| This
program provides machine control for cyclic tests designed to measure
changes in dynamic characteristics of a car seat, during an endurance
test. A block consists of several stages, each stage can be set at
different vibration bed amplitude or acceleration ‘G force’, frequency
and number of cycles. The peak and trough of control channel as well
as peak and trough of other transducers are plotted in real time providing
an early assessment of possible aging or damage. During the test the
vibration amplitude is adjusted in small increments until the desired
acceleration is achieved. Trips can be set on any number of channels.
At a user-selected interval, the vibration is stopped; the location
of the buttock pan is recorded,the vibration is stopped; the location
of the buttock pan is recorded.
Another test on a car seat is the frequency
sweep. The user sets lower and upper frequencies, the vibration
amplitude, and number of cycles and time interval at each frequency.
The resulting amplitude ratio (sample displacement / table displacement)
versus frequency plot can be used to establish at where the resonance
occurs. The natural frequency, fn, and
the peak ratio at that frequency, pr, are
calculated.
During a log damping test, the buttock
pan is raised above the seat at a height depending on the type of
seat, then is released onto the seat surface. The displacement vs.
time plot, a dampened oscillation provides some performance parameters.
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