Force transmission

Any material which contains a geometrical discontinuity will experience an increase in stress in the vicinity of the discontinuity. This stress concentration effect is caused by the re-distribution of the lines of force transmission through the material when they encounter the discontinuity. Causes of stress concentration include holes, notches, keyways, comers, etc as illustrated in Fig. 2.62. 

Pneumatic systems can be used for applications that require low to medium pressure and only accurate control. Applications that require medium pressure, more accurate force transmission and moderate motion control can use a combination of hydraulics and pneumatics, or hydropneumatics. Hydraulics systems must be used for applications that require high pressure and/or extremely accurate force and motion control. 

Influence of the Friction on the Force Transmission under Limited Slip.704... 

Tire traction describes the force transmission between tire and road under aU eventualities. It is the prerequisite for controlled steering, acceleration, and braking of self-propelled vehicles on flat tracks. It finds its upper limit in the frictional force when total sliding occurs. Two aspects have therefore to be considered The mechanics of force transmission of elastic wheels and its relation to rubber friction. 

When forces are transmitted between tire and road the tire is deformed to some extent. It still adheres to the road in part of the contact area, but slides locally when the ratio of tangential stress to the local pressure exceeds the friction coefficient and wear occurs. It is this partial adhesion and sliding which on the one hand allows a control over the force transmission and on the other hand leads to wear of the tire. 

The chapter concentrates on the aspect of force transmission during limited sliding. The friction contribution to traction and the resulting wear, both in laboratory experiments and in tire traction and... 

INFLUENCE OF THE FRICTION ON THE FORCE TRANSMISSION UNDER LIMITED SLIP... 

When forces are transmitted, slip occurs because the wheel is being deformed. The relation between force and slip is one of the most important laws in tire mechanics, because it influences the all important properties of traction, durability, and tire wear. (This is not only true for tires, but also for all force transmission by adhesion friction). 

Danowski, B. A., Imanaka-Yoshida, K., Sanger, J. M., and Sanger, J. W. (1992). Costa-meres are sites of force transmission to the substratum in adult rat cardiomyocytes. J. Biol. Chem. 118, 1411-1420. 

In tissues, microfibrils form loosely packed parallel bundles. X-ray fiber diffraction of hydrated zonular microfibril bundles identified one-third-staggered junctions that may modulate force transmission (Wess et al., 1998a), and quick-freeze deep-etch analysis of zonules has identified molecular links between microfibrils (Davis et al., 2002). 

The relationship between the mechanical response of an individual particle to a directly applied stress and that of a powder of the particles is complex because the force transmission to an individual particle is mediated by other particles. As an example consider an amorphous excipient and assume the particles are spherical and have a mono-disperse size. The response to an applied stress of an individual particle should be independent of the direction of application as we re assuming the particle structure is isotropic (unlike a crystal which may exhibit a different response to stress in different directions due to the anisotropic structure dictated by periodic packing constraints). 

The centrical force transmission is obtained by gluing sections of the same adherend thickness onto the adherends in the force transmission area. The adherend extension will be eliminated by a larger adherend thickness (5 mm instead of 1.6 mm) and a reduced overlap length. Due to the homogeneous stress distribution, the respective test results are thus based on defined shear stress conditions. Adhesive layer values, to a large extent independent of the adherend, such as shear modulus, shear strength and deformation behavior, are available as a basis for precise calculations. 

Butt joints are unfavorable for force transmission in the case of metal materials adhesive designs with shear stress acting on the adherend surface (overlap joints) are to be preferred. 

As we shall see in the surface characterization and force transmission chapters, both the physical dimensions and the dimension of time over which the CMP mechanisms act are important in giving a proper perspective to the critical processes. Many components and subcomponents are... 

Static Parameters Force Transmission Physical Environment... 

It is difficult to see how the force transmission would degrade as the asperity topography flattens out with wear. To a first-order approximation, the volume of material removed should be linearly proportional to the force times the bearing area (F x A). As the asperity peaks are smoothed out to a planar surface, the individual forces that were exerted by the fewer peaks is reduced, but in the same proportion as the increase in the bearing area. Unless one can justify a threshold force (vis-a-vis activation energy), linearity should hold and the material removal rate (MRR) should not decrease as the individual asperities are worn down. 

As we have seen, the primary functions of the pad are (a) force transmission, (b) slurry distribution, and (c) byproduct removal. The MRR is a function of all three elements, in a proportion depending upon the application, the consumable set, the device structures under process, the CMP tool configuration, the length of the process (on one wafer, or between calibrations), and so on. More study is needed to differentiate the individual effects and the interaction effects of these elements. 

FIG. 20 Force transmission chains through a granular material while under compressive stress (from Yan and Barbosa-Canovas, 2000). Width of lines represents the relative magnitude of local stress the principal stress is vertical. 

As the neighboring cells of smooth muscle tissues are mechanically coupled, the contractile apparatus of each individual cell exerts tension on its neighbors. Force transmission across the sarcolemma of smooth muscle cells occurs at membrane-associated dense plaques found over the entire cell surface. When isolated smooth muscle cells contract, the points of attachment of contractile filaments are drawn into the cell, resulting in out-pouching of the membrane areas between the plaques (Harris and Warshaw 1991, Draeger et al 1990). 

Frank ED, Warren L (1981) Aortic smooth muscle cells contain vimentin instead of desmin. Proc Natl Acad Sci U S A 78 30203024 Fuglsang A, Khromov A, Torok K, Somlyo AV, Somlyo AP (1993) Flash photolysis studies of relaxation and cross-bridge detachment higher sensitivity of tonic than phasic smooth muscle to MgADP. J Muscle Res Cell Motil 14 6677 Furst DO, Cross RA, De Mey J, Small JV (1986) Caldesmon is an elongated, flexible molecule localized in the actomyosin domains of smooth muscle. EMBO J 5 251257 Gabella G (1984) Structural apparatus for force transmission in smooth muscles. Physiol Rev 64 455477... 

In addition to impact forces, transmission of vibrations to the product can result in damage. Characteristic vibration transmissibility plots for foams are also available, which can be matched with the product s susceptibility to damage. Of course, the design process should be followed by the preparation of a model package and suitable testing of the producl/package system, or in case of a very expensive product, a mock-up used with accelerometers to determine actual performance. 

Horii E., Garcia-Elias M., An K.N., et al. 1990. Effect of force transmission across the carpus in procedures used to treat Kienbock s disease. /. Bone Joint Surg. 15A 393. 

Mathur, A. B., Truskey, G. A., and Reichert, W. M. 2000. Atomic force and total internal reflection fluorescence microscopy for the study of force transmission in endothelial cells, Biophys J 78,1725-1735. 

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