Ahmet Gökay Öztürk 030050143 7th week

WORK HARDENING

An important method used to strengthen steels is deformation strengthening. Strengthening

achieved with crystal deformation can be judged from the shape of stress train curves. The

actual shape of these curves largely depends on the crystal lattice type of the metal, its purity,

and therm al treatment.

In the case of cubic lattice metals, strengthening curves are parabolic, whereas for

Hexagonal lattice metals a nearly linear dependence is observed between the stress and the

strain. This fact suggests that plastic deformation strengthening is determined mainly by

the interac tion of dislocations and is associated with the structural changes that impedethe

movement of dislocations. Metals with a hexagonal lattice are less prone to deformation

strengthening than cubic lattice metals because the hexagonal lattice has fewer easy slip

systems. In cubic lattice metals, the slip proceeds in several intersecting planes and directions.

(George E. Totten, Steel Heat Treatment Handbook 2nd. ed., pg. 158)


Collaborative Manufacturing

CM is a very broad arena which incorporates many other topical themes of the day, including team design, computer-supported collaborative work, agile manufacturing, enterprise integration, virtual enterprises, high-performance distributed computing, concurrent engineering, computer-integrated manufacturing, virtual reality, global sourcing, and business process reengineering. In general, CM is defined by the following attributes:
• Integrated product and process development, including customers and suppliers;
• Flexible manufacturing distributed over networks of cooperating facilities;
• Teamwork among geographically and organizationally distributed units;
• High-technology support for the collaboration, including high-speed information networks and integration methodology;
• Multidisciplines and multiple objectives.

What is the payoff for CM? Companies that can engage effectively in CM will have the potential for
• Better market opportunities;
• A wider range of design and processing options over which to optimize;
• Fewer and looser constraints restricting their capabilities;
• Lower investment costs;
• Better utilization of resources;
• Faster response to changes.

( Frank Kreith, CRC Press Mechanical Engineering Handbook 1999, ch.13 pg.120)

Photoelasticity

The method of photoelasticity is based on the physical behavior of transparent, noncrystalline, optically isotropic materials that exhibit optically anisotropic characteristics, referred to as temporary double refraction, while they are stressed. To observe and analyze these fringe patterns a device called a polariscope is used. Two kinds of polariscope are common, the plane polariscope and the circular polariscope.

( Frank Kreith, CRC Press Mechanical Engineering Handbook 1999, ch.1 pg.99)

Polymer Degradation

Polymeric materials also experience deterioration by means of environmental interactions.
However, an undesirable interaction is specified as degradation rather
than corrosion because the processes are basically dissimilar.Whereas most metallic
corrosion reactions are electrochemical, by contrast, polymeric degradation is physiochemical; that is, it involves physical as well as chemical phenomena. Furthermore,
a wide variety of reactions and adverse consequences are possible for polymer
degradation. Polymers may deteriorate by swelling and dissolution. Covalent bond
rupture, as a result of heat energy, chemical reactions, and radiation is also possible,
ordinarily with an attendant reduction in mechanical integrity. It should also be
mentioned that because of the chemical complexity of polymers, their degradation
mechanisms are not well understood.

(William D. Callister, Materials Science and Engineering An Introduction 7th ed., pg. 655)