| There are many mechanical problems in the process of harvesting,drying,threshing and processing of corn kernels,some of which even directly affect the quality and economic benefits of the products.The mechanical properties of corn are important factors to determining the quality of processing.The results of the analysis were analyzed by variable analysis and coefficient of variation.The results were as follows: the subsequent experiments were carried out,the stability of maize of in situ compression test was carried out,and the morphological changes of grain were observed by Olympus microscope in real time.Pearson correlation analysis was carried out to analyze the correlation between the in situ compression test results and the traditional mechanical tests.The results of the compression experiment were analyzed by Pearson correlation analysis with the experimental results of traditional texture puncture and shear.The relationship between the in situ test and the traditional mechanical properties of two maize kernels was studied.The feasibility of the in situ test was studied.The images were analyzed by Image J software.The relationship between the image parameters and the in situ compression mechanics parameters was analyzed by Pearson correlation analysis and difference analysis.The relationship between maize grain image and in situ compressive force was found.The main research contents and results are as follows:1.The puncture force-displacement curve was obtained by the puncture test of corn kernels.And the maximum load capacity of maize kernel was different between parts of the corn.The maximum load capacity of cuticle endosperm was the highest,and the endosperm was the smallest.With the increase of water content,the maximum bursting force of endosperm,powdery endosperm and embryo were decreased.With the increase of water content,the deformation of cuticle end increased first,then decreased steadily and slowly.The deformation of endosperm of silty was showed a steady trend,and the deformation of embryo gradually increased.The loading rate had little effect on the maximum rupture force,deformation and total work of the various parts of the grain.When the water content was 14.78%,the variation coefficient of each part of maize grain was small and the result was stable.Considering the equilibrium moisture of corn and the safe moisture of storage and transportation,the water content is 14.78%.The test result is more stable and more representative.There was no significant difference in the maximum rupture force,deformation and total workability at different rates of maize grain at different rates.There was no significant difference in the rate of puncture in different parts of maize.In order to consider the stability and loading effect of the puncture results,the loading rate is 0.1mm/s in the follow-up experiment,which can guarantee the stability and reliability of the loading result,and meet the quasi-static loading requirements.2.The shearing force-displacement curve was obtained by shearing the corn kernel.As the contact area between the various parts and the cutting tool is not uniform,and the organization of the various parts is different,results in that the various parts of the shear cracking force are different.In the three parts,the shear fracture force of the long axis is the largest,the shear fracture force of the minor axis is the second,and the shear force on the side is the smallest.With the increase of water content,the shearing force of each part of grain showed a decreasing trend irregularly.The deformation of long axis and short axis decreased first and then increased gradually.The total weight of the side decreased with the increase of water content and showed a linear decrease.The shear rate of the long axis increases greatly,and the shear force decreases with the increase of the loading rate.With the increase of the loading rate,the shear rate of the long axis increases smoothly;loading rate on the short axis of the variable have a certain impact.The loading rate has little effect on the lateral shear mechanics parameters.The results showed that there was no significant difference in the shear mechanics variance between the four parts at 14.78%,and the coefficient of variation was less stable and the results were more stable.The results showed that when the water content was 14.78%,the variance analysis and coefficient of variation analysis of the mechanical parameters of the shear test at 5 loading rates showed that there was no significant difference in the loading rate of 0.1mm/s.The coefficient of variation was small and the results were stable.3.The results show that there is a difference in the maximum load force of maize grain under different placement modes by analyzing the pressure-displacement curve of corn seed in situ compression.When the maize grain is placed flat,the maximum load force is the largest;when the maize grain is placed stand-up,the maximum load force is the second;when the maize grain is placed by side,the maximum load force is the smallest.The analysis of the mechanical parameters of maize inbred under different water content was found that the compressive and rupture forces of the grains decreased with the increase of the water content;the compressive deformation of the three kinds of methods increased with the increase of the water content;the total compressive power of the three kinds of placing modes decreases with the increase of the water content.For the three kinds of placement methods,when the compressive mechanical parameters in the water content of 14.78%,there is no significant difference,and the overall results are better.The overall coefficient of variation fluctuates is in a smaller range,and the stability of the results is acceptable.The compressive mechanical parameters of the three methods are significantly correlated with the puncture and shear mechanics parameters at level of 0.05,and the correlation is good.The linear regression analysis of mechanical parameters with significant correlation between maize grain puncture and in situ compression was carried out.The results showed that the linear regression analysis between the mechanical parameters with significant correlation was significant.The linear regression analysis of the mechanical parameters with significant correlation between maize grain shear and in situ compression was carried out.The results showed that the linear regression analysis between the mechanical parameters with significant correlation was also significant.4.Through the processing of the original crack image,the ideal crack image is obtained by image cropping,image gray scale,image threshold segmentation and image crack skeleton extraction for crack parameter extraction.Pearson correlation analysis showed that the crack width was significantly correlated with the F1,W1,F3,D3,W3 at the level of 0.05,and the correlation coefficients were 0.889,0.890,0.896,-0.931,0.929.The results show that F1,W1,F3,W3 increase with the increase of crack width,R2 are 0.6966,0.8757,0.9019,0.9233;D3 decreases with the increase of crack width,when R2 is 0.9432.Crack width and D3 linear regression of the best results,when R2 to 0.715.Pearson correlation analysis showed that the crack circumference was significantly correlated with the in situ compression W1 at the level of 0.05,and the correlation coefficient was 0.936;F1 and W3 of the crack circumference and the in situ compressed were significantly correlated at the level of 0.01,and the correlation coefficients were 0.963,0.970.The results show that F1,W1 and W3 increase with the increase of crack circumference,and R2 is 0.9527,0.825 and 0.8124.The results show that F1,W1 and W3 increase with the increase of crack circumference.The cracked perimeter and F1 have the best linear regression effect,and R2 reaches 0.9527.Pearson correlation analysis showed that the fractal dimension of fractures was significantly correlated with D1 and W3 at the level of 0.05,and the correlation coefficients were-0.886 and 0.9434 respectively;the fractal dimension of fracture and in-situ compression is significantly correlated with W1 at the position of 0.01,and the correlation coefficient is 0.983.It shows that W1 and W3 increase with the increase of the fractal dimension of the crack,and R2 is 0.8314 and 0.7421 respectively;the D1 decreases with the increase of the fractal dimension of the crack,and R2 is 0.6425.The fractal dimension of crack is the best linear regression effect of W1,and R2 reaches 0.8314.Through the traditional mechanics research and in situ experimental study,the traditional mechanical characteristics are summarized.At the same time,it is compared with the in situ test,and it is found that there is a good correlation between the in situ test and the mechanical parameters of the traditional mechanical test.The test can be applied to the mechanics of maize kernels.In situ test also observed and obtained the micro-morphological changes of maize kernels in the test,which provided the basis for the analysis of the mechanical properties of maize kernels,which provided a new idea for the study of the mechanical properties of grain kernels. |
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