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Linear Elastic Fracture Mechanics
Published in T.L. Anderson, Fracture Mechanics, 2017
When the resistance curve is flat, as in Figure 2.10a, one can define a critical value of energy release rate, 𝒢c, unambiguously. A material with a rising R curve, however, cannot be uniquely characterized with a single toughness value. According to Equation 2.37 a flawed structure fails when the driving force curve is tangent with the R curve, but this point of tangency depends on the shape of the driving force curve, which depends on the configuration of the structure. The driving force curve for the through-crack configuration is linear, but 𝒢 in the DCB specimen (Example 2.2) varies with a2; these two configurations would have different 𝒢c values for a given R curve.
Introduction and Review of Linear Elastic Fracture Mechanics
Published in Ashok Saxena, Advanced Fracture Mechanics and Structural Integrity, 2019
The considerations involved in characterizing the fracture toughness behavior of thin plates and sheets are somewhat different from the measurement of KIc. Due to enhanced plastic deformation in the crack tip region at comparable K levels, instability in the specimen is preceded by stable crack growth. The stable crack growth behavior is characterized by crack growth resistance curves in which the crack extension, Δa, is correlated with K, as shown schematically in Figure 1.15a. Thus, the entire K-resistance curve represents the fracture toughness behavior of the material as opposed to a single number KIc. The instability point in this case is determined by different considerations.
Experimental Methods
Published in Cameron Coates, Valmiki Sooklal, Modern Applied Fracture Mechanics, 2022
Cameron Coates, Valmiki Sooklal
Previously, analytical relationships based on the stress intensity factor K for linear elastic fracture mechanics (LEFM) and the J integral and crack tip opening displacement (CTOD) for elastic plastic fracture mechanics (EPFM) were discussed. However, in order to successfully predict failure when designing engineering structures and components, the critical values of these parameters need to be assessed through experimental testing [1]. The measurement of the fracture toughness provides an indication of a material’s resistance to crack extension. Testing methods can yield a single value of fracture toughness like KIC, or the toughness may be plotted against crack extension to produce a resistance curve.
Effect of glass nanofibers on mode I interlaminar fracture toughness of glass/epoxy composites
Published in The Journal of The Textile Institute, 2022
Seyed Jalaledin Najafi, Hooshang Nosraty, Mahmood Mehrdad Shokrieh, Ali Akbar Gharehaghaji, Seyed Hajir Bahrami
To fully characterize the delamination behavior, the curve of the strain energy release rate variation for the growth of the crack length (Figure 6) is used. This curve is called the resistance curve or the so-called R curve. The variation of the resistance curve depends on the thickness, type of fiber, resin and adhesion between fiber and resin, the fiber bridging phenomenon, the growth of the crack, and in general, it is due to energy absorption mechanisms affecting the growth trend of the crack.