Laboratory tests revealed that palletized fiberboard boxes of Bartlett
pears are most susceptible to bruising damage at vibrational frequenc
ies below 40 Hz (cycles/s), which are common in refrigerated highway t
railers. Damage studies indicate that of the four frequency regions ob
served in-transit (3.5 Hz, 9 Hz, 18.5 Hz, and 25 Hz), Bartlett pears a
re most severely damaged at 3.5 Hz and 18.5 Hz. Laboratory studies als
o show that fiberboard boxes of pears amplify vibration at frequencies
below 40 Hz such that, for some frequencies, the lid of the top box i
n a pallet is accelerated three to four times more than the level inpu
t to the bottom box.