End Effects for Anti-Plane Shear Deformations of Periodically Laminated STrips with Imperfect Bonding

The axial decay of Saint-Venant end effects is investigated for anti-plane shear deformations of semi-infinite generally laminated anisotropic strips. Imperfect bonding conditions are imposed at the interfaces. The analytical approach, using a displacement field which decays exponentially in the axial direction, gives rise to a transcendental equation for the real eigenvalues. The decay rate for the stresses is given in terms of the smallest positive eigenvalue. Laminated strips with periodic layout are then considered. In the presence of imperfect bonding, the effective shear elastic moduli, computed through a homogenization method, depend on the total number of slipping interfaces in the laminate. Numerical examples confirm that the decay lengths computed with effective shear moduli represent the asymptotic values (for an increasing number of layers) for those of periodically laminated strips. This revised version was published online in July 2006 with corrections to the Cover Date.     

Nonlinear steady-state oscillations of an elastic plate floating on the surface of a liquid of finite depth

In addition to obtaining solutions by the perturbation method it is shown that in the case of nonlinear wave interaction given a certain relationship between the parameters of the interacting waves steady-state compound waves may exist.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 3, pp. 146–154, May–June, 1989.     

Creep of thick-walled cylinders subjected to internal pressure and axial load

A creep theory is presented to predict deformations at any specified time for a thick-walled cylinder subjected to internal pressure and axial load. The theory is based on the usual assumptions that the deformations are infinitestimal, that the material is incompressible and that the total strain theory is valid. The stress-strain-time relation for the material is assumed to be represented by an isochronous stress-strain diagram which is approximated by an arc hyperbolic sine function. The experimental part of the investigation included tests of thick-walled cylinders made of high-density poly-ethylene whose ratio of outside to inside radii were either 1.5 or 2.0. The test cylinders were either tested as closed-ented cylinders with internal pressure or subjected to a combination of internal pressure and axial load. Also, the application of the theory for varying load conditions was studied. Good agreement was found between theory and experiment.     

Source below the free surface of a heavy liquid

The problem of the motion of a source under the free surface of an infinitely deep heavy liquid has been studied by Keldysh [1] under the assumptions used in the theory of small amplitude waves. However, these assumptions are no longer valid [2] for large Froude numbers F.A method using only one of the four assumptions of small amplitude wave theory (the assumption that the absolute value of the velocity at the free surface is nearly constant) was described in [2], In the following, this method is used to construct a solution of the problem which becomes exact as F . When F is not large our results are close to those of Keldysh if the source intensity is low. For F=0, both methods lead to exact results.     

Creep in materials with different tension and compression behavior

Experimental data on creep in tubular specimens loaded in tension and in compression are cited. It is demonstrated experimentally that the resulting vector of the creep strain rates is orthogonal to the curve of constant scattering intensity. Approximate analytical formulas making it possible to describe the creep process undergone by materials having different behavior patterns in tensile and compressive loading are derived.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 5, pp. 136–139, September–October, 1970.     

Nicht-lineare Elastizitätstheorie der Versetzungen und Eigenspannungen

Ohne Zusammenfassung Vorgelegt von J. Meixner Herrn Professor Dr. Dr. h. c. Richard Grammel zu seinem siebzigsten Geburtstag am 3. März 1959 gewidmet     

Experimental investigation on tunnel sonic boom

Upon the entrance of a high-speed train into a relatively long train tunnel, compression waves are generated in front of the train. These compression waves subsequently coalesce into a weak shock wave so that a unpleasant sonic boom is emitted from the tunnel exit. In order to investigate the generation of the weak shock wave in train tunnels and the emission of the resulting sonic boom from the train tunnel exit and to search for methods for the reduction of these sonic booms, a 1300 scaled train tunnel simulator was constructed and simulation experiments were carried out using this facility.In the train tunnel simulator, an 18 mm dia. and 200 mm long plastic piston moves along a 40 mm dia. and 25 m long test section with speed ranging from 60 to 100 m/s. The tunnel simulator was tilted 8° to the floor so that the attenuation of the piston speed was not more than 10 % of its entrance speed. Pressure measurements along the tunnel simulator and holographic interferometric optical flow visualization of weak shock waves in the tunnel simulator clearly showed that compression waves, with propagation, coalesced into a weak shock wave. Although, for reduction of the sonic boom in prototype train tunnels, the installation of a hood at the entrance of the tunnels was known to be useful for their suppression, this effect was confirmed in the present experiment and found to be effective particularly for low piston speeds. The installation of a partially perforated wall at the exit of the tunnel simulator was found to smear pressure gradients at the shock. This effect is significant for higher piston speeds. Throughout the series of train tunnel simulator experiments, the combination of both the entrance hood and the perforated wall significantly reduces shock overpressures for piston speeds ofu _p ranging from 60 to 100 m/s. These experimental findings were then applied to a real train tunnel and good agreement was obtained between the tunnel simulator result and the real tunnel measurements.     

Blast wave measurements close to explosive charges

The paper reports the results of experimental measurements of the reflection pressures close to spherical charges of TNT. These measurements were made using a pressure bar technique. Charge weights of up to 3.6 kg were used, with the reflecting plane in the range 25 to 300 mm from the charge surface.A possible wave interaction model is discussed, to account for the observed pressure profiles, and its qualitative correctness checked by means of numerical simulation.This article was processed using Springer-Verlag T_EX Shock Waves macro package 1.0 and the AMS fonts, developed by the American Mathematical Society.     

Electrohydrodynamic monodispersion of liquids

In electrostatic dispersion of a liquid from a meniscus at the end of a capillary through which the liquid is passed the emitted droplets are unstable with respect to their self-charge and break up, ejecting about 100 smaller (by two orders of magnitude) droplets. However, if the liquid is passed through the capillary under pressure, then, depending on the pressure, there exist ranges of values of voltages applied to the electrodes for which the emitted droplets are stable both with respect to their self-charge and with respect to the external electric field of the system of electrodes. In this paper, the sizes, charges, and specific charges of such droplets are calculated on the basis of the principle of least dissipation of the energy.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 32–40, March–April, 1991.     

Subcritical Motions of a Fluid with Temperature-Dependent Viscosity

Convective motions of a fluid with temperature-dependent viscosity are studied using numerical experiments. The results obtained provide data for laboratory experiments aimed at determining the hardness of the instability.