Surface notch tensions

Reduction/Removal of Surface Notch Tensions by Etching... 

The type of loading. Represented in the figure are conditions of simple tension, with and without notches, tension in the outer surface of bent specimens, and precracked specimens such as i and j. 

Specimen type CT compact tension, SCT center surface cracked tension, DCT disk-shaped compact tension, SNB side notched bend CNT center through-thickness notched tension... 

R. P. Kusy and D. T. Turner, Influence of molecular weight of poly(methylmethacrylate) on fracture surface energy in notched tension, Polymer 17, 161-166 (1976). 

SCT center surface cracked tension SNT side notched tension... 

Lenz, Amo T., Viscosity and Surface Tension Effects on V-Notch Weir Coefficients, Trans. ASME 108 759-802, 1943. 

A change in the surface tension does not exert essential influence on the mechanical properties of metals and vice versa however, a significant decrease in surface tension caused by adsorption should promote corrosion (Kolotyrkin, 1967). Plastic deformation can arise at the site of the stress concentrations, i.e., notches, asperities, scratches, inclusions and surface irregularities (Chiu, 1999). 

Lenz, A. T. (1943). Viscosity and surface tension effects on V-notch weir coefficients. Trans. AICHE, 108, 759-820. 

The brittle-ductile transition temperature depends on the characteristics of the sample such as thickness, surface defects, and the presence of flaws or notches. Increasing the thickness of the sample favors brittle fracture a typical example is polycarbonate at room temperature. The presence of surface defects (scratches) or the introduction of flaws and notches in the sample increases Tg. A polymer that displays ductile behavior at a particular temperature can break in the brittle mode if a notch is made in it examples are PVC and nylon. This type of behavior is explained by analyzing the distribution of stresses in the zone of the notch. When a sample is subjected to a uniaxial tension, a complex state of stresses is created at the tip of the notch and the yield stress brittle behavior known as notch brittleness. Brittle behavior is favored by sharp notches and thick samples where plane strain deformation prevails over plane stress deformation. 

Pa-s (1 to 150 cP) and surface tension over the range of 0.03 to 0.07 N/m (30 to 70 dyn/cm). His equation predicts about an 8 percent increase in flow for a liquid of 0.1-Pa-s (100-cP) viscosity compared with water at 0.001 Pa s (1 cP) and about a 1 percent increase for a liquid with one-half of the surface tension of water. For fluids of moderate viscosity, Ranga Raju and Asawa [Proc. Am. Soc. Civ. Eng., J. Hydraul. Div., 103 (HY 10), 1227-1231 (1977)] find that the effect of viscosity and surface tension on the discharge flow rate for rectangular and triangular-notch ((j) = 45°) weirs can be neglected when... 

Scientists (Ref 12) welded HSLA-65 using tungsten-base tools. Subjected to bend tests, a 10 mm (0.4 in.) thick weld passed, and a 6 mm (0.24 in.) thick weld failed when bent with the root in tension, due to the formation of surface cracks. Tensile properties of the 10 mm thick welds exceeded the specifications for the base metal. Some 6 mm thick welds exceeded the plate specifications, while others were approximately 10% below the plate specifications. Charpy V-notch (CVN) toughness at both -29 and 0 °C (-20 and 0 °F) were below the base material toughness but exceeded the minimum specification of the plate. The surface of the welded material was found to have small defects due to the roughness caused by the interaction between the shoulder and the surface of the plate. Salt spray corrosion tests indicated no preference for corrosion in the weld zone. 

The Izod test is a variant of the notched bending test. A swinging pendulum hits a clamped bar (Fig. 9.16) and loses kinetic energy. The bar has a width of 12.5 mm and a thickness representative of the plastic product considered. The 2.5 mm deep, 45° notch has a tip radius of 0.25 mm. Section 9.3.2 showed that the tensile stress in the yielded zone at the notch tip can exceed the uniaxial tension yield stress by up to 118%. It is common to use 3.2 mm thick specimens, which restricts the value of the data to products of similar thickness. The lower half of the bar is clamped in vice, and the upper part is struck 22 mm above the notch by the pendulum. The results can be quoted as the absorbed energy divided by the specimen thickness, in Jm , or as the absorbed energy divided by the area of one fracture surface, in J m . ... 

It should be emphasized that two fundamentally different types of craze tests were performed in this work. The test described initially, in which the craze stress below a notch was calculated from the slip line plasticity theory, without exposure to solvent, is a test in which the strain is changed as a function of time. The craze stress itself is calculated assuming that both slip line plasticity theory and the simple von Mises yield criterion are both applicable. The second test, used to determine the effect of solvent on crazing, is a surface crazing test under simple tension in which the strain... 

A sharp notch 0.1 mm long is introduced into the surface of a fused silica plate. The plate is then loaded to 100 MPa in tension normal to the notch, (a) Will the plate fracture (b) If not, what is the applied stress that would lead to fracture (c) If the plate was made of an LAS glass-ceramic what applied stress would lead to fracture ... 

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