Showing papers on "Discontinuity (geotechnical engineering) published in 1977"

Fracture of Boron/Aluminum Composites with Discontinuities

Abstract: Boron/aluminum laminates in symmetric layups of [±45] and [±45/02] containing discontinuities in the form of holes and slits were tested in tension. Both layups exhibited decreases in failure stress with discontinuity size. However the two exhibited quite different failure modes. The [±45 ] failed with interlaminar shear as the dominant mode whereas the [±45/02] specimens reacted to discontinuities catastrophically in a manner suggestive of the effect of cracks on homogeneous metals. A correlation is proposed for the fracture of the [±45/02] laminate.

Chatanika observations of the latitudinal structure of electric fields and particle precipitation on November 21, 1975

Abstract: By using a new multiposition experimental procedure the incoherent scatter radar facility of Chatanika, Alaska, has been used to obtain detailed latitudinal structure of ion velocities and electric fields in the afternoon and midnight sectors during a period of moderate magnetic disturbance. In particular, the latitudinal and local time structure of the Harang discontinuity has been investigated. In agreement with other observations it is found that the convection flow direction changes from westward through south to eastward over a fairly wide local time range (1-2 hours), the highest latitudes displaying the widest region. The Harang discontinuity encounter is accompanied by an abrupt increase in electron precipitation, the most intense part being located slightly east of the center of the discontinuity. It is suggested that this injection is due to processes closely connected with the discontinuity region itself, rather than to a substorm-related energization.

Display panel constructions eliminating discontinuities between adjacent panels

Abstract: A display comprises a plurality of addressable display panels each having a display zone for displaying visual information and arranged in a formation so as to collectively provide a composite display of increased area. A fibre optic image transform construction is arranged in front of the display panels for transforming an image collectively provided by the panels into a corresponding continuous image in which discontinuity between adjacent panel display zones is eliminated.

Dynamic analysis of cracked plates in bending and extension

Abstract: The present chapter deals with dynamic loading of flat plates containing a through crack where inertia effects can no longer be neglected. Two types of dynamic-load sources are considered: namely, vibratory and impact. When the applied load is time dependent, waves travel through the plate and result in a complex stress pattern upon striking the crack modeled as a plane of discontinuity in the material. Because of the complexities encountered in the treatment of elastodynamic crack problems in three dimensions, simplifying assumptions are made to relax the system of equations in the theory of elasticity. The classical approach in the development of plate theories [1–3] is to assume that the stress distribution in the thickness direction of the plate is known as a priori. For the elastostatic crack problem, Hartranft and Sih [4] suggested to determine the stress variations through the plate thickness from the plane strain condition. Although their method also applies to elastodynamic crack problems, it will not be discussed here.

Recording monitor for structure faults

Abstract: A finger tip actuated structural crack monitor operation wherein a conductive array is adhered to a structure which is susceptible to development of cracks upon fatigue. An interrogation module is mounted on the structure and is connected to the array with circuit means in the module to sense any momentary discontinuity in the array and to store a failure condition therein upon detection of such discontinuity. A readout means is manually operated to provide a human sensible indication of the existence of the failure condition.

Propagation of Sonic Waves in Radiating Gases

Abstract: The paper discusses the propagation of a sonic discontinuity in a radiating gas. The velocity of propagation is determined and it is shown that the velocity of propagation of the sonic discontinuity is not influenced by the radiative heat transfer under thin gas approximation. The fundamental differential equations governing the growth of the sonic discontinuity are obtained and solved. It is concluded that if the sonic discontinuity is a compressive wave of order 1, then it terminates into a shock wave after a critical time tc which has been determined. But on the other hand, if it is an expansion wave of order 1, it will decay and be damped out ultimately. Particular cases of plane and spherical wave fronts have been discussed in details.

Apparatus for toppling conveyed articles

Abstract: An apparatus for toppling conveyed articles of rectangular outline (having opposite long sides and opposite short sides) has a travel surface; a discontinuity in the travel surface; first carrier elements traveling at a distance above and along the travel surface for advancing the articles by sliding them, on one of their short sides, on the travel surface up to the discontinuity and for advancing the articles by sliding them on one of their long sides, on the travel surface downstream of the discontinuity; and at least one second carrier element which is driven in a closed path and which engages the conveyed article or article stack as the latter reaches the discontinuity in the travel surface. The speed of the second carrier element is, in the direction of article advance, greater than the speed of the first carrier elements; thus the second carrier element takes over the conveyance of the article in the zone of the discontinuity and effects, in cooperation with the discontinuity, a toppling of the article from its upright position to a lying position in which the article engages the travel surface with one of the long sides downstream of the discontinuity, where the first carrier elements take over the conveyance of the articles. The second carrier element, at least during that portion of the closed path during which it engages the article, is located at a greater distance above the travel surface than the first carrier elements.

Gated can end with shear offset defining gate and method for manufacture of the same

Abstract: A can end includes a pushdown gate formed in a panel portion below a narrow, underfolded rim at the opening in the end. The outline of the gate is a frangible discontinuity in the panel portion underneath the rim and the same may be ruptured by pushing the gate downwardly and into the can. A method of drawing and folding the end material permits the frangible discontinuity to be formed before the rim is folded over the discontinuity.

Gated can end with shear offset defining gate

Abstract: A can end includes a pushdown gate formed in a panel portion below a narrow, underfolded rim at the opening in the end. The outline of the gate is a frangible discontinuity in the panel portion underneath the rim and the same may be ruptured by pushing the gate downwardly and into the can. A method of drawing and folding the end material permits the frangible discontinuity to be formed before the rim is folded over the discontinuity.

Prediction of the slope discontinuity in stress-strain behaviour of polymeric composites with spherical inclusions

Abstract: The estimation of the point of discontinuity in the slope of stress-strain curves (commonly referred to as “knee”) generally observed with composite polymeric materials could be an important problem for the specific application of the composite items. In this work, we have used the results from classical elasticity theory to calculate the residual thermal stresses and proposed simplifying assumptions to calculate a “lower bound” on the applied stress value at which the “knee” can occur. The theoretical predictions have been then compared with the experimental data on various polymeric composites containing glass beads and the agreement is found to be very sound. The proposed equation can be reliably used in engineering design.

Method of driving step motors

Abstract: PURPOSE:To start a step motor smoothly by increasing the starting torque and to run it smoothly thereafter during continuous operation by decreasing the discontinuity in driving torque.

On a magneto-elastic system with discontinuous coefficients and the propagation of a weak discontinuity

Abstract: In this paper we deduce the magneto-elastic system of equations in the three-dimensional case. As an application we study the propagation of a weak discontinuity when a strong discontinuity also occurs.

Scattering of a surface wave from a curvature discontinuity on a convex impedance surface

Abstract: An asymptotic "boundary-layer" set of quasimodes is constructed for the representation of fields in the vicinity of a convex reactive surface, whose formal structure is the same as that of the exact modes for the corresponding straight surface. These quasimodes are then used to solve for the scattering of a surface wave at a curvature discontinuity in a reactive surface. The present approach is a generalization of the perspective of the geometrical theory of surface waves, and is compared and contrasted with others presently available in the literature. Finally, the scattering at the discontinuity is compared with the power continuously radiated by the surface wave in traveling around the bend, providing some insight for design of curved surface waveguide structures.

A preliminary study of the crustal structure and the geological significance of the central portion of the himalayan mountain range

Abstract: In this work, the method of "Compressed Mass Plane" is used to draw from gravity data the depth contours of the Mehorovicic Discontinuity, the Conrad Discontinuity and the lower surface of the granite layer I beneath the central portion of the Himalayan Mountain Range. It can be seen from such contours that within the Himalaya region, the depth of the abovementioned crustal discontinuities varies rather abruptly. The Himalayan mountain range is situated on the sloping part of these crustal discontinuities. The crust in this region appears to have no "mountain root" and it has not reached the stage of isostatic equilibrium. However, in southern Tibet, north of the line running from Chu Zhong, Cha Dang to Ge Long Gong Ba (楚中,查当至戛隆公巴), the crust seems to be in isostatic equilibrium. The gradual uplifting at present of the Himalayan mountain region possibly involves the existence of forces relating to plate tectonic movements which may be considered as much stronger than that of the isostatic adjustments. Besides, earthquake source mechanism analysis giving a south-north direction for the axis of compression, and also in view of the thrusting character of a series of major faults observed in this region, it may be inferred that the Indian Plate moving northward pushes and collides with the Asian Plate. Again, all such facts as the epicentral distribution of shallow earthquakes of the Himalaya region forming belts, the structural peculiarity of the crustal layers, abrupt change of the depth of the Mohorovicic Discontinuity and finally the state of incomplete isostatic equilibrium constituent the tectonic background for the frequent occurrence of strong earthquakes in this region.

On the shape and fine structure of the K absorption discontinuity of cobalt in the metal and in its compounds, PrCo5 and SmCo5

Abstract: The shape and the extended fine structure (EFS) of the X-ray K absorption discontinuity of cobalt have been studied in the pure metal and in two of its compounds, namely PrCo5 and SmCo5. The main absorption discontinuity is found to split into two components for cobalt metal and the compounds. The shapes of the discontinuities have been interpreted in the light of the bidirectional orbital approximation (BOA). The absorption maxima in the EFS have been explained on the basis of Lytle's theory. The average bond lengths for the systems have been determined from the fine structure employing Levy's method.

Study of an impedance step in a microstrip line

Abstract: The additional discontinuity capacitance associated with an abrupt impedance step in a microstrip line is calculated using Schwartz Chirstofell transformation technique under static assumptions. The computed results are compared with the other available data.

Radiation characterristics of a step discontinuity in a monomode optical fibre

Abstract: The radiation pattern of the junction between two different monomode optical fibres is calculated by using the Huygens-Kirchhoff theory of diffraction. The radiation field in the plane of discontinuity is determined with the help of the mode-matching technique. The transverse field distributions of both waveguides are approximated by Gaussian profiles.

Discontinuity wave propagation in continua with dislocations

Abstract: The problem of discontinuity wave propagation is treated for an elastic body with a continuous distribution of dislocations and explicit values for speeds are obtained.