Earth-moving Machines Research Articles

FORECASTING THE ENERGY CAPACITY OF CUTTING SOILS CONTAINING STONE INCLUSIONS IN A PROBABLE ASPECT

It has been established that the geometric shapes, sizes of stony inclusions, and their location in the soil massif are stochastic in nature. In the article, on the basis of the known laws of distribution of mineral soil particles is analytically determined, the probabilistic rounded amount of pebble and boulder inclusions of soil. An analytical expression is given to determine the probabilistic energy intensity of cutting soil containing various stony inclusions. Taking into account the probabilistic amount of a stony inclusion is calculated of the i-th size, j-th shape, which progressively moves in different ways when cutting the soil, the energy intensity of cutting the soil with various stony inclusions. A computational analysis of the change in the energy consumption of soil cutting is carried out depending on the size, shape of a rocky inclusion, the type of destruction, strength and rockiness of the soil, by the working body of an earth-moving machine.

Operating conditions and assessment of the bottom background of deep-sea vehicles

The creation of competitive deep-sea soil-mining machines and complexes allows the transition to the development of deep-water deposits of polymetallic nodules and metalliferous silts, the extraction of sand and sapropel from the bottom of the sea, thus providing parity access to the mineral and energy resources of the World Ocean. The purpose of the work is to create methods and technical means for determining the strength characteristics of bottom soils in the surface layer, aimed at reducing the time of creation and effective use of machines by ensuring that their parameters correspond to real operating conditions.
 Usually, the properties of deep-sea soil in its natural bedding (in situ) are determined from the data of photo- and geoacoustic sounding or from cores raised from the seabed to the surface, and the working loads of machines, the resistance of the soil to destruction and other mechanical characteristics are estimated on the basis of the data obtained by geological methods. New methods and devices for point and continuous sampling of the bottom, adequately applied both on the surface and under water, provide sufficient reliability of the information obtained for practical use. The objectives of the study are to substantiate the theory of gravity sensing of underwater soils and their cutting, to determine the deformation and strength properties of the surface layer of the seabed, resistance to mechanical destruction and the characteristics of the interaction of machine mechanisms with silty soil.
 The novelty of the research is to establish the features of the interaction of the working bodies and the undercarriage of earth-moving machines with underwater viscoplastic soils, depending on the parameters of the working process, strength properties of the soil, characteristics of dynamic loading and geophotoprofiling of underwater routes. The practical value lies in the substantiation of the operational loads of deep-water earth-moving machines; an assessment of the characteristics of bottom soils in natural bedding, as well as a comprehensive study of bottom massifs, which make it possible to reduce the number of sampling stations, the total labor intensity of voyage operations, to establish an operational bottom background and optimal routes of mining systems.

Wheel rolling on deformable ground with slippage

A characteristic feature of wheeled earth-moving machines and tractors is their operation on deformable soils. This makes it necessary to consider the features of the interaction of elastic wheels with the ground, including such issues as the depth of the track and power losses for rutting, wheel movement along the laid track, rolling with pull, forces and moments acting on the wheel, the effect of wheel parameters and rolling mode etc. When a pneumatic wheel with a high internal air pressure rolls on a deformable soil, the nature of the interaction of the wheels with the soil is such that the wheel can be considered rigid, since its normal deformation is small. This greatly simplifies the calculations associated with the analysis of the operation of wheeled machines taking into account the transforming properties of the wheeled propulsion unit, in particular, the determination of the kinematic and power parameters of the wheel. In this paper, using the motion reversal method, the picture of physical phenomena in the contact of the wheel with the ground has been considered, which made it possible to obtain relatively simple expressions for calculating the circumferential thrust force and the coefficient of tangential elasticity of the pair “wheel-deformable soil”.

Finite element-based safety prediction for hydraulic excavator rollover protective structure and experimental validation

Tractor and earth-moving machine rollover has become one of the leading causes of occupational death in the agricultural/constructional industry. Therefore, these machines need proper protective structures to protect operators. In this study, explicit finite element (FE) analysis is adapted to predict the performance of rollover protective structure (ROPS) of a hydraulic excavator in the early design stage based on ISO 12117-2. The virtual test includes three sequential quasi-static loads applied in side, longitudinal and vertical directions, one at a time. Well-organized load sequence enables the simulation model to take the cumulative deformations caused by the three sequential loads into account and reduce the computational cost. A ROPS prototype is fabricated and tested to validate the FE model. The simulation-based results have a close agreement with the experimental test results. This FE-based safety prediction could be used to assess the new design in the early design stage to save design time and money.

FOPID Control with Parameter Optimization for Hydrostatically-Actuated Autonomous Excavators

This article presents our recent work towards development of a controller for the new class of modernized excavators. There is an increasing demand to develop autonomous earth-moving machines that are: more efficient than the conventional ones and capable of operating with minimal supervision by operators. A fractional-order pro-portional-integral-derivative (FOPID) control is applied to a newly designed electro-hydrostatic actuator (EHA) circuit for these machines. We further employ the Oustaloup recursive method for which the parameters of the controller are chosen based on the modified Nelder-Mead optimization algorithm. Our experimental results indicate that the proposed controller is capable of controlling the speed of the link with a negligible error. This work paves the road for development of autonomous, energy efficient, off-road mobile machines.

Attenuation of Mechanical Vibration During Transmission to Human Body Through Mining Vehicle Seats

Operators of mining vehicles are exposed to high levels of whole-body vibration (WBV) and are therefore at risk of developing vibration-related health disorders. For implementing an effective control strategy, it is imperative to locate the source(s) of vibration, and the specific changes that might occur to the vibration signals during its transmission through the seats to the recipient human body. With this objective, Seat Effective Amplitude Transmissibility (SEAT) values of seat modules used in dumpers (n = 10) and other heavy earth-moving machines (n = 11) were evaluated in an iron ore mine. Vibration was measured simultaneously on the seat and on the cabin floor beneath the seat using tri-axial and uni-axial accelerometers. The study aims at determining the quality of seat modules of the transport and non-transport vehicles from the perspective of their natural resonance frequencies and capability of any such seat in reducing harmful vibration. The highest acceleration values were observed in the z-axis for all the dumpers. SEATrms values ranged from 78 to 133% and SEATvdv values ranged from 72 to 130% for the dumpers. For other HEMMs, SEATrms values ranged from 55 to 125% and SEATvdv values ranged from 56 to 123%. Mechanical vibration contains multiple frequency components. To understand the changes taking place to the different signals at these frequencies, 1/3 octave band analysis was carried out for the signals recorded both on the seat and the floor. There was significant attenuation (38 to 57%) at 4 Hz for three Dumper seats, whereas they resonated in the range of 1.6–2.5 Hz. The transmissibility(%) in the resonating frequencies ranged from 108 to 156%. Resonance frequencies for the remaining seven dumpers ranged from 3 to 8 Hz. The spine has been reported to resonate at 4 Hz, whereas resonance at 1.6 Hz has little significance to human beings in regard to WBV of a seated person. Hence, the characteristic resonant frequency of 4 Hz of seats as observed in the present study has the potential of causing adverse impacts on spinal health. Evaluation of SEAT factors and resonance characteristics of seats are therefore recommended to be examined while selecting a mining vehicle for regular deployment in mines.

Influence of intermediate layer on the strength of freezing of soil with the metal surface of machines at negative temperatures

The development of moist cohesive soils in conditions of negative temperatures leads to a decrease in the productivity of earth-moving machines due to the increase in adhesion and friction. When wet soil and a metal bucket interact, the soil freezes to the sides of the bucket, which leads to a decrease in the useful volume of the bucket and, therefore, to a decrease in the productivity of the machine. The experimental studies have been carried out on the effect of the intermediate layer at the interface between the soil and the working body of the machine, on adhesion. The prophylactic lubricant "Niogrin" was used as an intermediate layer. As a result of processing the obtained experimental data, a regression equation was obtained; the dependence of the soil shear stress on various factors is presented and the influence of external factors on the adhesion of soils at negative temperatures is estimated. The comparison of the obtained dependencies showed that the strength of soil freezing when using a preventive liquid decreases 1.5-2 times.

Study of the Spatial Distribution of Forces and Stresses on Wear Surfaces at Optimization of the Excavating Part of an Earthmoving Machine Transverse Profile

The relevance of this research lies in the need to develop a scientifically-grounded methodology for designing the optimal profile of the contact frontal surface of an energy-efficient earthmoving machine operating device, which ensures the redistribution of resistance forces along the cutting elements during the excavation of frozen soil when extracting hydrocarbons. The relevance is confirmed by the need to improve domestic methods for designing the profiles of effective operating devices, ensuring the excavation of frozen soils during the laying of oil and gas pipelines and geological exploration in permafrost areas. Increasing the energy efficiency and service life of highly loaded ripper teeth is done by optimizing the geometric profile and designing a spatial shape that provides minimal resistance to cutting the soil. The object of the research is the process of dynamic interaction of the ripper tooth cutting profile with the frozen soil environment. The research method used was kinematic analysis and force calculation. The cyclic process of dynamic loading of the ripper operating device was investigated. The methodology of system analysis, as well as the method of distribution of resistance forces over the geometric elements of the cutting edge, were used. The mathematical apparatus has been effectively applied to establish the dependences of the change in energy and power properties on performance indicators, soil rheology, and dynamic loads of the ripper tooth. The process of interaction of the ripper tooth tip with frozen soil was investigated. A method for substantiating the design parameters of the operating device by using Legendre polynomials was proposed. Separate calculation results subject to the introduced restrictions were presented for the condition for solving the problem. The optimal parameters of the transverse profile of the contact frontal surface of the earth-moving machine operating device were determined taking into account the coefficient of reducing the fracture resistance of frozen soils.

A Survey of Powertrain Technologies for Energy-Efficient Heavy-Duty Machinery

This article presents a comprehensive, multidisciplinary overview of the development of powertrain technologies for energy-efficient heavy-duty earthmoving machines. The heavy-duty earthmoving equipment industry has been among the biggest contributors to emissions globally. However, due to high power demand and multidisciplinary powertrain structures, improving the energy efficiency of heavy-duty mobile machines has been a pressing and challenging task in the industry. To cope with this challenge, hydraulics and power electronics (PE) have been the key driving forces. As such, the relative developments in both fields are covered in this article. For hydraulics, developments of efficient hydraulic circuits will be overviewed in detail along with the introduction of hydraulic energy recovery technologies. In addition, developments of PE architectures in hybrid and electrified machines will be introduced. Furthermore, potential medium-voltage dc mining site power distribution and the valves of wide bandgap devices will also be discussed with the hope to open up new research opportunities in PE. Moreover, emerging hybrid electrohydraulic drive technology is introduced. Based on the overview in this article, it is anticipated that electrohydraulic hybridization will be the future trend in the earthmoving machine industry. Deeper collaboration between the two areas is desirable.

ПРОБЛЕМИ, НАПРЯМКИ ТА ПЕРСПЕКТИВИ СТВОРЕННЯ І МОДЕРНІЗАЦІЇ ЗЕМЛЕРИЙНИХ МАШИН БЕЗПЕРЕРВНОЇ ДІЇ СПЕЦІАЛЬНОГО ПРИЗНАЧЕННЯ

The article addresses directions and horizons in the creation of highly efficient specialized continuously operating earthmoving machines and provided a technical proposal for the multipurpose earthmoving machine. Study subject: continuously operating earthmoving machines. Objective: To create a power-efficient special-purpose earthmoving machine. Study method: experimental. Existing dimension-types of trenching excavators allow digging lengthy excavations of the assigned profile with minor deviations from their nominal width and depth. Creating of excavations of different profiles is being achieved via machine re-equipment with different implements. A sustainable solution is to create multipurpose earthmoving machines that are capable to perform lengthy excavations of various widths and depths with the same implement and without constructional alterations. There are known machine designs for trenching on the basis of a wheeled tractor with a mounted chain-bucket implement that is able to perform the lateral oscillatory displacements in relation to the vertical axis on the hull back of the tractor. Alteration of the implements oscilative motion amplitude allows to excavate the tranches of differnt width. This is the essence of the multipurpose earthmoving machine. The existing kinematics chain sections of the implement in relation to the tractore can't ensure the consistency of the machine load due to inconsistency of the borings along the width of excavation. This leads to significant pulsation of the load on the implement, loss of the longitudinal stability and, in the end, reduces the potential productivity of the machine by half. We have performed a set of studies in creating of the multipurpose earthmoving machines (MEM). As the experimental study objects we've used physical models of the MEM implements and full-size prototypes of the machines. Results of the study experimentally confirm the possibility to create a highly productive MEM with rotary implement, which efficiently performs trenches as well as wide construction pits in the mode of reciprocating approach of the rotary implement to excavation by means of equalization and minimization of power load parameters values. KEYWORDS: EARTHMOVING MACHINE, ENERGY INTENSITY, KINEMATICS, PRODUCTIVITY, SOIL

Analytical Determination of Fuel Economy Characteristics of Earth-Moving Machines

The article considers the problem of the analytical determination of the fuel economy performance of earth-moving machines by the example of the road grader. The values of the road grader fuel consumption when performing the technological operations have been obtained and analyzed. The fuel balance of the EMM in the traction mode is presented. The fuel balance of the motor grader when digging soil has been defined and analyzed.

ФАКТОРЫ, ВЛИЯЮЩИЕ НА ПРОЦЕСС РАЗРУШЕНИЯ ГРУНТОВОГО И ГОРНОГО МАССИВА

The article is devoted to the analysis of the process of impact destruction of solid and frozen soils and rocks. The classification of factors influencing the energy efficiency of excavation and mining is presented. The main attention in the study is paid to the analysis of rock mass destruction by single and double percussion tools. The schemes of the deformations development in the massif as a result of the impact on it with one or two indenters under impact action are considered. The schemes of the destruction phases’ development of soil and rock massif, both with single and paired impact of percussion instruments, are considered step by step. It is noted that when a double percussion tool is applied to a destructible medium, the efficiency of rock mass destruction increases due to the intensive formation of a general stress field between the indenters, which leads to the formation of a compaction core in this zone with the subsequent destruction of the monolith. It was found that the optimal distance between indenters operating in pairs is a constant value for each rock and does not depend on the indenter diameter. The schemes of dynamic loads propagation from the sources to the operator with the rigid connection of the working body and the working body equipped with an additional connection are presented. Analysis of rock mass destruction by percussion tools made it possible to propose constructive solutions for the executive bodies of earth-moving machines that ensure the redistribution of the reactive forces arising from the impact into the zone of destruction of the soil or rock mass, which significantly reduces the effect of dynamic loads on the base machine and the operator. On the example of a percussion ripper with a balancing weight, an analytical dependence is presented in which the impact energy is redistributed to the zone of destruction of the massif

Study and calculation of earth-moving machines for the construction by "wall in the ground” method

Study and calculation of earth-moving machines for the construction by "wall in the ground” method

The equation of the oscillatory motion of the blade of the earth-moving machine depending on the properties of the ground and the parameters of the blade

The influence of the design parameters and technological properties of the ground on the nature of the oscillatory movement of the blade of the working body of the earth-moving machine is investigated. The purpose of the study is to identify the force factors of the interaction of the oscillatory working body of the earth-moving machine with the ground and determine its optimal parameters. The equation of the oscillatory motion of the blade of the working body of the earthmoving machine depending on its design parameters and technological properties of the ground is obtained. The results can be used in the development and determination of the optimal design parameters of the working bodies of earth-moving machines.

Actuality of development of new means of ground cutting spatially oriented knifes of dynamic action when working with earth machines

Using the sources of patent documentation, a patent search was conducted to determine the relevance of the problem of cutting the soil with spatially oriented knives when working with earthmoving machines and further analysis of the proposed technical solutions. As a result of the study, we found that the topic remains relevant for the period under consideration. It was found that different types of persons were involved in this area: individuals, scientific and educational institutions, research institutes and equipment manufacturing organizations, in particular by Caterpillar, Komatsu and John Deere, which indicates the relevance and importance of this problem. The study of cutting soils with spatially oriented knives of dynamic action is relevant for achieving a decrease in the energy consumption of the process of cutting soils. The proposed research direction is a continuation of the scientific schools of the Department of Construction Machines KNUBA, namely, dynamic cutting and creation of cutting elements of earth-moving machines with spatial orientation.

The dynamic loads of mobile continuous earthmoving machine during the working body lock

working body is locked significant dynamic loads appear that influence the drive shaft and might lead to the machine breakdown. Preliminary approximate calculation of these loads is made according to oneor two-mass dynamic loads. For more detailed and precise analysis of dynamic load in drive shaft elements of the earth moving machines it is necessary to review the multimass model machine element movement. Goal. The aim of research is definition of the dynamic load and working out methodology that appears in the continuous earth digging machine elements during working body lock. Methodology. The discreet dynamic system dynamic and mathematical model construction is performed by means of the programming language Modelica. The model relevance is assessed via a two-mass model analytical solution. Results. Drive shaft element loading is assessed via the dynamic coefficient, which depends on kinematic, flexible and inertial machine parameters. Originality For the first time the continuous earth digging machine dynamic model that enables the automobile chassis drive shaft to interact with the continuous digging chain is constructed. It was determined that the drive shaft dynamic loading parameter correlation change upon the earth digging machine working body meaningful parameters. With designed model usage, the input data for transmission element engineering calculation was defined and the automobile basic chassis construction, equipped with the continuous digging chain. Practical value. The obtained dynamic factor value and developed methodology can be applied during continuous earth moving machine designing and calculation. Dynamic load decrease is possible through shaft stiffness and rotating mass inertia adjustment, and also by introducing elastic protecting frictional coupling with a controlling device.

АНАЛИЗ СУЩЕСТВУЮЩИХ ЧИСЛЕННЫХ МЕТОДОВ МОДЕЛИРОВАНИЯ ВЗАИМОДЕЙСТВИЯ РАБОЧИХ ОРГАНОВ ЗЕМЛЕРОЙНЫХ И ПОЧВООБРАБАТЫВАЮЩИХ МАШИН С ПОЧВЕННЫМИ СРЕДАМИ

Carrying out theoretical studies of the working processes of various machines and units today has ample opportunities when using modern computer technologies. The use of programs greatly speeds up the study of complex systems under study. The use of simulation methods is advisable when the cost of carrying out real experimental research is high or, due to certain circumstances, making research on a real system impossible, and the calculation of the analytical model will allow many assumptions and approximations that will affect the entire system and change it. In the article, special attention is paid to the selection of the most suitable modeling method for studying the process, liquidation of a forest fire with a flow of soil, using serial software products. The analysis of existing numerical methods for modeling the interaction of working bodies of earth-moving and tillage machines with soil media is carried out. The studies performed by the discrete element method (DEM), the finite element method (FEM), the computational fluid dynamics (CFD) method, and the smooth particle hydrodynamics (SPH) method are analyzed. Conclusions are drawn on the prospects for the applicability of each of the methods for modeling the system of processes of processing and throwing soil.

Mathematical model of a motor-grader movement in the process of performing working operations

The design features of a motor-grader help it perform a wide range of working operations, which puts it on a par with the main machines in the construction industry. Unlike other earth-moving machines, the motor-grader can perform work operations not only in a cyclic mode, but also in a continuous action mode. Considering these features, not only productivity should be addressed as the main indicator of the efficiency of this machine, but also the indicators of the quality of the working operations performed, in particular, the indicators of road-holding ability in the process of performing continuous working operations. The work has substantiated and developed a mathematical model of the motor-grader movement during working operations. This model makes it possible to predict the expected trajectory of the motor-grader on the basis of deterministic dependencies, which enables to assess the indicators of road-holding ability. The difference between the proposed model and the existing ones is the consideration of a two-stage mode of machine movement: plane motion at the first stage and rotational around the stop point at the second. When describing the external forces acting on the motor-grader, the differences in the formation of resistance forces on the blade during various working operations are taken into account.

The use of a heating element to combat soil freezing to the working bodies of machines

The development of wet cohesive soils at negative temperatures leads to soil freezing to the working bodies of earth-moving machines, which leads to a decrease in the useful volume of buckets and, consequently, to a decrease in the productivity of the machine. This article discusses the thermal effect on the simulator of the working body of an earth-moving machine. As a heat source, a tape heating element was used, namely, a carbon heating flexible tape. The technical characteristics of this heating tape and its technical device are presented. The results of experimental studies of the heating of the ladle simulator are presented and the temperature-time characteristics of the heating tape are constructed. The one-factor regression equations for the heating temperature of the bucket simulator at different ambient temperatures are presented. Research has been carried out on the effect of heating the bucket simulator by the heating tape belt on the soil shear force.

Quick method of the grunt prisms gravity centers’ exact compliance with vertical area planning

The article discusses the methods for improving the accuracy of calculating the soil movement distances along the vertical layout of areas, which is one of the first works for leveling the construction site surface [3, 5, 6, 14]. This work is usually performed using the earth-moving machines [12, 17, 19, 20]. Norms of time for their work are given in Unified Standards and Prices E2-1 [13] with gradation of the soil movement distances of 100 and 10 m. When vertical planning is required on the large areas with the soil movement over the distances of several hundred meters and with large working elevations, the options for using faster motor vehicles are possible [1, 2, 10, 11]. However, not all standards indicate between which points and how to set these distances. We believe that it is advisable to install them using the positions of the soil bodies’ gravity centers instead of the commonly used the centers’ positions of their areas [9, 18]. This will increase the reliability level of the soil movement distance to establish the appropriate costs of computer time [7, 8]. The formulas for determining the positions of the gravity centers of bodies (BGC) are given in the reference book [9] and in other sources.