1978 Volume 40 Issue 1 Pages 61-67
In-transit mechanical injury of fruits and vegetables was thought to be a fatigue failure due to the accumulation of damage caused by vibrating force during the transportation. For the purpose of estimating the in-transit injury of the products, S-N curve which was available for the fatigue analysis of metalic materials was used to determine the degree of damage or injury under the sinusoidal and random in-transit vibration. Degree of damage, D, was expressed as follows:
(a) Under the sinusoidal in-transit vibration, D=1/β∑iniGiα
(b) Under the random in-transit vibration,
D=f0T/β(√2σ)αΓ(1+α/2)
2. The magnitude of vibrating acceleration was determined in connection with the simulation time based on the analytical acceleration in the actual transportation. The magnitude of vibrating acceleration, G or G′, was expressed as follows: (a) When the same simulation time is used as for the actual transportation time, (i) When the occuring frequency of vibrating acceleration during the actual transportation was known at every acceleration level,
G=(∑iniGiα/∑ini)1/α
(ii) When RMS value and expected frequency f0 of random vibrating acceleration during the actual transportation were known,
G=√2σΓ(1+α/2)1/α
(b) When simulated transportation time T is shorter than that of actual transportation T0,
G′=G(T0/T)1/α
3. Judging from power spectrum density of vibrating acceleration, the components of vibrating frequency were grouped into the following three classes of 2-5Hz, 10-14Hz and 20-24Hz. The former two components could be observed at every speed of vehicle and the components of 2-3Hz and 20-40Hz were increased with the speed was gathered.
4. The relationship between the mean magnitude of vibrating acceleration G, and the speed of vehicle V, was obtained as G=0.028V0.3
5. These analysis were applied to determine the factors of simulated transportation test for lettuce from Nagano to Tokyo and from Miyazaki to Osaka. The values of α and β in S-N curve were considered to be 4.17 and 5320 respectively from the previous work.
