Fracture causes

When you pour boiling water into a cold bottle and discover that the bottom drops out with a smart pop, you have re-invented the standard test for thermal shock resistance. Fracture caused by sudden changes in temperature is a problem with ceramics. But while some (like ordinary glass) will only take a temperature "shock" of 80°C before they break, others (like silicon nitride) will stand a sudden change of 500°C, and this is enough to fit them for use in environments as violent as an internal combustion engine. 

All metallic materials can suffer electrolytic corrosion. Fractures caused by cathodic hydrogen only occur when the activity of the absorbed hydrogen and the level of the tensile stress, which can be external or internal, reach a critical value. In general, critical hydrogen absorption is achieved only in the presence of promoters. However, under very severe conditions such as at very low pH or very negative potential, critical hydrogen absorption can occur. Steels with a hardness greater than HV 350 are particularly susceptible. 

The main causes of failure in gear couplings are wear or surface fatigue caused by lack of lubricant, incorrect lubrication, or excessive surface stresses. Component fracture caused by overload or fatigue is generally of secondary importance. 

B. L. Gall, D. R. Maloney, C. J. Raible, and A. R. Sattler. Permeability damage to natural fractures caused by fracturing fluid polymers. In Proceedings Volume, pages 551-560. SPE Rocky Mountain Reg Mtg (Casper, WY, 5/11-5/13), 1988. 

Gall, B.L., et al. "Permeability Damage to Natural Fractures Caused by Fracturing Fluid Polymers," SPE paper 17542, 1988 SPE Rocky Mountain Regional Meeting, Casper, May 11-13. 

Fig. 9. A transmitted electron micrograph of an ultramicrotomed section of an aluminum-epoxy interphase. The highly ordered structure in the center is a 3.3 micron thick aluminum oxide layer present on the base metal. The featureless area is the epoxy matrix. The light areas within the oxide are fractures caused by the microtoming. The epoxy has however penetrated to the bottom of all of the 50 nm pores in the oxide...

In general, hydraulic fracturing with sand propping provided adequate void space for emplacement of the NG1 in these explosive-fracturing tests in the oil shale. Explosive fracturing caused significant increases in fracture permeability when a sufficient NG1 charge was detonated. 

The collapse of the cavity causes stress modification (known as readjustments) in the medium around the chimney, and can generate secondary fracturing. This fracturing can take the form of either vertical fractures, roughly parallel to the walls of the chimney, or radial fractures caused by the subsidence of the geological layers near the chimney. 

In a prospective study, 64 patients with a recent history of at least one vertebral fracture caused by primary and secondary osteoporosis were recruited from six osteoporosis centers in Germany between December 1999 and April 2001 (63). Transdermal fentanyl 25 pg/hour was the recommended starting dose, with incremental steps of 25 pg/hour if there was insufficient analgesia. Treatment was stopped after less than 28 days in 15 patients (23%). In 10 of these, fentanyl was stopped because of nausea and/or vomiting and/or dizziness. In 49 patients, pain at rest (55% reduction) and on motion (47% reduction) abated significantly from baseline. The starting dose of 25 pg/hour of fentanyl was sufficient in most patients (70%). 

The high permeability of fractures causes them to preferentially focus fluid flow. The effectiveness of fractures as mass transport systems for fluids is evident from a casual examination of mineralisation in fractured rocks and leakage of groundwater at fracture outcrops. Similarly, these fractures act as preferential hydrocarbon pathways, focusing their flow from source beds to surface. 

In the early stage of the disease, patients suffer from pains in the lumbar areas, shoulders, and eventually the entire body due to renal tubular dysfunction and decrease in the bone mass. In the later, more serious stage, patients may experience difficulty in mobility due to osteomalacia with severe pains, and may further experience spontaneous bone fracture caused by the slightest external pressure, such as coughing. Finally, patients waste away and eventually die due to significant weight loss. 

B26. Bloom, W. L., and Flinchum, D., Osteomalacia with pseudo-fractures caused by the ingestion of aluminium hydroxide. /. Am. Med. Assoc. 174, 1327-1330 (1960). 

Figure 12.4. Geometry and formation parameters used to model a hydraulic fracture caused by very heavy oil-based mud.

Vik et a/. (1991) suggested that hydraulic fracturing caused gas to escape from reservoirs in the Halten Vest region, and used the coinciding overlap between overpressured regions and the regions where the Are Formation coals today are overmature, to tentatively indicate this assumed Are derived gas to be responsible for the overpressure development. Vik et al. (1991) did not have data available to indicate that several of these stmctures they report to be dry... 

Much more important is the velocity distribution in a fracture caused by aperture variations. Abelin et al. (1991, 1994) have observed that in real fractures a large part of the fractures carry no water and that some or a few small parts carry the water and with different velocities. Should a water package split between a fast and a slow stream in the fracture this would cause part of the packet to arrive later than the other part. This would cause a spread in the Residence Time Distribution, RTD of the combined streams. 

The elastic effects in polymer melts are associated with the molecular coil deformation shown in Fig. 3.9. The effects include die swell, a diameter increase when the melt exits from a die and flow instabilities such as melt fracture (causing a rough surface). One measure of the elastic effects is the tensile stress difference — a-yy that occurs in shear flow in the xy axes. There can be a tensile stress in the direction of flow, or a compressive stress (Tyy on the channel walls, or a combination of the two. Figure 5.7 shows that, as the shear rate increases, the value of m... 

McCulloch, D.S. 1966. Slide-induced waves, seiching, and ground fracturing caused by the earthquake of March 27,1964 at Kenai Lake, Alaska, U.S. Geological Survey Professional Paper 543-A. 

In mild steels, blisters, cracks, and terraced fractures caused by slag and sulfide lines can occur under sufficiently high hydrogen uptake and static tensile stress below the yield point at low temperature (room temperature). Residual stress is often sufficient te generate local plastic deformation and initiate cracking. 

In comparison with die compaction, isostatic pressing can provide compacts with much less defects or flaws. However, delamination and fracture caused by springback could be present if the pressure is released too fast. In addition, isostatic pressing has been rarely used to directly compact ceramic powders, due to its difficulty in handling powder samples. In most cases, it is used to further increase the density of green bodies either before or after the calcination step. Usually, the increase in density after isostatic compaction is less than 10 %, but that is sufficient to promote the densification of green bodies of most transparent ceramics. 

Sharpness can be defined as the attribute which allows the instrument to perform the cutting operation with the minimum effort. The fundamental mechanism of a knife cut is a compressive fracture caused by high pressure from the very small area of the single edge of the knife a razor blade, for example, requires one fine edge, whereas an ice pick requires a sharp point. In order to achieve the maximum sharpness of a blade, the edge angle must be low and the tip radius must be small. ... 

Ben-Menachem Y, Coldwell DM, Young JWR, et al. (1991) Hemorrhage associated with pelvic fractures causes, diagnosis, and emergent management. AJR Am J Roentgenol 157 1005-1014... 

Crazing and fracture caused by absorbed liquids and vapours is one of the most serious limitations on the use of plastics in engineering applications. The terms solvent crazing and environmental stress cracki are... 

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