Search Results for randomized block experiments

After the failure analysis team hypothesizes failure causes, prepares a failure mode assessment and assignment, and evaluates all potential failure causes, it may find in some cases that several causes are still suspect but cannot be confirmed. In this situation, an experiment is necessary to confirm or rule out suspected causes. This chapter discusses two predominant methods for doing this, namely analysis of variance (ANOVA) and Taguchi methods (a more powerful technique based on ANOVA).

This article provides an introduction to the dynamic random access memory (DRAM) operation with a focus to localization techniques of the defects combined with some physical failure analysis examples and case studies for memory array failures. It discusses the electrical measurement techniques for array failure analysis. The article then presents know-how-based analysis techniques of array failures by bitmap classification. The limits of bitmapping that lead to well-known localization techniques like thermally induced voltage alteration and optical beam induced resistance change are also discussed. The article concludes by providing information on soft defect localization techniques.

Fatigue life analysis and crack growth life prediction require an accurate interpretation of the load spectrum. This appendix presents two methods for interpreting load spectra and provides several data plots and tables comparing fatigue test data with analytically predicted values.

This article describes the most common, general-purpose analog design-for-test (DFT) methods, analog test buses and loopback, and shows their advantages and limitations in diagnosability and automatability. It also describes DFT and built-in self-test (BIST) techniques for the most common analog functions, namely phase-locked loop, serializer-deserializer, analog/digital converters, and radio frequency. Lastly, the challenges of creating BIST for analog functions are summarized, along with seven principles that must be exploited to meet these challenges. These principles show how the design constraints for analog BIST circuitry can be more relaxed than for the circuit under test, while delivering the required test accuracy and speed.

Powder metallurgy plays a central role in the production of nearly all beryllium components. This chapter describes the primary steps in the powder metal process and the work that has been done to improve each one. It explains how beryllium powders are made and how they are consolidated prior to sintering. It also compares and contrasts the properties of beryllium products made using different methods and provides composition and particle size data on commercially available powders.

Unlike metals, in which fatigue failures are due to a single crack that grows to a critical length, the effects of fatigue in composites are much more distributed and varied. As the chapter explains, there are five major damage mechanisms that contribute to the progression of composite fatigue, those being matrix cracking, fiber breaking, crack coupling, delamination initiation, and delamination growth. The chapter describes each mechanism in detail along with related factors. It also discusses the primary differences between composites and metals, the effect of manufacturing defects, damage tolerance, and testing and certification.

This chapter discusses design and certification considerations, including materials and process selection, the building block approach to certification, design allowables, and design guidelines. It also includes information on damage tolerance and environmental sensitivity.

This chapter provides a practical overview of the tools and techniques used to assess the tribological aspects of metal forming processes. It describes test methods that have been developed to evaluate bulk deformation and sheet metal forming processes along with lubricant rheology, friction forces, and stress and strain distributions. It explains how to measure temperature between tooling and workpiece surfaces as well as surface topography and composition, film thickness, and wear. It also discusses the benefits of reduced-scale and simulation testing and the transfer of results from one process to another.

The vast majority of beryllium products are manufactured from blocks, forms, or billets of compacted powder that are machined or worked into shape. This chapter describes the metalworking processes used, including rolling, forming, forging, extrusion, drawing, and spinning. It covers the qualitative and quantitative aspects of each process and provides examples showing how they are implemented and the results that can be achieved. The chapter also discusses the issue of beryllium’s low formability and describes some of the advancements that have been made in near-net shape processing.

This chapter discusses the processes and procedures involved in tribotesting, the significance of test parameters and conditions, and practical considerations including test metrics and measurements and the interpretation of wear damage. It also describes the different types of erosion tests in use and common approaches for adhesive wear and abrasion testing.

This chapter provides an overview of a computational method, called CALPHAD, used for the study of phase equilibria in multicomponent systems. It describes the thermodynamic models and calculation techniques employed in the software and explains how it applies to complex alloys used in industry. It also provides examples showing how CALPHAD has been used to determine the formability of metallic glass, calculate the dilation of stainless steel during phase transformation, and predict the beta transus and approach curves of commercial titanium alloys.

This chapter discusses the various factors pertinent to gravity permanent mold (GPM) castings, along with their advantages, limitations, and significance. The discussion covers the geometric factors, process and manufacturing elements, gating practices, and feeding principles of and pouring systems in GPM. The influences of mold coatings on GPM and low pressure permanent mold castings are described. The chapter also discusses various processes involved in the engineering of core boxes and cooling of GPM for casting integrity and cycle time control. It provides information on some of the processes involved in post-casting operations, namely de-coring and de-gating. The key design aspects for consideration in water quenching during the T6 heat treatment are reviewed. The chapter also provides information on two critical cycle events important in engineering at the manufacturing facility: tipper cycle planning and table or cell cycle planning.

In forgings of both ferrous and nonferrous metals, the flaws that most often occur are caused by conditions that exist in the ingot, by subsequent hot working of the ingot or the billet, and by hot or cold working during forging. The inspection methods most commonly used to detect these flaws include visual, magnetic particle, liquid penetrant, ultrasonic, eddy current, and radiographic inspection. This chapter provides a detailed discussion on the characteristics, process steps, applications, advantages, and limitations of these methods. It also describes the flaws caused by the forging operation and the principal factors that influence the selection of a nondestructive inspection method for forgings.

Composite systems for cryogenic applications are discussed in this chapter. This chapter emphasizes filamentary-reinforced composites because they are the most widely used composite materials. It begins with a discussion on the approach to designing and fabricating with low-pressure laminate composites. This is followed by a section providing an overview of the materials in modern cryogenic technology. Then, the chapter describes the effect of cryogenic temperatures on materials properties; it also introduces the various joining techniques developed for composite materials. The effects of radiation on the properties of the materials are covered as well as the processes involved in testing laminates at cryogenic temperatures. Finally, the chapter provides information available on concrete aggregate composites.

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 some of the technological milestones of the early 20th century, including the invention of tungsten carbide tool steel, the use of age-hardening aluminum in the Wright Flyer , the development of a new heat treating process for aluminum alloys, and Ford’s pioneering use of weight-saving vanadium alloys in Model T cars. It explains how interest in chromium alloys spread throughout the world, spurring the development of commercial stainless steels. The chapter concludes with a bullet point timeline of early 20th century achievements and a brief assessment of more recent innovations.

This chapter provides an overview of key elements in controlling the casting process, systems to confirm the quality of outgoing components, and the steps needed to launch a novel product. The discussion also provides information on process control tools and techniques; incoming material control; process control of sand preparation and system maintenance; metallic charge materials; product quality control; and melting, metallurgical, and mechanical testing.

This chapter provides a view of magnetism in materials used at low temperatures. The discussion covers the concepts, definitions, and systems of units that are unique to the study of magnetic properties. The chapter provides a description of some of the techniques and devices used for determining magnetic properties.