Additive manufacturing (AM) offers expansive design freedoms for realizing parts that are more complex and customized than their conventionally fabricated counterparts, but all AM technologies impose restrictions on buildable geometries and features. Design rules capture those restrictions in the form of best practices to successfully design for AM. This article discusses how design rules can potentially support and accelerate the process of developing part geometry for AM. The discussion provides examples of design rules that are independent of any specific AM process and then discusses design rules specific to particular AM processes.

Additive manufacturing (AM) provides exceptional design flexibility, enabling the manufacture of parts with shapes and functions not viable with traditional manufacturing processes. The two paradigms aiming to leverage computational methods to design AM parts imbuing the design-for-additive-manufacturing (DFAM) principles are design optimization (DO) and simulation-driven design (SDD). In line with the adoption of AM processes by industry and extensive research efforts in the research community, this article focuses on powder-bed fusion for metal AM and material extrusion for polymer AM. It includes detailed sections on SDD and DO as well as three case studies on the adoption of SDD, DO, and artificial-intelligence-based DFAM in real-life engineering applications, highlighting the benefits of these methods for the wider adoption of AM in the manufacturing industry.

This article provides an introduction to architected cellular materials, their design, fabrication, and application domain. It discusses design decisions involving the selection, sizing, and spatial distribution of the unit cell, property-scaling relationships, and the integration of cells within an external boundary. It describes how manufacturing constraints influence achievable feature resolution, dimensional accuracy, properties, and defects. It also discusses the mechanical behavior of architected cellular materials and the role of additive manufacturing in their fabrication.

Additive manufacturing (AM) processes fabricate parts in a layer-by-layer manner by which materials are added and processed repeatedly. This article introduces the general concepts and approaches to design for AM (DFAM) and outlines important implications for part characteristics, design opportunities, manufacturing practices, supply chains, and even business models. It presents contrasting perspectives on DFAM, followed by a discussion on more general and overarching opportunistic design methods and on design for constraints, similar to conventional DFM. It concludes with a presentation of a design approach to the AM process chain, acknowledging that AM-fabricated parts typically undergo several postprocessing steps and that it is important to design taking into account these steps.

This article focuses on two streams of the research on part consolidation (PC): PC in the conventional manufacturing context, and PC in the additive manufacturing (AM) context. It reviews the challenges of applying AM-PC potentials. The article includes research literature on the selection of part candidates for consolidation and summarizes the conversion of assembly design to consolidated design. Then, a holistic approach for supporting PC design is introduced with integrated modules of part filtering and fusion of parts. Details of the key techniques of the two modules are later introduced with a gas pedal example. Finally, emerging trends in PC research are discussed.

This article discusses the operating principles, advantages, and limitations of scanning electron microscopy, atomic force microscopy, x-ray photoelectron spectroscopy, and secondary ion mass spectroscopy that are used to analyze the surface chemistry of plastics.

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 scanning electron microscope (SEM) is one of the most versatile instruments for investigating the microscopic features of most solid materials. The SEM provides the user with an unparalleled ability to observe and quantify the surface of a sample. This article discusses the development of SEM technology and operating principles of basic systems of SEM. The basic systems covered include the electron optical column, signal detection and display equipment, and the vacuum system. The processes involved in the preparation of samples for observation using an SEM are described, and the application of SEM in fractography is discussed. The article covers the failure mechanisms of ductile failure, brittle failure, mixed-mode failure, and fatigue failure. Lastly, image dependence on microscope type and operating parameters is also discussed.

Powder-bed additive manufacturing (AM) processes are some of the most commonly used techniques, necessitating the accurate measurement of powder flowability properties. This article discusses some powder flow tests that occur in powder-bed AM machines. These include the Hall/Carney flow test, bulk/tap density, rheometer, and the revolving or rotating drum technique. The three categories of powder properties that are available from rheometer experiments are discussed: bulk, dynamic flow, and shear properties. The article also describes the basic principles and applications of micro-X-ray computed tomography in studying powder porosity characteristics nondestructively.

This article provides detailed information on the instrumentation and principles of the scanning electron microscope (SEM). It begins with a description of the primary components of a conventional SEM instrument. This is followed by a discussion on the advantages and disadvantages of the SEM compared with other common microscopy and microanalysis techniques. The following sections cover the critical issues regarding sample preparation, the physical principles regarding electron beam-sample interaction, and the mechanisms for many types of image contrast. The article also presents the details of SEM-based techniques and specialized SEM instruments. It ends with example applications of various SEM modes.

Transmission electron microscopy (TEM) approach enables essentially simultaneous examination of microstructural features through imaging from lower magnifications to atomic resolution and the acquisition of chemical and crystallographic information from small regions of the thin specimen. This article discusses fundamentals of the technique, especially for solving materials problems. Background information is provided to help understand basic operations and principles, including instrumentation, the physics of signal generation and detection, image formation, electron diffraction, and spectrometry techniques with data analysis.

This article is a detailed account of the principles of electron-excited X-ray microanalysis. It begins by discussing the physical basis of electron-excited X-ray microanalysis and the advantages and limitations of energy dispersive spectrometry (EDS) and wavelength dispersive spectrometry for electron probe microanalysis. Key concepts for performing qualitative analysis and quantitative analysis by electron-excited X-ray spectrometry are then presented. Several sources that lead to measurement uncertainties in the k-ratio/matrix corrections protocol are provided, along with the significance of the raw analytical total. Sections on accuracy of the standards-based k-ratio/matrix corrections protocol with EDS and processes of analysis when severe peak overlap occurs are also included. The article provides information on low-atomic-number elements, iterative qualitative-quantitative analysis for complex compositions, and significance of standardless analysis in the EDS software. It ends with a section on the processes involved in elemental mapping for major and minor constituents.

This article is intended to provide the reader with a good understanding of the underlying science, technology, and the most common applications of focused ion beam (FIB) instruments. It begins with a survey of the various types of FIB instruments and their configurations, discusses the essential components, and explains their function only to the extent that it helps the operator obtain the desired results. An explanation of how the components of ion optical column shape and steer the ion beam to the desired target locations is then provided. The article also reviews the many diverse accessories and options that enable the instrument to realize its full potential across all of the varied applications. This is followed by a detailed analysis of the physical processes associated with the ion beam interacting with the sample. Finally, a complete survey of the most prominent FIB applications is presented.

This article provides an overview of scanning probe microscopes (scanning tunneling microscope and atomic force microscope (AFM)), covering the various operating modes and probes used in these instruments and providing information on AFM instrumentation, applications, and analyses.

This article focuses on laboratory atomic force microscopes (AFMs) used in ambient air and liquid environments. It begins with a discussion on the origin of AFM and development trends occurring in AFM. This is followed by a section on the general principles of AFM and a comprehensive list of AFM scanning modes. There is a brief description of how each mode works and what types of applications can be made with each mode. Some of the processes involved in preparation of samples (bulk materials and those placed on a substrate) scanned in an AFM are then presented. The article provides information on the factors applicable to the accuracy and precision of AFM measurements. It ends by discussing the applications for AFMs in the fields of science, technology, and engineering.

This article discusses the fundamentals and operating principles of the following acoustic microscopy methods: scanning laser acoustic microscopy, C-mode scanning acoustic microscopy, and scanning acoustic microscopy. It describes the applications of acoustic microscopy for detecting defects in metals, ceramics, glasses, polymers, and composites with examples.

This article provides an overview of the characteristics of Rayleigh waves plus methods for generation and detection of waves, including using piezoelectric transducers or noncontact techniques such as lasers, electromagnetic acoustic transducers, or air-coupled ultrasonics. It reviews the methods for using Rayleigh waves for defect detection and materials characterization, alongside nonlinear ultrasonic inspection and surface acoustic wave (SAW) microscopy. The article concludes with information on the standards that use Rayleigh waves for nondestructive evaluation (NDE) of different structures.

This article first describes surface forces, and the methods of measuring them, followed by a discussion on adhesion. It discusses the instrumental requirements and techniques, including Atomic Force Microscopy (AFM), used for the measurement of surface forces. Measurements of surface roughness, with AFM, can provide a precise picture of surface roughness and can be used as input for contact mechanics computer models. The article also describes microscale adhesion and adhesion measurement methods using microelectromechanical systems technologies. It reviews certain considerations used for the measurement of adhesion, such as fundamental adhesion measurements, history dependence and sample preparation, and practical adhesion measurements. The article describes various arrangements that can be employed in adhesion tests.

This article describes the determination of wear loss by measuring either mass change or dimensional change of lubricants and materials. It discusses the principles, advantages and disadvantages of mass loss measures and dimensional measures of wear. The article details wear measurement at the nanoscale, such as atomic force microscopy (AFM) measurement and scanning electron microscopy measurement. It reviews the techniques of wear measurement at the atomic level, namely, transmission electron microscopy (TEM) measurement and AFM combined with TEM measurement.