Internal crack

Stress crack Internal or external defect in a plastic caused by tensile... 

Description Conventional wet fluorescent AC yoke magnetic particle inspection used for detection of cracks at a surface. Blending the welds and sanding smooth increases sensitivity. Polish and etch as in a creep evaluation looking for microscopic damage. Replicas can be taken for laboratory analysis. Conventional radiography used to inspect welds for cracks. Internal visual inspection of pressure vessels for surface blistering. Monitors the sound that cracks emit when they are stressed. 

Because particles may be hard and smooth in one case and rough and spongy in another, one must express densities with great care. Density is universally defined as weight per unit volume. Three types of densities—true density, particle density, and bulk density—can be defined, depending on the volume of particles containing microscopic cracks, internal pores, and capillary spaces. 

In the described set of experiments ami Parsons observed three types of product flaws, internal cracks, discontinuous cracks, and continuous surface cracks. Internal cracks were foum) to be due to voids in the billet material and could be avoided by the use of v(rid-ffee billets. Discontinuous cracks v e attributed to environmental stress... 

Measured CGR data for Type 304 SS in dilute sulfuric acid solutions at various temperatures show a maximum in the CGR versus temperature at around 175 °C. Previously, this temperature-dependent CGR behavior has been modeled using the CEFM without a temperature-dependent crack-tip strain rate, with any temperature dependence being attributed to the electrochemical reactions that occur on the external surface and at the crack tip and to the transport properties of ions in the crack-internal and external environments. 

Fig. 7 Coupling of crack-internal and crack-external environments. Note that in the steady state, the crack can grow only as fast as the positive current flowing from the crack can be consumed on the external surfaces by oxygen reduction.

In this numerical version of the CEFM, a potential mouth i assumed at the crack mouth, the boundary between the crack-internal and the crack-external environments, and this potential is then iterated until the external current (/ext. obtained via solving Laplace s equation) and the internal current (/jnt, obtained via solving the Nernst-Planck equations) match for the prevailing Econ (Fig- 8), that is, until /,nt = /ext- This is the practical implementation of the CEFM statement... 

Zang W. and Gudmundson P. (1993) An analytical model for the thermoelastic properties of composite laminates containing transverse matrix cracks. International Journal of Solids and Structures, 30, 3211-3231. 

Notch sensitivity, not to be confused with brittleness, is a measure of the ease with which a crack will propagate through a plastic from a preexisting notch, crack, internal void. 

IGSCC damage cannot be bounded by methods given in NRC Bulletin 80-13 [6.3] and plant specific ageing management of the core spray internal piping is required. If continued operation with un-repaired cracked internal core spray lines is pursued, a plant specific safety evaluation will need to be performed to demonstrate that plant safety is not compromised. 

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