Search Results for meshed-solution method

There are numerous approximate methods, both analytical and numerical, for analyzing forging processes. None are perfect because of the assumptions made to simplify the mathematical approach, but all have merit. This chapter discusses the slab, upperbound, and finite element methods, covering basic principles, implementation, and advantages and disadvantages in various applications.

This chapter provides an overview of how the disciplines of design, material, and manufacturing contribute to engineering for functional performance. It describes the interaction of product designers and casting engineers in product development. It discusses the consequences of component failure, uncertainty in data and assumptions, and selection of the factor of safety. The chapter also presents an overview of the functional requirements for product performance and provides an overview of product design development. It also presents a partial list of the different tests that are performed on prototypes and examples of product testing. The chapter describes the requirements of a traceability system.

This chapter describes some of the processes used to concentrate beryllium-rich minerals from ores. It discusses the flotation of bertrandite and phenacite from calcite, mica, fluorspar, and quartz-containing ores, the flotation of beryl from pegmatitic gangues and low-grade deposits, and the use of chemical activators and conditioning agents. It also explains that hand sorting is still very common because of processing challenges and inefficiencies.

This article describes in detail the process of corrosion control by cathodic and anodic protection. The discussion covers the basic concept of cathodic and anodic protection systems, their types and equipment used, and the advantages, limitations, and applications of these protection systems. The types of cathodic protection systems include sacrificial cathodic protection and impressed-current cathodic protection systems. Some of the technical problems associated with cathodic protection include the effects of stray currents on the corrosion of adjacent metal structures, the effects of the chemical reactions occurring at the surface of the protected structure, and the effects of cathodic protection on coatings.

This chapter describes some of the chemical processes that have been developed to extract beryllium from different types of ore. It covers the Kjellgren-Sawyer sulfate method, the Degussa method, Copaux-Kawecki fluoride extraction, solvent extraction, and leaching and settling. It also provides information on electrolytic extraction and the use of electrorefining.

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.

Aluminum shapes, rod, bar, tubes, and wire may be produced directly as extrusions or by subsequent processing of continuous cast stock. This chapter describes the key aspects of aluminum extrusion and wire production focusing on the more common hot extrusion process and presenting the general types of aluminum extrusion alloys. An overview of free-machining alloys and products, and weldable 6xxx and 7xxx high-strength structural alloys is also provided.

Increasing growth of high-pressure cold spraying applications on the industrial scale have forced global powder producers to face this challenge and develop specific powders for cold spray applications. This chapter provides information on the properties, classification, characteristics, manufacturing, and procedures for packaging of powders specific to cold spray applications.

This appendix is a compilation of terms and definitions associated with the processing, microstructure, and properties of powder metal stainless steels.

This chapter discusses the use of modeling and simulation technology in the development of sheet metal forming processes. It describes the five major steps involved in finite-element analysis and the various ways functions of interest can be approximated at each point or node in a finite-element mesh. It explains how to obtain input data, what to expect in terms of output data, and how to predict specific types of defects. In addition, it presents several case studies demonstrating the use of finite elements in blanking and piercing, deep drawing of round and rectangular cups, progressive die sequencing, blank holder force optimization, sheet hydroforming, hot stamping, and springback and bending of advanced high-strength steels. It also discusses the factors that affect the accuracy of finite element simulations such as springback, thickness variations, and nonisothermal effects.

The need for precise targeted interactive surgery on boards or modules is the main driver of backside preparation technology. This article assists the analyst in making decisions on backside thinning and polishing requirements. Thinning of the substrates can be accomplished by flat lapping, laser assisted chemical etch, plasma reactive ion etch, and CNC based milling and polishing. The article discusses the general characteristics, key principles, advantages, and disadvantages of these processes. It also contains case studies that illustrate the application of these processes to ceramic cavity devices, injection molded parts, and ball grid arrays.

Gearbox vibrations are classified as synchronous or nonsynchronous depending on whether or not they are related to the rotational speed of an internal or connected component. This chapter presents a turbogenerator case study that demonstrates the source of nonsynchronous vibration. It then provides a detailed discussion on spiking vibrations and presents design improvement and reduction of spiking vibrations.

Gearbox vibrations can often be dealt with in the field by modifying, replacing, and repositioning components and adjusting operating conditions and control parameters. Every gearbox design, however, eventually reaches a point where problems due to vibration are not so easily addressed. This chapter discusses such a case, that of an epicyclic reducer plagued by subsynchronous vibration, and explains how the gearbox was redesigned, improving lifetime as well as efficiency.

This chapter reviews the fundamentals of stress, strain, and deformation and demonstrates some of the tools and techniques used to analyze how materials and structures respond to tension, compression, bending, and shear. It begins with an overview of the behavior of perfectly elastic and plastic materials and viscous substances. It then describes the stress-strain response of two- and three-dimensional solids, explaining how to determine principle stresses and strains using Mohr’s circle and how to derive equivalent stress and strain using the von Mises relationship. It then goes on to analyze the stress state of load-bearing members, pressurized tubes, and pin-loaded lugs, accounting for the effect of geometric discontinuities, such as cutouts, fillets, and holes, as well as cracks. It also explains how finite element methods are used to solve problems involving complex geometric and loading conditions.

Mechanical tests are performed to evaluate the durability of gears under load. The chapter first discusses the processes involved in the computations of stress for test parameters of gear. Next, the chapter reviews the four areas of specimen characterization of a test program, namely dimensional, surface finish texture, metallurgical, and residual stress. The following section presents the tests that simulate gear action, namely the rolling contact fatigue test, the single-tooth fatigue test, the single-tooth single-overload test, and the single-tooth impact test. Finally, the chapter describes the test procedures for surface durability (pitting), root strength (bending), and scoring (or scuffing) testing.

This chapter introduces the key powder fabrication attributes to assist in the identification of the right powders for an application. First, it describes the characteristics of engineering powders such as particle size distribution, powder shape and packing density, surface area, powder flow and rheology, and chemical analysis. The chapter then describes the general categories of powder fabrication methods, namely mechanical comminution, electrochemical precipitation, thermochemical reaction, and phase change and atomization. It provides information on the two largest contributors to powder price, namely raw material cost and conversion cost. The applicability of various processes to specific material systems is mentioned throughout this chapter.

Cleaning procedures serve to remove scale, tarnish films, and other contaminants that form or are otherwise deposited on the surface of titanium during processing operations such as hot working and heat treatment. This chapter explains what makes titanium susceptible to the formation of scale and how it can be removed via belt grinding, abrasive blasting, and molten salt descaling baths. It also discusses the role of acid pickling, barrel finishing, polishing, and buffing as well as the use of chemical conversion coatings and protective platings.

The cyclic nature of gearbox vibration lends itself well to the analysis in the frequency domain where the effects of a gear mesh, bearing defects, and other sources of vibration are effectively set apart, making it much easier to identify and correct the underlying causes of vibration. This chapter presents spectral maps that show how gearbox vibrations change with the rotational speed of components. It then explains how to identify the sources of vibration in a high-speed gearbox. The chapter also discusses other errors including backlash, ghost frequencies, unbalance, misalignment, mechanical looseness, and index variation form errors. It also presents the calculation of gear frequencies on gearbox vibration spectra and the influence of operating conditions.

This chapter explains how to prepare metallographic samples for light microscopy and how to anticipate and avoid related problems. It describes standard practices and procedures for sectioning, mounting, grinding, and polishing and identifies common defects along with their causes and cures. It also provides recommendations for handling specific materials and addresses safety concerns.

Gas turbine disks made from nickel-base superalloys are often produced using powder metallurgy (P/M) techniques because the alloy compositions normally used are difficult or impractical to forge by conventional methods. This chapter discusses the P/M process and its application to superalloys. It describes the gas, vacuum, and centrifugal atomization processes used to make commercial superalloy powders. It explains how the powders are consolidated into preforms or billets using hot isostatic pressing, extrusion, or a combination of the two. It also provides information on spray forming and consolidation by atmospheric pressure, and includes a section on powder-based disk components, where it discusses the general advantages of P/M as well as the effects of inclusions, carbon contamination, and the formation of oxide and carbide films due to prior particle boundary conditions. The chapter concludes with a detailed discussion on mechanically alloyed superalloy compositions, the product forms into which they are made, and some of the applications where they are used.