Quantifying a fault-tree analysis is a useful tool for assessing the most likely causes of a system failure. This chapter addresses fault-tree analysis event probabilities and ranking of failure causes based on these probabilities. Failure rates, failure-rate sources, probability determinations, mean times between failure, and related topics are also discussed. The discussion covers the practices observed in fault-tree analysis quantification and processes involved in calculating the probability of the top undesired event.

Diagnosing the root cause of a failure is particularly challenging if the symptom of the failure is not consistently observable. This article focuses on Laser Assisted Device Alteration/Soft Defect Localization (LADA/SDL), a global fault isolation technique, for detecting such failures. The discussion begins with a section describing the three steps in LADA/SDL analysis setup: create the test loop with the fail flag and loop trigger, select the laser dwell time, and select the shmoo bias point. An overview of LADA/SDL workflow is then presented followed by a brief section on time-resolved LADA. The closing pages of the article consider in detail SDL laser interaction physics and LADA laser interaction physics.

This chapter discusses the importance of failure analysis and the role it plays in a society driven by technological advancement. It explains why failure rates are highest in the early and later stages of the life of any product and shows the extent to which failure rates increase when products are subjected to an aggressive operating environment.

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.

Although zirconium resists stress-corrosion cracking (SCC) where many alloys fail, it is susceptible in Fe3+- and Cu2+-containing solutions, concentrated HNO3, halogen vapors, mercury, cesium, and CH3OH + halides. This chapter explains how composition, texture, stress levels, and strain rate affect the SCC behavior of zirconium and its alloys. It describes environments known to induce SCC, including aqueous solutions, organic liquids, hot and fused salts, and liquid metals. It also discusses cracking mechanisms and SCC prevention and control techniques.

Elevated-temperature failures are the most complex type of failure because all of the modes of failures can occur at elevated temperatures (with the obvious exception of low-temperature brittle fracture). Elevated-temperature problems are real concerns in industrial applications. The principal types of elevated-temperature failure mechanisms discussed in this chapter are creep, stress rupture, overheating failure, elevated-temperature fatigue, thermal fatigue, metallurgical instabilities, and environmentally induced failure. The causes, features, and effects of these failures are discussed. The cooling techniques for preventing elevated-temperature failures are also covered.

This chapter compares and contrasts the high-temperature behaviors of metals and composites. It describes the use of creep curves and stress-rupture testing along with the underlying mechanisms in creep deformation and elevated-temperature fracture. It also discusses creep-life prediction and related design methods and some of the factors involved in high-temperature fatigue, including creep-fatigue interaction and thermomechanical damage.

This chapter focuses on short-term tensile testing at high temperatures. It emphasizes one of the most important reasons for conducting hot tensile tests: the determination of the hot working characteristics of metallic materials. Two types of hot tensile tests are discussed in this chapter, namely, the Gleeble test and the conventional isothermal hot-tensile test. The discussion covers equipment used and testing procedures for the Gleeble test along with information on hot ductility and strength data from this test. The chapter describes the stress-strain curves, material coefficients, and flow behavior determined in the isothermal hot tensile test. It also describes three often-overlapping stages of cavitation during tensile deformation, namely, cavity nucleation, growth of individual cavities, and cavity coalescence.

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 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.

Creep occurs in any metal or alloy at a temperature where atoms become sufficiently mobile to allow the time-dependent rearrangement of structure. This chapter begins with a section on creep curves, covering the three distinct stages: primary, secondary, and tertiary. It then provides information on the stress-rupture test used to measure the time it takes for a metal to fail at a given stress at elevated temperature. The major classes of creep mechanism, namely Nabarro-Herring creep and Coble creep, are then covered. The chapter also provides information on three primary modes of elevated fracture, namely, rupture, transgranular fracture, and intergranular fracture. The next section focuses on some of the metallurgical instabilities caused by overaging, intermetallic phase precipitation, and carbide reactions. Subsequent sections address creep life prediction and creep-fatigue interaction and the approaches to design against creep.

This chapter discusses the factors that play a role in fatigue failures and how they affect the service life of metals and structures. It describes the stresses associated with high-cycle and low-cycle fatigue and how they differ from the loading profiles typically used to generate fatigue data. It compares the Gerber, Goodman, and Soderberg methods for predicting the effect of mean stress from bending data, describes the statistical nature of fatigue measurements, and explains how plastic strain causes cyclic hardening and softening. It discusses the work of Wohler, Basquin, and others and how it led to the development of a strain-based approach to fatigue and the use of fatigue strength and ductility coefficients. It reviews the three stages of fatigue, beginning with crack initiation followed by crack growth and final fracture. It explains how fracture mechanics can be applied to crack propagation and how stress concentrations affect fatigue life. It also discusses fatigue life improvement methods and design approaches.

Hydrogen damage is a form of environmentally assisted failure that results most often from the combined action of hydrogen and residual or applied tensile stress. This chapter classifies the various forms of hydrogen damage, summarizes the various theories that seek to explain hydrogen damage, and reviews hydrogen degradation in specific ferrous and nonferrous alloys. The preeminent theories for hydrogen damage are based on pressure, surface adsorption, decohesion, enhanced plastic flow, hydrogen attack, and hydride formation. The specific alloys covered are iron-base, nickel, aluminum, copper, titanium, zirconium, vanadium, niobium, and tantalum alloys.

Environmentally assisted cracking is a generic term that includes various cracking phenomena such as stress-corrosion cracking (SCC), corrosion fatigue cracking, and liquid-metal embrittlement. This chapter describes these cracking mechanisms beginning with SCC and the factors that influence its formation. It covers alloy selection and mitigation techniques and includes examples of SCC in aircraft components. The chapter also addresses corrosion fatigue, explaining how different environments and operating conditions affect crack propagation, fatigue strength, and fatigue life. It includes information on liquid-metal embrittlement as well.