Stress area

Stress Corrosion Crocking. Stress corrosion cracking occurs from the combined action of corrosion and stress. The corrosion may be initiated by improper chemical cleaning, high dissolved oxygen levels, pH excursions in the boiler water, the presence of free hydroxide, and high levels of chlorides. Stresses are either residual in the metal or caused by thermal excursions. Rapid startup or shutdown can cause or further aggravate stresses. Tube failures occur near stressed areas such as welds, supports, or cold worked areas. 

But it is possible that the first peak of the force, F, , may act either downwards or upwards. In which case only four fasteners would be sharing the force at a time. Stress area of four bolts... 

Highly stressed areas generally corrode faster than areas of lower stress. This is due to the fact that the more stressed areas are usually anodic and corrode more readily. The drillstem just above the drill collars is often susceptible to abnormal corrosion damage. High stresses and bending moments in this region may be partially responsible for this failure. 

It is often difficult to conduct laboratory tests in which both the environmental and stressing conditions approximate to those encountered in service. This applies particularly to the corrosive conditions, since it is necessary to find a means of applying cyclic stresses that will also permit maintenance around the stressed areas of a corrosive environment in which the factors that influence the initiation and growth of corrosion fatigue cracks may be controlled. Among these factors are electrolyte species and concentration, temperature, pressure, pH, flow rate, dissolved oxygen content and potential (free corrosion potential or applied). 

Stressed areas such as those at welds, rivets, threads or areas that undergo cyclic temperature or pressure changes. 

The viscoelastic nature of the material requires not merely the use of data sheet information for calculation purposes, but also the actual long-term performance experience gained that can be used as a guide. The allowable working stress is important for determining dimensions of the stressed area and... 

There are other conditions that result from the frozen-in stresses. In materials such as crystal polystyrene, which have low elongation to fracture and are in the glassy state at room temperature, a frequent result is crazing it is the appearance of many fine microcracks across the material in a direction perpendicular to the stress direction. This result may not appear immediately and may occur by exposure to either a mildly solvent liquid or vapor. Styrene products dipped in kerosene will craze quickly in stressed areas. 

These tests are considered significant in explaining the cracks sometimes found in highly stressed areas of an otherwise apparently resistant material. In addition, Cherrington and Ciuffreda27 have emphasized the need for removing notches (stress concentrators) in hydrogen service equipment. 

Paradoxically, such a mechanical fatigue apparently acts as a treatment for relaxation of stress and allows flaws, located at the stress areas to be partly dissipated. Also, mechanical fatigue treatments can eliminate effects of a previous thermal treatment. Two samples that were initially different became more similar with regard to their crystallinity after 50 x 103 cycles. They had a medium level of crystallinity characterized by disorder parameter values that are particularly low. 

Munawar, M., Munawar, I.F., Burley, M., Carou, S. and Niblock, H. (2003) Multi-trophic bioassessment of stressed "Areas of Concern" of the Lake Erie watershed, in M. Munawar (ed.), Sediment Quality Assessment and Management Insight and Progress, Aquatic Ecosystem Health and Management... 

Controlling flow or viscosity is an important part of the adhesive formulation process. If the adhesive has a propensity to flow easily before and during cure, then one risks the possibility of a final joint that is starved of adhesive material. If the adhesive flows only with the application of a great amount of external pressure, then one risks the possibility of entrapping air at the interface and getting too thick of a bond line. These factors could result in localized high-stress areas within the joint and reduction of the ultimate joint strength. 

Beryllium and its alloys (e.g., beryllium copper) have gained interest in the aerospace industry and specialty sports equipment industry in recent years. Brazing or riveting can be used for joining, but these methods are expensive, and distortion or highly stressed areas may be encountered. The metal must be handled with care when the processing produces dust, chips, scale, slivers, mists, or fumes, since airborne particles of beryllium and beryllium oxide are toxic with latent health effects. Abrasives and chemicals used with beryllium must be disposed of properly. 

In this paper Synchrotron Radiation X-Ray White-beam Topography (SRXWT) was used to investigate the defects of yttrium orthovanadate crystal, dislocations, inclusions and stress area were found in (001) and (100) wafers. Analysis showed that inclusions were the main cause of dislocations and stress area. Electronic Probe Microscopic Analysis (EPMA) indicated that these inclusions resulted from impurities appearing on the annealed (001) wafer, which revealed that there lied small amount of ferrum and aluminium. 

Stress at craze II initiation Lower yield stress Area... 

The results of the evaluations indicated that lowering the ramp rate from approximately 500 psi/min to 150 psi/min and performing a vacuum bake after every cycle drastically decreased or eliminated the evidence of cracks or discolored (stressed) areas in the epoxy. This indicates that the lower ramp rates decreased the stress on the epoxy and that the vacuum baking acted as a stress relief by removing the carbon dioxide gas which was absorbed in the epoxy. 

When a load is applied to the surface of a large mass of uniform soil, the induced stresses propagate in all directions and attenuate with distance from the point of load application. Except for directly beneath the load, where stress can be calculated by dividing the load by the application area, the actual value of stress cannot be found by simple arithmetic. This is because the size of the stressed area is not known, and the stress intensity over the stressed area varies. 

Stress in plastic composites and profiles can decrease the free energy of activation of oxidation processes and, hence, speed up the oxidation degradation of the materials in the stressed areas. Besides, stress decreases local densities (specific gravities) of composites and thereby increases porosity and provides space for oxygen from air to diffuse in and oxidize the material from inside. ... 

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