| There are two ways to Research and Design of Furrow Openers, One is the Finite Element method (FEM) which is based on continuum mechanics, but this method as a whole to be considered for Furrow Openers and soil, while the complexity of the soil structure and changeability under different conditions, the method can not analyze accurately each particle movement and interaction in soil particles groups, so it is not a good solution for the design of the Furrow Opener; Another method is to rely on the experience of designer or experiment, but this method is time-consuming and laborious, and sometimes it can't get the desired result.Discrete Element Method (DEM) is not a numerical simulation method which can analyze discrete material, put forward by Cundall of United States scientists in the 1970s. The is a universal methods which can analyzing discrete particle kinematics, it used to analyzing the interaction between soil particle and Furrow Opener and flow of soil particle in the process of Furrow Openers ditching the soil, it can also evaluate the work capabilities of Furrow Opener, such as saving power etc, it also can dynamically simulate the ditching process ,analyze the working mechanism and to invent new-principle Furrow Opener, This can't come true by the existing methods and techniques .This paper chose the northeast soil with different moisture of the same type and three Furrow Openers for testing.selected the octagonal ring sensors which is commonly used in agriculture and DH-3817 dynamic strain measurement system equipment, according to specific requirements of the Furrow Opener field test, establish a indoor dynamic test system. Through experiments, from the perspective of qualitative and quantitative, it's working resistance changes were analyzed with different dolly speed, ditching depth, and different moisture content of soil. For the same Furrow Openers, when ditching depth and moisture content are constant, the dolly speed increases, horizontal work resistance which suffered increase evidently, but the vertical work resistance don't increase very clear; when the dolly speed and ditching depth are certain, with the soil moisture content increasing, it's horizontal and vertical work resistance both increased evidently; when the soil moisture content and dolly speed are certain, with the ditching depth increasing, the work resistance which suffer increased dramatically.According to the need of the discrete element analysis, the physical and mechanical properties of the same soil with three different moisture content testing, including soil texture, density, moisture content, friction coefficient, elasticity modulus etc. However, the test data measured is macroscopical, this paper determine the internal friction angle through using discrete element to simulate the accumulation of soil particles, determine some relevant microcosmic parameters through using dimensional analysis and discrete element method to simulate biaxial test and the direct shear test.Last, According to the microcosmic parameters needed by DEM to simulate Furrow Opener of ditching process determined in the foregoing method, use the two-dimensional integrate analysis software based on the DEM developed by this research group to simulate three Furrow Openers ditching process. Simulate and analyze the Furrow Openers work resistance. Know from the analytic results: the same Furrow Opener at the same condition , ditching resistance increase with ditching speed, ditching depth, soil moisture content increase, at the same condition ditching depth influence the ditching resistance greatest, secondly is soil moisture and dolly speed. This paper also uses commercial software PFC2D to simulate the Furrow Openers ditching process. Results show that the simulation results are basically the same with the simulation result by DEM analysis software developed by this research group.Through laboratory tests and the DEM simulation tests, from the perspective of qualitative and quantitative, deeply research of the three different types of Furrow Openers work resistance under the same soil with different soil moisture content. Research shows that DEM can reveal the change rule of the Furrow Openers work resistance from soil of microscopic structure, and simulation results are basically the same with the experimental results. Therefore discrete element method can be used as a new method for Furrow Openers of digital design to explore a new approach. |
