Effect of trash board on moldboard plough performance at low speed and under two straw conditions

Draught requirement is an important parameter for tillage tool performances. This study investigated the influence of trash board on the performance of moldboard plough and the system optimization. Draught and vertical forces acting on the plough were measured with and without a trash board under two straw conditions, i.e. with only stubbles and with dense straw cover. Field soil moisture content was kept at 30%. The study also used the finite element method (FEM) to simulate stress distribution on the plough. Results showed that draught significantly increased without trash board under dense straw cover as compared with only stubbles. The trash board attachment reduced draught significantly. Similar trend was also true for vertical force. FEM results were found to be compatible with the experiment. The simulated maximum equivalent stress acting on the mouldboard plough was 279.43 MPa, while the material’s yield stress was 250 MPa. Attaching trash board with the moldboard plough is important where straw cover was dense.     

The determination of plough draught—Part II the measurement and prediction of plough draught for two mouldboard shapes in three soil series

The draught of a 3-furrow reversible plough fitted with two types of bodies was measured at five separate test sites. Each site was ploughed on four different days to provide a range of soil moisture contents. The plough was operated at three different speeds in sequence for each type of body. The horizontal and vertical forces transmitted to the tractor were measured on a three-point linkage dynamometer. Tachogenerators monitored tractor wheel speed and fifth wheel ground speed. Cone index and soil specific weight were recorded at 30 mm intervals throughout the top-soil profile. Cone index at median plough depth was found to be a satisfactory measure of soil strength for the prediction of plough draught. Characterising specific plough draught by soil cone index, specific weight, moisture content, plough mouldboard tail angle and ploughing speed provided predicted values in closer agreement with measured draught compared with earlier equations. The sensitivity of cone index to soil moisture content supports the use of the cone penetrometer as a practical monitor of soil conditions in the field and as a management tool for judging the opportune times for agricultural tillage operations.     

Effect of animal drawn puddling implements on hydraulic conductivity of lateritic sandy clay loam soil in West Bengal, India

To determine out the suitable animal drawn puddling implement in terms of reduction in hydraulic conductivity of soils were investigated in this research study. In rice (Oriza sativa L.) cultivation in West Bengal, India, reduction in hydraulic conductivity of soil facilitates better rice growth. To determine, the effect of puddling implements, i.e., an animal drawn rotary puddler (I₁), a 3-tine tiller (I₂) and a local plough (I₃), and number of passes of the implements on hydraulic conductivity of the puddled as well as the non-puddled layer of a lateritic sandy clay loam with respect to relative age (i.e., elapsed time after puddling operation) was studied under controlled soil-bin conditions. It was concluded that the hydraulic conductivity of soil decreases with the number of passes and relative age. A mathematical model was developed for calculating the hydraulic conductivity of puddled soil layer. It was concluded that the hydraulic conductivity obtained with the rotary puddler was 2.27 times less than that with the 3-tine tiller and 3.09 times that with local plough after the fifth pass of puddling operations.     

The determination of plough draught—Part I. prediction from soil and meteorological data with cone index as the soil strength parameter

Using cone index as an indication of soil strength, empirical equations are developed in accordance with soil mechanics theory to relate soil moisture content to plough draught. The plough draught equation comprises a quasi-static component dependent on cone index and a dynamic component which is a function of the soil specific weight, plough speed and mouldbard tail angle. It is further argued that the cohesive and frictional components of the cone penetration resistance can be predicted by means of a simple equation comprising a reciprocal function of the square of the soil moisture content and a linear function of the soil specific weight. The cone index equation explained 98% of the experimental data for threthree soils over a wide range of moisture contents. These empirical equations, together with a soil moisture model, provide a method of predicting plough draught directly from soil and meteorological data.     

Spatial distribution of soil forces on moldboard plough and draft requirement operated in silty-clay paddy field soil

Spatial distribution of soil forces on the surface of plough is an important aspect that can help engineers for improving efficiency of tillage implement. It was analyzed at eleven different points of the moldboard plough with the help of sensors accompanied with the virtual instrument developed in LabView software with the aid of other supporting instruments. It was observed that soil forces increased with an increase in speed and depth. Depth changed soil forces more at upper parts than lower parts whereas speed affected rear parts more than the front part of the plough. Draft forces followed almost similar trend and least value of 308.17 N experimental draft force was found at 1 m/s speed and 5 cm depth under 33% moisture content. Cumulative soil forces found too smaller than the draft as they represented the force spatial distribution of specific parts of plough. It was observed that sensor technology provided real time picture of force variation during tillage process that could save time and effort.     

The universal earthmoving equation applied to chisel plough wings

This paper compares the results of tests which examined the effect of chisel plough wing geometry on tillage forces with those predicted by the Universal Earthmoving Equation as presented in E. McKyes' book Soil Cutting and Tillage, published by Elsevier (1985). The tests were conducted in the SAIT Tillage Test Track (an outside continous soil bin which contains a sandy loam soil) and in two field soild, one sandy loam and the other a red brown earth. The tests were conducted using a range of speeds from 5 to 15 km/h and at depths of 50 and 70 mm. The tests compared the effects of varying share wing width and rake angle. The comparison of the measured and predicted draft and vertical force responses showed a good correlation between the Universal Earthmoving Equation predictions and the measured width responses, but it did not always predict the correct rake angle responses.     

Performance evaluation of an animal drawn puddling implements under controlled soil-bin conditions

Trials were conducted to evaluate the performance of three commonly used puddling implements, i.e. animal drawn rotary puddler (I₁), 3-tine tiller (I₂) and local plough (I₃) under controlled soil bin conditions for different numbers of passes of each implement. The performance of the rotary puddler was found to be better when operated more than twice under the controlled conditions in terms of quality and quantity of puddling. It was found that the rotary puddler gave a higher puddling index and required less energy to puddle the soil. The rotary puddler provided good “puddle” with a puddling index of 50% after two passes whereas, the other two implements required more than five passes for the same quality of puddling or puddling index in sandy clay loam soil     

接触应力对轮轨材料滚动摩擦磨损性能影响

利用MMS-2A型微机控制摩擦磨损试验机研究了接触应力对轮轨材料的滚动摩擦磨损性能影响.结果表明：随接触应力的增加,滚动摩擦系数呈增加趋势,车轮和钢轨试样磨损加剧;相同接触应力水平下,车轮试样磨损量大于钢轨试样,表面损伤严重;随接触应力的增加,车轮试样表面从犁沟且轻微剥落向严重剥落损伤转变,钢轨试样表面损伤主要表现为犁沟效应并伴随有剥落现象,但相比车轮试样的剥离损伤要轻微.     

Characteristic loading of light mouldboard ploughs at slow speeds

A study on four mouldboard ploughs, that are commonly used with animal traction in Kenya, was conducted. Draught, suction and torsion loads were measured and specific draught evaluated in field tests on four sites with typical agricultural soil conditions. Draught and suction are the horizontal and vertical components of the reaction to soil force, respectively, while torsion is the resisting moment about the plough shank. The objective was to quantify these parameters and to study their characteristics under variable conditions at operation, at speeds up to 1.12 m/s and tillage depths between 0 and 150 mm in an attempt to optimize the design, selection and utilization of mouldboard ploughs for animal traction in Kenya. It was found that depth of tillage is the most critical factor, and draught and suction increased significantly with depth while specific draught increased or decreased depending on the soil type. Draught and specific draught increased significantly with speed. The increase in suction with depth probably implies an increased stability in the ploughing operation, while its reduction with speed indicates a potential instability of plough control with varying speeds. Consequently, aiming for steady motion in the utilization of animal traction may aid in the optimization. It was also found that ploughs with a high specific draught (kN/m) are expected to experience higher torsional loads on the shanks. The characteristic draught, specific draught and suction loads of the ploughs were described by quadratic functions in speed and depth of tillage with coefficients of determination (R₂) ranging from 0.55 to 0.99. A significant difference in the coefficient of variation of draught loads in the three soil types probably implies that optimal duration for use of animal traction in tillage should be dependent on soil type.     

Technology showcase applications of enamel coating in agriculture

Recently various experiments were conducted at the Asian Institute of Technology, Bangkok, to study the effect of enamel coating on the performance of some agricultural equipment. In order to reduce soil adhesion on cage wheel lugs, nine different coating materials were tried and enamel coating was found to be the best among these materials. It reduced soil adhesion on cage wheel lugs considerably to avoid cage wheel blocking. To investigate effect of coating on lug forces detailed lab studies were undertaken to measure the lug forces. The effects of lug slip, soil moisture content and sinkage were investigated. It was observed that enamel coating did not affect the lug forces. The pull and lift forces generated by the enamel coated and uncoated lugs were almost the same. When enamel coated bolt-on plates were mounted on the power tiller cage wheel lugs and trials were conducted in actual field conditions, it was observed that in actual field conditions enamel coated bolt-on plates on cage wheel lugs improved the performance of a power tiller. Studies about coating effects on the drag force required to pull floats on soil surface were also conducted. It was observed that enamel coating on floats reduced the drag force significantly. It also greatly improved the scouring of a mouldboard plough used in a wet, sticky clay soil.     

Modification of a mouldboard plough surface using arrays of polyethylene protuberances

Surface design modifications have recently exhibited a means of reducing soil-tool adhesion. The tribological characteristics of soil-burrowing animals were employed on tillage machinery to study the effect on adhesion. Considering the characteristics of dung beetles, ultra high molecular weight polyethylene (UHMW-PE) protuberances were mounted as embossed arrays on a mouldboard plough. To investigate a suitable geometry of such protuberances, five shapes were studied (flat, semi-spherical, semi-oblate, semi short-prolate and semi long-prolate) using a combination of base diameters and protrusion heights. The dimensionless height to diameter ratio (HDR) was used to characterize the geometry. Experiments were conducted to evaluate the resultant influence of various geometrical shapes and sizes of the protuberances (base diameter: 20–50 mm; protrusion height: 0–50 mm) on lowering the ploughing resistance of the mouldboard plough in Bangkok clay soil. A comparison was made between the modified and the conventional plough in dry (21.8% (d.b.)), sticky (37.2% (d.b.)), wet (49.1% (d.b.)) and flooded (64.3% (d.b.)) Bangkok clay soil at 1, 3 and 5 km/h forward speeds. Percent reduction in ploughing resistance of bionic mouldboard plough in these soil conditions with HDR = 0 was 1–6% in dry soil, 16–22% in sticky soil, 14–20% in wet soil and 8–12% in flooded soil. With HDR = 0.25 the ploughing resistance was reduced by 2–7% in dry soil, 18–36% in sticky soil, 17–33% in wet soil and 15–28% in flooded soil. Similarly with HDR = 0.5, it reduced by 10–16% in sticky soil, 6–17% in wet soil and 12–26% in flooded soil. Whereas, HDR > 0.5 increased the ploughing resistance by 7–29%.     

Characteristics of adhesion between soil and solid surfaces

The capillary attraction and viscous resistance caused by a water film between two solid surfaces were evaluated theoretically. The surface morphology of soil at the soil-solid adhesion interface was examined by scanning electron microscopy. The contact models of the soil adhesion interface are given and mechanism of the normal adhesion is discussed. The wettability and normal soil adhesion of polytetrafluoroethylene (PTFE) sheet, polyethersulforne (PES)-PTFE coating, enamel coating, iron base alloy-epoxy composite coating and the conventional material were determined. The draft force of ploughs with mouldboards coated with PES-PTFE, enamel and iron base alloy-epoxy and the conventional mouldboard plough were measured. The soil surface at the soil-solid interface displays rough structure at various sizes. The adhesion force between soil and solid is mainly composed of Laplace pressure, meniscus tension and viscous resistance caused by water film and loops. Polymers can reduce both normal adhesion and sliding resistance, whereas, enamel coating or iron base alloy-epoxy composite coating can reduce the sliding resistance to some extent.     

新型牙齿正畸丝材料在唾液中的往复滑动摩擦磨损特性研究

采用小振幅往复滑动摩擦磨损试验机评价了新型牙齿正畸丝材料13Cr24Mn0.44N不锈钢在水和唾液中的摩擦磨损行为,并探讨其磨损机理.结果表明:在唾液中活性成分的作用下,试样表面生成了软质易剪切的表面膜,使得摩擦系数降低,同时部分残留于磨痕中的磨屑在水或唾液介质润滑下承担了类似滚动轴承中"滚珠"的角色,进一步降低了摩擦系数;在2种介质中磨痕深度均随载荷增大而增加,但在唾液中的磨痕深度均小于在水中的磨痕深度,磨损和腐蚀之间呈现"负交互"作用;不锈钢在水中的磨痕呈现微切削和犁沟机制,在唾液中小载荷下的磨痕与水中相似,磨痕呈现微切削和犁沟机制,但在较大载荷时的磨损机制为疲劳脱层并伴有显微切削.     

Reliability-based design for soil tillage machines

Using classical design methods for tillage machines does not completely guarantee a safety and satisfactory performance, due in part to the randomness of tillage forces. This randomness is derived from the variability in soil engineering properties and the variations in tool design parameters and operational conditions. In this paper, a reliability-based design approach was developed, for the first time, by integrating the randomness of tillage forces into the design analysis of tillage machines, aiming at achieving reliable machines. The proposed approach was based on the uncertainty analysis of basic random variables and the failure probability of tillage machines. The failure probability was estimated according to two performance criteria related to the structural design requirement and the quality of tillage operation. Two reliability methods, namely the Monte Carlo simulation technique and the first-order reliability methods were used for this purpose. This approach was implemented for the design of a chisel plough shank.The results showed that there were many values of the shank dimensions that guaranteed the required reliability level. However, in order to achieve the best design solution from an economic point of view, minimizing the volume of the shank structure was integrated into the reliability-based design approach. This led to the reduction of the initial volume of the shank structure by 6.86%. It was concluded that integrating the economical constraint into the reliability-based design approach can lead to optimal designs of tillage tools that ensures the required reliability level at low cost.     

纳米化纯铁在干摩擦及油润滑条件下的磨损行为研究

利用往复摩擦磨损试验机研究了深度轧制纳米化纯铁及其退火态和普通轧态纯铁在干摩擦和油润滑下的磨损行为,采用冲击划痕法和声发射划痕法研究材料的塑性变形能力,并对纳米化影响纯铁磨损行为的原因进行初步探讨.结果表明,在干摩擦条件下深度轧制纯铁的抗磨粒磨损性能较普通轧态纯铁差,抗犁削能力也较弱;在油润滑条件下,深度轧制纯铁显示出优良的耐磨性;经深度轧制后,纳米化纯铁具有较高的表面活性,但同时由于塑性的丧失只能承受较小的剪切力.     

Comparison of the effects of measured and computed thermophysical properties of nanofluids on heat transfer performance

This article reports a comparison of the differences between using measured and computed thermophysical properties to describe the heat transfer performance of TiO₂–water nanofluids. In this study, TiO₂ nanoparticles with average diameters of 21 nm and a particle volume fraction of 0.2–1 vol.% are used. The thermal conductivity and viscosity of nanofluids were measured by using transient hot-wire apparatus and a Bohlin rotational rheometer, respectively. The well-known correlations for calculating the thermal conductivity and viscosity of nanofluids were used for describing the Nusselt number of nanofluids and compared with the results from the measured data. The results show that use of the models of thermophysical properties for calculating the Nusselt number of nanofluids gave similar results to use of the measured data. Where there is a lack of measured data on thermophysical properties, the most appropriate models for computing the thermal conductivity and viscosity of the nanofluids are the models of Yu and Choi and Wang et al., respectively.     

Mobility algorithm evaluation using a consolidated database developed for wheeled vehicles operating on dry sands

A substantial number of laboratory and field tests have been conducted to assess performance of various wheel designs in loose soils. However, there is no consolidated database which includes data from several sources. In this study, a consolidated database was created on tests conducted with wheeled vehicles operating in loose dry sand to evaluate existing soil mobility algorithms. The database included wheels of different diameters, widths, heights, and inflation pressures, operating under varying loading conditions. Nine technical reports were identified containing 5253 records, based on existing archives of laboratory and field tests of wheels operating in loose soils. The database structure was assembled to include traction performance parameters such as drawbar pull, torque, traction, motion resistance, sinkage, and wheel slip. Once developed, the database was used to evaluate and support validation of closed form solutions for these variables in the Vehicle Terrain Interface (VTI) model. The correlation between predicted and measured traction performance parameters was evaluated. Comparison of the predicted versus measured performance parameters suggests that the closed form solutions within the VTI model are functional but can be further improved to provide more accurate predictions for off-road vehicle performance.     

Preliminary results of MCPHE by experimental studies

The influence of grooves in the U-turn areas for the multi-channel-plate heat exchangers (MCPHEs) is significant due to the friction and flow phenomena in this region. In this study, two types of MCPHE made of acrylic plates were tested: one with grooves in the U-turn area, one without. During this series of experiments, heat transfer rate, overall volumetric heat transfer coefficient, Nusselt number and overall pressure drop (i.e., including the entrance and exit losses) were measured and calculated in order to understand the overall performance of these two different constructions of MCPHE. The experimental results show that the heat exchanger without grooves in the U-turn area possessed higher heat transfer performance and lower overall pressure drop.     

无压浸渗SiC/Al复合材料的摩擦磨损性能研究

采用无压浸渗法制备不同碳化硅粒度和体积分数的SiC/Al复合材料,利用销-盘摩擦磨损试验机考察了碳化硅的粒度和体积分数等对SiC/Al复合材料干摩擦磨损性能的影响,采用扫描电子显微镜观察磨损表面形貌并分析其磨损机理.结果表明,SiC/Al复合材料的磨损率随碳化硅体积分数增加而降低.与灰铸铁配副时,材料的摩擦系数与磨损率明显依赖于碳化硅粒度,二者均随碳化硅粒度增加而降低.复合材料的磨损机制以碳化硅颗粒的碎裂、脱落和表面犁沟为主要特征.     

Prediction of soil deformation beneath temporary airfield matting systems based on full-scale testing

This paper presents results from full-scale evaluations of an aluminum structural mat system with regard to carrying heavy aircraft across graded, but unimproved, soil with California Bearing Ratios (CBRs) of 6, 10, 15, 25, and 100. The objective was to determine relationships among soil deformation rate, the mat’s flexural modulus, the number of applied passes, and the underlying soil’s CBR. Current prevailing performance prediction models for aluminum mat systems are based on full-scale tests using historic aircraft loads over soils having a CBR of 4 that were never validated for soils with higher CBR values. Full-scale test results presented herein demonstrated the inability of current models to accurately predict mat permanent deformation. Strong correlations were found between measured and predicted data across the entire spectrum of soil CBRs. These relationships can be used to noticeably improve the accuracy of performance prediction models. An empirical equation was developed to reasonably predict subgrade deformation for any number of passes and soil CBR for the loading and mat system tested.