With many 'flexible' structures such as large span bridges, tall buildings, towers, cable roofs, etc., being built, the need to understand the dynamics behavior of structures has become a necessity for many engineers. The recent problems with the millinium bridge is simply another reminder. The many devastating earthquakes in many parts of the world leading to severe loss of life in densely inhabited urban areas alos has underlined the need for a fundamental understanding of structural behavior.
FRICTION is the resistance to movement of one body over body. The word comes to us from the Latin verb fricare, which means to rub. The bodies in question may be a gas and a solid (aerodynamic friction), or a liquid and a solid (liquid friction); or the friction may be due to internal energy dissipation processes within one body (internal friction).
This chapter provides classification of metal forming processes based on types of forces applied onto metals. • Mechanics of metal forming will be outlined to understand stress criterion for plastic deformation. • Differences between hot and cold working will be highlighted and advantages-disadvantages of hot and cold working will be given. • Effects of deformation speed and friction on metal working process will be included.
The book contains an introduction to matrix analysis, and to the basic algorithms of numer-
ical linear algebra. Further results can be found in many text books. The book of Horn and
Johnson [HJ85] is an excellent reference for theoretical results about matrix analysis; see also
[Bha97]. The subject of linear algebra, and matrix analysis in particular, is treated in an original
and illuminating fashion in [Lax97].
While such investigations yield differing effects dependent on the situation, the common observation of a temperature change has been associated with the presence of mechanical energy, which is required to overcome frictional resistance as sliding at the contact interface occurs. The energy, dissipated through conversion into thermal energy, is manifested as a temperature rise. At the microlevel, this increase can be substantial. A localized change in material properties, an enhancement in chemical reactivity, and ultimately, failure of the mechanical system can result.
On the theory side, research has proceeded along two distinct fronts. First, one
needs to explain what prevents rational arbitrageurs from eliminating these and other
predictable patterns in returns. Work in this “limits to arbitrage” vein has focused on the
risks and market frictions that arbitrageurs face. These include simple transactional
impediments, like short-selling constraints, as well as a variety of other complications.
The tribology term comes from the Greeks of the words ‘’ tribos’’ meaning ‘’ friction ‘’,
and ‘’logos’’ meaning ‘’ law ‘’. Therefore Tribology is defi ned as “ a science which studies
surfaces moving one compared to the other “ and also a fi eld of science studying
lubrication, friction, and wear.
Harrison, J.A. et al. “Atomic-Scale Simulation of Tribological and Related...” Handbook of Micro/Nanotribology. Ed. Bharat Bhushan Boca Raton: CRC Press LLC, 1999
Atomic-Scale Simulation of Tribological and Related Phenomena
Judith A. Harrison, Steven J. Stuart, and Donald W. Brenner
11.1 Introduction 11.2 Molecular Dynamics Simulations
Interatomic Potentials • Thermodynamic Ensemble • Temperature Regulation
The lubrication of rolling bearings –
similar to that of sliding bearings – mainly
serves one purpose: to avoid or at least
reduce metal-to-metal contact between
the rolling and sliding contact surfaces,
i.e. to reduce friction and wear in the
Oil, adhering to the surfaces of the
parts in rolling contact, is fed between the
contact areas. The oil film separates the
contact surfaces preventing metal-to-metal
contact (»physical lubrication«).