The design of a controller for a flexible system under the influence of friction is presented. A linear programming technique for finding an optimal control of linear flexible systems is extended to frictional systems. A floating oscillator is used in the development, where friction and control input forces are acting on the first mass. The result of the linear programming is a control profile ...

Synovial fluid plays an important role in lubricating synovial joints. Its main constituents are hyaluronic acid (HA) and γ-globulin, acting as boundary lubricants for articular cartilage. The aim of the study was to demonstrate the concentration-dependent effect of HA and γ-globulin on the boundary-lubricating ability of human osteoarthritis (OA) cartilage. Normal, early and advance stage arti...

The microstructure investigated in this study was inspired by the anisotropic microornamentation of scales from the ventral body side of the California King Snake (Lampropeltis getula californiae). Frictional properties of snake-inspired microstructured polymer surface (SIMPS) made of epoxy resin were characterised in contact with a smooth glass ball by a microtribometer in two perpendicular di...

Few measurements have been made of the frictional forces within living joints. Barnett and Cobbold (1962) recorded that the coefficient of friction at the distal interphalangeal joint of the middle finger in six healthy adults could be as low as 0 0075, a figure of the same order as that in excised joints (Jones, 1936; Charnley, 1959). Rydell (1965) measured, in a patient fitted with a hip pros...

This paper presents the effect of preload on static and dynamic performance characteristics of several gas-lubricated noncircular journal bearing configurations. The linearized system approach using finite element method is used to obtain both steady state and dynamic characteristics. The results of the investigation shows that preload has a significant effect on frictional power loss and the ...

In vivo frictional properties of human skin and five materials, namely aluminium, nylon, silicone, cotton sock, Pelite, were investigated. Normal and untreated skin over six anatomic regions of ten normal subjects were measured under a controlled environment. The average coefficient of friction for all measurements is 0.46+/-0.15 (p<0.05). Among all measured sites, the palm of the hand has the ...

Smooth muscle myosin light chain kinase was purified from turkey gizzards. The enzyme was extracted from washed myofibrils and the final step of purification was affinity chromatography using calmodulin coupled to Sepharose 4B. The purified enzyme was characterized with respect to its physical, chemical, and kinetic properties. It has a molecular weight of 130,000 by sodium dodecyl sulfate poly...

When a compliant sheet of material is dragged over a curved surface of a body, the frictional forces generated can be many times greater than they would be for a planar interface. This phenomenon is known to contribute to the abrasion damage to skin often suffered by wearers of incontinence pads and bed/chairbound people susceptible to pressure sores. Experiments that attempt to quantify these ...

Solid lubricants used in aerospace applications must provide low friction and a predictable operation life over an extreme range of temperatures, environments and contact conditions. PTFE and PTFE composites have shown favorable tribological performance as solid lubricants. This study evaluates the effect of temperature on the friction coefficient of neat PTFE, a PTFE/ PEEK composite and an exp...