This article discusses the molecular mechanism, environmental criteria, and material optimization of environmental stress crazing (ESC) in glassy thermoplastics, polyethylenes, and nylons. In addition, it provides information on various tests used to determine relative susceptibility to ESC, namely constant tensile load testing and constant-strain testing.

This article is a detailed account of the mechanisms of fatigue failure of polymers, namely thermal fatigue failure and mechanical fatigue failure. The mechanical fatigue failure is discussed in terms of fatigue crack initiation and fatigue crack propagation.

In an attempt to explain the stresses encountered in the plastics industry, this article first defines the different types of internal stresses in amorphous polymers. Each type of thermal stress is then discussed in detail, with reference to the mechanism of generation and the effect on engineering properties. Methods of detecting and measuring internal stresses are also presented. The article then describes the combined effects of thermal stresses and orientation that result from processing conditions. Finally, it discusses numerous aspects of physical aging and the use of high-modulus graphite fibers in amorphous polymers.

This article discusses various factors influencing general polymeric behavior, ductile-brittle transitions, crazing, and the brittle fracture of polymeric materials. The discussion covers the effects of environment on glassy thermoplastic, several parametric descriptions of craze initiation, the kinetics of craze growth, and the effect of crazing on toughness of the plastic. In addition, the article provides information on various tests to determine stress-to-craze value, strain-to-craze value, and fracture toughness of the plastic.

This article briefly describes the historical development of fracture resistance testing of polymers and reviews several test methods developed for determining the fracture toughness of polymeric materials. The discussion covers J-integral testing, the methods for determining linear elastic fracture toughness, testing of thin sheets and films, normalization methods, and hysteresis methods.

The susceptibility of plastics to environmental failure, when exposed to organic chemicals, limits their use in many applications. Environmental factors can be classified into two categories: chemical and physical effects. This article discusses the effects of these environmental factors on the mechanical properties of plastics.

This article describes the general aspects of and practical problems of failure analysis of creep, stress relaxation, and yielding for homogeneous polymers. The effect of temperature and strain rate on the relationship between yield point and elastic modulus and the aging effect that polymers often undergo at room temperature are also discussed.

This appendix provides references for additional information on titanium and its alloys. The references are organized by topic based on the author’s recommendations. Topics include physical metallurgy, corrosion, processing, applications and developments, and general background.

This article focuses on characterization techniques used for analyzing the physical behavior and chemical composition of thermoset resins, namely chromatography and infrared spectroscopy. The main purpose is to give sufficient detail to permit the reader understand a particular test technique and its value to the thermoset resin field. Epoxy resins are emphasized in the examples because they dominate the airframe and aerospace industries. The article also provides information on two categories of characterization of the processing behavior of thermoset. The first studies the thermal properties of reactive thermoset systems, while the second utilizes these thermal characteristics as the basis for monitoring and control during processing.

Polymer composite materials are subject to degradation if not appropriately protected from the environment. Composite materials having polymeric matrices are susceptible to degradation from heat, sunlight, ozone, atomic oxygen (in space), moisture, solvents (chemicals), fatigue, excessive loading, and combinations of these environmental conditions. This chapter discusses the effects of heat, ultraviolet-light, and atomic oxygen on composite materials.

This appendix includes selected references on topics related to the production and application of superalloys, including properties and microstructure; melting/ingot breakdown; forging/powder metallurgy; machining, heat treating, joining, refurbishment/repair; investment casting; coatings/corrosion; and modeling.

This chapter discusses some important factors involved in the atmospheric corrosion of engineering materials. The discussion begins with a description of elements necessary for the operation of a galvanic corrosion cell and corrosion reactions, followed by the types of atmospheric corrosion attack. Some of the atmospheric parameters and their effects on the corrosion of several metals are then reviewed. The following sections provide information on air chemistry, principal pollutants inducing corrosion, thermodynamics as well as models for prediction of atmospheric corrosion, and use of Pourbaix diagrams. The phenomenon of precipitation runoff on the corroded metal surface is then discussed. The chapter also describes the role of microbes or bacteria in the corrosion of metals. It concludes by providing information on the trends in atmospheric corrosion research and methods.

This chapter covers various consolidation techniques used in powder metallurgy, including laser sintering (pressureless sintering), hot pressing, high-pressure torsion, microwave sintering, spark plasma sintering, and pulse plasma sintering. It also discusses the effect of milling parameters on mechanically alloyed powders, their consolidation characteristics, and the properties of bulk components.

This chapter summarizes the progress that has been made in the study of high-entropy alloy (HEA) systems and the process-structure-property relationships that define them. It describes the various ways HEAs can be strengthened and explains how alloying elements influence tensile and yield strength, fracture toughness, and fracture strength. It discusses the stages of plastic deformation in HEAs and the role of dislocations and twinning in the evolution of microstructure. It reviews some of the work that has been done on fatigue behaviors and the methods developed to assess fatigue performance. It discusses the influence of defects on fatigue life, the effect of temperature and grain size on fatigue-crack propagation, and the role of nanotwinning in crack-growth retardation. It describes the methods used to produce HEAs in bulk and powder form and to apply them as protective coatings and films. It also identifies potential applications based on properties such as strength, hardness, density, wear resistance, high-temperature stability, and biocompatibility.

The second-generation composite materials were added to increase the strain to failure of the primary phase and/or create a dispersed second phase, thereby enhancing the fracture toughness of the thermosetting matrix. These matrices offered novel design capabilities for composites in a variety of aircraft applications. To improve the damage tolerance of composite materials even further, an engineering approach to toughening was used to modify the highly stressed interlayer with either a tougher material or through the use of preformed particles, leading to the third generation of composite materials. This chapter discusses the development, processes, application, advantages, and disadvantages of dispersed-phase toughening of thermoset matrices. Information on the processes of particle interlayer toughening of composite materials is also included.

This article reviews fatigue test methodologies, provides an overview of general fatigue behavior (crack initiation and propagation) in engineering plastics, and discusses some of the factors affecting the fatigue performance of polymers. In addition, it provides information on fractography that provides useful insight into the nature of fracture processes.

This chapter concentrates on the better-known and widely studied phenomenon of pitting corrosion of passive metals. The discussion focuses on different parameters that influence pitting corrosion, namely environment, metal composition, potential, temperature, surface condition, and inhibitors. It also provides information on various stages of pitting: passive film breakdown, metastable pitting, pit growth, and pit stifling or death.

This chapter describes the conditions under which copper-base alloys are susceptible to stress-corrosion cracking (SCC) and some of the environmental factors, such as temperature, pH, and corrosion potential, that influence crack growth and time to failure. It explains that, although most of the literature has been concerned with copper zinc alloys in ammoniacal solutions, there are a number of alloy-environment combinations where SCC has been observed. The chapter discusses several of these cases and the effect of various application parameters, including composition, microstructure, heat treatment, cold working, and stress intensity. It also provides information on stress-corrosion testing, mitigation techniques, and basic cracking mechanisms.

This article describes the mechanisms of moisture-induced damage in polymeric materials, covering the characteristics of important structural plastics; the effects of moisture on glass transition temperature, modulus, creep, and stress relaxation of plastic materials; and moisture-induced fatigue failure in composites. The effect of moisture on the mechanical properties of thermoset resins and thermoplastics are also discussed.