Integration of high-speed imaging, pressure-sensitive film, and finite element method for predicting drop damage in postharvest collision of 'Dangshansuli' pears (Pyrus bretschneideri Rehd.) with different contact materials.

Mechanical damage during postharvest handling is a primary cause of quality deterioration and loss of marketability in 'Dangshansuli' pear (Pyrus bretschneideri Rehd), which is closely related to its high internal pressure and brittle tissue characteristics. This study integrated high-speed imaging, pressure-sensitive film technology, and the finite element method (FEM) to investigate impact damage from fruit drop to quantitatively analyze the transient collision behavior of pears and predict damage. Drop height ranged from 20 to 80 cm, covering four contact materials: steel plate (SP), rubber plate (RP), corrugated cardboard (CC), and foam board (FP). The results showed that damage area increased linearly with impact energy (R2 > 0.96), while the coefficient of restitution (COR) exhibited a nonlinear decay with increasing impact energy (R2 > 0.93), reflecting an increased energy dissipation within the fruit's brittle tissue. A critical impact energy threshold of 0.528 J was identified, below which FP effectively inhibited the formation of macroscopic bruising. Quantitative analysis of pressure-sensitive films revealed distinct contact stress patterns: for rigid surfaces (SP and RP), a stress threshold of 0.2 MPa predicted damage area with >91% accuracy; for cushioning materials (CC and FP), a threshold of 0.3 MPa was more applicable. The developed high-fidelity FEM model accurately captured millisecond-scale stress evolution, achieving >81% prediction accuracy under rigid surface conditions. Hence, this research provides a useful digital tool and theoretical reference for damage-reducing design of postharvest equipment and protective packaging optimization, particularly under rigid contact conditions.