Analysis of Vibration Harvesting Properties and Fracturing Structures of Soapberry (Sapindus Mukorossi)

Highlights Analyzing the fruit removal force and harvesting time of Sapindus fills a gap of Sapindus research. A dual excitation vibration method for harvesting Sapindus and the best harvesting parameters were obtained. The microstructure of the different fracturing locations was analyzed for the first time. Abstract.To address the issue of labor intensity in the harvest of Sapindus fruit, it is necessary to understand the harvesting properties of Sapindus mukorossi. In this study, a fruit removal force (FRF) test platform was used to analyze the relationship between the FRF and maturation time. An eccentric vibration harvesting test was conducted to obtain the frequency, acceleration, and other parameters of the Sapindus tree. According to the different falling locations of fruit, the fracturing locations were observed by a scanning electron microscope (SEM). The results revealed that the optimal time (9 to 12 November) to harvest is in the middle of the harvest period. Additionally, the shear force from 1.0N to 5.2 N was less than the tensile force from 2.7 to 10.2 N. Therefore, back and forth swinging is the major fracturing form of the fruit. Moreover, dual excitation is preferable to single-point excitation, and the acceleration root mean square (RMS) of the dual excitation was two to three times the acceleration RMS of single point excitation. The harvesting efficiency of dual excitation was 92.3% at 20 Hz. Additionally, there existed four fracturing locations for harvested fruit, as the frequency increased. Furthermore, the fracturing in the ear and stem was the most important form of fracturing, and microscopic observations revealed that it had a thinner and tidier cell wall and cell cavity. Keywords: Sapindus, Fruit removal force, Vibration, Microstructure.