Ultimate tensile stress

Division 2. With the advent of higher design pressures the ASME recognized the need for alternative rules permitting thinner walls with adequate safety factors. Division 2 provides for these alternative rules it is more restrictive in both materials and methods of analysis, but it makes use of higher allowable stresses than does Division 1. The maximum allowable stresses were increased from one-fourth to one-third of the ultimate tensile stress or two-thkds of the yield stress, whichever is least for materials at any temperature. Division 2 requkes an analysis of combined stress, stress concentration factors, fatigue stresses, and thermal stress. The same type of materials are covered as in Division 1. 

Fig. 2. Schematic stress—strain diagram, where UTS = ultimate tensile stress and (-------------) represents the demarcation between elastic and plastic behavior.

Fig. 9. Variation of tensile properties and grain stmcture with cold working and annealing A, elongation B, yield stress and C, ultimate tensile stress.

Chow demonstrated theoretically [143] that for anisodiametrical particles, the ultimate tensile stress is inversely proportional to square root of the effective or characteristic filler particle size (in this case by effective particle size the ratio of particle volume to surface area is implied). 

For materials not subject to high temperatures the design stress is based on the yield stress (or proof stress), or the tensile strength (ultimate tensile stress) of the material at the design temperature. 

The following analyses are oversimplified in the case of most tissues because most tissues show directional dependence of the mechanical properties (they have different ultimate tensile stresses and moduli when pulled in different directions). For this reason the information shown in this chapter is an oversimplified picture of the mechanical behavior. Therefore the values of ultimate tensile strength and moduli presented are estimates that depend on how the experimental results were obtained. 

The elements have not the close-packing of atoms typical of true metals. Zinc and cadmium have distorted h.c.p. structure with axial ratios 1.87 instead of the ideal 1.63 (Fig. 275). These are contributory factors to their low tensile strengths the ultimate tensile stress of zinc is 7.5 tons per sq. in., of copper 15 tons. Mercury gives rhombohedral crystals with 6 6 co-ordination... 

Ultimate tensile stress calculated from break strength... 

The pure aluminum is the very soft metal with hardness 210 MPa and yield stress 10 -h 15 MPa. But the modem methods of alloying made possible to increase hardness of A1 alloys to 2200 MPa, yield stress to 700 MPa and ultimate tensile stress to 800 MPa. High strength characteristics of these alloys are combined with plasticity to fracture 5 15 % that is enough for the practical use. 

Composition of some alloys investigated in [16] and their mechanical properties (yield stress YS. ultimate tensile stress UTS and elongation to fracture 3) are given in the Tab.3. It is seen from Fig.2 that additions of Sc have eliminated the dendrite structure and leads to the formation of a finegrained equiaxial structure. 

The remaining two failure properties, the cohesion and the ultimate tensile stress are not used in hopper design directly but are used by many industries as general measures of powder... 

The cohesion is the intercept with the shear stress axis whilst the ultimate tensile stress is the negative value of normal stress at the intercept with the x-axis. 

Note 3. The expre.ssion ultimate tensile stress" is sometimes used in textiles as a synonym for tenacity, but in some other disciplines ultimate tensile stress" and tenacity relate to the maximum tensile force per unit cross-sectional area of the test piece (Fig. 15). 

Counit type M (x10- ) Counit (moi%) Crystaiiinity (%) Oc (%) a (%) b (%) iVloduius (iVIPa) Yieid stress (iVIPa) Ultimate tensile stress Draw ratio at break... 

Ultimate tensile stress MPa Dejjends on MW and counit content, has (19)... 

Since the flow stress, ay (the average of yield and ultimate tensile stresses), for this alloy at 4 K is unknown, //c at 4 K was obtained by extrapolating the resistance curve to Aa = 0. Estimates of Kic for this material were derived from the expression... 

FIGURE 8.6 (a) Dependence of the ultimate tensile stress of human coitical bone on volume fraction (expressed as a percentage). Ages of the specimens were in the range 20 to 100 years. From Ref. 10.) b) Modulus versus calcium content (in mg/gm of dehydrated bone tissue) for cortical bone taken from 18 different species. From Ref 24.)... 

Chitosan absorbs a significant amount of water when placed in aqueous solution. Equilibrium water content of 48 percent was determined by immersing chitosan films in deionized water. Tensile testing on these wet films resulted in an ultimate tensile stress of aj roximately 1600 psi with 70 percent elongation at break. ... 

From the tensile tests presented, it appeared that the nanocomposites made by alkyl silane-functionalized sepiolite give the best mechanical performances, in particular for what concerns the yield stress. In fact, the sepiolite surface fimctionalization by silane is a reactive treatment, which decreases the interparticle aggregation (improved dispersion) and, at the same time, increases the matrix-filler interactions. The addition of fimc-tionalized polymers is, instead, a nonreactive surface treatment. It leads to a decrease of the particle-particle interaction but can also reduce the matrix-particle interaction, which leads to lower yield stress and ultimate tensile stress. 

Young s moduli increasing from about 1.3 to 14GPa and the ultimate tensile stress from about 50 to 550 MPa (for tapes drawn 24 times X = 24). In contrast, the strain at break is reduced to 5%. 

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