Relative stress gradient

Whether a growing crack can be stopped in this way depends on how rapidly the stress decreases at the notch root. To quantify this decrease, we define the relative stress gradient at the notch root... 

Table 10.3. Relative stress gradient of some geometries [76] geometry...

Here we want to stress the difference between the relative stress gradient X and the stress concentration factor Kt which both depend on geometry only. The stress concentration factor quantifies the concentration of the stress at... 

Fig. 10.36. Dependence of the notch support fax tor on the relative stress gradient for several iron-base materials (after [147])...

Around mid 1950s, Siebel and Stieler [19] introduced a new parameter that they indicated with the symbol x and called relative stress gradient (RSG) at notch root. The fundamental concept is always the same that is to say that fatigue is governed by the stress gradient rather than by the maximum stress at notch tip. Stress gradient means distance over which a stress level is maintained. The x parameter takes the form... 

Beyond the critical point (FRPl) the gel expands slightly as drying continues. This implies that around the liquid-vapour interface (the drying front) differential strains (and stress) gradients are relatively large. 

Analytical solutions for thermoelastic stress distributions within moving material, irradiated with two-dimensional CW Gaussian beams (P 1 = 0), have also been obtained [24], For a material characterized by k = 50.2 W/mK, p = 7880 kg/m3, c = 502 J/kgK, PI2r = 105 W/m, 7 = 4 mm/s, P = 10 5 K-1, v = 0.3, and p = 105 MPa (the material shear modulus), the dimensionless surface stress component varies with Pe as shown in Fig. 18.9. Here, Pe was varied by changing the beam radius, and the beam moves relative to the surface in the positive x direction. At large Pe, stresses are relatively uniform, while, at extremely small Pe, stress gradients... 

A typical voltammetric response for a polypyrrole film is shown in Fig. 36.3. A correlation can be established between the electric charge consumed to oxidize the polymer and the potential applied at each moment. If the stress gradient at the polymer/polymer interface is linked to the relative change of volume and this is related to the consumed charge, the angle described by the free end of the bilayer will be related to the electric potential. This fact was experimentally confirmed fl6], as can be observed in Table 36.1. The reversibility of the movement is guaranteed by the reversibility of the redox process each position is recovered when the bilayer is submitted to the corresponding potential. 

KINEMATICS AND STRESSES OF DEFORMABLE BODIES 23 In terms of the relative deformation gradient tensor t ), Eq. (2.29) may be written as... 

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