Research on Apples' Mechanical-Structural Damage Behavior During Dropping Collision With High-Speed Observation

Apples have been constantly damaged in collecting, transporting, and processing, leading research focus on apples' mechanical-structural damage behavior. To research apples' mechanical-structural damage behavior during collision, a dropping collision damage testing device was self-established, with PLC control, data acquisition-processing, in situ high-speed observation. The effect of impact material, drop height, impact orientation on apple deformation and bruise area was investigated with self-established device, considering three typical kinds of apples. The results indicated that apple dropping collision can be divided into two stages: dropping down contact deformation stage and recovering contact deformation stage. Three kinds of apples demonstrate the largest deformation and bruise area when the impact material is steel and acrylic plate. The deformation is similar when apples collide with soil and foam, apples have no bruise area when the impact material is foam. The correlation between apple deformation, bruising area, and drop height was established, reflecting the relationship between drop height and apples' mechanical-structural damage behavior. Yellow Marshal apple deformation is the largest compared to other two kinds of apples under the same collision condition. Red Fuji apple bruise area is the largest compared to other two kinds of apples. The largest bruise area of Yellow Marshal apple and Guoguang apple are in apple transverse, and Red Fuji apple is in apple top. The study can provide basic theoretical and practical guidance for apples postharvest work.