Crack propagation, schematics

Fig. 7. Schematic representation of hydration causing crack propagation in a wedge test specimen. The increase in volume upon hydration induces stresses at the crack tip that promote crack growth 19,391.

Fig, 7.17. Schematic illustrations of sub-crack propagation along the laminar interface of the composite intermittently bonded with perforated films. After Jea and Felbeck (1980). 

Fig. 2 a and b. Schematic load versus displacement curves for crack propagation in epoxy polymers obtained using a double torsion specimen a Stable continuous propagation, b Unstable stick/slip propagation... 

Figure 6.56 Schematic of the regions of crack propagation as a function of the crack tip stress-intensity magnitude factor K expressed in MPa Jm (Jones)5...

Schematic representation of crack propagation by the film rupture model (Jones)5...

Fig. 17 Contact mechanics analysis of Herztian cracks within brittle materials.a Schematic description of a Hertzian cone crack induced under normal indentation by a rigid sphere, b Reduced plot of JC-field as function of cone crack length and for increasing loads pf < p// < pm during sphere-on-flat normal indentation of brittle materials. Arrowed segments denote stage of stable ring crack extension from Cf to cc (initiation), then unstable to ci at P = P,n (cone-crack pop-in) (From [67]). Branches (1) and (3) correspond to unstable crack propagation (dK/dc > 0), branches (2) and (4) to stable crack propagation (dK/dc < 0)...

It has been shown that fracture is a very complex process and the fracture performance depends on both the initiation and the propagation of a defect [6-10] in the material. Under impact, most polymers break in very distinct manners. Several types of fracture have been identified depending on the amount of plastic deformation at the crack tip and the stability of crack propagation. For each type, an appropriate analysis has been developed to determine the impact fracture energy of the material. These methods have also been verified in various plastics [11,12]. The different fracture behaviors in most polymers are illustrated in Figure 27.1, which shows a schematic drawing of the load-deflection diagram of Charpy tests on HIPS [13] under an impact velocity of 2 m/s at various temperatures. 

Fig. 42. Schematic representation of correlation between loading phase with crack propagation, craze growth and striation formation during continuous crack growth (in PMMA)...

Fig. 4.4. Schematic representation of the two modes of fatigue crack propagation in polymers...

Last is that the mechanism of compact failure also depends on strain rate. Figure 21-118 illustrates schematically the crack behavior observed in compacts as a function of capillary number. At low Ca, compacts fail by brittle fracture with macroscopic crack propagation, whereas at high Ca, compacts fail by plastic flow, which is more desirable to promote growth. 

These fracture mechanisms are shown schematically in Figure 8. In the particulate-filled resins that have a strong particulate-matrix interface, both thermal shock resistance and fracture toughness are improved. When the particulate itself is strong enough to withstand crack propagation, as is the case... 

Figure 8. Schematic of the three types of crack-propagation processes that occur in ceramic-particulate-filled resins under thermal shock conditions.

Figure 7.6 Schematics of crack propagation in reinforced plastics...

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