Syudy On Mechanicl Properties Of Cotton Stalk

Xinjiang is the main cotton production base of china and there is a large amount of cotton stalks remaining every day, which leads to increased demand for farm machinery relating to cotton stalks industry. China’s cotton straw harvesting mechanization is so low that foreign machinery and equipment are introduced, leading to being disconnected from China’s national conditions. Therefore, it is of great meaning and theories values for cotton harvest and design of processing machinery to studying mechanical properties of cotton stalks. In this paper, cotton stalks is used as the research object, using electronic universal material testing machine and self-made clamp into cotton straw compression(rift grain, stripes), shearing, bending and mechanical properties tests, which reveal the effect and change rule of different experimental factors on cotton stalks shear, bending, compression mechanical parameters, establishing relation model between multiple factors(moisture content, the sampling position, loading rate) and shear strength, flexural strength, and rift grain and stripes compressive strength and the geometric structure model of cotton stalks. In the end, cotton stalks compression and cotton stalks shearing property tests are carried out for finite element simulation analysis. The main contents and conclusions are as follows:1) The model of three factors on rift grain and stripes compressive strength of cotton stalks can reflect water content, sampling position and loading speed and interaction among them on the effects of rift grain, stripes compression. In single factor effect, the sampling site and water content have a significant effect on the rift grain, stripes compression strength of cotton stalks and loading speed have no significant effect on the rift grain, stripes compression strength of cotton stalks. In double factor effect, Interaction of the sampling site and water content have a significant effect on rift grain, stripes compression strength of cotton stalks and others have no significant effect on the rift grain, stripes compression strength of cotton stalks.2) By the analysis of rift grain compression test, rift grain compression strength firstly decreases and then increases with changes of the sampling position(from bottom to top) and the increase of water content. By the analysis of stripes compression test, stripes compression strength firstly increases and then decreases with changes of the sampling position(from bottom to top) and the increase of water content, difference of both changes may be due to changes of cotton stalks diameter and the internal organizational structure with different sampling positions. In addition, the diameter of cotton stalks is one of the important factors that influences rift grain stripes compression strength.3) Regression model of the shear experment of cotton stalks analysis reveals that loading rate has no significant effect on shear strength of cotton stalks and moisture content and sampling position has a very significant effect on the shear strength of cotton stalks. When the moisture content is 30%, shear strength of the lower part of the cotton stalk reach the maximum and its value is 8.69 MPa. Regression model of the bending experment of cotton stalk analysis reveals that the two item of moisture content and the sampling position have a significant effect on the flexural strength of cotton stalk. Using quadratic regression rotatable orthogonal design with three and two factors establishes the regression model between shear strength of cotton stalk and sampling position, moisture content and loading rate, and the regression model between bending strength of cotton stalk and moisture content and sampling position. The model obtained is effective and fits well with the actual, which provide basic parameters for the design of cutting, harvesting machinery of cotton stalks.4) Through the finite element simulation analysis(ANSYS), the deformation of simulated compression of cotton stalks is consistent with the deformation of the actual compression, and when the axial displacement is applied to a fixed value, the position that is close to the bottom of the cotton stalks appears cracking and expands outward, but the position that is close to the top of the cotton stalks has less deformation and the whole cotton stalks happens transverse deformation that is smaller. The results shows that calculation model of cotton stalks is effective.