The article provides an overview of the various types of testing machines: gear-driven or screw-driven machines and servohydraulic machines. It examines force application systems, force measurement, and strain measurement. The article discusses important instrument considerations and describes gripping techniques of test specimens. It analyzes test diagnostics and reviews the use of computers for gathering and reducing data. Emphasis is placed on universal testing machines with separate discussions of equipment factors for tensile testing and compressing testing. The influence of the machine stiffness on the test results is also described, along with a general assessment of test accuracy, precision, and repeatability of modern equipment.

Ultrasonic additive manufacturing (UAM) is a solid-state hybrid manufacturing technique that leverages the principles of ultrasonic welding, mechanized tape layering, and computer numerical control (CNC) machining operations to create three-dimensional metal parts. This article begins with a discussion on the process fundamentals and process parameters of UAM. It then describes metallurgical aspects in UAM. The article provides a detailed description of a wide range of mechanical characterization techniques of UAM, namely tensile testing, peel testing, and pushpin testing. The article ends with information on sensor embedding.

This article discusses the installation of the most commonly used force-monitoring devices, namely, load cells and piezoelectric force sensors. It describes the purpose and operation of commonly used displacement sensors, such as linear variable differential transformers, proximity sensors, photoelectric sensors, and ultrasonic sensors. The article provides information on the sensors used for detecting tool breakages and flaws in parts, the measurement of material flow during sheet metal forming, and lubrication. It also describes the operating stages of machine vision systems used for automated quality-control purposes. The theory of eddy-current-based material properties evaluation is also discussed.

Additive manufacturing (AM) has been growing as a significant research interest in academic and industry research communities. This article presents flexible and biocompatible energy-harvesting devices using AM technology. First, it discusses material selection for achieving piezoelectricity and triboelectricity. Then, the article highlights the structures of energy harvesters and describes their working mechanisms. Next, it covers the additively manufactured implantable piezoelectric and triboelectric energy harvesters. Further, the article describes the 3D-printed wearable energy harvesters as well as their applications. An overview of additively manufactured self-powered sensors is highlighted. Finally, the article discusses the issues for 3D-printed energy harvesters and their roadmap.

This article discusses the attempts made by the industry to create sensing approaches for modeling a process, part, and chemistry and kinetics. It reviews microwave curing of thick-section composites and the resin cure sensors that are used for resin cure monitoring. These include dielectric cure sensors, fiberoptics-based resin cure sensors, ultrasonics-based resin cure sensors, and dosimetry-based resin cure sensors. The article provides information on the resin cure control flow sensing, flow modeling, flow mapping, and resin flow. It addresses some practical issues in sensing resin cure and flow.

THE TENSION TEST is one of the most commonly used tests for evaluating materials. The material characteristics obtained from tension tests are used for quality control in production, for ranking performance of structural materials, for evaluation of alloys, and for dealing with the static-strength requirements of design. This article describes the stress-strain behavior during a tension test and provides the definition of terms such as stress, force, strain, and elongation. It explains the tensile properties obtained from the test results: the tensile strength and yield strength, which includes offset yield strength, extension-under-load yield strength, and upper yield strength. The article concludes with a description of the general procedures for conducting the tension test based on ASTM standards and the variability of tensile properties.

Additive manufacturing (AM) has been adopted as one of the most versatile and rapid design-to-manufacturing approaches for printing a wide range of two- and three-dimensional parts, devices, and complex geometries layer by layer. This article provides insights into the current progress, challenges, and future needs of AM of electronics from the space, defense, biomedical, energy, and industry perspectives.

Acoustic-emission inspection detects and analyzes minute acoustic-emission signals generated by discontinuities in materials under applied stress. This article discusses the types of acoustic emissions (continuous-type emissions and burst-type emissions) and applications, including laboratory testing, production testing, and structural testing. The article includes a section in which the characteristics of acoustic emission inspection are compared with other nondestructive testing methods. Further, it briefly reviews the key elements of the acoustic-emission instrumentation, which includes the acoustic-emission resonant sensor.

Additive manufacturing (AM) is a revolutionary technology that fabricates parts layerwise and provides many advantages. This article discusses polymer AM processes such as material extrusion, vat photopolymerization (VPP), powder-bed fusion (PBF), binder jetting (BJ), material jetting (MJ), and sheet lamination (SL). It presents the benefits of online monitoring and process control for polymer AM. It also introduces the respective monitoring devices used, including the models and algorithms designed for polymer AM online monitoring and control.

This article focuses on the methods that are being developed for detecting and monitoring corrosion: electrochemical methods, electromagnetic or sound wave methods, fiber-optic technology, fluorescence methods, and the Diffracto Sight method. It reviews the importance of data management and the Corrosion Expert System. It concludes with information on the simulation and modeling for incorporating the mechanisms of corrosion prevention into military hardware systems design and operation.

Aerosol jet printing (AJP) can digitally fabricate intricate patterns on conformal surfaces with applications that include flexible electronics and antennas on complex geometries. Given the potential performance and economic benefits, aerosol jetting was studied and compared with the well-known and competing inkjet printing (IJP). More than 35 of the most relevant, highly cited articles were reviewed, focusing on applications requiring fine features on complex surfaces. The following performance indicators were considered for the comparison of AJP and IJP, because these aspects were the most commonly mentioned within the included articles and were identified as being the most relevant for a comprehensive performance assessment: printing process, line width, overspray, complex surface compatibility, diversity of printable materials, and deposition rate. This article is an account of the results of this comparison study in terms of printing capabilities, ink requirements, and economic aspects.

Acoustic emission is the generation of stress waves by sudden movement in stressed materials. This article begins with a comparison of acoustic emission from most other nondestructive testing (NDT) methods, and discusses the range of applicability of acoustic emission. It describes the instrumentation principles of acoustic emission and reviews the role of acoustic emission in materials studies. The article illustrates the testing of metal-matrix composites (MMCs) using acoustic emission and the use of acoustic emission inspection in production quality control. It concludes with information on the structural test applications of acoustic emission inspection to find defects and to assess or ensure structural integrity.

Value analysis (VA) is a team problem-solving process to improve the value of a product from the viewpoint of a user. This article presents a comparison between VA and total quality management in materials selection and design. It discusses the key attributes, concepts, and activities of the VA. The application of value engineering in U.S. government contracts and the construction industry is reviewed. The article describes the eight phases of the VA process: preparation, information, analysis, creation, synthesis, development, presentation and report, and implementation and follow-up. It presents case studies that illustrate the materials-related aspects of the VA process.

This article provides a discussion on the mechanical properties of metals, ceramics, and polymers and fiber-reinforced polymer composites at low temperatures. It reviews the factors to be considered in tensile and compression testing of these materials. The article details the equipment used for low-temperature tensile and compression tests with illustrations. It concludes with a discussion on the various test methods and their ASTM standard for compression and tension testing.

In-process tool monitoring systems can electronically detect excessive tool wear or warn of impending tool failure to lessen machine downtime and prevent the production of out-of-tolerance parts. This article discusses the sensing technology available for manufacturing applications, as wells as the advantages and disadvantages of this technology. It describes the roles of the three basic elements to any modern sensing system: sensing source, signal amplifier, and microprocessor or translator. The article reviews two case studies from two different ends of the metal removal spectrum, broaching and drilling, to emphasize the cost effectiveness of using a tool condition monitoring system.

This article provides an overview of cavitation erosion with a specific focus on the estimation of mass loss. It describes the mechanisms of cavitation erosion and the types of laboratory devices to evaluate the resistance to cavitation erosion of materials. The laboratory devices include rotating disks, vibratory devices, cavitating liquid jets, and high-speed cavitation tunnels. The article discusses materials selection and surface protection to prevent cavitation erosion. It reviews the fluid-structure interaction that plays a role in cavitation erosion particularly for compliant materials. The article provides information on the numerical prediction of cavitation erosion damage by the finite element method (FEM).

This article describes the techniques for measuring friction, namely, inclined-plane method; friction test methods using weights and pulleys; friction tests of shafts and capstans; other types of friction tests, including standards; microscale friction tests; and friction testing under well-lubricated conditions. The procedural considerations that should be addressed to ensure that valid data are derived from a friction test are discussed. The article explains friction testing geometries, the major considerations implicit in their use as well as friction test parameters, such as speed and load. It also demonstrates how to report friction data and how these data can be entered into a database.