THEORETICAL ANALYSIS OF STRENGTH RESISTANCE TO DISPLACEMENT OF IMPROVED DIGGING WORKING BODY OF POTATOE HARVESTING COMBINE

The amount of energy required to perform technological processes in agriculture largely depends on the size of the resistance to the displacement of the working bodies of machines. The main factor of energy consumption performing the technological process of potato harvesting is the resistance to the displacement of the digestive working body. In order to reduce the resistance to displacement an improved design of the digging body is proposed. An analytical study was conducted to determine the problem of moving the working body in the soil environment. The strength of the soil resistance is determined and the regularity of the influence on its change of parameters and the shape of the blade and separation parts of the digging working body is established. Calculations are made using the Mathematica application programm. The graphic dependences and contours of the isoline of the traction flange of the working part of the working body are obtained. Analysis of the calculations allowed to set the parameters of the surface of the dashboard, which provide a minimum of traction resistance. The schedule and contours of isolines of the change of the total resistance to the displacement of the soil mass with the tubers by the separation surface of the working organ in the function of the distance between the bars and the size of their intersection are also obtained. Analysis of the dependence of soil resistance and tubers on the separation surface indicates that an increase in the size of the geometric size of the intersection of the rods leads to a significant increase in the resistance of the medium. The material presented in the article can be used for analytical determination of the resistance of the excavation working body of potato harvesting machines of arbitrary geometric shape in the soil medium with tubers.

Effect of Cover Crops Associated With Lettuce Production Under No-Tillage System

The use of cover crops has benefits for the chemical, physical and biological properties of the soil. However, together with the need for good vegetable productivity, considerable challenges arise in several regions of Brazil. The preparation of conventional soil for initiating no-tillage systems is necessary to create a management history and assimilate the benefits of the no-tillage system in vegetables, ensuring sustainable production. The objective of this research was to evaluate lettuce yield as a function of different cover crops as a function of resistance to soil penetration. The experiment was conducted in the horticulture sector of the University of Rio Verde, Rio Verde, Goiás, Brazil. The cover crops used were sunflower (Helianthus annuus), sunn hemp (Crotalaria juncea), and fallow, and the vegetable used was lettuce (Lactuca sativa). The variables analyzed were plant height and lettuce yield, straw decomposition, and soil resistance to penetration. The collected data were submitted to analysis of variance, and if significant, was compared by Tukey test (p < 0.05) and regression analysis. The lettuce height in the different management systems showed no statistical differences. The decomposition of the straw presented accentuated degradation for the evaluated cover crops and the productivity was bigger in the straw of crotalaria and fallow. Soil resistance for cover crops was not greater than 2 MPa.

Analysis of Dynamic p-y Curve Characteristics According to Mode Shape of Structure Using Shaking Table Tests

In the seismic design of pile foundations, a p-y curve representing the nonlinear behavior of the ground considering the dynamic load of the earthquake is required. Recently, p-y curve analyses reflecting the soil-structure interaction have been conducted, but studies on multilayer structures have not been investigated extensively. In this study, the p-y curve characteristics were analyzed, considering the influence of the ground-structure interaction based on the mode shape of the structure (no structure, single-story structure, and three-story structure) through shake table tests. It was found that (1) the bending moment and pile displacement increased with input acceleration, and (2) the maximum soil resistance and pile displacement occurred at the natural frequencies of each structure were observed. In addition, the bending moment, soil resistance, and p-y curve slope were higher in the single-story structure than in the three-story structure. The findings indicate that the seismic design simulated for a single-story structure is conservative.

Analysis of Soil Resistance under Horizontal Load of Rigid Antislide Pile

In order to study the bearing characteristics and failure mechanism of the rigid antislide pile under horizontal load, the stress of rigid antislide pile under transverse axial large displacement load is analyzed by using elastic-plastic theory, finite element analysis, and model test. The theoretical formula of the proximal plastic earth pressure near the pile with the depth of soil under the horizontal force is obtained. The results show that the standard is insensitive to the variation of soil parameters and the influence of soil parameters on allowable soil resistance in front of pile should be considered. With the increase of the horizontal force of the pile top, the soil near the pile is destroyed in this process gradually, which is the decline of the cross section of the maximum soil resistance of the pile. When the horizontal displacement of pile top is 20 mm and 70 mm, the soil resistance value and the ultimate soil resistance value in front of the pile can be selected, respectively. The plastic zone develops to the front and bottom of the pile at the same speed, at an angle of 45° with the direction of gravity. When the displacement reaches 34 mm, the plastic zone develops to the deeper depth obviously. The results can provide a theoretical basis for the design and application of antislide piles during the process of slope protections.

Investigation of the microrelief of the soil layer surface and its effect on the strength of soil resistance to tillage

The lack of the operating elements strength calculating methods providing sufficient accuracy of the results is a significant problem in modern agricultural machinery development. The using calculation models do not take into consideration the microrelief of the treated surface, which leads to a significant error in determining both extreme and long-term loads on the working bodies of mechanisms. In this article author analyzes the cultivated soil treated surface microgeometry influence on the forces arising in the tillage tool. The existing design model is considered on the needle harrow example, its disadvantages are indicated and a way to eliminate them is proposed. Experimental data on the soil surface profile microroughnesses size study are presented, regularities of the microroughnesses random distribution are revealed, in particular, the assumption of the normal nature of this distribution is confirmed. The dependences based on the obtained data are proposed for a more accurate acting on the tillage tool loads calculation.