Practical Design Tool Research Articles

Computer Analysis of Machines With Planar Motion: Part 2—Dynamics

A uniform procedure is described for establishing the dynamic equation of motion for machines with single or multiple degrees of freedom. The procedure, which utilizes the independent kinematic loops of the machine, is readily programmed for a digital computer. The basic program is largely independent of the specific machine being analyzed and is capable of treating input forces, internal springs and dampers, all of which may depend nonlinearly upon position, velocity, or time. As an example, the dynamic performance of a Stirling cycle engine is analyzed without recourse to simplifying approximations usually made in engine analysis (i.e., constant crank speed, use of approximate “rotating” and “reciprocating” weights, neglect of higher harmonics in piston motion). It is shown that the method not only predicts transient behavior, but is capable of predicting steady (long-term) behavior without loss of accuracy, or excessive computer costs. The method described satisfies the major criteria of generality, accuracy, and economy, required of a truly practical design tool.

STUDIES ON THE SHEAR DEFORMATION PROPERTIES OF PLAIN WOVEN FABRICS

A method of experimental testing of the shear deformation properties of woven fabrics using the biaxial tensile tester devised by S. Kawabata, et al. for testing large deformation properties of elastomer is studied here.Much effort is made to find the optimum size of test specimens and to survey better method to clamp the specimens. And successful method is obtained for measuring the shear deformation properties of fabrics by this method under both conditions, forced tensile deformation and forced tensile load.Experimental results from many kinds of fabrics are compared with the theoretical shear deformation properties calculated by the theory.In most cases, experimental results agree very well with results calculated theoretically and it has been confirmed that the theory will become a very powerful tool for practical design of the fabrics.

Numerical Comparison of Diffusion-Like Transport Approximations for Very Fast Neutrons

The simplified-Pl(SPl) and modified-P2(MP2) transport approximations have been considered for use as practical nuclear design tools, replacing diffusion theory in the first few-group of a four-group scheme. Two numerical comparisons of two-dimensional systems indicate that SPl can be a satisfactory design tool for situations where the total cross section is slowly varying and the geometry is not too severe. The MP2 approximation has certain computing advantages, but does not yield as uniform an improvement over P1 as SPl does.

Field distribution of plated wire memory elements and its effect on memory characteristics

An approximate method is presented for the solution of magnetic field distribution in plated wires. By treating only the essential parameters of the distribution and ignoring its fine details, a simple and general solution is obtained, portraying the relation between the distribution shape, the geometry of the drive lines, and the magnetic characteristics of the wire. The results indicate the existence of a characteristic length λ over which the applied field tends to be averaged and which represents the lowest practical limit of bit size. Several examples, involving adjacent bit interaction, drive current requirement, sense signal amplitude, and tolerance analysis, demonstrate the efficiency and flexibility of the described method as a practical tool for the magnetic design of plated wire memories.

Packaging with a Flexible Container for Oil-Filled or Evaporative-Cooled Electronic Equipment

In electronic packages where high voltages exist, a high dielectric strength environment surrounding the components is necessary. Liquid-filled units have used various oils which in addition to dielectric strength provide good thermal paths for cooling; evaporative-cooled units often use refrigerants. In either case allowance, volume-wise, must be made for thermal expansion of the fluid. A simple, novel, weight-saving technique for accomplishing this consists essentially of replacing the conventional container with a flexible one (for example, fabric-reinforced rubber). The flexible container then expands and contracts accomodating volume variations in the fluid. Design details, test results, and a general evaluation illustrating the adaptability of the flexible container as a practical design tool are discussed.

Thin Film Magnetization Analysis

A "Graphical Method" is used for analysis of the magnetization direction in terms of the magnetic energy, and for prediction of the hysteresis loop shape of ferromagnetic thin films. Three major magnetization conditions are discussed: 1) condition of magnetization with an 180° field applied: 2) condition of magnetization with a 90° field applied; and 3) condition of magnetization with both the 90° and the 180° field applied. Corresponding to these magnetization conditions, the hysteresis loop shapes are predicted and constructed showing close identity to those experimentally observed. These conditions are chosen because of their importance to computer applications. In the graphical method, the principle of superposition applies. Using this method, the magnetic energy relationships are readily established. The general expression for the total free energy equation is: E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</sub> = E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</sub> +E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">σ+E_{HΘ<s sub=""> where E_k is the anisotropy energy, E_σ is the magnetostriction energy, and E_{H#x00398;_{is the magnetization energy. Since the method of construction of the total free energy curve as well as the hysteresis loop is simple and mechanical, a quite complex magnetization condition with a multiplicity of fields of different magnitudes and directions may be simplified and handled by graphical means with ease. Thus, the present scheme should be a practical and useful tool for analysis and engineering design of magnetic devices and systems utilizing ferromagnetic thin films.}}</s>}</sub>