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Nanomechanical Properties of Solid Surfaces and Thin Films
Published in Bharat Bhushan, Handbook of Micro/Nano Tribology, 2020
The term A provides correction for the thickness-to-width ratio of the material. Units of stress-intensity factor are MPa√m. With more intense stress or with deeper cracks, the stress intensity becomes sufficient for the fracture to progress spontaneously. This threshold stress intensity is a property of the material and is called the critical stress intensity factor, K1c, or the fracture toughness of the material. Ceramics generally have relatively low fracture toughness, consequently, it is an important property to be considered for the selection of ceramics for industrial applications.
Two-Dimensional Contact and Crack Problems in Isotropic Elastic Media: Complex Variable Technique
Published in Arabinda Roy, Rasajit Kumar Bera, Linear and Non-Linear Deformations of Elastic Solids, 2019
Arabinda Roy, Rasajit Kumar Bera
where KI=p0πa is the stress intensity factor for a line crack in infinite medium. KI, the stress intensity factor is an important parameter in the study of fracture mechanics.
Mechanical Properties of Polymer/Ceramic Composites
Published in Noureddine Ramdani, Polymer and Ceramic Composite Materials, 2019
Fracture toughness is a property that characterizes the ability of a material containing a crack to resist fracture. It is also one of the most important mechanical parameters of materials. A parameter known as a stress-intensity factor is generally used to evaluate the fracture toughness of numerous materials. As the stress-intensity factor of a material attains a critical value (KIC), unstable fracture take place. This critical value of the stress-intensity factor is called the fracture toughness of the material. It can be tested by different technique, including single-edge notch bend (SENB) and indentation fracture toughness (IFT). The addition of ceramic micro- and nanoparticles has been reported as a prominent option to increase the fracture toughness of thermosetting polymers without compromising the stiffness.
The fracture behaviour of cement bitumen emulsion mixture through the digital image correlation (DIC) method
Published in International Journal of Pavement Engineering, 2023
Jian Ouyang, Wenting Yang, Peng Cao, Baoguo Han
The effect of cement dosage on the fracture toughness of CBEM with different notch depths is shown in Figure 15. It can be seen from Figure 15 that although notch depth can affect the fracture toughness of CBEM, the fracture toughness of CBEM with different notch depths has the same trend with the increasing cement dosage. The fracture toughness of CBEM increases significantly but then decreases moderately with the increasing cement dosage. CBEM with 3% of cement content has the maximum fracture toughness. Compared to CBEM, a bitumen emulsion mixture without cement has a very low fracture toughness. As mentioned in Figure 10, a bitumen emulsion mixture without cement is much more ductile than CBEM. Fracture toughness is a parameter of the resistance to brittle fracture, thus it may be not suitable for evaluating the fracture resistance of the bitumen emulsion mixture. Fracture toughness is the stress intensity factor corresponding to the initiation of the crack (Banyhussan et al.2020). It can be an index of the fracture resistance to heavy load. With regard to fracture toughness, the addition of cement is beneficial to the fracture resistance of CBEM.
Definition of mode-I fracture behaviour of plain and fiber reinforced various grades of concretes by digital image analysis
Published in Mechanics of Advanced Materials and Structures, 2023
Muhammed Gümüş, Abdussamet Arslan, Hüseyin Kalkan
The critical fracture toughness at the proportional limit load of the specimens used in this work was employed in the previous study [65] by the authors to predict the bearing capacity of RC beams produced with the same mix proportions. In this section, the effect of the steel fiber and concrete compressive strength on the unstable fracture toughness, KICun, of the specimen for the Mod-I crack was investigated. Fracture toughness is also known as the stress intensity factor in fracture mechanics because of the fact that it means the intensity of the stress singularity at the tip of an effective crack. For the three-point bending tests, KICun was calculated by substituting the maximum load, Pmax, and corresponding measured effective crack length, Leff, into Eq. (16) [64].
In situ stress inversion and fracture characteristics around local fault in deep heterogeneous strata
Published in Petroleum Science and Technology, 2022
Bohu Zhang, Xinxin Hu, Yan Wang, Yao Hu, Wei Chen
Fracture mechanics believes that the defects in rock are easy to form cracks, and the surrounding stress concentration is the reason for the occurrence and expansion of cracks. Griffith (Griffith 1921) proposed the crack propagation criterion of cracked glass by the energy balance method. Irwin (Irwin 1957) proposed the stress intensity method of crack propagation criterion based on the energy balance method. Stress intensity factor (K) is the mechanical parameter of crack propagation and the inherent property of the material. The general equation can be expressed as Eq. (8). where is a dimensionless parameter, which is determined by the geometry of the specimen and the crack. is the applied stress, is the half length of the crack.