Abstract: In the process of mechanical harvesting and post-harvest processing of water chestnuts, collision damage caused by the impact between harvesting machinery and water chestnuts is often encountered. To address this challenge, a finite element simulation analysis of impact damage to water chestnuts is conducted using Ansys software. This analysis aims to identify methods to enhance the quality of mechanical harvesting and post-harvest treatment processes. The existing elastoplastic model's inadequacies in accurately simulating energy dissipation during the collision process have prompted the adoption of a principal strain failure model. Initially, the average size of the water chestnut was measured, and a three-dimensional scanner was employed to scan a selection of samples to create an appearance model. The model was then divided into three sections: peel, pulp, and top bud. Uniaxial compression tests were then conducted to measure and calculate the intrinsic parameters of the flesh and peel of the water chestnut. To establish a comprehensive model of water chestnut, a meticulous selection process was undertaken, culminating in the selection of a linear elastoplastic and principal strain failure coupling model. The model parameters were calibrated and verified by slab drop tests at three heights, and the evolution laws of stress, energy, and rupture of the coupled model during the drop were analyzed. In addressing the issue of collision damage to water chestnuts by the screening device of a water chestnut harvester, a simplified rod model was developed to investigate the impact of collision on water chestnuts under various conditions. To this end, a three-factor, three-level full-factor collision simulation test was conducted, encompassing fall heights of 200, 400, and 600 millimeters, collision contact surface diameters of 14, 18, and 22 millimeters, and collision materials of structural steel, PVC, and rubber. The study employed a three-factor, three-level full-factor rod collision simulation test to assess the damage susceptibility of water chestnut to bruising, softening, and rupture. The analysis was conducted with the aid of analysis of variance (ANOVA), and the empirical formula of damage susceptibility under different materials was established.The measured elastic modulus, yield strength, and tangential modulus of water chestnut pulp were 7.916, 0.856, and 4.554 MPa, respectively. The principal strain failure value was determined to be 0.098. The impact damage distribution was simulated with the failure mesh volume and the stress interval volume exceeding 0.6 MPa. The relative errors in damage volume, rupture volume, and dissipated energy were determined to be 8.98%, 7.18%, and 6.62%, respectively. These findings suggest that the model can be utilized to describe the mechanical properties, rupture phenomenon, and energy dissipation of water chestnut under impact load. The findings of the rod impact test demonstrated that the drop height of the water chestnut exhibited a direct linear relationship with its damage susceptibility. The elastic modulus of the collision contact material exerted a substantial influence on the damage, and the impact of the contact diameter was found to be associated with the nature of the contact material. In the case of collisions with structural steel, the damage exhibited an initial increase and subsequent decrease with increasing diameter. Conversely, in collisions with PVC and rubber, the damage decreased with increasing diameter. The study also found that the damage to 2, 4, and 6 mm rubber-coated rod teeth was reduced by 9.3%, 13.7%, and 20.9%, respectively, compared to unwrapped rod teeth. These findings offer a valuable reference point for ongoing research endeavors focused on the quality of water chestnut mechanized harvest and the technology and equipment of postharvest treatment.