文档介绍：Section 1
FUNDAMENTALS OF NOISE, VIBRATION,
AND HARSHNESS
Lesson Objectives 1. Introduce
the
concepts
relating
to
Noise,
Vibration
and
Harshness
(NVH).
2. Define
NVH
terminology.
3. Develop
the
background
necessary
for
NVH
diagnosis
and
the
use
of
the
NVH
Analyzer.
4. Introduce
the
concepts
of
the
transmission
of
vibration
and
sound.
5. Introduce
the
concepts
of
preventing
vibration
and
noise.
6. Develop
skills
in
associating
NVH
symptoms
to
the:
• Sensation
• Frequency
range
• Operating
conditions
• Causes
• Vibrating
system
Section 1
FUNDAMENTALS OF NOISE, VIBRATION,
AND HARSHNESS
Introduction Noise
and
vibration
normally
exist
in
the
operation
of
a
vehicle.
When
they
e
unpleasant
to
the
senses
they
may
be
regarded
as
problems
by
the
customer.
NVH
(Noise,
Vibration
and
Harshness)
is
the
term
used
when
discussing
these
conditions.
Noise, Vibration
and Harshness
Fig. 1-1
We
experience
vibration
by
our
senses
of
touch
and
vision.
We
experience
sounds
by
our
sense
of
hearing.
People
can
perceive
the
same
noise
and
vibration
differently.
To
some
it
may
be
annoying,
to
others
merely
unpleasant
while
others
may
not
notice
it
until
it
is
pointed
out.
Sensing Vibrations
Fig. 1-2
Noise, Vibration, and Harshness - Course 472 3
Section 1
Introduction The
NVH
condition
that
is
a
concern
does
not
have
to
be
the
strongest
Continued vibration
or
the
loudest
noise.
It
could
be
one
that
was
not
there
before
or
one
that
is
not
acceptable
to
the
customer.
Therefore
it
is
critical
that
we
verify
the
customer’plaint.
For
example:
Tire
pattern
noise
from
a
vehicle
with
block
or
lug
pattern
tires
could
be
acceptable
to
the
owner
of
a
4
X
4.
plaint
on
the
same
vehicle
could
be
much
more
subtle,
caused
by
a
driveline
problem.
Because
we
sense
vibration
and
sound
using
different
senses,
we
tend
to
discuss
them
separately.
But
vibr