Showing papers in "Journal of Applied Mechanics in 1961"

Similarity and Dimensional Methods in Mechanics

Abstract: Similiarity and Dimensional Methods in Mechanics, 10th Edition is an English language translation of this classic volume examining the general theory of dimensions of physical quantities, the theory of mechanical and physical similarity, and the theory of modeling. Several examples illustrate the use of the theories of similarity and dimensions for establishing fundamental mechanical regularities in aviation, explosions, and astrophysics, as well as in the hydrodynamics of ships. Other interesting areas covered include the general theory of automodel motions of continuum media, the theory of propagation of explosion waves in gases, the theory of one-dimensional nonestablished motion in gases, the fundamentals of the gas-dynamics theory of atom-bomb explosion in the atmosphere and the theory of averaging of gaseous flows in channels. Aspects of modeling include the dimensionless characteristics of compressor operation, the theories of engine thrust, and efficiency of an ideal propeller for subsonic and supersonic speeds. Similiarity and Dimensional Methods in Mechanics, 10th Edition is an ideal volume for researchers and students involved in physics and mechanics.

The internal-combustion engine in theory and practice

Abstract: The internal-combustion engine in theory and practice , The internal-combustion engine in theory and practice , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

The Bending Stress Distribution at the Base of a Stationary Crack

Abstract: Extending an earlier paper dealing with extensional stress distributions, this study considers the stresses around a crack point owing to bending loads. It is found first that the stresses possess the characteristic inverse square-root singularity in terms of distance from the crack point. Along the crack prolongation direction the symmetric principal stresses are of opposite sign and in the ratio (1 − ν)/(3 + ν), in contrast to the extensional situation where they are identically equal. This leads to the observation that more yielding might be expected as the percentage of bending to extension stress at the crack increases. In the antisymmetrical loading, the shear stress is a maximum ±90 deg to the side of the crack, where the distortion energy is also a maximum. Interesting reciprocity relationships are also shown to exist between the symmetrical and antisymmetrical loading conditions for the isochromatic fringe lines and the stress trajectories. Finally, the results are discussed in connection with the combined extensional and bending loading.

On Transient Thermal Stresses in Viscoelastic Materials With Temperature-Dependent Properties

Abstract: : This paper deals with the quasi-static analysis of transient thermal stresses in the linear theory of homogeneous and isotropic viscoelastic solids with temperature-dependent physical characteristics The underlying constitutive law rests on the temperature-time equivalence hypothesis according to which a uniform temperature change affects the viscoelastic response of the material through a corresponding uniform shift of the logarithmic time scale If the temperature varies with time, the preceding hypothesis implies a dependence of the instantaneous stresses upon the entire temperature history Following an exposition of the theoretical background, exact solutions are deduced to two specific problems The first concerns the transient thermal stresses in a slab of infinite extent, generated by a temperature field that depends arbitrarily (Author-PL)

On the Buckling of Circular Cylindrical Shells Under Pure Bending

Abstract: : The stability of circular cylindrical shells under pure bending is investigated by means of Batdorf's modified Donnell's equation and the Galerkin method. The results have shown that contrary to the commonly accepted value, the maximum critical bending stress is for all practical purposes equal to the critical compressive stress. (Author)

Combined Stresses in an Orthotropic Plate Having a Finite Crack

Abstract: Using a formulation in integral equations, a solution for the combined extension-classical bending stress and displacement solution is presented for the case of an infinite orthotropic flat plate containing a finite crack. While the solution can be expressed in closed form for the entire field, primary emphasis is placed upon the stresses near the crack point. Qualitatively, no major difference in behavior due to orthotropy was found although certain quantitative features are noted, mainly as a function of the characteristic rigidity ratio (Ex /Ey )1/2 . The inverse square-root character of the isotropic stress bending and extension is not changed by orthotropy, although amplitudes and distribution are affected. Account is taken of recent important work by Knowles and Wang dealing with Reissner bending of the plate which shows that the extensional and surface bending stresses are identical in singular character and circumferential distribution. A bending-extension interaction curve for fracture initiation is derived and shown to be linear when based upon the more exact bending theory.

Diffraction of a Pressure Wave by a Cylindrical Cavity in an Elastic Medium

Abstract: An infinitely long cylindrical cavity in an infinite elastic homogeneous and isotropic medium is enveloped by a plane shock wave whose front is parallel to the axis of the cavity. An integral transform technique is used to determine the stress field produced in the medium by the diffraction of the incoming shock wave by the cavity. Expressions for the radial stress σrr , the hoop stress σθθ , and the shear stress σrθ are derived as inversion integrals, and numerical results are presented for the time-history of the hoop stress σθθ at the boundary of the cavity. The amplifications of the hoop-stress concentration factors due to the dynamic loading are noted. The problem is considered for pressure waves with a step distribution in time. These results may be used as influence coefficients to determine, by means of Duhamel integrals, the stress field produced by waves with time-varying pressures.