MODAL-ANALYSIS OF THE DYNAMIC BEHAVIOR OF PINEAPPLES AND ITS RELATIONTO FRUIT FIRMNESS

The experimental modal analysis technique as well as the finite elemen t method were used for investigate the dynamic behavior of the pineapp le. The pineapple exhibit the first torsional mode and the second sphe rical mode, both of which are related to the flesh firmness by the sti ffness factor f2m2/3. Since the spherical resonant frequency appears t o be insensitive to skin quality and mainly reflects flesh firmness in terms of modulus of elasticity, it is suggested as a measure of quali ty evaluation. The necessary location and direction of the acceleromet er for measuring the modes are identified. The spherical resonant freq uency was related to the refractometric sugar content and the surface chlorophyll content.