| What
I liked most is the chapter on dampers (shock absorbers). It gave me
the answers to lots of questions that I had before reading this published
work, for example how to choose "ride/handling compromise"
when adjusting damping ratio? Why stiffer dampers are more comfortable
on large-amplitude bumps, while softer dampers provide smoother ride
on small-amplitude bumps? "In an automobile, a suspension is used
to reduce the discomfort induced by unevenness in the highway. As measure
of discomfort is the vertical acceleration that the passenger is subjected
while sitting in the vehicle". The book demonstrates the model
where the passenger is linked to the road via three springs in a sequence:
tire, coil and the seat, and one damper (shock absorber). There is a
graph showing passenger vertical acceleration depending on the amplitude
(frequency) of road irregularities, for distinct shock absorbers with
various damping ratios. For a stiff shock absorber this diagram shows
relatively flat curve, where the vertical acceleration is almost independent
of frequency of bumps. For the soft shock absorber, there is a very
high peak (several times higher comparing to a stiff damper) of vertical
acceleration for the low-frequency bumps, and this acceleration curve
quickly decays as the frequency increases. There is another graph, "transient
load transfer analysis", which shows that with soft dampers, the
suspension load in a turn fluctuates. This is another answer to the
question why stiffer dampers (to a certain extent) provide better handling.
The order of the chapters is somewhat sporadic. The books is a mixture
of sections of engineering information (formulas), historical background,
sketches (e.g. torque arm rear axle suspension), recipes (KONI's published
instructions for damper adjustment), and sample data (e.g. Goodyear
tire data). Nevertheless, the work is so deep that in a couple of years
after it's publication, it had been started being used as a university
textbook. Based on comments from faculty, SAE have requested the authors
to prepare a supplementary book of problems, to help the universities
to examine the students. |
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