Mechanical Failure of Two Varieties of Watermelon Under Quasi Static Load

Watermelon is handled and stored in bulk package as some other fruits and vegetables are. Package height must be so appropriately selected that bottom fruit layers will receive no damage or failure. This research was performed to determine and compare the mechanical properties of two varieties in three sizes of watermelon under static load conditions to obtain parameters used in transportation as well as in storage. A statistical factorial experiment in the form of a completely randomized design (2×3×2) of five replications was employed to determine the mechanical properties of watermelon in whole watermelon. Such factors as failure force, failure deformation and fruit rind thickness were among those determined. It is found that the failure force was affected by the direction in which it was exerted. Failure force in the longitudinal direction was less than that in the transverse direction while variation in size of the fruit did not significantly affect either failure force or failure deformation. Results also indicated that failure force and failure deformation were significantly affected by variety. Mean failure forces for Charleston Gray and Crimson Sweet varieties were 1.1 and 1.8 kN, respectively. Investigation of rind thickness in different varieties and sizes of watermelon demonstrated that five millimeter increase in rind thickness can increase failure force up to 70%.