Search Results for dynamic fracture toughness

This article summarizes the metallurgy of carbon and alloy steels, followed by discussions on their major mechanical properties, namely, static fracture toughness, dynamic fracture toughness, fatigue or sustained-load crack growth rates, and fatigue or sustained-load thresholds. It addresses fatigue crack propagation and sustained-load crack propagation, as well as the fundamental aspects of fracture in steels. The article illustrates the effects of variations in the alloy chemistry, microstructure, temperature, strain rate, and environment on various fracture toughness or crack growth rate parameters.

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 discusses the fatigue and fracture behavior of various types of cast iron, such as gray iron, ductile iron, malleable iron, compacted graphite iron, and white iron, as a function of chemical composition, matrix microstructure, and graphite morphology.

This article describes the test methods of fracture toughness, namely, linear-elastic and nonlinear fracture toughness testing methods. Linear-elastic fracture toughness testing includes slow and rapid loading, crack initiation, and crack arrest method. Nonlinear testing comprises J IC testing, J-R curve evaluation, and crack tip opening displacement (CTOD) method. Other methods used include the combined J standard method, the common fracture toughness test, transition fracture toughness testing, and the weldment fracture testing method.

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 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 describes a method for determining the dynamic indentation response of metals and ceramics. This method, based on split Hopkinson pressure bar testing, can determine rate-dependent characteristics of metals and ceramics at moderate strain rates. For example, dynamic indentation testing reveals a significant effect of loading rates on the hardness and the induced plastic zone size in metals and on the hardness and induced crack sizes of brittle materials. The article also explains the rebound and pendulum methods for dynamic hardness testing.

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.