# Test Trials and Analysis of Pod-Shattering Characteristics of Harvested Rapeseed Silique
## 1 Introduction  
Rapeseed is an ancient cultivated crop, planted all over the world, with the planting area and yield second only to soybean in oil crops. China is one of the countries with the longest history of rapeseed origin and cultivation, with a perennial planting area of about 100 million acres, and the area and production account for about 20% of the global total [1; 2; 3; 4]. A high harvesting loss of the rapeseed machine is prominent, with the loss of rapeseed siliques to pod shattering caused by the action of reels or plant pulling each other during harvesting accounting for a high percentage. Losses due to silique shattering have been reported in the literature to be 8-12% of the total seed yield, and shattering loss canincrease to 20% if harvesting time is delayed [5; 6; 7; 8]. Therefore, analyzing the pod-shattering characteristics of rapeseed during the harvesting time when the siliques are subjected to external forces is of great value in selecting and breeding machine-harvestable rapeseed varieties, optimizing the design of the reel branch mechanism and movement parameters, and reducing the shattering of rapeseed to reduce the harvesting losses [9; 10; 11; 12].  
The screening of crack-resistant varieties can reduce the silique shattering loss during the process of machine harvesting. In order to screen crack-resistant rapeseed varieties, domestic and foreign scholars have proposed a variety of shatter-resistant test methods [13; 14]. [PERSON] et al. [15] assessed the shatter resistance of rapeseed siliques by experimentally determining the force or energy required to bend the siliques. [PERSON] et al. [16] put forward the tensile method of cracking with a pulling meter to test the shatter resistance of rapeseed siliques. [PERSON] et al. [17] used the random collision method to test the shatter resistance of rapeseed siliques. [PERSON] et al. [18; 19] proposed an impending fracturing method to evaluate the shatter resistance of rape siliques. However, the existing rapeseed shatter resistance evaluation methods do not evaluate the shatter resistance performance from the aspects of the actual stress process and the state of the silique during rapeseed harvesting, and the screening of some varieties can help reduce the shattering that occurs when using a harvesting machine and when external force is applied. Reducing the external force on the siliques during harvesting can also reduce shattering, some scholars have optimized the design of large-diameter non-uniform velocity rolling over reels, changed the rotational speed of the reels, the installation position, and the angle of the reel teeth to reduce the collision force of the reel teeth on the rapeseed silique in the process of harvesting, designed the bidirectional electric driven side vertical cutter, etc., so as to reduce the perturbation of cutting and branching, reduce the vibration of rapeseed siliques, and decrease the shattering loss caused by the cutting and vibration of the branching [20; 21; 22; 23; 24; 25; 26; 27]. However, due to the lack of research on the relationship between silique stress and shattering, there is a lack of basis for the optimization of the reel or branching mechanism. Material heat treatment and material collapse can reduce collision damage, but they have not been used in rape harvesters [28; 29].  
In this paper, based on the actual force process of rapeseed siliques during harvesting, the pendulum method is used to simulate the collision and impact process of external force on the silique, and the impending fracturing method is used to test the different support and force surfaces of the silique; the two methods are compared and verified to study the factors affecting the shattering of rapeseed siliques during harvesting, so as to provide the theoretical basis for the screening of the machine-harvesting varieties of shatter-resistant rapeseed, rapeseed cutting table reel branch design, and parameter optimization.