Stress diagram

Fig. 4. (a) Shear stress diagram for elastic ideal plastic material (b) partiady plastic thick-waded cylinder. 

Bingham-plastic slurries require a shear stress diagram showing shear rate vs. shear stress for the slurry in order to determine the coefficient of rigidity, T], which is the slope of the plot at a particular concentration. This is laboratory data requiring a rheometer. These are usually fine solids at high concentrations. 

Melt fracture occurs when the rate of shear exceeds a critical value for the melt concerned at a particular temperature (that is, the critical shear rate ). There is a corresponding critical shear stress and the relevant point on the flow curve (or the shear rate-shear stress diagram) is known as the critical point. It is believed that it is reached in the die entry region (that is, where material is being funnelled from the die reservoir into the capillary of a capillary rheometer)—which, in an extruder, corresponds with the point at which melt moves into the die parallel portion of the die. Some further complicating effects may occur at the wall of the die. 

Figure 8-18 Rate-of-Shear-Shear Stress Diagrams of Bingham Bodies. (A) Ideal case, and (B) practical case. The yield values are as follows lower yield value (1), upper yield value (2), and Bingham yield value (3).

A typical example of a stress diagram is shown in Fig. 8.15 for two drying... 

Fig. 8.18. Reversible stress diagram of boehmite membranes dried at 40°C with RH values changing cyclic between 60 and 90% RH. From Voncken et al. [26].

Plastic flow can also set up residual stresses. The beam shown in Fig. I6-2(a) is supported at two points and loaded by two equal forces Fapplied near each end. At any point between the two supports the stress in the outside fibers is constant, tensile on the top of the beam and compressive on the bottom. These stresses are a maximum on the outside surfaces and decrease to zero at the neutral axis, as indicated by the stress diagram at the right of (a). This diagram shows how the longitudinal stress varies across the section AA, when all parts of the beam are... 

The principal strain magnitudes at a point are a set of three numbers comparable with the principal stresses diagrams resembling Figures 6.5-6.7 can be drawn and equations resembling eqn. (6.1) written (eqn. 7.2) but the strain equations are exact only for small strains. 

At zero shear rate, the network yield stressOn equalsOo the yield stress obtained by extrapolation of the shear rate-shear stress data to zero shear rate. The Bingham yield stress (Ob) can be obtained by extrapolation of only the linear portion of the shear rate-shear stress diagram to zero shear rate. 

Figure 2. The stress diagram of burst coal body.

Figure 1. Stress diagram of cast aluminium enclosure. Figure 3. Schematic diagram of sealing head structure.

The soft clays were modelled using effective stress parameters, assuming linear elastie behaviour bounded by a Mohr-Coulomb envelope t/s = sin

shear stress/normal stress diagram for plane strain, in which the Mohr-Coulomb envelope is marked, together with a typical effective stress path for undrained behaviour of a normally consolidated clay. This path reaches failure at point F on the Mohr-Coulomb envelope with undrained strength c . 

The m values were determined from the log strain rate versus log flow stress diagram. 

The time to failure vs. applied stress diagrams are often used for empirical determination of the design life expectancy and stress level where SCC crack growth initiates (Xiscc)-... 

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