T-stress

To describe properties of solids in the nonlinear elastic strain state, a set of higher-order constitutive relations must be employed. In continuum elasticity theory, the notation typically employed differs from typical high pressure science notations. In the present section it is more appropriate to use conventional elasticity notation as far as possible. Accordingly, the following notation is employed for studies within the elastic range t = stress, t] = finite strain, with both taken positive in tension. 

Beamte, Beamter, m. official officer, beaaspnichen, v.t. stress, strain, load require claim. 

Stress response genes t Stress response genes ... 

In the MBL approach7 (see Fig. 5) we increased the stress intensity factor and the T-stress linearly from zero to K, =34.12 MPaVin and T /cr0 =-0.316 (Fig. 5a), respectively over 1 sec, and we then kept them constant. These magnitudes of the stress intensity factor Kt and T-stress are for the axial crack of depth a = 1.9 mm (a/h = 0.2) we analyzed in the full field formulation at 15 MPa hydrogen pressure. 

The last issue that remains to be addressed is whether the MBL results are sensitive to the characteristic diffusion distance L one assumes to fix the outer boundary of the domain of analysis. In the calculations so far, we took the size L of the MBL domain to be equal to the size h - a of the uncracked ligament in the pipeline. To investigate the effect of the size L on the steady state concentration profiles, in particular within the fracture process zone, we performed additional transient hydrogen transport calculations using the MBL approach with L = 8(/i — a) = 60.96 mm under the same stress intensity factor Kf =34.12 MPa /m and normalized T-stress T /steady state distributions of the NILS concentration ahead of the crack tip are plotted in Fig. 8 for the two boundary conditions, i.e. / = 0 and C, =0 on the outer boundary. The concentration profiles for the zero flux boundary condition are identical for both domain sizes. For the zero concentration boundary condition CL = 0 on the outer boundary, although the concentration profiles for the two domain sizes L = h - a and L = 8(/i - a) differ substantially away from the crack tip. they are very close in the region near the crack tip, and notably their maxima differ by less than... 

Lastly, we studied the effect of 7-stress on the effective time to steady state and the corresponding magnitude of the peak hydrogen concentration. We found that a negative T -stress (which is the case for axial pipeline cracks) reduces both the effective time to steady state and the peak hydrogen concentration relative to the case in which the T -stress effect is omitted in a boundary layer formulation under small scale yielding conditions. This reduction is due to the associated decrease of the hydrostatic stress ahead of the crack tip. It should be noted that the presented effective non-dimensional time to steady state r is independent of the hydrogen diffusion coefficient D 9. Therefore, the actual time to steady state is inversely proportional to the diffusion coefficient (r l/ ). 

The word viscosity comes from the Latin word for mistletoe, viscum. Anyone familiar with this plant is aware that it exudes a viscous sticky sap when harvested. Viscosity is defined after Isaac Newton in his Principia as the ratio of stress to shear rate and is given the symbol T. Stress (a) in a fluid is simply force/area, like pressure, and has the units of pascals (Pa S.I. units) or dynes/cm2 (c.g.s.). Shear rate or strain rate (y or dyldt) is the differential of strain (y) with respect to time. Strain is simply the change in shape of a volume of fluid as a result of an applied stress and has no units. The shear rate is in fact a velocity gradient, not a flow rate. It has the bizarre units of 1/time (sec-1) and is the velocity at a given point in the fluid divided by the distance of that point from the stationary plane. 

Nishiyama T, Yamashita K, Yokoyama T. Stress hormone changes in general anesthesia of long duration isoflura-ne—nitrous oxide vs sevoflurane—nitrous oxide anesthesia. J Clin Anesth 2005 17(8) 586-91. 

Yui K, Goto K, Ikemoto S, Ishiguro T. Stress induced spontaneous recurrence of methamphetamine psychosis ... 

Yamada K, Nabeshima T. Stress-induced behavioral responses and multiple opiod systems in the brain. Behav Brain Res 1995 67 133-145. 

Shear stress, N/m or Iby/ft t turbulent shear stress ir , laminar shear stress t , stress at wall Tq, threshold stress for Bingham plastic... 

When particles move on a surface while under a rotating and compressed foam roll, the surface is subjected to normal ( a ) and shear ( t ) stresses. The total contact stress can be determined from a strain energy relationship. 

Smith DJ, Ayatollahi MR, Pavier MX 2001. The role of T-stress in brittle fracture for linear elastic materials under mixed mode loading. Fatig Fract Engng Mater Struct, (24) 137-50. 

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