Showing papers on "Indentation published in 1972"

Electron microscope investigation of the microplastic deformation mechanisms of silicon by indentation

Abstract: The specific features of the dislocation structure, occuring in the vicinity of indentations have been studied using Si single crystals under different conditions of deformation (at temperatures of 20 to 700 °C and loadings of 0.5 to 10 p). It is shown, that the deformation of crystals at temperatures of 350 to 650 °C results in twin formation with {111} twinning plane. Flat defects with {115} habit plane are revealed. They are shown to be platelets of a new phase, which is of the hexagonal structure with c = 6.31 A and a = 3.86 A. The possible mechanism of the phase transformation is discussed. [Russian text ignored].

Hardness testing apparatus

Abstract: A hardness testing apparatus of the indenter type wherein the work is held against movement during indentation by a fluidactuated indenter and subsequent measurement of the indentation by a laser-scanner-photoreader carried by the test head.

Laminated windshield with built-in antenna

Abstract: An automobile windshield of laminated glass having an indentation in the lower edge of one of the glass sheets, an antenna carried by the plastic interlayer and made up of fine wire elements that include horizontally extending elements and vertical elements that extend from the horizontal elements toward the bottom of the windshield, and a tinned metal plate also carried by the interlayer in alignment with the indentation in the glass sheet for connecting the antenna to the car radio.

Applications of plasticity theory to selected problems in soil mechanics

Abstract: Two topics in plane strain perfect plasticity are studied using the method of characteristics. The first is the steady-state indentation of an infinite medium by either a rigid wedge having a triangular cross section or a smooth plate inclined to the direction of motion. Solutions are exact and results include deformation patterns and forces of resistance; the latter are also applicable for the case of incipient failure. Experiments on sharp wedges in clay, where forces and deformations are recorded, showed a good agreement with the mechanism of cutting assumed by the theory; on the other hand the indentation process for blunt wedges transforms into that of compression with a rigid part of clay moving with the wedge. Finite element solutions, for a bilinear material model, were obtained to establish a correspondence between the response of the plane strain wedge and its axi-symmetric counterpart, the cone. Results of the study afford a better understanding of the process of indentation of soils by penetrometers and piles as well as the mechanism of failure of deep foundations (piles and anchor plates). The second topic concerns the plane strain steady-state free rolling of a rigid roller on clays. The problem is solved approximately for small loads by getting the exact solution of two problems that encompass the one of interest; the first is a steady-state with a geometry that approximates the one of the roller and the second is an instantaneous solution of the rolling process but is not a steady- state. Deformations and rolling resistance are derived. When compared with existing empirical formulae the latter was found to agree closely.

Plastic Deformation of Metal Surface Induced by Ultrasonic Hammering

Abstract: In this paper, it is proposed how to calculate the metal surface property values during ultrasonic hammering, which has a lot of merits as the method of giving the plastic deformation of the metal surface, by the depth for the indentation and others in this working. Then the behaviours of the deformation of the metal surface during the hammering is examined.The main results are as follows:1. The surface stiffness and the rate of the elastic recovery can be calculated by the two arbitrary values from among those of the depth of the indentation, the contact time and the stationary load produced by the hammering on the metal surface with the vibrating tool.2. The applicability of this calculating method is confirmed by the comparison between the calculated values of the depth of the indentation and the experimental results.3. The depth of the indentation is affected by the repetition of the hammering on the same region of the surface. In the case of copper, the amount of the depth of the indentation increases a little by this repetition but in the case of S 15 C steel, hardly increases.4. In the case of the low movement speed of hammering point, the nominal surface stiffness and the rate of the elastic recovery during working correspond with those given by the static and repeated indenting test.

Study of Deformation and Defects Occurrence in Advanced Forging Techniques.

Abstract: : A two-part investigation was performed to study the relationship between defects formation and deformation characteristics in plane-strain side- pressing and axisymmetric plastic indentation. In the first part, the investigation was undertaken to examine the detailed deformation characteristics involved in axisymmetric plastic indentation. Circular punches with flat and hemispherical ends were indented into specimens prepared from SAE 1215 steels under as-received and annealed conditions. In the second part, the detailed mechanics of the side-pressing of circular cylinders under plane-strain conditions were obtained, based on the observed flow patterns of commercially pure aluminum and copper specimens. Slip-line fields and corresponding hodographs were constructed, and stress calculations were made, taking into account the actual material properties.

Fluid pressure retaining seals for high temperature joints

Abstract: 1,267,662. Joint-making packing. JOSEPH LUCAS (INDUSTRIES) Ltd. 12 June, 1969 [29 March, 1968], No. 15170/68. Heading F2B. Joint packing for use between two parts 14, 15 comprises a thin resilient metal E-ring 10 of channel-shaped cross-section, the web of the channel having an indentation 11 and the sides of the channel having outwardly directed sealing lips 12, and a metal wire ring 13 located in the indentation and having a cross-sectional diameter greater than the depth of the indentation. The ring 13 bears against the base of a groove formed between the parts 14, 15 and, in use, the lips 12 are urged into contact with the respective parts by the sealed fluid pressure.

Indentation Hardness of Optical Glass

Abstract: This investigation was made to clarify how the indentation hardness of optical glass depends upon the effect of densification or plastic flow.To examine the effect densification has upon indentation hardness, optical glasses with Knoop indentations were heat-treated at temperatures below their transition temperature. After heat-treatment, the percentage of change in the longer diagonal length of Knoop indentations was measured. These experiments were carried out on fused silica, BK, K, KF, F, SF, SK, SSK, BaF and BaSF glasses. Indentation recovery was found to be very small in optical glasses. Further, it was found that SF glasses which have the largest indentations show little or no change, while BK glasses which have small indentations show a much greater percentage of change. These results show that indentations in optical glasses are not always related to densification.Using an interference microscope, Knoop indentation perimeters were observed in BK, KF, LLF, LF, F, SF, SK and SSK glasses. Without exception, a hump was found to be formed entirely around each indentation. This humping phenomenon shows that plastic flow occurs during indentation. Moreover, it was found that the ratio of the width (c′) of the hump around the shorter diagonal to the shorter diagonal length (a′) is approximately proportional to c/a calculated from Hill's theory on plastic-elastic materials, where (a) is the spherical radius of the cavity generated by a pressure and (c) is the spherical radius of the plastic region around the cavity. This means that Hill's theory can be applied to the indentation phenomenon of optical glass and accordingly the indentation of optical glass is always related to plastic flow.The relationship between Young's modulus and glass composition was found to be almost parallel to the relationship between Knoop hardness and glass composition. Both Knoop hardness and Young's modulus increased with the content of net-work former. This supports Hill's theory. It was also found that c/a decreases with the content of glass net-work former.From these experimental results, it would be concluded that the indentation hardness of optical glass, which contains a large amount of net-work modifier, is far more an expression of resistivity to plastic flow than densification.

Nature of the deformation and flow of metals at and near the interface during abrasion, and its relation to the friction

Abstract: The direction of flow of various metals (Pb, Al, Au, Ag, 62.1 At. % Au–Ag alloy, Cu, Ni, 25.7 At. % Ni–Cu, Mo, W, U, Ti, Mg, and Zn) past the faces of a ploughing Vickers diamond pyramid of dihedral angle 136° is shown in ploughing (a) parallel to the side of the initial square indentation, (b) parallel to the diagonal, (c) in and intermediate asymmetrical direction. In all these cases, with this obtuse indenter, the metal flow at the interface is close to the direction lying in a plane through the ploughing direction, normal to the surface of the specimen. Approximate theoretical expressions are derived for the friction coefficient µ for such conditions.The form of the flow past an indenter is also indicated by observations on the ploughing of macroscopic metal pyramids and cones in Plasticene built from superposed layers of different colours.Observations are also made on the widths of grooves ploughed by the diamond on various metals, compared with the width of the static indentation. These are considered in relation to the theoretical expressions and the factors which may affect the groove development.

Derivation and Use of Equations for Loading Indentation Curves

Abstract: Normally during testing two curves are plotted commonly termed loading and unloading curves. Significance is attached to the area existing between these curves as it is a measure of the hysteretic loss of the foam. This loss (so called hysteresis loop) is an inherent function of a particular foam formulation. Common practices at present are to visually compare the loading curves plotted from test data of foam from one formulation with that of another by reference to a particular strategic point on the

Basic Studies of Plastic Working with Vibration : 1st Report, Ultrasonic Vibro-Indentation Hardness of Carbon Steels

Abstract: In this report, "ultrasonic vibro-Brinell hardness Hur" is defined in order to estimate the resistance to the plastic deformation of materials under the ultrasonic pulsating loads. The ultrasonic vibro-indentation hardness testing (20 kHz, 500 W, the ratio of the load amplitude and the mean indentation load : Pa/Pm=0.5) of annealed carbon steels (0.15% and 0.55% carbon included respectively) with a spherical indenter, made of hardened steel, was performed. Experimental results show that this testing method is useful as a simulative test of the plastic working under the ultrasonic pulsating compressive load, and that for the same material the differences of the estimating methods of the vibro-indentation load give different results, as "vibro-softening" of "vibro-hardening".