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.

Fracture toughness is an empirical material property that is determined by one or more of a number of standard fracture toughness test methods. This article describes the fracture toughness test methods in a chronological outline, beginning with the methods that use the linear-elastic parameter. After this, the methods that use the nonlinear parameters are discussed. The article reviews some of the work in progress to update the standard test methods, namely, common fracture toughness test method and transition fracture toughness test method. Finally, an overview of fracture toughness testing for ceramic and polymer materials is provided.

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.

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.

This article discusses the J-integral-based single and multiple specimen techniques of the ASTM E 1737 test method for determining plane strain fracture toughness of polymeric materials. It describes the fracture toughness testing of thin sheets and films. The article concludes with information on the alternative methods for determining the fracture toughness of polymer materials.

Optimized modeling of fracture-critical structural components and connections requires the application of elastic-plastic fracture mechanics. Such applications, however, can require sophisticated analytical techniques such as crack tip opening displacement (CTOD), failure assessment diagram (FAD), and deformation plasticity failure assessment diagram (DPFAD). This article presents the origin and description of FAD and addresses R6 FAD using J-integral. It details the fracture criteria of BS 7910. The factors to be considered during the use of FAD and the applications of FAD are also reviewed.

This article introduces the concepts of linear-elastic fracture mechanics (LEFM) and elastic-plastic fracture mechanics (EPFM). It reviews the fracture mechanics of ceramics and ceramic matrix composites (CMCs). The article describes some fracture toughness measurement techniques used on ceramics and CMCs: single edge notch bending, compact tension, double cantilever beam testing, chevron notch methods, and double torsion. It presents descriptions organized by their specimen types, and includes the advantages and disadvantages, as well as the experimental control schemes employed for each specimen type.

This article discusses the conditions for collapse in center-cracked panels and describes the energy criterion for fracture. Measurement of toughness of any material by means of tensile and crack test is discussed. The procedures to be followed for linear elastic fracture mechanics cases are reviewed, along with elastic-plastic fracture mechanics and plastic fracture mechanics procedures with the aid of residual strength diagram. The article also explains the geometry factors needed to determine the toughness of materials.

This article discusses the concepts underlying linear elastic fracture mechanics and elastic-plastic fracture mechanics as well as their importance in characterizing the fracture behavior of the high-strength aluminum alloys. It describes the three methods used for analyzing elastic-plastic fracture, namely R-curve concept, J-integral concept, and crack tip opening displacement method. The article considers the primary measures used to assess the toughness of aluminum alloy castings and wrought alloys: notch toughness, tear resistance, and plane-strain fracture toughness.

Fracture toughness is the ability of a material to withstand fracture in the presence of cracks. This article focuses on the use of fracture toughness as a parameter for engineering and design purposes. Both linear elastic and elastic-plastic fracture mechanics concepts are reviewed as they relate to fracture toughness and design process. The article explores the use of plane strain fracture toughness, crack-tip opening displacement, and the J-integral as the criteria for the design and safe operation of structures and mechanical components. It discusses the variables affecting fracture toughness, including yield strength, loading rate, temperature, and material thickness. A summary of different fatigue and fracture mechanics design philosophies and their relationship with fracture toughness is provided. The article concludes with information on the examples of fracture toughness in design.

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.

The primary goal of failure analysis is to prevent the recurrence of product failures. This article discusses the sequence of activities in failure analysis and offers insight on how to gather background information, examine and assess damage, and identify the cause of the problem. It also explains where to look for evidence and how to collect samples for various types of testing. In addition, the article provides an introduction to fracture mechanics and explains how to predict and avoid fractures, including fatigue fracture, through testing and computational techniques.

This article is a compilation of terms related to mechanical testing and evaluation of metals, plastics, ceramics, and composites.

This article summarizes the general fatigue and fracture properties of cast steels, namely, toughness, fatigue, and component design factors such as section size and discontinuities. It describes the various factors that influence fatigue of cast steels. These factors include section size, defect size, stress modes, and waveform types. The article discusses various fracture mechanics in cast steels: cyclic stress-strain behavior and low- and high-cycle fatigue life behavior; plane-stress fracture toughness; plane-strain fracture toughness; constant-amplitude fatigue crack initiation and growth; and variable-amplitude fatigue crack initiation and growth.

The concepts of fracture mechanics are basic ideas for developing the methods of predicting the load-carrying capabilities of structures and components containing cracks. This article provides an introduction to the methodology for computing the onset of fracture and describes plane strain fracture toughness, denoted as K IC . It presents formulas for the stress-intensity parameter as a function of crack size, crack shape, applied stress (or load), and geometry of load application.

This article reviews the various types of mechanical testing methods, including hardness testing; tension testing; compression testing; dynamic fracture testing; fracture toughness testing; fatigue life testing; fatigue crack growth testing; and creep, stress-rupture, and stress-relaxation testing. Shear testing, torsion testing, and formability testing are also discussed. The discussion of tension testing includes information about stress-strain curves and the properties described by them.

This article describes concepts and tools that can be used by the failure analyst to understand and address deformation, cracking, or fracture after a stress-related failure has occurred. Issues related to the determination and use of stress are detailed. Stress is defined, and a procedure to deal with stress by determining maximum values through stress transformation is described. The article provides the stress analysis equations of typical component geometries and discusses some of the implications of the stress analysis relative to failure in components. It focuses on linear elastic fracture mechanics analysis, with some mention of elastic-plastic fracture mechanics analysis. The article describes the probabilistic aspects of fatigue and fracture. Information on crack-growth simulation of the material is also provided.

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.