Biological Micro- and Nanotribology: Nature’s SolutionsEver since the genesis of life, and throughout the course its further evolution, Nature has constantly been called upon to act as an engineer in solving technical problems. Organisms have evolved a variety of well-defined shapes and structures. Although often intricate and fragile, they can nonetheless deal with extreme mechanical loads. Some organisms live attached to a substrate; others can also move, fly, swim and dive. These abilities and many more are based on a variety of ingenious structural solutions. Understanding these is of major scientific interest, since it can give insights into the workings of Nature in evolutionary processes. Beyond that, we can discover the detailed chemical and physical properties of the materials which have evolved, can learn about their use as structural elements and their biological role and function. This knowledge is also highly relevant for technical applications by humans. Many of the greatest challenges for today's engineering science involve miniaturization. Insects and other small living creatures have solved many of the same problems during their evolution. Zoologists and morphologists have collected an immense amount of information about the structure of such living micromechanical systems. We have now reached a sophistication beyond the pure descriptive level. Today, advances in physics and chemistry enable us to measure the adhesion, friction, stress and wear of biological structures on the micro- and nanonewton scale. Furthermore, the chemical composition and properties of natural adhesives and lubricants are accessible to chemical analysis. |
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Page 15
... radius of curvature R is expressed by 1 1 1 + R r1 T2 . ( 2.19 ) When one of the radii goes to infinity , then the contact of sphere and flat sample can be calculated . The deformation ( flattening or indentation ) is con- sidered as ...
... radius of curvature R is expressed by 1 1 1 + R r1 T2 . ( 2.19 ) When one of the radii goes to infinity , then the contact of sphere and flat sample can be calculated . The deformation ( flattening or indentation ) is con- sidered as ...
Page 16
... radius of curvature reduces to the radius of the ball , the effective elastic modulus according to 1 3 K 4 ( 1- v E1 1 – v2 + E2 9 ( 2.20 ) R = r1 , and K is ( 2.21 ) where ; are the Poisson ratios and E ; are the Young's moduli of the ...
... radius of curvature reduces to the radius of the ball , the effective elastic modulus according to 1 3 K 4 ( 1- v E1 1 – v2 + E2 9 ( 2.20 ) R = r1 , and K is ( 2.21 ) where ; are the Poisson ratios and E ; are the Young's moduli of the ...
Page 17
... radius of the contact area ; see Fig . 2.8 . Without applied normal force this radius disappears and the ball returns its initial form , no hystere- sis effects occur . The theory can be applied to dry surfaces where adhesion is ...
... radius of the contact area ; see Fig . 2.8 . Without applied normal force this radius disappears and the ball returns its initial form , no hystere- sis effects occur . The theory can be applied to dry surfaces where adhesion is ...
Page 19
... radius of the remaining contact area is determined by ао = 4πуR2 2K 13 ( 2.28 ) Contrary to the models discussed so far , the DMT model requires numeric solutions with a computer . This disadvantage is caused by the fact that the ...
... radius of the remaining contact area is determined by ао = 4πуR2 2K 13 ( 2.28 ) Contrary to the models discussed so far , the DMT model requires numeric solutions with a computer . This disadvantage is caused by the fact that the ...
Page 20
... radius over particle radius can be so large that the parabolic approximation used in the JKR model does not hold . By means of exact sphere profiles the theory was extended . Other geometries like cones or paraboloids were considered by ...
... radius over particle radius can be so large that the parabolic approximation used in the JKR model does not hold . By means of exact sphere profiles the theory was extended . Other geometries like cones or paraboloids were considered by ...
Contents
7 | |
Biological Frictional and Adhesive Systems | 78 |
Frictional Devices of Insects | 129 |
Microscale Test Equipment 153 | 152 |
Nanoscale Probe Techniques | 179 |
Microscopy Techniques | 193 |
Samples Sample Preparation | 223 |
Friction | 243 |
Material Properties 251 | 250 |
A Contact Models | 259 |
List of Symbols | 273 |
Index | 299 |
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Biological Micro- and Nanotribology: Nature’s Solutions Matthias Scherge,Stanislav Gorb No preview available - 2010 |
Common terms and phrases
adhesion adsorbed animals applied asperities atoms attachment pads ball and flat beam behavior Biol biological body byssus cantilever capillary action capillary bridge capillary force cartilage cells chemical collagen contact area cuticle decrease deflection deformation distal distance double-layer elastic electron elytra endomysium energy epicuticle epidermal flat sample fluid force curve friction force function glands Hertz humidity hydrophilic hydrophobic increasing indentation insect interaction interlock layer Lett lubrication material mbar measured method microscopy microtrichia molecular molecules monolayer muscle nanometer normal force obtained oscillation oxide Phys plant probe profilometer protein pull-off pull-off force range roughness scanning sclerites secretion Sect sections sensor shear shown in Fig shows silicon SILICON model system sliding velocity smooth solid specimen staining stick/slips structure substrate surface synovial fluid tangential force techniques Technol temperature tissues Tribol Tribology vacuum vibration viscoelastic viscosity water film thickness water molecules