Search Results for failure modes and criticality analysis

Any threat to personal safety should be regarded as a hazard and treated as such. This article discusses threats from several sources, such as kinematic/mechanical hazards, electrical hazards, energy hazards, human factors/ergonomic hazards, and environmental hazards. It describes hazard analysis in terms of failure modes and effects analysis, failure modes and criticality analysis, fault tree analysis, fault hazard analysis, and operating hazards analysis. The article examines fail-safe designs, such as fail-passive designs, fail-active designs, and fail-operational designs. It also provides information on various types of warnings, such as visual warning, auditory warnings, olfactory warnings, tactile warnings, and tastable warnings.

A sandwich structure is comprised of layered composite materials formed by bonding two or more thin facings or facesheets to a relatively thick core material. This article describes the sandwich panel failure modes. It tabulates the nomenclature and definitions for loads, geometry, and material properties. The article illustrates critical strength-check locations for a flat sandwich panel. It discusses the analysis methods formulated for flat rectangular honeycomb panels; curved sandwich panel; and for each of the various sandwich panel failure modes. The article concludes with a discussion on flat panel stability analysis methods.

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.

Risk and hazard analysis can be effectively used during design reviews to provide valuable feedback to the design to avoid failures. This article discusses the types of risks, namely, real risk, statistical risk, predicted risk, and perceived risk. It describes the principle and technical methods of risk/hazard analysis practiced in the industry to identify possible hazards and the resources necessary to avoid or reduce risks. These methods include the failure mode and effect analysis, fault tree analysis, event tree analysis, risk/benefit analysis, safety analysis, and probabilistic estimates.

Detailed analyses and test correlations are typically required to support design development, structural sizing, and certification. This article addresses issues concerning building block levels ranging from design-allowables coupons up through subcomponents, as these levels exhibit a wide variety of test-analysis correlation objectives. At these levels, enhanced analysis capability can be used most effectively in minimizing test complexity and cost while also reducing design weight and risk. The article discusses the examples of tests for which good correlative capability has shown significant benefit. These include notched (open and/or filled hole) tension and compression, inter/intralaminar shear and tension, and pin bearing.

This article addresses the issue of the implementation of composite damage tolerance requirements as it relates to military aircraft. It presents a brief introduction on the durability impact threat, damage tolerance impact threat, and other damage tolerance damage threats. The article summarizes damage tolerance criteria and durability criteria for military aircraft. It discusses the damage tolerance design philosophy for metallic structures and composite structures of the aircraft. The article describes the implementation of a damage tolerance analysis methodology in terms of the mechanics based model, the regression algorithm, and the semi-empirical analysis.

Delamination is one of the most commonly observed failure modes in composite materials. This article describes the three fundamental fracture failure modes of composite delamination, namely, opening, in-plane shearing, and tearing or scissoring shearing modes. It discusses the characterization and analysis of delamination. The article also reviews the prediction of delamination factors, such as flexbeam fatigue life, and skin/stiffener pull-off strength and life.

This article explores why structural element and subcomponent testing are conducted. It discusses the different types of failure modes in composites, and provides information on the testing methodology, fixturing, instrumentation, and data reporting. The article reviews various standard elements used to characterize composite materials for the various failure modes. Simple structural-element testing under in-plane unidirectional, multidirectional, and combined loading, as well as out-of-plane loading are discussed. Simple bolted and bonded joints, as well as data correlation are reviewed with analytical predictions. The article also provides a list of the ASTM testing standards applicable at the element level of testing for both polymer-matrix composites and metal-matrix composites. It concludes with a discussion on durability and damage tolerance testing.

This article discusses the need for design allowables, development of design allowables, and important factors that affect the selection of the allowable. It provides a comparison between lamina and laminate allowables. The article discusses laminate results and specific techniques used in the statistical development of allowable values.

The basic quality analysis tools are cause-and-effect diagrams, check sheets, control charts, histograms, Pareto charts, scatter diagrams, and run charts. This article reviews how basic quality analysis tools are built upon to become a more advanced set of quality tools. It describes the advanced quality tools: advanced product quality planning, failure mode and effects analysis, control planning, measurement systems analysis, lean tools, statistical process control, production viability and tryout, and Six Sigma.

This article is a compilation of terms related to analysis and prevention of engineering failures.

This article is a compilation of terms and definitions related to failure analysis and prevention. This glossary is intended to help promote clear thinking and useful failure analysis. The definitions presented are those used in this volume and reflect common and modern understanding of these terms as used in the literature and in reports by practicing failure analysts.

This glossary is a compilation of terms related to the analysis and prevention of component and equipment failures. It is intended to help promote clear thinking and useful failure analysis. The definitions presented are those used in this Volume and reflect a common and modern understanding of these terms as used in the literature and in reports by practicing failure analysts.

This article describes the two critical goals in a failure investigation: damage mechanisms and damage modes. It explains the determination of primary and secondary damage mechanisms and discusses the methodology used to classify the damage mechanisms.

This article presents the failure of polymer-matrix composites and the methodology for fractography. It provides a detailed discussion on the types of translaminar, interlaminar, and intralaminar failures. The article also presents a discussion on the types of fatigue failures, and the influence of composite architecture. It provides details of the fractography associated with defects and damage.

Failure analysis is an investigative process that uses visual observations of features present on a failed component fracture surface combined with component and environmental conditions to determine the root cause of a failure. The primary means of recording the conditions and features observed during a failure analysis investigation is photography. Failure analysis photographic imaging is a combination of both science and art; experience and proper imaging techniques are required to produce an accurate and meaningful fracture surface photograph. This article reviews photographic principles and techniques as applied to failure analysis, both in the field and in the laboratory. The discussion covers the processes involved in field and laboratory photographic documentations, provides a description of professional digital cameras, and gives information on photographic lighting and microscopic photography. Special techniques can be employed to deal with highly reflective conditions and are also described in this article.

The principal task of a failure analyst during a physical-cause investigation is to identify the sequence of events involved in the failure. Technical skills and tools are required for such identification, but the analyst also needs a mental organizational framework that helps evaluate the significance of observations. This article discusses the processes involved in the characterization and identification of damage and damage mechanisms. It describes the relationships between damage causes, mechanisms, and modes with examples. In addition, some of the more prevalent and encompassing characterization approaches and categorization methods of damage mechanism are also covered.