Search Results for mechanical design

This chapter introduces the basic concepts of mechanical design and its general relation with the properties derived from tensile testing. It begins with a description of the basic objective of product design. Next, a simple tie bar is used to illustrate the application of mechanical property data to material selection and design and to highlight the general implications for mechanical testing. Material subjected to the basic stress conditions is considered to establish design approaches and mechanical test methods, first in static loading and then in dynamic loading and aggressive environments. The chapter then briefly describes design criteria for some basic property combinations such as strength, weight, and costs as well as stiffness in tension. Additionally, it describes the processes involved in mechanical testing for stress at failure and elastic modulus. Finally, the chapter examines the correlation between hardness and strength.

This chapter presents an overview of some of the major causes of tool and die failures. The chapter describes fracture and fracture toughness of tool steels, and the influence of factors such as steel quality and primary processing, mechanical design, heat treatment, grinding and finishing, and distortion and dimensional change.

This chapter focuses on engineering drawings for casting production, providing information on machining and casting drawings and machining and tooling references.

In some cases, the failure analysis team finds that all components meet their requirements, the system was properly assembled, and it was not operated or tested in an out-of-specification manner, yet it still failed. When this occurs, the only conclusion the failure analysis team can reach is that it missed something in its analysis or that the design is defective. This chapter focuses on the latter possibility by discussing the various factors that a failure analysis team should consider to identify the causes of defects in system design. These include requirements identification and verification, circuit performance, mechanical failures, materials compatibility, and environmental factors. Examples that illustrate the value of design analysis are also presented.

This chapter provides a brief review of industry’s battle with fatigue and fracture and what has been learned about the underlying failure mechanisms and their effect on product lifetime and service. It recounts some of the tragic events that led to the discovery of fatigue and brittle fracture and explains how they reshaped design philosophies, procedures, and tools. It also discusses the influence of material and manufacturing defects, operating conditions, stress concentration and intensity, temperature and pressure, and cyclic loading, all of which play a role in the onset of fatigue cracking and thus should be considered when predicting useful product life.

This chapter provides an overview of factors that must be considered in the design of structural components for satisfactory service performance in terms of mechanical behavior of steel castings. The chapter discusses designing against yielding, excessive deflection, and creep and stress rupture. The chapter describes the three main approaches to evaluating and designing structures relative to fatigue resistance: the S-N curve approach for high cycle fatigue, the strain range approach for low cycle fatigue, and the fracture mechanics approach. Two approaches to design against brittle fracture are described, the ductile to brittle transition concept and the fracture mechanics approach. The chapter also discusses several types of corrosion behavior and emphasizes the need to interact with corrosion specialists in the design process. It illustrates the unique advantages that designers may gain by designing components as castings to achieve low stress concentrations economically.

This chapter gives an overview of how steel castings may be effectively adapted to modern concurrent engineering processes. The chapter discusses computer aided design programs, solid modeling, solidification simulation programs, and rapid prototyping.

This chapter provides information on the biennial International Wear of Materials Conference, which is the inspiration for this book. It reviews the fundamentals of tribology, tribosystems, and related terminology. The glossary at the end of this chapter is intended to familiarize readers with some of the fundamental tribology terms that will be repeated throughout this book.

This chapter briefly reviews the experience-based guidelines that were developed for forming and welding advanced high-strength steels (AHSS). It discusses the benefits of using HSS in car body structures and components that are analyzed by the performance indices developed for materials selection.

This appendix provides information on temper designations for strain-hardened aluminum, heat treatable aluminum alloys, and annealed aluminum products.

This chapter addresses some of the challenges involved in materials selection, providing context for much of the information presented in the book. It describes a typical four-step design scenario, noting material-related considerations and information needs. It explains how design decisions are complicated by the interconnected nature of material properties, design geometry, and manufacturing requirements and effects. The chapter also assesses the design impact of several materials and discusses codes, standards, and specifications.

The load-displacement capabilities of a mechanical press are determined largely by the design of its drive mechanism or, more precisely, the linkage through which the drive motor connects to the slide. This chapter discusses the primary types of linkages used and their effect on force, velocity, and stroke profiles. It begins by describing the simplest drive configuration, a crankshaft that connects directly to the slide, and a variation of it that uses eccentric gears to alter the stroke profile. It then discusses the effect of adding a fixed link, knuckle joint, or toggle to the slider-crank mechanism and how gear ratios, component arrangements, and other design parameters affect slide motion. The chapter also explains how to assess load and energy requirements, time-dependent characteristics, and dimensional accuracy and discusses overload protection, shutheight adjustment, and slide counterbalancing as well.

This chapter reviews the experience-based guidelines that were developed for forming and welding AHSS.

This chapter discusses the effect of friction in the context of design. It explains how friction coefficients are determined and how they are used to make sizing and selection decisions. It covers practical issues associated with rolling friction, the use of lubricants, and the tribology of metal, ceramic, and polymer surfaces in contact. It also discusses the nature of rolling friction and provides helpful design guidelines.