Non-contact and non-destructive firmness assessment of pawpaw fruit using experimental modal analysis

Abstract

We performed firmness assessment of pawpaw fruit by a non-contact and non-destructive vibration test. A laser-induced plasma shock wave generated with a high-output Nd: YAG pulsed laser is applied to pawpaws as a non-contact and non-destructive impulse excitation force. Vibration responses of pawpaws were measured using a laser Doppler vibrometer during the laser excitation. We succeeded to obtain natural frequencies and their mode shapes (₀S₂ mode) of pawpaws by experimental modal analysis. Relationship between natural frequencies (₀S₂ mode) and storage time has been revealed.