Abhangigkeit der Normalspannungsdifferenz von der Schubspannung / Relationship between the Normal Stress Difference and the Shear Stress

1995 ◽  
Vol 5 (1) ◽  
pp. 29-33 ◽  
Author(s):  
Dimiter Hadjistamov
Keyword(s):  
Shear Stress ◽  
Normal Stress ◽  
Normal Stress Difference ◽  
Stress Difference

Suspensions in a tilted trough: second normal stress difference

2011 ◽  
Vol 686 ◽  
pp. 26-39 ◽  
Author(s):  
Étienne Couturier ◽  
François Boyer ◽  
Olivier Pouliquen ◽  
Élisabeth Guazzelli
Keyword(s):  
Shear Stress ◽  
Normal Stress ◽  
Volume Fraction ◽  
Behavioural Change ◽  
Normal Stress Difference ◽  
Stress Difference ◽  
Rigid Spheres ◽  
First Normal Stress Difference ◽  
Second Normal Stress Difference ◽  
Neutrally Buoyant

AbstractWe measure the second normal-stress difference in suspensions of non-Brownian neutrally buoyant rigid spheres dispersed in a Newtonian fluid. We use a method inspired by Wineman & Pipkin (Acta Mechanica, vol. 2, 1966, pp. 104–115) and Tanner (Trans. Soc. Rheol., vol. 14, 1970, pp. 483–507), which relies on the examination of the shape of the suspension free surface in a tilted trough flow. The second normal-stress difference is found to be negative and linear in shear stress. The ratio of the second normal-stress difference to shear stress increases with increasing volume fraction. A clear behavioural change exhibiting a strong (approximately linear) growth in the magnitude of this ratio with volume fraction is seen above a volume fraction of 0.22. By comparing our results with previous data obtained for the same batch of spheres by Boyer, Pouliquen & Guazzeli (J. Fluid Mech., 2011, doi:10.1017/jfm.2011.272), the ratio of the first normal-stress difference to the shear stress is estimated and its magnitude is found to be very small.

Four-Wire Bridge Measurements of van der Pauw Stress Sensors on (100) and (111) Silicon

2013 ◽  
Author(s):  
Richard C. Jaeger ◽  
Mohammad Motalab ◽  
Safina Hussain ◽  
Jeffrey C. Suhling
Keyword(s):  
Shear Stress ◽  
Normal Stress ◽  
Normal Stress Difference ◽  
Stress Difference ◽  
Plane Shear ◽  
Plane Normal ◽  
Stress Sensors ◽  
Van Der Pauw ◽  
Contact Sensors

Four-wire resistance characterization of van der Pauw stress sensors is discussed. Under the proper orientations and excitations, the output of the four-contact sensors can be shown to depend upon only the in-plane shear stress or the in-plane normal stress difference on (100) silicon. The other stress terms are cancelled out by the symmetry of the structure, and the measurements are inherently temperature compensated. In bridge-mode, each sensor requires only one measurement and produces an output voltage that is directly proportional to the shear stress or in-plane normal stress difference, and the sensitivity is 3.16 times that of the equivalent resistor sensors, just as in the normal van der Pauw mode. Experimental, theoretical, finite-difference and finite-element and simulation results are presented demonstrating the behavior of the sensor. The two sensors can be merged into one eight-contact device, or n- and p-tye sensors can be overlaid in standard IC processes. Similar results apply to sensors on (111) silicon.

Comparison Study on the Effect of Traction Speed on the GAE and Traditional Extrusion Forming of Four-Lumen Plastic Micro-Catheter

2021 ◽  
Vol 881 ◽  
pp. 39-44
Author(s):  
Zhong Ren
Keyword(s):  
Shear Stress ◽  
Normal Stress ◽  
Flow Rate ◽  
Volume Flow Rate ◽  
Axial Flow ◽  
Normal Stress Difference ◽  
Stress Difference ◽  
First Normal Stress Difference ◽  
Micro Catheter ◽  
Flow Velocities

In this paper, the effect of traction speed on the four-lumen plastic micro-catheter (FLPMC) was numerically studied. Moreover, the numerical simulations of FLPMC based on two kinds of extrusions, i.e., traditional extrusion and gas-assisted extrusion were performed and compared. Numerical results show that with the increase of traction speed, the sizes of FLPMC for both extrusions all decrease. The sizes of FLPMC based on gas-assisted extrusion are sightly larger than those of the traditional extrusion. To ascertain the reasons, the flow velocities, pressure, shear stress and first normal stress difference distributions of melt based on both extrusions under two different traction speeds were obtained and compared. Results show that with the increase of traction speed under the fixed volume inlet flow rate, the radial flow velocities of melt at the outlet of die decrease but the axial flow velocities increase, which results in the decrease of the die swell at the outlet of die and the size shrinkage of exit face for the FLPMC based on both extrusions. However, for the gas-assisted extrusion, the axial velocities are larger, and the pressure, shear stress and first normal stress difference are far less than those of traditional extrusion, which results in the larger unit volume flow rate, then the sizes of cross-section face are larger than those of the traditional extrusion.

Viscoelastic Behavior of Disperse Systems with Silicone Oil and Different Fillers

2002 ◽  
Vol 12 (6) ◽  
pp. 297-302 ◽  
Author(s):  
Dimiter Hadjistamov
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Normal Stress ◽  
Silicone Oil ◽  
Flow Behavior ◽  
Normal Stress Difference ◽  
Filler Concentration ◽  
Stress Difference ◽  
Disperse Systems ◽  
First Normal Stress Difference

Abstract The rheological behavior of model suspensions with the silicone oil M20000 and different concentrations of Cab-o-sil TS 720 resp. Durcal 5 are compared. The increase of the Cab-o-sil concentration changes the flow behavior of the suspension from shear-thinning, to pseudoplastic, and to plastic flow behavior. The first normal stress difference rises at the same time at certain shear rate. The disperse systems with Durcal 5 keep the structural viscous behavior of the silicone oil even with a filler concentration of 40.5 wt%. The dependence of the first normal stress difference on shear rate represents for suspensions with Durcal 5 only one straight line with a slope of n = 2. The normal stress has double the amount of the silicone oil M20000 at given shear rate and is independent of the used Durcal 5 concentration. It was established that suspensions with the silicone oil M20000 have a first normal stress difference that can, depending on the filler type, either increase (with Cab-o-sil TS 720) or decrease (with Durcal 5) at certain shear stress with increasing filler concentration. It is to be supposed that the decrease of the normal stress at a given shear stress, with increasing Durcal concentration, is a softening effect, caused by the filler.

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