Search Results for impact absorbed energy

Notch toughness is an indication of the capacity of a steel to absorb energy when a stress concentrator or notch is present. The notch toughness of a steel product is the result of a number of interactive effects, including composition, deoxidation and steelmaking practices, solidification, and rolling practices, as well as the resulting microstructure. All carbon and high-strength low-alloy (HSLA) steels undergo a ductile-to-brittle transition as the temperature is lowered. The composition of a steel, as well as its microstructure and processing history, significantly affects both the ductile-to-brittle transition temperature range and the energy absorbed during fracture at any particular temperature.. Th article focuses on various aspects of notch toughness including the effects of composition and microstructure, general influence of manufacturing practices and the interactive effects that simultaneously influence notch toughness. With the exception of working direction, most of the same chemical, microstructural, and manufacturing factors that influence the notch toughness of wrought steels also apply to cast steels. The Charpy V-notch test is used worldwide to indicate the ductile-to-brittle transition of a steel. While Charpy results cannot be directly applied to structural design requirements, a number of correlations have been made between Charpy results and fracture toughness.

This article focuses on some of the factors pertinent to atomic absorption spectroscopy (AAS). It begins by describing the working principle, critical components, and construction of flame atomic absorption instrumentation. This is followed by sections discussing various types of interferences in AAS, namely vaporization, ionization, matrix interferences, and background correction. Some of the methods for the analysis of microliter-sized samples and methods of standard additions to the sample solution for generating calibration standards are then reviewed. The article concludes with a section on processes involved in matrix matching.

This article describes methods for analyzing impact-damaged composites in the aircraft industry. These include C-scan and x-radiography methods and optical microscopy. The article reviews brittle-matrix composite and tough-matrix composite failures. It explains the different types of composite failure mechanisms such as thermoplastic-matrix composite failure mechanisms, untoughened thermoset-matrix composite failure mechanisms, toughened thermoset-matrix composite failure mechanisms, dispersed-phase and rubber-toughened thermoset-matrix composite failure mechanisms, and particle interlayer-toughened composite failure mechanisms.

Paints and protective coatings are the most common means of protecting materials from deterioration. This article focuses on coating degradation that results from the environmental interaction with the coatings. The major environmental influences of the degradation include energy (solar radiation, heat and temperature variation, and nuclear radiation), permeation (moisture, solvent retention, chemical, and oxygen), stress (drying and curing, vibration, and impact and abrasion), and biological influences (microbiological and macrobiological).

Measurement and analysis of fracture behavior under high loading rates is carried out by different test methods. This article provides a discussion on the history and types of notch-toughness tests and focuses exclusively on notch-toughness tests with emphasis on the Charpy impact test. It reviews the requirements of test specimens, test machine, testing procedure and machine verification, application, and determination of fracture appearance and lateral expansion according to ASTM A370, E 23, and A 593 specifications. In addition, the article includes information on the instrumentation, standards and requirements, and limitations of instrumented Charpy impact test, which is carried out in specimens with induced fatigue precrack. The article concludes with a review of the requirements of drop weight testing and the specimens used in other notch-toughness tests.

Ultraviolet/visible (UV/VIS) absorption spectroscopy is a powerful yet cost-effective tool that is widely used to identify organic compounds and to measure the concentration of principal and trace constituents in liquid, gas, and solid test samples. This article emphasizes the quantitative analysis of elements in metals and metal-bearing ores. The instrumentation required for such applications consists of a light source, a filter or wavelength selector, and some type of visual or automated sensing mechanism. The article examines common sensing options and provides helpful information on how to set up and run a variety of UV/VIS absorption tests.

This article describes the processes involved in photochemical aging and weathering of polymeric materials. It explains how solar radiation, especially in the UV range, combines with atmospheric oxygen, driving photooxidation and the development of unstable photoproducts that cause various types of damage when they decompose, including the scission of carbon bonds and polymer chains. The article illustrates some of the degradation reactions that occur in different polymers and presents an overview of the strategies used to prevent such reactions or otherwise mitigate their effects.

This article discusses the environmental influences on protective coating films that can result in deterioration. These environmental factors can be classified into four groups: (1) energy: solar, heat; (2) permeation: moisture, solvent, chemical, and gas; (3) stress: drying and curing-internal stress, and vibration-external stress; and (4) biological influences such as microbiological, mildew, and marine fouling.

This article provides an overview of polymer fractography, with examples of various fracture surfaces created under diverse loading conditions. The focus is on the interpretation of polymer fracture-surface features in light of the unique viscoelastic nature of polymers. The article presents fractographic examples of three time-dependent cracking mechanisms: fatigue fracture, creep rupture, and environmental stress cracking. It details characteristic fractographic features that can be observed in optical microscopy (OM) and scanning electron microscopy (SEM).

This article reviews the impact response of plastic components and the various methods used to evaluate it.. It describes the effects of loading rate on polymer deformation and the influence of temperature and strain rate on failure mode. It discusses the advantages and limitations of standard impact tests, the use of puncture tests for assessing material behavior under extreme strain, and the application of fracture mechanics for analyzing impact failures. It also develops and demonstrates the theory involved in the design and analysis of thin-walled, injection-molded plastic components.

There are many different types of polymeric materials, ranging from glassy to semicrystalline polymers and even blends. Their mechanical properties range from pure elastic with very high strains to fracture (elastomers) to almost pure linear elastic (Hookian behavior) with low strains to fracture (glassy polymers). This article provides an overview of historical development of fracture behavior in polymers. It discusses the processes involved in three fracture test methods for polymers, namely linear elastic fracture mechanics, elastic-plastic fracture mechanics, and post-yield fracture mechanics.

Two high-strength low-alloy (HSLA) families, acicular-ferrite steels and pearlite-reduced steels, contain microalloying additions of vanadium and niobium. Vanadium, niobium, and titanium combine preferentially with carbon and/or nitrogen to form a fine dispersion of precipitated particles in the steel matrix. This article summarizes the metallurgical effects of vanadium, niobium, molybdenum, and titanium. The metallurgical fundamentals were first applied to forgings in the early 1970s. The ultimate strength of first- and second-generation microalloy steels is adequate for many engineering applications, but these steels do not achieve the toughness of conventional quenched and tempered alloys under normal hot-forging conditions. Third-generation microalloy steels differ from their predecessors in that they are direct quenched from the forging temperature to produce microstructures of lath martensite with uniformly distributed temper carbides. Without subsequent heat treatment, these materials achieve properties, including toughness, similar to those of standard quenched and tempered steels.

Nuclear power plants benefit from thermal spray coatings for corrosion and erosion minimization and dimensional restoration of worn parts. This article provides a detailed discussion on the advantages of thermal spray coatings, fission reactor component coatings, and coatings for nuclear fuel processing before and after irradiation for power plant applications. Nuclear fusion research is divided into two primary fields of study categorized by the method for confining the fusion fuel: magnetic confinement fusion and inertial confinement fusion.

The use of 3D bioprinting techniques has contributed to the development of novel cellular patterns and constructs in vitro, ex vivo, and even in vivo. There are three main bioprinting techniques: inkjet printing, extrusion printing (also known as bioextrusion), laser-induced forward transfer (LIFT) printing, which is also known as modified LIFT printing, matrix-assisted pulsed-laser evaporation direct write, and laser-based printing (laser-assisted bioprinting, or biological laser printing). This article provides an overview of the LIFT process, including the LIFT process introduction, different implementations, jetting dynamics, printability phase diagrams, and printing process simulations. Additionally, materials involved during LIFT are introduced in terms of bioink materials and energy-absorbing layer materials. Also, the printing of single cells and 2D and 3D constructs is introduced, showcasing the current state of the art with the ultimate goal for tissue- and organ-printing applications.

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.

This article describes weathering and environmental factors that contribute to degradation in plastics, including temperature variations, moisture, sunlight, oxidation, microbiologic attack, and other environmental elements. It presents a general overview of aging factors, their effects on plastic materials, and the accelerated test methods that can be used to estimate the reaction of a plastic component during actual use. The article focuses on the determination of service temperature as it indicates the ability of a material to retain a certain property, when exposed to elevated temperatures for an extended period of time. It concludes by describing various degradation processes, namely, thermal degradation, thermal oxidative degradation, photooxidative degradation, environmental corrosion, and chemical corrosion and discussing the ways of detecting these degradation processes.