Natural Or Resonant Frequency; Resonance; Front Suspension - Suzuki XL7 2007 Service Manual

0A-23 General Information:

Natural or Resonant Frequency

The natural frequency is the frequency at which an
object tends to vibrate. Bells, guitar strings, and tuning
forks are all examples of objects that tend to vibrate at
specific frequencies when excited by an external force.
Suspension systems, and even engines within the
mounts, have a tendency to vibrate at certain
frequencies. This is why some vibration complaints
occur only at specific vehicle speeds or engine RPM.
The stiffness and the natural frequency of a material
have a relationship. Generally, the stiffer the material,
the higher the natural frequency. The opposite is also
true. The softer a material, the lower the natural
frequency. Conversely, the greater the mass, the lower
the natural frequency.

Resonance

1. Frequency - cps
2. Suspension Frequency
3. Unbalanced Excitation
4. Point of Resonance
5. Problem Speed
All objects have natural frequencies. The natural
frequency of a typical automotive front suspension is in
the 10-15 Hz range. This natural frequency is the result
of the suspension design. The suspension's natural
frequency is the same at all vehicle speeds. As the tire
speed increases along with the vehicle speed, the
disturbance created by the tire increases in frequency.
Eventually, the frequency of the unbalanced tire will
intersect with the natural frequency of the suspension.
This causes the suspension to vibrate. The intersecting
point is called the resonance.
The amplitude of a vibration will be greatest at the point
of resonance. While the vibration may be felt above and
below the problem speed, the vibration may be felt the
most at the point of resonance.