effects of transport vibrations on modulus of elasticity watermelon, variety crimson sweet

vibration generated by vehicles during road transport has an important impact on agricultural products' damage process, particularly in the case of fruits and vegetables. modulus of elasticity is one of the most conspicuous mechanical properties of fruits, the variation in which can be described as one of the most affecting damage criteria during transportation. this research was conducted to evaluate the effects of vibration parameters (frequency, acceleration and duration) as well as fruit position in the bin, on damage inflicted upon watermelon. vibration frequency and acceleration were initially measured of different points of truck-bed to obtain the range of vibration frequency and acceleration distribution during transport. a laboratory vibrator was then employed to determine the factors influencing the damage incurred by watermelons during transportation. the damage was described as a difference of modulus of elasticity of watermelon (flesh and hull) before and after the test. according to the results obtained from tests carried out on the truck-bed, vibration frequency mean values were 7.50 hz and 13.0 hz for 5-10 hz and 10-15 hz frequency intervals, respectively. furthermore, vibration acceleration mean values were 0.30 g and 0.70 g for 0.25-0.50 g and 0.50-0.75 g intervals, respectively. vibration frequency and acceleration mean values were used in vibration simulation. vibration durations were 30 and 60 min and the damage was measured for watermelons positioned at top, middle and bottom in the bin. laboratory studies indicated that, vibration frequency, vibration acceleration, vibration duration, as well as fruit position, which were taken into consideration as controlled variable parameters, significantly affected the extent of the damage. damage incurred to watermelon flesh was higher than that to watermelon hull. vibration with a frequency of 7.5 hz, acceleration of 0.70 g, and duration of 60 min caused the highest damage. fruits positioned at the top position in the bin incurred more damage than those in the middle and bottom positions