Finite-element-based Modal Analysis of Fruit Firmness

Nondestructive methods for testing the firmness of fruit can be based on the measurement of the resonant frequency of the fruit. Finite element modeling of the dynamics of apple and pineapple revealed the first flexural vibrational mode and the second longitudinal vibrational mode, both of which are related to the elastic modulus of the fruit by the stiffness factor f2m2/3. The finite element method was also used to analyze the effect of the fruit geometry on the dynamic behavior as well as to decide the best locations of the force excitation and the response measurement sensors. Numerical and experimental results are compared.