Tension geometry

A limited number of KIC values were obtained with a compact tension geometry for which KIC is calculated with Eq. (3)... 

FIGURE 10.15 Diagrammatic representation of film on and fiber tension geometry. (Adapted from Dynamic Mechanical Analyser 2980 Operator s Manual, TA Instruments, New Castle, DE, 1996.)... 

Capillary Primed Siphons Siphons, which are also rotationally actuated, are low-pass valves that result from the interplay between the centrifugal field, surface tension, geometry, and contact angle. In the basic configuration of a hydrophilic siphon, the low contact-angle channel sector starts at the outlet of an upstream reservoir and bends inwards past a crest point which is located closer to the center than the (equilibrium) liquid level. At high rotational frequencies, liquid is retained in the siphon, while at slow rotation the siphon channel is primed by capillary action (Fig. 3a). 

Finally, the fracture energy, Gf, of asphalt-aggregate mixtures using the disc-shaped compact tension geometry may also be used to describe the fracture resistance of asphalt concrete. The test is performed in accordance to ASTM D 7313 (2013) specifications. 

Determination of fracture energy of asphalt-aggregate mixtures using the disc-shaped compact tension geometry... 

For the important compact tension geometry (Fig. 12c), K is generally expressed in terms of the applied load P ... 

A feature of the instrument is a rotating analysis head, which can be oriented through 180° to adjust the analysis configuration for different test types and sample geometries. In addition to operation in the dynamic mechanical mode, the DMA 8000 operates in a constant-force (TMA) mode versus time or temperature. Applications such as thermal expansion coefficient, softening and penetration, or extension or contraction in the tension geometry provide data equivalent to those obtained by many conunerdal standalone TMA instruments. 

The combination of modulus and sample size must be chosen to suit. Tension mode, see Figure 4.5c, is the best mode for thin films (<20 (jim) having a modulus between 10 and 10 Pa. The stiff nature of tension geometry compensates for the low sample stiffness and best suits the stiffness range of the DMA. If there is a need to measure the rubbery modulus of films, then thicker films (> 100 pim) will enable the use of longer free lengths, which will yield more accurate moduli. A dynamic displacement amplitude of 10 (jim will result in a 0.1% peak strain for a 10 mm long sample. 

The main purpose of DMA is to make measurements as a function of temperature. This invariably results in a compromise between optimum modulus determination and the best use of the DMA stiffhess range, as discussed in Section 4.3.2. Three-point bending and tension geometry are the best modes for accurate modulus determination. 

The Imass Dynastat (283) is a mechanical spectrometer noted for its rapid response, stable electronics, and exact control over long periods of time. It is capable of making both transient experiments (creep and stress relaxation) and dynamic frequency sweeps with specimen geometries that include tension-compression, three-point flexure, and sandwich shear. The frequency range is 0.01—100 H2 (0.1—200 H2 optional), the temperature range is —150 to 250°C (extendable to 380°C), and the modulus range is 10" —10 Pa. 

Grease Retention, Wrinkle Resistance, and Durable Press. On bending or creasing of a textile material, the external portion of each filament in the yam is placed under tension, and the internal portion is placed in compression. Thus, the wrinMe-recovery properties must be governed in part by the inherent, tensional elastic deformation and recovery properties of the fibers. In addition to the inherent fiber properties, the yam and fabric geometry must be considered. 

The systematic study of piezochromism is a relatively new field. It is clear that, even within the restricted definition used here, many more systems win be found which exhibit piezochromic behavior. It is quite possible to find a variety of potential appUcations of this phenomenon. Many of them center around the estimation of the pressure or stress in some kind of restricted or localized geometry, eg, under a localized impact or shock in a crystal or polymer film, in such a film under tension or compression, or at the interface between bearings. More generally it conveys some basic information about inter- and intramolecular interactions that is useful in understanding processes at atmospheric pressure as well as under compression. 

Effect of Physical Properties on Drop Size Because of the extreme variety of available geometries, no attempt to encompass this variable is made here. The suggested predictive route starts with air-water droplet size data from the manulac turer at the chosen flow rate. This drop size is then corrected by Eq. (14-195) for different viscosity and surface tension ... 

The mass-transfer coefficients depend on complex functions of diffii-sivity, viscosity, density, interfacial tension, and turbulence. Similarly, the mass-transfer area of the droplets depends on complex functions of viscosity, interfacial tension, density difference, extractor geometry, agitation intensity, agitator design, flow rates, and interfacial rag deposits. Only limited success has been achieved in correlating extractor performance with these basic principles. The lumped parameter deals directly with the ultimate design criterion, which is the height of an extraction tower. 

The apparent difference between the curves for tension and compression is due solely to the geometry of testing. If, instead of plotting load, we plot load divided by the actual area of the specimen, A, at any particular elongation or compression, the two curves become much more like one another. In other words, we simply plot true stress (see Chapter 3) as our vertical co-ordinate (Fig. 8.7). This method of plotting allows for the thinning of the material when pulled in tension, or the fattening of the material when compressed. 

The data presented in Figure 19.7 were obtained on a Sonntag-Universal machine which flexes a beam in tension and compression. Whereas the acetal resin was subjected to stresses at 1800 cycles per minute at 75°F and at 100% RH, the nylons were cycled at only 1200 cycles per minute and had a moisture content of 2.5%. The polyethylene sample was also flexed at 1200 cycles per minute. Whilst the moisture content has not been found to be a significant factor it has been observed that the geometry of the test piece and, in particular, the presence of notches has a profound effect on the fatigue endurance limit. 

For V-bell applications D and d are sheave pilch diameters. From the geometry ol Figure 3-22, 6 is always less than or equal to 180° or n radians. The lower guideline for 6 is approximately 150°. Below this value there will be increasing tension and slip, which will result in decretised life of the V belts. This limit on 6 imposes a lower limit on the center distance and thus a practical limit on the speed ratio attainable is a given V-belt design. 

Volkov and Sushko [335] described a technique that is based on the use of nets. This method provides direct absorption spectra, but is very complex to perform The net must be placed in a chamber that ensures a pure inert atmosphere so as to avoid hydrolysis of the melt, and the temperature and geometry of the net must be kept very stable. Other major limitations of the method are the requirements that the surface tension of the melt be such that its position on the net is ensured, and that the vapor pressure of the material in molten state be as low as possible... 

Observe that this is a geometric property, not to be confused with the modulus of the material, which is a material property. I, c, Z, and the cross-sectional areas of some common cross-sections are given in Fig. 3-1, and the mechanical engineering handbooks provide many more. The maximum stress and defection equations for some common beamloading and support geometries are given in Fig. 3-2. Note that for the T- and U-shaped sections in Fig. 3-1 the distance from the neutral surface is not the same for the top and bottom of the beam. It may occasionally be desirable to determine the maximum stress on the other nonneutral surface, particularly if it is in tension. For this reason, Z is provided for these two sections. 

The mechanisms that affect heat transfer in single-phase and two-phase aqueous surfactant solutions is a conjugate problem involving the heater and liquid properties (viscosity, thermal conductivity, heat capacity, surface tension). Besides the effects of heater geometry, its surface characteristics, and wall heat flux level, the bulk concentration of surfactant and its chemistry (ionic nature and molecular weight), surface wetting, surfactant adsorption and desorption, and foaming should be considered. 

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