Quantitative Detection And Experimental Study Of Grain Internal Damage In Rice Based On Micro-CT

Rice was one of the three largest grain crops in the world and an important grain crop in China.It has an important influence on the national economic development of our country.In view of the current fragmentation of grain threshing rice,internal damage and other issues,the Micro-CT scanning technology,combining with the digital image processing method were used to establish a new model of quantitatively characterize the grain damage.This study provided new ideas for the characterization of internal damage detection of grain and provide theoretical guidance to the design of the key parts of the threshing device with low damage.This paper mainly studied the following aspects:Mechanical properties of rice grain.The mechanical characteristics of rice grain in different directions were tested by texture analyzer,and the process of grain damage and fragmentation under different loading modes was analyzed,which was the preparation for CT scanning test.The results showed that:The destructive force of the rice seeds under different loading methods were different,the most destructive force was in the frontal extrusion,the second was the lateral pressure,and the destructive force of the vertical pressure was the smallest.In the process of loading,first to reach the destructive power of brown rice,began to crack,with the load increased,brown rice ruptured,and finally the chaff ruptured.Quantitative characterization of internal damage of rice grain based on Micro-CT image processing.Micro-CT scanning experiments on rice grains under different loading methods were conducted,combined with digital image processing methods such as pseudo-color image processing,grayscale histogram analysis,threshold segmentation and three-dimensional reconstruction.Two quantitative characterization methods were studied based on two-dimensional slice and 3D reconstruction.then,the crack morphology was extracted from the three-dimensional reconstruction of the figure and the crack growth rules under different loading modes were established.The reasons for the crack propagation were analyzed,during the positive pressure and thelateral pressure,the cracks were produced in the endosperm and along the load application direction of expansion,vertical pressure,the cracks were produced in the part of embryo and endosperm connecting and performed for cracking along the length direction of rice grain with larger loads.The quantitative analysis of damage showed that the quantitative characterization method based on the three-dimensional reconstruction map was more accurate,the same load,the maximum damage of vertical pressure was the largest.Finite element analysis of the mechanical properties of rice grain extrusion.The ANSYS Workbench software was used to simulate and analyze the mechanical properties of rice grain.It was concluded that the peak value of the equivalent stress of rice grains under different loading modes was different.The maximum value of vertical pressure and the minimum positive pressure were consistent with the experimental results of mechanical properties.The feasibility was verified compared with the distribution of three-dimensional reconstruction cracks in rice grain and the law of expansion.Analysis and test of threshing damage based on Micro-CT model of internal damage evaluation of rice.According to the existing evaluation index of threshing broken rate,loss rate,combined with the internal damage evaluation model introduced in this paper,carried out threshing tests on hege16 threshing machine and analyzed threshing components line speed,threshing clearance,feed intake on the influence factors of rice grain threshing damage and device performance.The single factor test and orthogonal test are carried out,and the orthogonal test results show that threshing gap has the most significant impact on loss rate,breakage rate and internal damage rate.threshing cylinder speed has the most significant influence on average internal damage degree,and feed rate has the least influence.The optimum parameters of the threshing test were as follows: the threshing clearance was 13 mm,the threshing cylinder speed was 18m/s,and the feeding amount was 1.6g/s.