Research on Camellia oleifera Shell Mechanical–Structural Cracking Behavior During Collision Hulling with In Situ Testing

Shelling Camellia oleifera fruit (COF) is a fundamental step in its oil extraction and further processing. Mechanical shelling mainly relies on cracking through collision. Determining the collision mechanics and structural damage to COF during shelling under specific conditions is crucial for the design of the shelling equipment. In this study, a self-established COF collision mechanical–structural cracking damage test platform was built, with observation in situ using a high-speed macro camera. The main influencing factors on the impact force and structural damage during shelling were analyzed in depth, including the collision material, position, drying temperature, and impact angle. The experimental test results show that the COF collision cracking behavior can be divided into two stages—initial contact to maximum deformation, cracking, and propagation—matching with the mechanical–structural testing. Collision along the y-axis obviously causes more damage than that along the x-axis. Cracking of the COF occurs when the impact speed exceeds 3.27 m/s. The collision materials 304 stainless steel and 7075 aluminum alloy significantly facilitate cracking, while fresh fruit and polyurethane as collision materials cause no obvious damage. The drying temperature reduces the shell-breaking force for COF, with a drying temperature of 110° leading to the best shell-breaking. This research identifies key factors influencing the cracking behavior in COF shelling, such as the material selection, impact speed, and drying temperature. Optimizing these parameters can enhance shelling efficiency, reduce equipment wear, and increase throughput. This tailored approach supports scalable, cost-effective, and high-quality COF oil production with minimized waste and energy use.