Showing papers on "Contact area published in 1982"

The shear properties of Langmuir-Blodgett layers

Abstract: The sliding friction between two highly oriented monolayers has been studied by using molecularly smooth mica substrates in the form of contacting orthogonal cylinders. The monolayers in the form of various normal alipathic carboxylic acids and their soaps were deposited with the aid of the Langmuir-Blodgett technique by transfer from aqueous substrates. The normal alkyl group has been varied in length from 14 to 22 methylene repeat units. Data are reported also on the influence of partial saponification of the carboxylic acid and fluorination of the alkyl chain. Most of the investigation has been confined to two contacting single monolayers although a limited amount of data is presented for multilayers sliding over one another. The character of the sliding motion depends not only on the machine but also on the monolayers, particularly their chemistry. Most of the monolayers studied provide a continuous rate of energy dissipation. However, a small number, such as certain soaps, show discontinuous or stick-slip motion. The experimental arrangement allows simultaneous measurement of the sliding frictional force, contact area and film thickness to be made during sliding. In some experiments this friction is the monotonic sliding friction but in others it is the mean maximum value during the stick phase. The film thickness measurement is accurate to 0.2 mm which allows a precise assessment of the shear plane during sliding. In all cases the monolayers and multilayers were found to be extremely durable and shear invariably occurred at the original interface between the monolayers. The sliding friction data are presented as the dynamic specific friction force or interface shear strength, and a number of contact variables have been examined. These include the applied normal load per unit contact area or mean contact pressure, the temperature and the sliding velocity. The interface shear strength is found, to a good approximation, to increase linearly with mean contact pressure but to decrease linearly with temperature in the ranges studied. The influence of sliding velocity is more complex. In the case where intermittent motion is detected the mean maximum values decrease linearly with the logarithm of the velocity.

Method of providing raised electrical contacts on electronic microcircuits

Abstract: A method of providing a raised contact portion on a contact area of an electronic microcircuit in which a ball is formed at one end of a metal wire by means of thermal energy, the ball is pressed against a contact area of the electronic microcircuit and is connected to said contact area. A weakening is created in the wire near the ball and the wire is then severed at the area of the weakening to provide the desired raised contact portion.

Direct Contact Condensation

Abstract: Publisher Summary This chapter introduces the direct contact condensation (DCC) in the design of equipment such as contact condensers, cooling towers, contact feed water heaters and deaerators. The DCC studies are usually related to single-component, two-phase (steam-water) systems, either pure or including traces of noncondensables (air). The advantages of direct contact condensation over the conventional processes using metallic transfer surfaces are due to the relative simplicity of design, less corrosion and scaling problems, lower maintenance costs, higher specific transfer areas, and higher transfer rates. Direct contact condensation can be accomplished by utilizing various contacting devices that include: cross-flow sieve tray columns, concurrent pipe contactors, spray columns, baffle-tray columns, and packed bed columns. All are designed to increase the vapor–liquid contact area. Direct contact condensation is utilized in various chemical process industries, usually for quenching and partial or total condensation, particularly when corrosive vapors are involved. The chapter discusses the large-scale applications of DCC of current interest that includes: emergency core cooling systems, water desalination systems, and geothermal energy recovery processes. The chapter concludes that condensation on a solid surface is limited in practice only by the extent of the surface and the rate of cooling the surface, DCC is inherently limited by the balance between the latent heat of condensation and the sensible heat that the liquid can absorb until saturation.

Influence of Dwell Time on the Adherence of Elastomers

Abstract: We have studied the influence of the time of application of a given force, pressing a rigid spherical punch against a viscoelastic solid, on the kinetics of detachment when a known tensile force is applied suddenly. The edge of the contact surface is treated as a crack tip propagating in mode I at the interface between the two solids. It is shown that the general kinetics equation proposed earlier, G - w = wo(aTv), relating strain energy release rate G, Dupre's work of adhesion w, and the dissipation function o characteristic of the material tested, is confirmed provided that w is given higher values than those usually deduced from measurement of the contact area by the theory of adherence of elastic solids of Johnson et al. 21 It is found both that the time required for fracture varies with contact time (in direct proportion with t0.2 and that the work of adhesion varies directly with t0.1; this latter point means that the increase in adherence cannot be attributed to the diffusion of the free e...

Image reproducing apparatus

Abstract: An image reproducing apparatus of the type in which a toner image formed on a charge receptor is transferred to a transfer member and is fixed on said transfer member by the application of pressure and heat by use of an intermediate transfer belt. An auxiliary pressure contact roller is disposed so as to come into contact, via the intermediate transfer belt, with a support roller forming a transfer-fixing portion, disposed inside the intermediate transfer belt and opposing a pressure contact roller via the intermediate transfer belt, so that the contact area between the support roller and the intermediate transfer belt is enlarged.

Pressure-sensitive conductive elastic sheet

Abstract: A pressure-sensitive, conductive elastic sheet for use in a graphics digitizing tablet through which various letters or figures can be detected, the characteristics of which are such that the contact pressure is almost constant irrespective of contact area or increases with increasing contact area. The pressure-sensitive sheet according to the present invention comprises a silicon rubber in which a number of coarse, ferromagnetic, conductive metal particles with a diameter of 30 to 150 micron are mixed with a number of fine, ferromagnetic, conductive metal particles with a diameter of 10 micron or less or 50 micron or less at a predetermined proportion in such a manner that the coarse particles are aligned vertically through the interior thereof and the fine particles are dispersed near at least one surface thereof. To properly align the particles, the sheet is allowed to set within a uniform magnetic field.

The true area of contact at a liquid metal‐solid interface

Abstract: The properties of a liquid‐solid interface are usually understood under the assumption that contact is continuous over the entire interface, regardless of the surface roughness of the solid. This letter presents results of an analysis which suggest that this assumption is not valid when the liquid is a metal characterized by weak adhesion to the solid. Under these conditions the true area of contact at the interface depends on the surface microtopology of the solid and may differ considerably from the area of nominal contact. Experimental evidence in support of these conclusions is presented.

Fractography off cast gypsum

Abstract: A fractographical study of dental cast gypsum was made in order to correlate the mechanical properties with the microstructure. Wet specimens fractured under tensile stress showed intercrystalline fracture and the tensile strength depended on the porosity present. Thus, it was assumed that tensile strength was dependent on the contact area between individual gypsum crystals and changes in porosity approximated to changes in contact area. Strength differences among specimens of a given W/P ratio, therefore, can be related to differences in intercrystalline contact areas. These theoretical considerations suggest that the classification of dental die stone and dental stone into high and low strength types based on strength properties only would be more practical and less confusing than at present.

Wheel and brake-drum configuration for vehicles

Abstract: A brake-drum flange is bolted to a wheel disk by an interface surface structure which limits the engagement area and avoids contact around the fastening bolts. In the case of a twin-wheel configuration, the two wheels are placed back-to-back, whereby the contact area has larger diameters than the contact areas between the brake drum and the one-wheel disk.

Method of making a pin type electrical connector contact

Abstract: A two piece contact assembly characterized by a method of making the assembly by press fitting a stamped and formed inner sleeve (10) into a cold drawn tubular member (20) to provide an electrical contact having a seamless pin type contact area.

Surface temperature measuring device with reversible thermochromic film

Abstract: An array of thermochromic cells is formed along the end portion of a thin, highly conductive blade. Each cell is visually responsive to a critical temperature incrementally different from the critical temperatures of the other cells. The thermochromic array defines a set of temperature ranges, set off by the critical temperatures. The undersurface of the end portion is pressed down into contact with the hot surface of an object of unknown temperature. The contact pressure is established and maintained constant by bending the blade against the surface. The high elastic strength of the blade permits generous bends having high bending moments without creating a permanent set in the blade. Heat from the hot surface flows upward across the contact area and into the interior of the thin blade. The interior increase in temperature uniformly, with minimum pertubation; and the end portion rapidly obtains an equilibrium temperature substantially equal to the temperature of the object surface. Heat transients are minimal because the contact area is very large relative to the extreme thinness, and small thermal mass, of the blade. The array of thermochromic cells on the top surface of the end portion simultaneously receive heat from the interior. The cells having a lower critical temperature then the equilibrium temperature undergoes the visual change. The condition of the array reveals the equilibrium temperature to within one temperature increment.

Studies of the frictional heating of polycrystalline diamond compact drag tools during rock cutting

Abstract: A numerical-analytical model is developed to analyze temperatures in polycrystalline diamond compact (PDC) drag tools subject to localized frictional heating at a worn flat area and convective cooling at exposed lateral surfaces. Experimental measurements of convective heat transfer coefficients of PDC cutters in a uniform crossflow are presented and used in the model to predict temperatures under typical drilling conditions with fluid flow. The analysis compares favorably with measurements of frictional temperatures in controlled cutting tests on Tennessee marble. It is found that average temperatures at the wearflat contact zone vary directly with frictional force per unit area and are proportional to the one-half power of the cutting speed at the velocities investigated. Temperatures are found to be much more sensitive to decreases in the dynamic friction by lubrication than to increases in convective cooling rates beyond currently achievable levels with water or drilling fluids. It is shown that use of weighted drilling fluids may actually decrease cooling rates compared to those achieved with pure water. It is doubtful that tool temperatures can be kept below critical levels (750/sup 0/C) if air is employed as the drilling fluid. The degree of tool wear is found to have a major influencemore » on the thermal response of the friction contact zone, so that for equal heating per contact area, a worn tool will run much hotter than a sharp tool. It is concluded that tool temperatures may be kept below critical levels with conventional water or mud cooling as long as the fluid provides good cutter-rock lubrication.« less

Changes in bone conduction thresholds with vibrator contact area.

Abstract: An experimental bone conduction vibrator was used to measure force and acceleration directly at the point of contact, the subject’s forehead. Force and acceleration at threshold were measured for six subjects over a frequency range of 250 to 6000 Hz and over a contact area range of five to one. These measurements suggest that for any test subject, the variation in force of threshold with contact area is much smaller than the corresponding variation in acceleration at threshold.

Connection device, using mechanical clamping, for a cable or for a bar for connection to a contact area of an electrical apparatus.

Abstract: The invention relates to a mechanical clamping connection device for a cable or for a bar for connection to a drilled-out contact area of an electrical apparatus having a moulded case. It comprises a stirrup clamp 38 interacting with the contact area 16 in order to constitute either a clamping cage intended to surround the area during a connection using cable inserted between the cage and the lower face of the area 16 or a nut joined to the lower face of the area 16 during a connection using a bar. An intermediate part 44 in the shape of an angle bracket has a flange 44a serving as a bearing surface for the screw 40 and another flange 44b pierced through by a hole 46 for the passage of a screw 40. Application: connecting low-voltage electrical apparatus.

Piezoelectric contact microphone - has contact area supporting and operating stressed piezo pillar under its elasticised lower retaining flange diaphragm

Abstract: The contact microphone is for speech reproduction and is designed for constructional simplicity together with low susceptibility to interfering background noise. A piezo-electric element (2) is prestressed between the greater mass housing (4) and the contact element (1) which transmits the pressure waves from the body surface to the piezo-electric element. The piezo-electric element (2) is prestressed by the elasticised lower flange (1a,1b) of the contact element (1). The flange (1a,1b) fits over the sprung sides of the heavier metal housing (4) and exerts the prestress tension on longer dimension of the piezo-electric element. The piezo-electric element (2) is supported in a central recess on the under side of the contact element (1) and contained in a central compartment of the main housing (4). The contact element (1) is considerably larger in contact area than the piezo-element itself. Electrical connection is from a plate (3) at the base of the piezo-element (2) and a second contact (6) at the base of the housing thereby using the piezo as a high pass capacitor.

Low resistance contact for high density integrated circuit

Abstract: A novel process for fabricating low resistance contacts for high density integrated circuits is described wherein during the initial processing of the device, after a scaled MOSFET is formed, contact openings, having vertical walls with respect to the underlying substrate, are provided. An apertured masking layer, having apertures which provide an open are a somewhat larger than the original contact opening, is formed on the structure after which, the structure is subjected to a high energy deep implant step followed by a low energy, shallow, supplemental implant step. The high energy implant serves to provide the device with a deep junction at the contact area to minimize spiking and, by reason of the shallow implant, good ohmic contact may be made. Since the oxide surrounding the contact opening is also implanted, there is provided means for tapering the edges of the contact opening.

Method of forming protruded contact

Abstract: A method of providing a raised contact portion on a contact area of an electronic microcircuit in which a ball is formed at one end of a metal wire by means of thermal energy, the ball is pressed against a contact area of the electronic microcircuit and is connected to said contact area. A weakening is created in the wire near the ball and the wire is then severed at the area of the weakening to provide the desired raised contact portion.

Investigation of Optimum Crowning in a Line Contact Cylinder-to-Cylinder Rolling Contact Fatigue Test Rig

Abstract: The cylinder-to-cylinder rolling contact fatigue rig is a line contact type of accelerated test rig As an example of the test results from this rig, an investigation of the influence of the full crowning value on the rolling contact fatigue life is described In the contact stress distribution along the axis of the line contact, the contact stress at the crowning edge, P e d g e , has a 14 times larger influence on the rolling contact fatigue life than the maximum contact stress, P m a x , at the center of the contact area; the rolling fatigue life is therefore determined by P m a x or 14 P e d g e , whichever is larger This result can also be interpreted by the contact stress at the edge, Q m a x , calculated by Moyer's method Then the rolling fatigue life is determined by P m a x or Q m a x , whichever is larger The optimum crowning value is the value which gives P m a x = 14 P e d g e or P m a x = Q m a x

Microscopic and macroscopic contact angles

Abstract: A simple relation is derived between the microscopic and macroscopic angles of contact of a fluid interface with a solid by taking into account the interaction of the interfaces in the region of contact. It is also shown how the macroscopic angle can be related to the perturbed interfacial tensions. Both angles are a property of the three phases in contact, independent of geometry and weak gravitational fields. Finally, calculated profiles of axially symmetric fluid interfaces in the neighbourhood of a planar solid surface are compared with those that would occur in the absence of interaction between the interfaces.

Method and device for production of quick cooling material for melt

Abstract: PURPOSE:To improve cooling effect considerably with a wide contact area by forming the circumferential part of at least one cooling body into easy to deform and restore construction in plural rotary cooling bodies which revolve under pressure contact with each other at part of the surfaces of the circumference. CONSTITUTION:A rotary cooling body 1 of elastic construction consisting of a surface layer consisting of, for example, copper or the like having good heat conductivity and prescribed strength, an elastic body 4 consisting of, for example, deformable and restorable nylon rubber or the like on the lower side thereof, and a shaft core body 6 is formed. A rotary cooling body 7 and a temp. control roll 8 of rigid construction are brought in press contact with the body 1. A molten material 11 charged into a vessel 10 is heated with a heating means 12, and is ejected continuously onto the cooling body surfaces near the press contact surface areas of the two bodies 1, 7 through a nozzle 13 provided in the lowermost part of the vessel 10, whereby it is quickly cooled and solidified and is released as a thin strip shaped material 14. Thereby, the cooling distance of the material 11 is made long, and a metallic material 14 of a thin strip shape having high surface accuracy and plate thickness accuracy is obtained.

Some Aspects of the Mechanical Behavior of Films in Boundary Lubrication

Abstract: In boundary lubrication, the wear process is often controlled by the formation of colloidal agglomerations in the contact. These agglomerations are due to collected products of chemical reactions between metal Surfaces and environment (1). They make a non-homogeneous thin film in the interface. Their accumulation gives rise to the formation of adherent films in the case of antiwear additives (zinc dithiophosphates and organophosphorous compounds). The purpose of the paper is to show that small agglomerations (called lump), compressed between two solid bodies, can plastically deform the surface and can grooves when the two surfaces slide. Experiments involving plasticine are presented. The first shows that, during static compression, the thickness of the film and local friction coefficients are important parameters in explaining the plastic deformation of the substratum. The second shows the mechanical conditions that favor the entry of the lump into the contact area and give the give the mild scartch-type...

Non-destructive metal coating thickness measurement - uses electrodes in contact with surface, local layer, carrier resistance differences

Abstract: An arrangement for non-destructive measurement of the thickness of a metallic surface layer (2) on a carrier body (1) is applicable where the layer and carrier body electrical conductivities are significantly different. It operates irrespective of the atomic wts. of the carrier body and the surface layer material. Two electrodes (3,4), which are connected to a voltage source via an adjustable series resistor, are placed on the surface layer (2) at a defined separation distance (1) and with a defined application pressure. The thickness of the layer is determined from the locally different electrical resistance values of the carrier body and the surface layer at the measurement point. The electrodes are rectangular, and in partic. square, with a contact area small compared to the electrode separation.

Wear mechanism based on adhesion

Abstract: Various concepts concerning wear mechanisms and deformation behavior observed in the sliding wear track are surveyed. The mechanisms for wear fragment formation is discussed on the basis of adhesion. The wear process under unlubricated sliding conditions is explained in relation to the concept of adhesion at the interface during the sliding process. The mechanism for tearing away the surface layer from the contact area and forming the sliding track contour is explained by assuming the simplified process of material removal based on the adhesion theory.