and procedures. It explains how welding alters the structure and properties of titanium and how it is influenced by composition, surface qualities, and other factors. It describes several welding processes, including arc welding, resistance welding, and friction stir welding, and addresses related issues such as welding defects, quality control, and stress relieving. The chapter also covers mechanical fastening techniques along with adhesive bonding and brazing.

This article describes the weldability tests that are used to evaluate the effects of welding on such properties and characteristics as base-metal and weld-metal cracking; base-metal and weld-metal ductility; weld penetration; and weld pool shape and fluid flow. It also describes several weldability tests for evaluating cracking susceptibility, classified as self-restraint or externally loaded tests. The article discusses the processes, advantages, and disadvantages of the weld pool shape tests, the weld penetration tests, and the Gleeble test.