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RESEARCH PAPERS

J. Eng. Ind. 1960;82(4):283-300. doi:10.1115/1.3664228.

The special test equipment and procedures developed for the evaluation of ultrashort-time elevated-temperature mechanical properties of materials are described herein. The tensile and high-stress creep data obtained for Haynes N-155 alloy sheet are reported. At rapid strain rates, the high-temperature tensile strengths were up to 300 per cent higher than those obtained at conventional testing speeds. At high temperatures and high stress levels, however, creep rates were shown to be extremely rapid, and in most cases, the creep strength became a critical factor. The application of rapid-strain-rate tensile data and high-stress creep data in short-life designs is discussed.

Commentary by Dr. Valentin Fuster
J. Eng. Ind. 1960;82(4):303-307. doi:10.1115/1.3664233.

Direct measurements of the distributions of normal and frictional stresses on a rake face under cutting conditions have been considered to be practically impossible. However, as reported in this paper, the stress distributions have been successfully obtained photoelastically by using a tool made of a photoelastic material. According to the authors’ experiment, the frictional stress on the rake face is distributed uniformly over a wide range of the tool-chip contact length, but it decreases rapidly near the point of chip-separation on the rake face. As to the normal stress, it has a peak near the cutting edge, being rather stationary in the middle part of the contact length and decreasing gradually toward the point of chip-separation.

Commentary by Dr. Valentin Fuster
J. Eng. Ind. 1960;82(4):309-313. doi:10.1115/1.3664236.

With the advent of high-temperature-resistant materials in the sheet-metal industry, it is becoming increasingly important to treat the subject of minimum or “critical” bend radius analytically. A simple equation is presented that correlates the minimum bend radius with the percentage reduction of area of the material. The theoretical derivation as well as experimental data are given, with very good agreement between the two. Consequently, it is possible to predict the minimum bend radius for a specific material, provided that the percentage reduction of area, as determined by a standard tensile test, is known. The relationship applies equally well to metals and nonmetals.

Commentary by Dr. Valentin Fuster
J. Eng. Ind. 1960;82(4):324-332. doi:10.1115/1.3664240.

Metal-cutting studies were made with free-cutting steel SAE 1112 and alloy steel SAE 4135 in the as-received condition with artificially controlled tool-chip contact areas and flank contact areas (artificial wear lands). The experimental results for steel SAE 1112 at a speed range of 0.083 to 1010 fpm, reveal that friction under metal-cutting conditions on the rake face can be explained satisfactorily by a junction model with possible superimposed general plastic flow above the junctions in accordance with the general rules of plastic deformation (von Mises instantaneous yield criterion). The experimental results also reveal that the friction mechanism at the controlled flank-wear contact area is essentially the same as that occurring at the tool face. The difference in behavior of the two steels was attributed to the role that manganese sulfide appears to play in free-cutting steels.

Commentary by Dr. Valentin Fuster
J. Eng. Ind. 1960;82(4):333-347. doi:10.1115/1.3664241.

The following alloys were investigated in orthogonal metal-cutting tests at varying cutting speeds, rake angles, and feeds: Steel SAE 1112 annealed and as-received; steel SAE 1020 as-received; steel SAE 4135, annealed, as-received, and Rockwell hardnesses 27 and 35–37; aluminum alloy 2024-T4; aluminum alloy 6061 in the 0 and T6 conditions; alpha brass. The new data obtained in the present investigation under wide variation of test conditions (speed for SAE 1112 annealed and as-received was varied from 0.083–1010 fpm) confirmed earlier observations [1, 3] that the shearing stresses are independent of the test conditions investigated. These observations were supported by theoretical considerations. Correlation of metal-cutting data with compression data on the basis of the incremental or distortion-energy theory was good for the ductile metals. Less perfect correlation was observed with SAE steel 4135 and aluminum alloy 2024-T4. It was found further that none of the known theoretical angle relationships were in agreement with all of the experimental data.

Commentary by Dr. Valentin Fuster
J. Eng. Ind. 1960;82(4):348-357. doi:10.1115/1.3664242.

Revelation of the significance of “ploughing” in the metal-cutting process, which occurs because of the finite sharpness of the cutting edge, leads to a better understanding of the mechanics of the metal-cutting process. The concept of the ploughing force on the extreme cutting edge allows the development of a more complete force diagram which separates the ploughing force from the chip-tool interface force. Components of this more detailed force diagram have been verified experimentally. In terms of the new force diagram the real value of the coefficient of friction on the chip-tool interface has been found and the paradox of variation of the coefficient of friction with variation of rake angle explained. The paper also contributes to a better understanding of such events as the effect of cutting velocity upon tool forces, built-up edge, chip curling, and residual stresses in the work surfaces.

Commentary by Dr. Valentin Fuster
J. Eng. Ind. 1960;82(4):359-362. doi:10.1115/1.3664245.

In the preliminary design of missile systems it is necessary to consider the weight of the individual components which comprise the missile. The usual procedure in weight approximation is to consider that an article is composed of small regular-shaped bits, each of whose weights is easily found and whose sum approximates the weight of the total article. When the component is such an irregular shape that a simple approximation cannot be made, or where the number of digital operations is excessive, the estimation of its weight becomes a tedious procedure. In this report, a method is derived for approximating the structural weight of such an article, namely, the divergent section of a bell-shaped nozzle for a rocket motor.

Commentary by Dr. Valentin Fuster
J. Eng. Ind. 1960;82(4):363-366. doi:10.1115/1.3664246.

A method is derived for specifying economically optimum tolerances for a variety of sheet materials for use in flight vehicles. The results indicate a significant disparity between present industry practices and the apparent optimum tolerances. These tolerances are listed as possible target requirements for rolling programs of new and future metals.

Commentary by Dr. Valentin Fuster
J. Eng. Ind. 1960;82(4):369-375. doi:10.1115/1.3664250.

The behavior of a single degree of freedom system consisting of a single mass mounted on a spring and damper attached to an oscillating base is investigated. Steady-state and transient sinusoidal oscillations are applied to the base to which the suspension is attached. The response of the mass is recorded for various combinations of linear and nonlinear springs and dampers. Solutions are obtained with a differential analyzer.

Commentary by Dr. Valentin Fuster
J. Eng. Ind. 1960;82(4):377-380. doi:10.1115/1.3664253.

First and second finite-difference expressions are derived for the first three derivatives of displacement with respect to time. The numerical results obtained by applying these difference expressions to a specific cam-follower mechanism are found to be in good agreement with the values obtained by successive differentiation of the displacement-time equation. Procedures for evaluating and improving the numerical results are also discussed.

Commentary by Dr. Valentin Fuster
J. Eng. Ind. 1960;82(4):382-386. doi:10.1115/1.3664257.

In the design of high precision, rotating equipment such as air bearings, gyroscopes, etc., it has become possible to reduce the frictional torques to “almost zero” values. The measurement and classification of the sources of these minute torques during rotation is exceedingly difficult, but very important for correct application and further design improvement. It is the purpose of this paper to present two techniques for the measurement and discrimination of the torques, and an example showing the accuracy of these techniques. Although these methods were designed specifically for the measurements of low torques, they work equally well for any magnitude and as such present a good evaluation technique. A comparison made with the values obtained by one of the better “direct” methods indicates that the direct method is inadequate.

Commentary by Dr. Valentin Fuster
J. Eng. Ind. 1960;82(4):387-391. doi:10.1115/1.3664258.

The traditional safety factor has a qualitative meaning only. However, it can be quantitatively interpreted through the possible variations of the components in a design as well as the probability of safety. The proposed design method based on such a safety factor gives not only a more rational but also a more economic design than the conventional methods.

Commentary by Dr. Valentin Fuster
J. Eng. Ind. 1960;82(4):393-398. doi:10.1115/1.3664261.

The motion of a body sliding under boundary friction, at a velocity slower than a particular critical velocity of the system, proceeds in a discontinuous or stick-slip form. This paper presents a theoretical analysis and an experimental study of the critical velocity of stick-slip sliding. The influence of various parameters such as friction, damping, stiffness, and sliding mass of the system on the critical velocity was studied on a mechanical model arranged on a milling machine. The arrangement was also simulated on an electric analog computer. Good correlation was observed between the theoretical values and the experimental results on the mechanical model and on the analog computer.

Commentary by Dr. Valentin Fuster
J. Eng. Ind. 1960;82(4):399-406. doi:10.1115/1.3664262.

A new type of mechanical variable-speed transmission, which owes its improved efficiency and wear-life to the utilization of multiple point contacts in pure rolling, has a power capacity in proportion to the maximum tractive forces and rolling velocities developed by a large number of small steel balls. Designing for maximum power capacity depends on finding the point at which the components of tractive force arising from inertial effects at high speed become so large as to interfere with the proper kinematic action of the balls. Consideration is given to the influence of a number of design and operating parameters, such as ball diameter, cage diameter, cage velocities, and velocity ratio.

Topics: Force , Wear , Steel , Design
Commentary by Dr. Valentin Fuster
J. Eng. Ind. 1960;82(4):407-414. doi:10.1115/1.3664265.

Cycloidal motions have many applications in mechanical engineering. The multi-lobed epicycloid has sharply pointed cusps; therefore, a machine element performing an epicyclic motion can be utilized for performing operations requiring a corresponding action, like folding of flexible materials or feeding of components from a stack. A speed reducer, distinguished by extreme compactness, is based on the use of an epitrochoidal cam. Linkages which perform approximately straight-line motions can be designed so that they approximate the motion of the center of the generating circle of an orthocycloid.

Commentary by Dr. Valentin Fuster
J. Eng. Ind. 1960;82(4):415-422. doi:10.1115/1.3664266.

The behavior of a simple mechanical connection over an extended frequency range is analyzed with particular reference to vibration transmission and isolation. The limitations inherent in a simplified analysis are clarified by a more refined treatment of the problem. The significance of higher critical frequencies associated with the distributed mass of the connection is pointed out, and this leads to a more generalized concept of rigidity. A qualified definition of rigidity is subsequently introduced, and the corresponding performance characteristics of a vibration transmitter and isolator are discussed. The dependency of performance criteria on the type of excitation is emphasized, and the essential ideas embodied in the paper are illustrated in an example.

Commentary by Dr. Valentin Fuster
J. Eng. Ind. 1960;82(4):423-438. doi:10.1115/1.3664267.

The problem of a circular plate, with a central hole, elastically constrained against rotation and deflection, acted upon by a transverse linear temperature gradient or a general axisymmetrical loading condition is considered in this paper. With the aid of presented graphs and simple algebraic equations, it is a relatively simple matter to construct the desired deflection and stress pattern for any combination of elastic constraints and load distribution.

Commentary by Dr. Valentin Fuster
J. Eng. Ind. 1960;82(4):439-442. doi:10.1115/1.3664270.

Spring design, in many instances, is still a trial-and-error process. The underlying reason is the large number of complex variables which must be related to the allotted space which the spring will occupy and to the desired loads throughout the working range. This paper presents a system of parameters which enables the spring designer to graphically portray these variables for a given problem. Derivations are based on the total number of coils as well as the outside diameter which accurately defines the entire space required for the spring. Charts are presented for springs with two dead coils and a torsion modulus of 11,500,000 psi.

Commentary by Dr. Valentin Fuster

DISCUSSIONS

Commentary by Dr. Valentin Fuster
Commentary by Dr. Valentin Fuster
Commentary by Dr. Valentin Fuster
Commentary by Dr. Valentin Fuster
Commentary by Dr. Valentin Fuster
Commentary by Dr. Valentin Fuster
Commentary by Dr. Valentin Fuster

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