Showing papers on "Contact area published in 1975"
TL;DR: In this article, it was shown that despite the van der Waals' forces being capable of increasing the elastic contact area between the ball and the plane, the force that is required to overcome the molecular forces arising when the contact is broken does not increase thereby.
3,951 citations
TL;DR: In this paper, the elastic contact of an isotropically rough surface with a plane is treated by approximating the summits of a random process model by paraboloids with the same principal curvatures and applying the classical Hertzian solution for their deformation.
710 citations
TL;DR: In this article, the thermodynamics of an idealized rough surface is treated, using the geometry of a vertical plate partially immersed in a liquid, and gravity is included explicitly in the theory.
263 citations
TL;DR: In this paper, the authors present an optical study of contact area time effects between smooth rubber and rigid surfaces and show in a simple way how these optical observations may be used to predict the rate of rolling of a ball bearing on smooth rubber.
140 citations
TL;DR: In this paper, a special bond element is proposed with the help of which the energy dissipation process in the contact area is described, with the assumption that a relation between the shear stress and the frictional deformation is known.
66 citations
TL;DR: In this article, the sliding of rubber over glass when waves of detachment are responsible for the relative motion at the interface has been studied and the frictional force and the velocity and frequency of the waves were recorded for various sliding conditions.
52 citations
Patent•
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TL;DR: In this article, a heat transfer device or heat pipe characterized by integral screen-wick structure providing relatively great contact area between the internal working fluid or condensable medium and the heat input was proposed.
Abstract: The invention contemplates a heat-transfer device or heat pipe characterized by integral screen-wick structure providing relatively great contact area between the internal working fluid or condensable medium and the heat input.
49 citations
Patent•
18 Apr 1975
TL;DR: A push-button switch has a spring contact plate and a circuit board in superposed position as discussed by the authors, each switch position comprising a prestressed domed portion surrounded by a common flat sheet portion.
Abstract: A push-button switch has a spring contact plate and a circuit board in superposed position. The spring contact plate has one or more switch positions, each switch position comprising a prestressed domed portion surrounded by a common flat sheet portion. The spring contacts of each prestressed dome portion selectively engage peripheral contact areas on the circuit board followed by the central contact portion engaging subsequently with a further fixed central contact area on the circuit board. Accordingly, plural inputs of electronic logic circuits may be preselected prior to simultaneous activation upon subsequent closure of the central contacts at a given switch position. Release of the push button enables the domed portion to snap back to the stable position.
48 citations
Patent•
18 Aug 1975TL;DR: In this paper, a film-like material such as thermoplastic sheets, coated paper, or metallic foil is clamped together for radiant energy welding by directing jets of gas against the outer surfaces of two opposed sheets to press or clamp the sheets firmly into contact with each other.
Abstract: Sheets of film-like material such as thermoplastic sheets, coated paper, or metallic foil may be clamped together for radiant energy welding by directing jets of gas against the outer surfaces of two opposed sheets to press or clamp the sheets firmly into contact with each other; and, then by irradiating the contact area to heat the material to its welding temperature, the sheets will be fused together.
32 citations
TL;DR: The thermal conductivity of porous pellets depends on the conductivities of the solid and fluid phases, the pore structure and the contact area between the particles making up the pellet as discussed by the authors.
31 citations
TL;DR: Photoelastic methods, strain gages, and other techniques using plastic models and bone samples, with several available compression plates, are used in an attempt to establish a model for the determination of the intraosseous stress field created in a fractured long bone due to the installation of a compression plate.
TL;DR: In this article, the authors derived predictions for the distribution of true contact area and the associated constriction resistance for a pressed contact between two surfaces which are flat when isothermal but become bowed in the presence of heat fluxes across the contact.
Abstract: Predictions have been derived for the distribution of true contact area and the associated constriction resistance for a pressed contact between two surfaces which are flat when isothermal but become bowed in the presence of heat fluxes across the contact. Induced thermal strains of the interfacial surfaces can lead to the preferential passage of heat in one direction across the contact. Experimental measurements of the thermal resistance of a contact between a specimen of En58B stainless steel and one of commercially-pure aluminium corroborate this theory. The study has identified some of the mistakes which can be made unconsciously, and remain unrecognized subsequently, in using standard measuring techniques for the thermal resistance of a pressed contact.
TL;DR: In this article, a pin on disc machine experiments were carried out to determine the wear transition stresses for several metals and a simple theory was developed to relate these stresses to the macroscopic hardness of the metals.
IBM1
TL;DR: In this article, the authors provide a theoretical analysis of the possibility of obtaining intermittent opens or high resistance caused by mechanically induced contact motion in electrical connectors and evaluate two actual connectors for each of the five possible mechanisms.
Abstract: Shock and vibration have been known to induce contact motion in electrical connectors and thereby cause failures or intermittent disturbances. This paper provides a theoretical analysis of the possibility of obtaining intermittent opens or high resistance caused by mechanically induced contact motion. Intermittent disturbances having time durations of less than one nanosecond are considered. Five possible mechanisms of creating intermit:ent opens are considered. They are: 1. Contact bounce 2. Contact sliding over surface irregularities 3. Contact sliding onto an insulating particle 4. Particle migration through contact area 5. Particle initially in the contact zone. Each possible mechanism is developed fully anc the important parameters are explored. Two actual connectors are evaluated for the possibility of obtaining intermittent opens for each of the five cases. The results of the evaluation are presented in this paper.
TL;DR: In this article, the relationship between the real contact area and compliance under high normal pressure was analyzed and the limit of classical theory validity has been obtained for different modes of contact deformation.
Patent•
05 Mar 1975
TL;DR: In this paper, a gear wheel with a hollow core along the tooth axis is used to increase the deformation of the gear wheel by increasing the contact area between the teeth, thus reducing the specific contact pressure.
Abstract: To increase the torque transmission capacity of a gear wheel, it is necessary to control the contact pressure on the tooth face. By increasing the elasticity of the gear tooth, it deforms more easily when a load is applied. This increases the contact area between the teeth, thus reducing the specific contact pressure. By producing a gear tooth with a hollow core (3) along the tooth axis, its deformability is increased. Lubrication oil, pumped via a central shaft hole and a cross hole reaches the core hole from where it is forced to the tooth contact surface through a hole normal to the pressure face.
01 Jan 1975
TL;DR: In this article, a method of determining the MODULI of deformation of a FISSURED ROCK MASS with EMPTY and FILLED CRACKS is described.
Abstract: THE AUTHOR DESCRIBES A METHOD OF DETERMINING THE MODULI OF DEFORMATION OF A FISSURED ROCK MASS AS A FUNCTION OF THE FOLLOWING PARAMETERS: MODULUS OF DEFORMATION OF THE NON-FISSURED ROCK, SIZE OF CRACKS, SURFACE OF CONTACT OF THE ROCK IN CRACKS, AND SPACING OF CRACKS. FORMULAE ARE PRESENTED FOR ROCK MASS WITH EMPTY AND FILLED CRACKS. IT IS SHOWN THAT THE DEFORMABILITY OF EMPTY CRACKS IS DETERMINED BY THE ROCK CONTACT AREA WHILE THAT OF FILLED CRACKS DEPENDS ON THE COMPRESSIBILITY OF THE MATERIAL FILLING THE CRACK. EXAMPLES ARE GIVEN OF CASES OF SYSTEMATIC AND RANDOM FISSURATION. A STATISTICAL METHOD IS DESCRIBED FOR DETERMINING THE ROCK CONTACT AREA. CALCULATED DEFORMATION MODULI ARE COMPARED WITH THOSE OBTAINED WITH IN-SITU BEARING PLATE MEASUREMENTS. TO FACILITATE THE CALCULATIONS, A COMPUTER PROGRAM HAS BEEN WRITTEN, WHICH IS GIVEN IN THE ARTICLE.
01 Oct 1975
TL;DR: In this article, the impact process of a cylindrical, a spherical and a conical water drop upon a rigid plane is studied with numerical methods and time variation of drop cross-section, pressure and velocity distribution are presented.
Abstract: The impact process of a cylindrical, a spherical and a conical water drop upon a rigid plane is studied with numerical methods. Time variation of drop cross-section, pressure and velocity distribution are presented. The maximum pressure remained at the center of the contact area for the cylindrical drop, but expanded outward with the edge of the contact area for the spherical and conical drops. The peak pressure for both cylindrical and conical drop reached approximately the value predicted by a one-dimensionless analysis. The pattern of pressure distribution on the liquid-solid boundary compared favorably with the existing experimental data.
Patent•
02 Jan 1975
TL;DR: In this article, the two hemicylindrical parts of the ring-like concentrator meet on one side of the bore with an insulating layer between them and on the other side they are in electrical contact, and a cutout is provided at the electrical contact surfaces which divides the contact area into two portions, one portion close to and one portion remote from the workpiece.
Abstract: The two hemicylindrical parts of the ring-like concentrator meet on one side of the bore with an insulating layer between them and on the other side of the bore they are in electrical contact. A cut-out is provided at the electrical contact surfaces which divides the contact area into two portions, one portion close to and one portion remote from the workpiece. These portions are pref. coated with a corrosion resistant highly electrical conductive material and ensure that an induced current flows in the concentrator, which current applies an even magnetic force around the workpiece circumference.
01 Aug 1975
TL;DR: In this article, stress relaxation and creep behavior of PC and PMMA were studied under conditions of constant velocity loading followed by halts, and the authors used this information to deduce relaxation-corrected, force-incursion depth behavior.
Abstract: : Stress relaxation and creep behavior of PC and PMMA were studied under conditions of constant velocity loading followed by halts. This information was used to deduce relaxation-corrected, force-incursion depth behavior. Measurements of force versus depth were also made on sinusoidally programmed indentation. The evaluation of the 'densified' zone forming under the contact area was followed cinematographically. Models were developed including one that leads to the time and velocity dependence of the stress relaxation. (Author)
Patent•
18 Sep 1975
TL;DR: In this article, a conveyor belt for bulk material is equipped with intermediate friction drive units, which are placed between the upper and lower conveyor sections of the belt, and the power that can be transmitted through the friction drives is a function of the coefficient of friction and the load on the conveyor.
Abstract: A conveyor belt for bulk material is equipped with intermediate friction drive units. The drive consists of a friction belt which is placed between the upper and lower conveyor belt section. The power that can be transmitted through the friction drives is a function of the coefficient of friction and the load on the conveyor. By using vertically adjustable support rollers, the tension in the drive belt and the contact area between drive belt and drive rollers can be varied. Sensors which detect the conveyor load and any slip that occurs between drive belt and conveyor are used to govern the power transmission of the intermediate drive units. Their size and number can therefore be kept to a minimum.
TL;DR: In this article, the formulation and solution for the shear stress and temperature in heavily loaded sliding elastohydrodynamic contacts are presented in dimensionless design charts, and the solutions are presented for the contact area will yield the traction.
Abstract: The formulation and solution for the shear stress and temperature in heavily loaded sliding elastohydrodynamic contacts is presented. The solutions are presented in dimensionless design charts. Integration over the contact area will yield the traction. Accuracy is expected to be very good over the nearly flat part of the contact area where the majority of the sliding traction is generated. The procedure presented is not appropriate for thick film lubrication, for the inlet region, or for the rolling friction of elastohydrodynamic contacts.
Patent•
11 Sep 1975
TL;DR: In this paper, a contact leaf spring is used to reduce the contact bounce of the relay during the attraction and the release of the armature, which is suitable for relays with relatively large strokes and low pull force.
Abstract: The apparatus is designed to ensure significant reduction of bounce both during the attraction and the release of the armature. There is a contact leaf spring (1) which is clamped at one end at (6). The small size of the relay makes it expedient to place the actuator (7) outside the contact area of the leaf spring. Contact bounce is limited with a cutout at the free end of the spring in order to match the spring rate to the force-stroke characteristic of the relay electromagnet. The method is suitable for relays with relatively large strokes and low pull force.
TL;DR: In this article, a finite element analysis of a rotating ceramic gas turbine blade consisting of an airfoil and root is discussed, and three-dimensional results were obtained for the blade using both isotropic and orthotropic material properties.
Abstract: A finite element analysis of a rotating ceramic gas turbine blade consisting of an airfoil and root is discussed Three-dimensional results were obtained for the blade using both isotropic and orthotropic material properties A two-dimensional study of the root considered the effects of friction, contact area, and root geometry
Patent•
23 Jan 1975
TL;DR: In this paper, to minimize the losses at the outer liquid metal contact, additional excitation coils are added concentric with the main coil but on a smaller diameter to produce a region of low flux density near the inner coils which can be positioned to coincide with the outer contact.
Abstract: The application is to high output heavy current generators comprising a number of parallel discs which rotate in a magnetic field generated by the main excitation coil. To minimise the losses at the outer liquid metal contact additional excitation coils are added concentric with the main coil but on a smaller diameter. The resultant flux of the two coils produces a region of low flux density near the inner coils which can be positioned to coincide with the outer contact. The eddy currents in the contact area are thus reduced which results in a corresponding reduction in loss and a more satisfactory contact operation. The inner contact is not affected as the angular velocity here is low.
Patent•
20 Mar 1975
TL;DR: In this article, an electrical connector is provided for coupling high current capacity electrical conductors such as copper busses or the like, where the connector is arranged in a "sandwiched" configuration in which a conductor plate contacts the buses along major surfaces thereof clamped between two stainless steel backing plates, and Belleville springs provided under the rim of each button cap are compressed and resiliently force the caps into contact with the bus's contacting surfaces to maintain a predetermined electrical contact area provided by the button cap tops.
Abstract: An electrical connector is provided for coupling high current capacity electrical conductors such as copper busses or the like. The connector is arranged in a "sandwiched" configuration in which a conductor plate contacts the busses along major surfaces thereof clamped between two stainless steel backing plates. The conductor plate is provided with a plurality of contact buttons affixed therein in a spaced array such that the caps of the buttons extend above the conductor plate surface to contact the busses. When clamping bolts provided through openings in the sandwiched arrangement are tightened, Belleville springs provided under the rim of each button cap are compressed and resiliently force the caps into contact with the busses' contacting surfaces to maintain a predetermined electrical contact area provided by the button cap tops. The contact area does not change with changing thermal or mechanical stresses applied to the coupled conductors.
TL;DR: In this article, a finite element analysis of a rotating ceramic gas turbine blade consisting of an airfoil and root is discussed, and three-dimensional results are obtained for the blade using both isotropic and orthotropic material properties.
Abstract: A finite element analysis of a rotating ceramic gas turbine blade consisting of an airfoil and root is discussed. Three-dimensional results were obtained for the blade using both isotropic and orthotropic material properties. A two-dimensional study of the root considered the effects of friction, contact area, and root geometry.
TL;DR: In this article, a fundamental torsional mode, transmitted through a homogeneous fused silica fiber of circular cross section, is used to probe the acoustic contact losses at the fiber supports.
Abstract: A fundamental torsional mode, transmitted through a homogeneous fused silica fiber of circular cross section, is used to probe the acoustic contact losses at the fiber supports. Losses introduced by clamping‐bar supports are measured over one to two decades of clamping force for clamping materials spanning a wide range of elastic properties. The data are found to agree approximately with an analysis proceeding from one basic assumption, that the power loss caused by an element of contact area is proportional to the area. Development of this concept leads to a loss exponent proportional to F 2/3 and s 2/3, where F is applied force and s is a mean compliance parameter for the fiber and support bars. Measurements also show that the frequency dependence of the loss exponent is either weak or nonexistent. The F 2/3 law plus a calculated dependence of loss on the fiber and support‐bar diameters are used to extrapolate the data to smaller loads and thinner supports to estimate losses for several types of supporting structures.