Ashok
Kumar C
Name : Ashok Kumar C.
Designation : Design Engineer
Qualification: Master
of Technology (
ME Dissertation Project
(2005):
“Characteristics
of Singular Stress Field around a Crack in a Smart Material”
Synopsis:
There is a
rapid growth in the use of smart materials, structures and systems in the
current day engineering technology due to their advanced and intelligent
features. Of the several smart materials used in practice, the shape memory
alloys are finding increasing applications. The novel characteristic associated
with these materials is that they have the ability to return to their shape
even after severe deformation.
One of the
most commonly used shape memory alloys with a wide variety of applications is Nitinol.
It is an alloy of two materials Nickel (Ni) and Titanium (Ti). The important mechanical properties, which
make it more attractive for structural applications are its ductility, high
fatigue life and corrosion resistance. Nitinol possess a peculiar and unique
constitutive behavior, which strongly depends on the applied load and operating
temperature. It exhibits typically two
elastic moduli when loaded up to failure. It has the ability to remember its
original shape even after subjected to severe deformation and restores to its
original condition. The basis for its shape memory behavior is that it can
easily transform from phase to phase (Austenitic to Martensitic and vice-versa)
with little change in volume. The load dependent phase change behavior of
Nitinol gives rise to a characteristic stress field around a crack in it. The
material very close to crack tip shows a martensitic behavior due to high
stress magnitudes encountered where as the other region away from the crack
will be under austenitic condition. Since the constitutive behavior strongly
depends on the phase conditions the singular stress field around the crack in
this case will be very much different from the one seen in conventional
monolithic materials.
This work
presents the results of an extensive investigation carried out to study the
singular stress field behavior near the tip of a central crack in a square
plate subjected to uniform in plane traction. The traction applied was large
enough to cause plastic deformation at crack tip. The fracture parameter
J-Integral for an elastic-plastic behavior was evaluated. A parametric study
was carried out by varying the crack length and keeping the applied traction
constant.
Some of the important results of
the investigation:
Contact Details:
Permanent Address:
LIG-II-24, Tilak Nagar,
Present Address:
H. No. 2-56/33/35/1,
Sainagar, Madhapur,
Phone : 08392-243703
E-mail: ashokkumar_ca@rediffmail.com
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