Showing papers on "Contact area published in 1980"

the contact area and pressure distribution pattern of the knee: A study of normal and osteoarthrotic knee joints

Abstract: Seven knees were studied to determine the contact area and pressure distribution of the tibiofemoral joint, under various loads and at 0° flexion, using the casting method and special sensor sheets. At a load of 1000N (Newton) the contact area of the knee was 11.5 × lCmm2 with menisci and 5.2 × lCmm2 without menisci, and the menisci occupied 70 per cent of the total contact area. Peak pressure at 1000N was 3MPa (Mega Pascal) with the menisci and 6MPa without them. the high pressure areas were located on the lateral meniscus as well as on the uncovered part of the articular cartilage of the lateral compartment, and on the uncovered cartilage in the medial compartment. After removal of the menisci the contact area decreased to below one half that of the intact knee and the contact pressure considerably increased. These facts imply that the menisci have load bearing and load spreading functions.The contact areas were also measured in two osteoarthrotic knees and they were significantly larger than those in n...

Load-bearing pattern of the ankle joint. Contact area and pressure distribution.

Abstract: The contact area of eight human talocrural joints was measured. After preparation, the talocrural joint was set into the compression machine. Under loading the casting was made by silicon rubber and the pressure distribution was measured by pressure sensor sheet. The contact area was localized at anterior and lateral parts. Under 1,500 N loading, the contact area was 522 mm2 and the maximum pressure was 9.9 MPa. Slight diastasis caused a decrease of the contact area and an increase of pressure.

Fracture Mechanics and Adherence of Viscoelastic Solids

Abstract: Contact of two elastic solids is treated as a thermodynamic problem. It is shown that U = UE+US and UE = US+UP+US are thermo-dynamic potentials respectively for transformations at fixed grips and at fixed load conditions (UE, UP, US are the elastic, potential, interface energies). Equations giving the displacement δ and the strain energy release rate G as a function of the contact area A and the load P appear to be the equations of state of the system. Two bodies in contact on an area A are in equilibrium if G=w, where w is the thermodynamic (or Dupre’s) work of adhesion. This equilibrium is stable if ∂G/∂A is positive, unstable if negative. The quasistatic force of adherence is the load corresponding to ∂G/∂A = o. But equilibrium may be stable at fixed grips and unstable at fixed load, so that the quasistatic force of adherence may depend on the stiffness of the measuring apparatus. When G>w, the separation of the two bodies starts, and can be seen as the propagation of a crack in mode I. G-w is the force applied to unit length of crack; under this force, the crack takes a limiting speed v, which is a function of the temperature, and one can write $$G - w = w\phi \left( {{a_T}v} \right).$$

Method of contacting a solar cell

Abstract: A solar cell comprises a semiconductor body with a p-n-junction, a metallized area on the light receiving surface of the semiconductor body, a connection or contact area on the light receiving surface, a reflection reducing layer completely covering the metallized area and the connection or contact area and a further contact on the rear face. A metal connector is fixed to the connection or contact area by placing the connector against the reflection reducing layer and conductively connecting the connector to the connection area while concurrently eliminating the reflection reducing layer from that area.

Adhesion energies at a metal interface: the effects of surface treatments and ion implantation

Abstract: Studies the effect of various surface treatments upon the nanometre-scale thermodynamic and plastic properties of titanium interfaces A mechanical microprobe technique gives curves of electrical contact resistance versus applied load The curve shape depends upon the state of the original titanium surfaces A characteristically stable contact area approximately=10-14 m2, can often be achieved through a combination of surface forces and a high enough load, despite the initial microroughness of the surface With the help of field emission measurements of contact geometry, surface cleanliness and extent of plastic deformation, values of gamma (Dupre adhesion energy) and H (nanometre-scale hardness of the softer of the two samples) are derived Ion implantation can reduce the value of gamma by a factor of three, and low values may be associated with the improved wear resistance that such treatment can give

Influence of Some Geometric Factors on Contact Resistance Probe Measurements

Abstract: The effect of variations in the geometry and preparation of gold probe tips for contact resistance measurements has been evaluated. Tips prepared by melting and by machining and possessing shapes ranging from a point to hemispheres with radii from 0.9 mm to 3.2 mm were used. The contact resistance values are nearly independent of probe geometry on gold and on very lightly filmed (<5 to 10 A) copper targets. On more heavily filmed copper and nickel targets, the contact resistance varies as much as 2½ orders of magnitude at a fixed contact force. The only known variable is the apparent contact area of the various tips, determined by examination in a scanning electron microscope (SEM) after use. It appears that contact pressure predicts contact resistance more reliably than does contact force.

Underwater-mateable electrical connector

Abstract: In an underwater-mateable connector system of the vented pin-and-socket t, the socket electrical contact system is composed of a contact ring cooperating with a contact band, the contact band being integrally provided with a multiplicity of resiliently deformable louvers. The pin electrical contact is composed of a rigid conductor disposed intermediate electrically insulating material and is arranged to provide electrical contact with the deformable louvers of the contact band. Electrically insulating interference seals are formed on either side of the contact area when mated due to differential diameters between the pin and socket. The preferred embodiment utilizes a Multilam® band (U.S. Pat. No. 3,453,587) as the contact band.

Transport of spatially inhomogeneous current in a compensated metal under magnetic fields. III. A case of bismuth in longitudinal and transverse magnetic fields

Abstract: Inhomogeneous current systems in bismuth specimens under longitudinal and transverse magnetic fields have been investigated by solving a boundary‐value problem of a rectangular parallelepiped medium to which current electrodes are attached with a finite contact area. The main results are as follows. In a longitudinal field, the current inhomogeneity governed by specimen geometry grows, extending toward the middle part of the specimen, and at the same time the current is condensed around the specimen axis parallel to the magnetic field. This current condensation increases the total resistance and decreases the potential difference measured on a side surface. In a transverse field, conversely, the current inhomogeneity degenerates to be confined in a narrow region near the end surface. Influences of specimen dimensions and electrode contact area are quantitatively discussed.

Static cylindrical monolithic structure having a large area of contact

Abstract: The invention relates to a static cylindrical monolithic cellular structure with a large contact area, said structure being used in particular for a static heat exchanger and including a plurality of parallel ducts. Its general organization is essentially cylindrical, and the ducts are defined by radial walls (10) and circumferential walls (11). Said ducts form groups for conveying different fluids with the groups being in an essentially radial configuration, i.e, with groups for conveying different fluids at least some of the radial type walls constituting the boundaries between different fluid flows. Application in particular to static exchangers and to filters.

Effect of Number of Impacts on Erosion of Polycrystalline MgF2 in the Elastic‐Plastic Response Regime

Abstract: Targets of MgF2 were subjected to impact conditions from single-particle to 1010 impacts, simulating a natural dust environment (quartz particles) in the subsonic velocity regime. The functional relation of erosion to particle size and velocity predicted by the elastic-plastic impact model is followed for this system. Impact damage is characterized by a heavily deformed contact area between particle and target, with radial cracks propagating outward from the contact zone and with subsurface lateral cracks propagating outward on planes nearly parallel to the surface. The laterally cracked regions are responsible for most of the erosion loss. This type of damage is also consistent with the elastic-plastic model. For a given particle size-velocity test condition, the volume of material removed for a single impact can vary over three orders of magnitude. This large variation is due primarily to differences in particle orientation during impact which results from the irregular shape of the angular natural quartz particles. For these conditions there is no significant difference between the amount of material removed by the first impact and by subsequent impacts on the damage area of the initial impact. The results imply that there is no incubation period or damage-enhancement effect for erosion in the elastic-plastic impact response regime.

Apparatus for the welding of strips of thermoplastic material lying on top of each other

Abstract: Apparatus for the welding of strips of thermoplastic material lying on top of each other which enables varying of the welding area and wherein the contact area between the jaws and the strip is larger than the welding area One jaw is fixed and the other jaw is swingable about a vertical axis through the strip while in pressure engagement with the ends of the strips to be welded

Field-effect transistors with micron and submicron gate lengths

Abstract: A method for forming ohmic contacts of gold and germanium gold on a gallium arsenide substrate in which a layer of silicon dioxide is placed over the gold in the contact area prior to sinter alloying to improve wetting and reduce contact resistance.

Process and device for the removal of proteins and their decomposition products from water

Abstract: 1. Process for the removal of protein and degradation products thereof from water, characterised in that the water to be purified is caused to flow around a contact material which is provided with a large contact area and consists of a plastic containing phthalic acid ester and that, in defined intervals, the contact material is cleaned or exchanged for new material.

Clutch driven plate assembly with variable friction area

Abstract: A clutch driven plate assembly for an automotive vehicle wherein the clutch plate has radially extending lobes carrying friction pads of a suitable material, with the pad being mounted on cushioning means so as to present a variable surface contact area to the engaging surfaces of the clutch assembly to decrease the clutching capacity at initial engagement to reduce chatter. As torque demand increases and clutch engagement continues, the clutch capacity is increased by the deforming of the cushioning means to allow the friction pads to flatten against the engaging surfaces and provide a larger contact area.

Application of polycrystalline silicon load for high performance bipolar memory

Abstract: N-type polysilicon was used for resistor load of high performance bipolar memory. Resistance area and contact area of polysilicon were made by low and high dose As+implantation, respectively. Resistance of polysilicon load was formed with standard deviation of 10% in wafer by controlling lateral diffusion of As from contact area to high resistance area of polysilicon load. A 256 bit ECL RAM with polysilicon resistor load of 9.8 kΩ was fabricated with a cell size of 1870 µm2Typical address access time of 4.6 ns and power dissipation of 340 mW were successfully obtained.

Numerical Contact Elastostatics

Abstract: Variational methods have increased the scope of numerically soluble problems in contact elastostatics. This is shown by giving examples of non-variational methods which appear to be confined to simple geometries, except when the problem is frictionless. Then ad-hoc variational methods are exemplified by the two that were used for three-dimensional frictional rolling contact. Finally virtual work based variational principles are presented. They enable proving existence and uniqueness theorems for the contact problem. Some applications are discussed, notably the rolling contact problem in which significant progress is made in comparison to the ad-hoc methods. Quantities like the resulting contact force come out very well, but in the variationally-numerical methods used to date the boundaries of the contact area and the areas of slip and adhesion are often badly represented.

Feed paper separation system

Abstract: PURPOSE:To improve a feed paper separating function by a system wherein an arm comprising a friction element is supported at the width direction center of the friction element, keeping the friction element into contact with the paper feed roller with a spring. CONSTITUTION:A separation friction element 210 is provided to the arm 200, a nip starting element 200a affixing the Teflon tape having a low friction factor. The arm 200 is supported by the trailing arm as a fulcrum which is fitted slightly on the axle 220 located on the bracket 260 secured with the main body, where the bearing width is narrow in locating at the center of the friction element 210 width and provided at the front side against the rotation direction of the roller 100. The friction element 210 presses the roller 100 with the spring 230. This enables the compression force applied to the paper feed roller of the friction element to become equal in the lateral direction for preventing the paper from skewing. Besides, this allows to widen the contact area between the friction element and the roller for preventing double feeding of the paper.

Dynamic Contact Angles of Viscous Liquids

Abstract: An empirical model has been developed which can predict the dynamic contact angle of a spreading drop of viscous liquid on a plane wettable surface from the contact area for contact angles between 90° and 0° within a specified drop size. This range of drop size is restricted to those drops having a contact area at a 90° cap condition (A90) between 0.10 cm2 and 0.20 cm2 The drop profile was found not to be that of a spherical segment and hence could not allow a simple geometric interpretation. The model strengthens the interpretation that contact angle development in this range of drop size is mainly the geometric result of spreading. The model was found to hold over a wide variety of polymer melt temperatures (155–240°C), molecular weights and molecular weight distributions, which combined would greatly influence drop profile. The time dependency of the dynamic contact angle was also evaluated by combining the present empirical model with a previous viscosity dependent model relating contact area...

[Area of contact between osteosynthesis plate and bone in internal fixation (author's transl)].

Abstract: The bone can be protected against excessive stress if the plate is properly adapted to the surface of the contact area between plate and bone, thus ensuring good and longlasting repositioning of the fracture. The article describes an in-vitro method for the quantitative evaluation of the contact area between plate and bone in osteosynthesis. With four different bones and the requisite plates, six expert surgeons were able to obtain an area of contact between plate and bone which varied between 13 and 60%, the average being 32%. The available data allow us to conclude that the peak loads of pressure occurring with small contact areas may be so great that they exceed the maximum compressive strength of the bone.

Coaxial receptacle with sleeve for outer conductor - has inner conductor contact with injected insulator between it and outer conductor sleeve

Abstract: The coaxial receptacle has a contact for the inner conductor held in an insulator The contact sleeve (1) for the outer conductor is provided in the contact area (4) on the sleeve inner wall with axial flexible elevations (3) The insulator (7) consists of an injected element surrounding the inner conductor contact (6) and filling the outer conductor contact sleeve (1) in the corresp area The insulator (7) forms a tight fitting arrangement around a cylindrical tube extension (2a, 2b) to the contact sleeve

Un-encapsulated compact integrated circuit carrier - incorporated into automatic machine readable identity cards and has device joined by film conductors to contact pads through windows

Abstract: The device is fixed by a contact system on the support. The conducting paths are fixed at one end to the device and at the other to contact pads. The contact pads are on one side of the supporting plate and the device on the other. Contact is established through windows cut in the plate with the connecting pads of the device. The windows may be directly aligned with the connecting pads and the conducting paths joined direct or extended conductors overlapping the windows joined to the connecting pads by their underside by gold filament wire. The conducting tracks may be inserted through the windows and lapped over the underside of the device which is glued to the plate or lapped over the underside of the plate and connected to the upper face of the device. Unencapsulated integrated circuits are incorporated in e.g. identity cards submitted to daily usage in automatic machines where a minimum contact area of 1 to 2 mm2 is required. The small dimensions of the integrated circuit carrier allows a small surface area to be subject to mechanical constraints.