Index of content:
Volume 13, Issue 11, 01 November 1942
13(1942); http://dx.doi.org/10.1063/1.1714818View Description Hide Description
13(1942); http://dx.doi.org/10.1063/1.1714819View Description Hide Description
THIS chapter deals with (a) the general features of plastic phenomena in solids, (b) the so‐called Prandtl model, giving a basic and pictorial explanation of plastic processes, (c) the physical theories of R. Becker and G. I. Taylor, bearing a closer relation to physically measurable quantities, and (d) some experimental results illustrating the chief features of plastic flow in solids.
A Rapid Infra‐Red Analytical Method for Hydrocarbon Mixtures and A Routine Spectrophotometer for Plant Control13(1942); http://dx.doi.org/10.1063/1.1714820View Description Hide Description
A rapid method has been developed for the infra‐red spectroscopic analysis of simple mixtures of hydrocarbons. Through the construction of special equipment this method has been reduced to a routine procedure which can be carried out by comparatively inexperienced operators. The instruments built have proven sufficiently sturdy to be used for control work in plant operation. By basing the analytical method on an empirical calibration, the calculations involved have been reduced to a minimum. The instruments are relatively simple and permit the use of comparatively large spectral slit widths. This has eliminated the necessity for amplification of the thermopile output energy and for the determination of any continuous absorption curve. However, small spectral slit widths can be attained with the more versatile spectrophotometer if this should be required.
13(1942); http://dx.doi.org/10.1063/1.1714821View Description Hide Description
It is shown that the methods of operational circuit analysis may be extended to give the steady state current of a circuit not only in the well‐known Fourier series form but also in the form of the sum function of this Fourier series. This sum function is very useful in determining the wave form of the current. Three methods of obtaining the steady state current are given along with their restrictions, and these methods involve a real integral, a finite series, and a complex integral. An example of the use of these methods is also given.
13(1942); http://dx.doi.org/10.1063/1.1714822View Description Hide Description
Utilizing a function H(x) defined by G. Stein, formulas are derived for the inductance per unit length of rectangular tubular conductors. An example illustrates use of these formulas. A table of Stein's function is given for values of the argument x between 0 and 1 at intervals of 0.01.
13(1942); http://dx.doi.org/10.1063/1.1714823View Description Hide Description
The effect of temperature and time of application of load on the growth and the apparent ``tensile strength'' of fabrics was studied with a number of new tests. The results gave considerable information about the mechanism of failure of mechanical fabrics at low loads in service which could not be obtained with standard textile tests.
A ``fatigue'' test was developed which measured the lives of samples at elevated temperatures when subjected to a constant average load and a superimposed cyclic stress. The change in life with temperature on this test is enormously greater than the change of tensile strength with temperature. Over a considerable range the logarithm of the life under a given load is a linear function of the reciprocal of the absolute temperature, showing that the failure depends on a viscous or plastic flow within the fibers. Calculated activation energies for this flow process increase for different fibers in the order rayon, cotton, Nylon. The construction of the fabric affects the absolute life, but not the calculated activation energy. When creep is negligible, a loaded cord contracts when the temperature is raised, analogous to the Joule effect in rubber.
13(1942); http://dx.doi.org/10.1063/1.1714824View Description Hide Description
The flow of air through compact bundles of parallel textile fibers has been studied in order to obtain values of the shape factor k 0 for the channels through which the flow takes place. When the fibers are cylinders and the flow is parallel to their axes, k 0 is an increasing function of the porosity ε. Tables and curves showing this relationship are given. For fibers such as cotton, where the shape and size of cross section changes along the fiber length, k 0 changes less rapidly with ε. Data are given for this relationship.