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CATEGORIES:Isaac Newton Institute Seminar Series
SUMMARY:Shear band dynamics - Davide Bigoni (University of
Trento)
DTSTART;TZID=Europe/London:20190815T163000
DTEND;TZID=Europe/London:20190815T170000
UID:TALK128641AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/128641
DESCRIPTION:When a ductile material is subject to severe strai
n\, failure is preluded by the emergence of shear
bands\, which initially nucleate \; \;in&n
bsp\; a \; small \; area\, \; but 
\; quickly \; extend \; rectilinearly 
\; and \; accumulate \; damage\, \; un
til \; they \; degenerate \; into 
\; fractures. \; \;Therefore\, research on
shear bands yields a fundamental understanding of
the intimate rules of failure\, so that it may be
important \;in the design of new materials wi
th superior mechanical performances.A shear band o
f finite length\, formed inside a ductile material
 \;at a certain stage of a continued homogeneo
us strain\, provides \; a \; dynamic \
; perturbation to an incident wave field\, which s
trongly \;influences the dynamics of the mater
ial and affects \; its \; path \; to&n
bsp\; failure. \; The \; investigation&nbs
p\; of \; this \; perturbation \; is&n
bsp\; presented \; \;for \; a \; d
uctile \; metal\, \; with \; reference
 \; to \; the \; incremental mechanics
of a material obeying the J2&ndash\;deformation t
heory of plasticity. \;The treatment originate
s from the derivation of integral representations
relating the incremental mechanical fields at ever
y point of \;the medium to the incremental&nbs
p\; displacement \; jump \; across \;
the \; shear \; band \; faces\, \;
generated \; by \; an \; impinging&nb
sp\; wave. \; The \; boundary \; \
;integral \; equations are numerically approac
hed through a collocation technique\, which keeps
into account the singularity at the shear band&nbs
p\;tips and permits the analysis of an incident wa
ve impinging a shear band. It is shown that the pr
esence of the shear band induces a resonance\,&nbs
p\;visible in the incremental displacement field a
nd in the stress intensity factor at the shear ban
d tips\, which promotes shear band growth. \;M
oreover\, the waves scattered by the shear band ar
e shown to generate a fine texture of vibrations\,
parallel to the shear band line and \;propaga
ting at a long distance from it\, but leaving a so
rt of conical shadow zone\, which emanates from th
e tips of the shear band [1\,2].
References
[1] Giarola\, D.\, Capuani\, D. Bigoni\, D. (2018)
The dynamics of a shear band. J. Mech. Phys. Soli
ds\, 112\, 472-490.
[2] Giarola\, D.\, Capuani\
, D. Bigoni\, D. (2018) Dynamic interaction of mul
tiple shear bands. Scientific Reports 8 16033
LOCATION:Seminar Room 1\, Newton Institute
CONTACT:INI IT
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