This article discusses the three legal theories on which a products liability lawsuit is based and the issues of hazard, risk, and danger in the context of liability. It describes manufacturing and design defects of various products. The article explains a design that is analyzed from the human factors viewpoint and details the preventive measures of the defects, with examples. It presents four paramount questions relating to the probability of injury which are asked even when one executes all possible preventive measures carefully and thoroughly.

This article describes the methodology for performing a failure modes and effects analysis (FMEA). It explains the methodology with the help of a hot water heater and provides a discussion on the role of FMEA in the design process. The article presents the analysis procedures and shows how proper planning, along with functional, interface, and detailed fault analyses, makes FMEA a process that facilitates the design throughout the product development cycle. It also discusses the use of fault equivalence to reduce the amount of labor required by the analysis. The article shows how fault trees are used to unify the analysis of failure modes caused by design errors, manufacturing and maintenance processes, materials, and so on, and to assess the probability of failure mode occurrence. It concludes with information on some of the approaches to automating the FMEA.

Materials selection is an important engineering function in both the design and failure analysis of components. This article briefly reviews the general aspects of materials selection as a concern in proactive failure prevention during design and as a possible root cause of failed parts. It discusses the overall concept of design and describes the role of the materials engineer in the design and materials selection process. The article highlights the significance of materials selection in both the prevention and analysis of failures.

The purpose of this article is to assist the reader in understanding the role that an engineering expert witness plays in evaluating incidents related to product liability, so that he or she may become better acquainted with the role that an engineer plays in such litigation. The topics covered are admissibility of expert opinions, how to evaluate data, factual evidence, mandatory and voluntary standards, physical evidence, medical records, scientific literature, design decisions evaluation, environment of use, user's contribution, reports of opposing experts, report of findings, and deposition and trial testimonies.

Materials selection is closely related to the objectives of failure analysis and prevention. This article briefly reviews the general aspects of materials selection as a concern in both proactive failure prevention during design and as a possible root cause of failed parts. Coverage is more conceptual, with general discussions on the following topics: design and failure prevention, materials selection in design, materials selection for failure prevention, and materials selection and failure analysis. Because materials selection is just one part of the design process, the overall concept of design is discussed. The article also describes the role of the materials engineer in the design and materials selection process. It provides information on the significance of materials selection in both the prevention and analysis of failures.

This article provides assistance to a failure analyst in broadening the initial scope of the investigation of a physical engineering failure in order to identify the root cause of a problem. The engineering design process, including task clarification, conceptual design, embodiment design, and detail design, is reviewed. The article discusses the design process at the personal and project levels but takes into consideration the effects of some higher level influences and interfaces often found to contribute to engineering failures.

This article briefly introduces the concepts of failure analysis, including root-cause analysis (RCA), and the role of failure analysis as a general engineering tool for enhancing product quality and failure prevention. It initially provides definitions of failure on several different levels, followed by a discussion on the role of failure analysis and the appreciation of quality assurance and user expectations. Systematic analysis of equipment failures reveals physical root causes that fall into one of four fundamental categories: design, manufacturing/installation, service, and material, which are discussed in the following sections along with examples. The tools available for failure analysis are then covered. Further, the article describes the categories of mode of failure: distortion or undesired deformation, fracture, corrosion, and wear. It provides information on the processes involved in RCA and the charting methods that may be useful in RCA and ends with a description of various factors associated with failure prevention.

Statistical techniques provide the design engineer with a powerful tool for the analysis of failure data. By means of an actual case study, steps required to design a test yielding statistically meaningful data and procedures used in graphical analysis of results are presented. The Weibull distribution is the statistical model used as a basis for these techniques. This method of failure analysis provides the engineer with clear, positive design direction.

The intent of this article is to assist the failure analyst in understanding the underlying engineering design process embodied in a failed component or system. It begins with a description of the mode of failure. This is followed by a section providing information on the root cause of failure. Next, the article discusses the steps involved in the engineering design process and explains the importance of considering the engineering design process. Information on failure modes and effects analysis is also provided. The article ends with a discussion on the consequence of management actions on failures.

This article briefly introduces the concepts of failure analysis and root cause analysis (RCA), and the role of failure analysis as a general engineering tool for enhancing product quality and failure prevention. It reviews four fundamental categories of physical root causes, namely, design deficiencies, material defects, manufacturing/installation defects, and service life anomalies, with examples. The article describes several common charting methods that may be useful in performing an RCA. It also discusses other failure analysis tools, including review of all sources of input and information, people interviews, laboratory investigations, stress analysis, and fracture mechanics analysis. The article concludes with information on the categories of failure and failure prevention.

Suspension lugs fabricated from AISI 4340 steel used to facilitate loading of bombs onto the underside of military aircraft could not sustain required loads during routine proof load testing. Three failed lugs underwent visual examination, chemical analysis, metallography, hardness testing, scanning electron microscopy, and energy-dispersive x-ray spectroscopy. It was determined that the failures were due to forging defects. Both forging laps and seams acted as stress concentrators when the lugs were loaded during proof testing.

Corrosion in potable and nonpotable water systems has been well documented in the past, and new research discusses innovations in water treatment and materials that are designed to enhance the quality of a water system, whether commercial or residential. This paper is a collection of five case histories on the failure of copper and steels as used in potable and non-potable water systems. The case histories cover a range of applications in which copper and steel products have been used. Copper and steel pipes are the two most commonly used materials in residential, commercial and industrial applications. The projects that are discussed cover these three important applications. The purpose of presenting this information is to allow the reader to gain an understanding of real life corrosion issues that affect plumbing materials, how they should have been addressed during the design of the water system, and how a water system should be maintained during service. We share this information in the hope that the reader will gain some limited knowledge of the problems that exist, and apply that knowledge in designing or using water systems in day-to day life.

Cracking was found in the heads on large Yankee dryers, large, cylindrical, rotating, pressurized, high-temperature, cast iron pressure vessels (ASME Boiler and Pressure Vessel Code Section VIII, Rules for Construction of Pressure Vessels), used to remove moisture from sheets of tissue paper during manufacturing. The typical components consist of a cast iron shell, two cast iron concave heads, and a large cast iron internal center stay attached to journals. The heads are attached to the shell and center stay with high-strength bolts. FEA and metallurgical investigation supported the conclusion that the cracking was caused by an unexpected type of load placed on the machine, namely corrosion product buildup at the head/shell interface causing the joint to displace open. It was also found that compressive bolting loads could slightly open the head/shell interface at the periphery. Recommendations included design changes in the head/shell joint, and detailed preventive maintenance inspection procedures were also suggested.

Sheet forming failures divert resources from normal business activities and have significant bottom-line impact. This article focuses on the formation, causes, and limitations of four primary categories of sheet forming failures, namely necks, fractures/splits/cracks, wrinkles/loose metal, and springback/dimensional. It discusses the processes involved in analytical tools that aid in characterizing the state of a formed part. In addition, information on draw panel analysis and troubleshooting of sheet forming failures is also provided.

In the EMD-2 Joint Directed Attack Munition (JDAM), the A357 aluminum alloy housing had been redesigned and cast via permanent mold casting, but did not meet the design strength requirements of the previous design. Mechanical tests on thick and thin sections of the forward housing assembly revealed tensile properties well below the allowable design values. Radiology and CT evaluations revealed no casting defects. Optical microscopy revealed porosity uniformly distributed throughout the casting on the order of 0.1 mm pore diam. Scanning electron microscopy revealed elongated pores, which indicated turbulent filling of the mold. Spherical pores would have indicated the melt had been improperly degassed. Based on these findings, it was recommended that the manufacturer analyze and redesign the gating system to eliminate the turbulent flow problem during the permanent mold casting process.

This article provides an overview of metal additive manufacturing (AM) processes and describes sources of failures in metal AM parts. It focuses on metal AM product failures and potential solutions related to design considerations, metallurgical characteristics, production considerations, and quality assurance. The emphasis is on the design and metallurgical aspects for the two main types of metal AM processes: powder-bed fusion (PBF) and directed-energy deposition (DED). The article also describes the processes involved in binder jet sintering, provides information on the design and fabrication sources of failure, addresses the key factors in production and quality control, and explains failure analysis of AM parts.

A multi-million dollar, four-color printing press used to produce a major weekly magazine was breaking pinions (shouldered shafts) on rolls. The cause of fracture was cyclic fatigue. Steel quality and heat treatment met expected standards. The pinion fracture showed multiple origins indicating rotational vibration fatigue. Keeping bolts tight solved this problem. In another case, grinding machines were unable to produce surfaces of uniform quality and smoothness on steel bearing products. Measurements showed that self-excited vibrations were created when particular steels were ground. It was found that the natural frequency of the wheel truing device was the culprit. A tuned damped absorber was designed and built to modify the resonance. This eliminated the problem.

Aircraft missile launcher attachment bolts fabricated from cadmium-coated Hy-tuf steel were found broken. Subsequent analysis of the broken bolts indicated three causes of failure. First, the bolts had been carburized, which was not in conformance with the heat treating requirements. Second, macroetching showed that the bolts has been machined from stock rather than forged, and the threads cut rather than rolled. It was also determined that hydrogen-assisted stress-corrosion cracking also played a part in the failure of the high-strength bolts.

A 10-in. diam, spiral-welded AISI 1020 carbon steel pipe carrying water under pressure developed numerous leaks over a four mile section. The section was fabricated using submerged-arc welding from the outside surface. Each welded length of pipe had been subjected to a proof pressure approximately twice the specified design pressure and two-thirds the approximate yield point of the parent metal. No failures or leakage were observed during proof testing. Metallurgical examination corroborated visual checks, indicating a distinct lack of root penetration in the split areas. Splitting occurred as a result of inadequate root penetration. The most likely source of difficulty in the welding process was the linear speed. Probably, the failures would not have occurred in absence of the welding problem. Also, the pipe was inadequate for the specified design pressure, as well as the reported maximum system pressure.

Some corrosion processes in the presence of chlorides, for steel embedded in concrete, are described and illustrated with the aid of scanning electron microscope EDXA data. Observations made of failure surfaces of reinforcements removed from the concrete beams after being subjected to sinusoidal load fluctuations at 6.7 Hz in air, 3% NaCl solution, and natural sea water are described. Reinforcement types studied included: hot-rolled mild steel bar, hot-rolled alloyed high strength bar, cold-worked high strength bar, galvanized bar of all these three types, nickel-clad bar and epoxy-coated bar.