Mechanics Based Design of Structures and Machines,
Journal Year:
2023,
Volume and Issue:
52(6), P. 3011 - 3037
Published: April 11, 2023
This
paper
presents
a
generalized
vibration-based
multiple
breathing
crack
localization
technique
in
beams
with
an
unknown
number
of
cracks
based
on
Singular
Spectrum
Analysis
(SSA).
Localization
is
highly
challenging
inverse
problem,
as
all
these
(more
than
two)
might
be
similar
state
(either
opening
or
closing
state)
at
any
particular
time
instant
contrasting
states
(while
some
are
opening,
others
during
vibration.
The
level
nonlinearity
vibration
response
strongly
dependent
not
only
each
size,
and
location
but
also
the
application
driving
force
along
cracked
beam.
concept
varied
input
frequency
excitation
sources
employed
present
work
for
identification
over
tedious
traditional
approach
varying
positions.
major
advantage
using
singular
spectrum
analysis
that
it
can
reliably
isolate
extract
very
low-amplitude
nonlinear
sensitive
components
(super
harmonics
intermodulation)
being
buried
total
pairwise
eigenvalue
property
harmonic
components.
Investigations
have
been
carried
out
by
number,
spatial
locations,
intensities
cracks.
Sensitivities
associated
measurement
noise
limited
sensors
investigated.
results
both
numerical
experimental
investigations
this
concluded
proposed
SSA
effectively
localize
closely
spaced
sparsely
(i.e.,,
spatially
far
apart)
data-driven,
works
sensors,
does
need
reference
healthy
measurements.
Mechanics of Advanced Materials and Structures,
Journal Year:
2023,
Volume and Issue:
31(17), P. 4019 - 4036
Published: March 20, 2023
The
modified
strain
gradient
theory
(MSGT)
with
flexoelectric
and
micro-inertia
effects
is
developed
to
study
the
free
vibration
of
tube
made
elastic
centrosymmetric
materials.
Within
this
theory,
internal
energy
density
function
tensor,
deviatoric
part
stretch
rotation
tensors,
dilatation
gradient,
polarization
vector,
electric
quadrupoles.
linear
coupled
governing
equations
boundary
conditions
are
derived
from
Hamilton
variation
principle.
torsional
problem
analytically
solved
for
non-piezoelectric
nanotube
fixed
edges.
effect
geometry,
coefficient,
micro-inertia,
micro-stiffness
parameters
on
natural
frequency
studied.
International Journal of Structural Stability and Dynamics,
Journal Year:
2023,
Volume and Issue:
23(15)
Published: Jan. 31, 2023
Micro
air
vehicles,
which
are
typical
small-sized
rotating-motion
systems,
have
seen
major
advancements
in
recent
years.
To
provide
some
theoretical
basis
for
developing
and
producing
micro
this
study
establishes
a
novel
rigid–flexible
coupling
dynamic
model
functionally
graded
(FG)
moderately
thick
rectangular
microplates
attached
to
central
rotating
rigid
hub
based
on
the
modified
couple
stress
theory
first-order
shear
deformation
theory.
The
proposed
incorporates
nonlinear
term
of
in-plane
reflect
stiffening
effect
caused
by
rotational
motion.
Material
characteristics
FG
microplate
linear
power-law
distribution
along
thickness
axis.
Further,
discrete
form
dimensionless
equations
their
numerical
solutions
obtained
combining
Euler–Lagrange
equation
Chebyshev–Ritz
method.
Convergence
comparative
studies
carried
out
demonstrate
accuracy
validity
model.
Thereafter,
influence
material
length
scale
parameter,
speed,
gradient
index,
aspect
ratio
frequency
is
investigated.
Numerical
results
reveal
that
effects
both
enhance
rigidity
microplates,
whereas
index
decreases
rigidity.
Nonlinear
leads
significant
differences
value
trace
line
can’t
be
ignored
rotative
structure.
In-plane
motion
its
terms
play
function
or
microplates.
increase
speed
will
reduce
size
dependency
microplate.
Furthermore,
trajectory
steering
corresponding
mode
transition
phenomenon
graphically
represented.
