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.

This article reviews high strain rate compression and tension test methods with a focus on the general principles, advantages, and limitations of each test method. The compression test methods are cam plastometer test, drop tower compression test, the Hopkinson bar in compression, and rod impact (Taylor) test. The flyer plate impact test, expanding ring test, split-Hopkinson bar in tension, and a test using a rotating wheel used for high strain rate tension are also discussed.

Mechanical tests are performed to evaluate the durability of gears under load. Gear tooth failures occur in two distinct regions, namely, the tooth flank and the root fillet. This article describes the common failure modes such as scoring, wear, and pitting, on tooth flanks. Failures in root fillets are primarily due to bending fatigue but can be precipitated by sudden overloading (impact). The article presents contact stress computations for gear tooth flank and bending stress computations for root fillets. Specimen characterization is a critical part of any fatigue test program because it enables meaningful interpretation of the results. The article describes four areas of the characterizations: dimensional, surface finish/texture, metallurgical, and residual stress. The rolling contact fatigue test, single-tooth fatigue test, single-tooth single-overload test, and single-tooth impact test are some of the gear action simulating tests discussed in the article.

This article reviews the dynamic factors, experimental methods and setup, and result analysis of different types of high strain rate shear tests. These include high strain rate torsion testing, double-notch shear testing and punch loading, drop-weight compression shear testing, thick-walled cylinder testing, and pressure-shear plate impact testing.

Impact tests are used to study dynamic deformation and failure modes of materials. This article discusses low-velocity impact experiments in single-stage gas guns. It describes surface velocity measurements with laser interferometric techniques. The article details plate impact soft-recovery experiments, pressure-shear friction experiments, and low-velocity penetration experiments. It reviews two types of plate impact soft-recovery experiments: normal plate impact and pressure-shear plate impact experiments. The article provides information on low-velocity penetration experiments, which include the setup for direct penetration experiment (rod-on-plate) and the reverse penetration experiment (plate-on-rod). It also considers high-temperature plate impact testing and impact techniques with in-material stress and velocity measurements.

The fracture-mechanics technology has significantly improved the ability to design safe and reliable structures and identify and quantify the primary parameters that affect structural integrity of materials. This article provides a discussion on fracture toughness of notched materials by explaining the ductile-to-brittle fracture transition and by correlating KId, KIc, and Charpy V-notch impact energy absorptions. It highlights the effects of constraint, temperature, and loading rate on the fracture transition. The article discusses the applications of fracture mechanism in limiting of operating stresses. It describes the mechanisms, testing methods, and effecting parameters of two main categories of fracture mechanics: linear-elastic fracture mechanics and elastic-plastic fracture mechanics. The article concludes with a discussion on the three major progressive stages of fatigue: crack initiation, crack growth, and fracture on the final cycle.

This article reviews the general mechanical properties and test methods commonly used for ceramics and three categories of polymers, namely, fibers, plastics, and elastomers. The mechanical test methods for determining the tensile strength, yield strength, yield point, and elongation of plastics include the short-term tensile test, the compressive strength test, the flexural strength test, and the heat deflection temperature test. The most commonly used tests for impact performance of plastics are the Izod notched-beam test, the Charpy notched-beam test, and the dart penetration test. Two basic test methods for a group or strand of fibers are the single-filament tension and tow tensile tests. Room temperature strength tests, high-temperature strength tests, and proof tests are used for testing the properties of ceramics.

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.

This article describes the fracture toughness behavior of austenitic stainless steels and their welds at ambient, elevated, and cryogenic temperatures. Minimum expected toughness values are provided for use in fracture mechanics evaluations. The article explains the effect of crack orientation, strain rate, thermal aging, and neutron irradiation on base metal and weld toughness. It discusses the effect of cold-work-induced strengthening on fracture toughness. The article examines the fracture toughness behavior of aged base metal and welding-induced heat-affected zones. It concludes with a discussion on the Charpy energy correlations for aged stainless steels.

Cr-Mo steels are preferred in the construction of high-temperature components because they possess excellent strength, toughness, and corrosion resistance relative to carbon steels and most low-alloy steels. This article discusses the composition and metallurgy of the heat-resistant Cr-Mo steels. It details the Charpy V-notch (CVN) toughness properties of Cr-Mo steels relevant to fatigue and fracture resistance. The fracture mechanics of Cr-Mo steels are reviewed. The article analyzes the characterization of low-cycle fatigue based on fatigue damage calculations. It concludes with information on fatigue crack growth and fatigue behavior of weldments.

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 discusses the factors to be considered in selecting and evaluating machining tests for the purpose of evaluating cutting tool performance and workpiece machinability. It provides a brief description of cutting tool materials, such as high-speed steels, uncoated and coated carbides, cermets, ceramics, cubic boron nitride, and polycrystalline diamond. The article considers the matrices that represent the range of tests performed on candidate cutting tool materials: the workpiece matrix, the property matrix, and the operation matrix. Various machine tests used to evaluate cutting tools, including the impact test, turning test, and facing test, are described. The article lists the factors to be taken into consideration in measuring the machinability of a material. The article presents general recommendations for proper chip groove selection on carbide tools and concludes with information on machining economics.