Study On Shear Process Of Wheat In Triaxial Tests Base On Digital Image Processing Technique

The barn is a kind of special structure used to store grain,grain during discharge,due to its own gravity,interaction between particles and grain,the silo wall are interacted,caused by dynamic lateral pressure of silo wall on the granary is increasing rapidly,far greater than the static pressure,larger than the static pressure,dynamic pressure is one of the barn structure design of main load Research shows that the mechanical properties of grain,especially the shear strength,shear deformation characteristics have great effects on the food stored in the interaction,so it is necessary to carry out experimental research on grain shearing process,to provide the experimental basis for grain silo design.In this paper,digital image measurement technology based on three axis automatic instrument For the transformation,wheat in Henan as the research object,explore the applicability of digital image measurement technology applied in grain three triaxial test,study of grain in the three axle shear test of strength and deformation characteristics.The main contents of this paper are as follows:(1)Based on digital image processing technique for automatic Triaxial apparatus are retrofitted for this instrument,saturated sand to calibrate for example,studies have shown that the instrument can be used for determination of granular materials the stress,volume and other parameters.(2)three axis test of Henan wheat using the instrument,the change of wheat void ratio,confining pressure and other factors were obtained in a parallel experiment,influencing factors of wheat under the stress-strain relationship curves and strain.(3)based on the theory of Mohr-Kulun,get samples of cohesion c and internal friction angle,test results show that,when the confining pressure is 25 kPa,50 kPa,75 kPa,100 kPa,pore ratio of 0.58,0.62,0.68 of wheat under the cohesion between 0.56 kPa and 0.32 kPa,the internal friction angle is 25.13 degrees to 23.57 degrees.(4)calculated in the void ratio is 0.58,Under low confining pressure,the dilatancy angle of wheat is between 16.29 and 13.85 degrees.When the confining pressure is 25 kPa and the(5)void ratio is 0.58,0.62,0.68,the dilatancy angle of wheat is between 16.29 and 15.13 degrees.(5)the instrument data postprocessing,draw out the wheat samples and the corresponding changes in the strain map vector diagram,using surfer software.The results showed that wheat samples were compressed,the appearance of specimens showed good symmetry,which belongs to the drum damage.