IntechOpen eBooks,
Год журнала:
2024,
Номер
unknown
Опубликована: Июль 3, 2024
Nowadays,
acoustic
black
holes
(ABHs)
are
very
popular
for
producing
efficient
vibration
reduction
at
high
frequencies
in
combination
with
some
damping
mechanisms.
However,
its
low-frequency
performance
is
hard
to
improve
since
the
ABH
effect
principally
occurs
beyond
cut-on
frequency.
Fortunately,
periodic
configuration
offers
bandgaps
below
that
frequency
wave
attenuation.
In
this
chapter,
a
topological
structure
suggested
produce
new
bandgap
low
frequencies,
by
taking
supercell
and
decreasing
distance.
The
Rayleigh-Ritz
method
(WRRM)
adopted
compute
complex
dispersion
curves.
Examinations
of
curves
transmissibilities
confirm
efficiency
capability
proposed
ABHs.
Journal of Sound and Vibration,
Год журнала:
2024,
Номер
589, С. 118524 - 118524
Опубликована: Май 30, 2024
Rainbow
trapping
filters
(RTFs)
have
been
so
far
investigated
to
achieve
broadband
unit
sound
absorption
in
closed-end
duct
terminations.
However,
opened
RTFs
scarcely
explored
realize
low-frequency
dissipation
of
waves
while
being
traversed
by
a
low
speed
flow.
To
bridge
the
gap,
we
propose
RTF
composed
coiled
cavities
whose
inner
radius
follows
flow-compliant
converging
profile,
referred
as
CCRTF
silencer.
An
effective
medium
approach
and
transfer
matrix
method
(TMM)
showed
ability
such
devices
produce
slow
sound,
impedance
matching
minute
reflection
transmission
over
wide
bandwidth,
confirmed
finite
element
simulations
scattering
measurements
without
A
causal
analysis
revealed
that
large
density
wall
resonators
enhances
silencer
performance
its
bandwidth
is
driven
coiling
factor,
convergent
contraction
ratio
axial
growth.
Particle
swarm
optimization
these
parameters
led
sub-wavelength
with
near-unit
3.5
octaves
from
200
Hz
upwards.
Extended
TMM
aeroacoustic
resilience
under
upstream
or
downstream
propagation
conditions
for
outlet
Mach
numbers
below
0.16,
thereby
opening
up
applications
like
design
silent
nozzles.
International Journal of Mechanical Sciences,
Год журнала:
2024,
Номер
282, С. 109591 - 109591
Опубликована: Июль 27, 2024
Metamaterials
are
capable
of
attenuating
undesired
mechanical
vibrations
within
a
narrow
band-gap
frequency
range;
however,
real-world
applications
often
require
adjustments
due
to
varying
loads
and
content.
This
study
introduces
self-aware,
thermo-active
metamaterial,
3D-printed
in
single
process
using
thermoplastic
material
extrusion.
The
adjustment
the
natural
region
is
achieved
through
resistive
heating
conductive
paths,
which
alters
stiffness
base
cell's
resonator.
Additionally,
these
paths
facilitate
detection
resonator's
excitation
temperature,
thereby
eliminating
need
for
external
sensors.
dynamic
adaptability,
experimentally
demonstrated
by
achieving
tuning
range
from
505
Hz
445
with
17
°C
temperature
difference,
highlights
potential
metamaterials
smart
structures
across
aerospace,
civil,
automotive
industries.
