In the article the mathematical model of the vehicle motion with elastic tires, which describes the phases of the initial rectilinear motion on the longitudinal slope of the road is shown. The mathematical model is valid for vehicle with two axles, one of which is driving axel and provided that the stopped vehicle on a slope is kept from rolling only by braking the non-driving axle. The aim of the study is to determine the equations to describe the process of vehicle initial rectilinear motion during moving uphill, which take into account the tires deformation energy on the stationary vehicle braking wheels. The presented equations described in the article are reflect the dynamic state of the stationary vehicle on a slope and the phase of its initial moving off uphill after brining the engine torque through the transmission to the wheels of the drive axle. The system of equations describing the vehicle dynamic behavior after brining torque to the drive wheels takes into account their false slip. The system of equations is obtained from the general dynamic equation in the form of balance of the elementary work of external forces and moments with the absence of external slipping of the driving wheels. The mathematical model of the vehicle initial rectilinear motion on a longitudinal slope of a highway described in the article can be used in theoretical basis for analyzing and synthesizing control algorithms for automatic driver assistance systems during vehicle initial motion.
The presence of analytical dependencies describing the process of static soil puncture by a working body with a conical asymmetric tip is necessary to create installations with the ability to control the trajectory of the soil puncture. The paper considers the features of the process of interaction of an asymmetric conical tip with the ground. Analytical relationships were obtained to determine its reactions during a static puncture, the deviation of the head trajectory from a straight line, to determine the size of the soil compaction zone and the magnitude of the destructive force that acts on adjacent communications and other underground objects. It was found that with an increase in the value of the displacement of the top of the cone, for example, from its axis from 0.02 m to 0.08 m with a borehole diameter of 0.2 m, the value of soil resistance increases almost four times. The greatest resistance is achieved when piercing a hard sandy sand. It was found that with an increase in the displacement of the tip of the tip cone, the deviation of the trajectory increases. The piercing head achieves the greatest deviation from the straight trajectory of movement with a sharper cone and a greater asymmetric deviation of its top, and, for example, in hard sandy loam can be up to 0.17 m with a span of 10 m. It was found that the size of the soil destruction zone will be almost 1.8 times larger than the tip in the form of a symmetrical cone and reaches from 8 to 12 borehole diameters, depending on the type of soil. The maximum pressure on adjacent objects can reach from 0.06 MPa in hard-plastic clay to 0.09 MPa in hard sandy loam. The calculated dependences obtained for determining the power and technological parameters depending on the geometric dimensions of the asymmetric tip of the working body can be used to create installations with a controlled static puncture for use in the most common soil conditions.
When modeling mechanical objects and their systems, mathematical models developed for an elastic domain are most often used, which in some cases can lead to significant inaccuracies in calculations. The use of mathematical models that take into account visco-elastic properties or energy dissipation allows to obtain more realistic models, which will make it possible to obtain more accurate calculation results. In the paper non-stationary loading of a mechanical system, consisting of a beam hinged at the edges, and an additional support installed in the span of the beam is considered. We use a beam deformation model, which is based on the hypotheses of S. P. Timoshenko and takes into account the inertia of rotation and shear. The system of partial differential equations describing the deformation of the beam is solved by expanding the desired functions into the corresponding Fourier series and subsequent using the integral Laplace transform. The additional support is assumed to be realistic rather than absolutely rigid, having linear elastic and viscous components. It is assumed that at the point of attachment of the additional support to the beam their displacements coincide. The reaction between the beam and the additional support is replaced by an external unknown concentrated force applied to the beam, which changes with time. The law of change in time of this unknown reaction is determined from the solution of the Volterra integral equation. A method for obtaining an integral equation for an unknown reaction is described. Analytical relations and calculation results for specific numerical parameters are given. The influence of stiffness and viscosity on the determined reaction of the additional support, as well as on the deflections of the beam at various points, is investigated. The results obtained can also be used for damping forced vibrations of mechanical systems.
At trenchless laying of engineering communications in soil the method of static puncture has received wide application at formation of a well. Power plants that implement it have small dimensions, which make them more effective in laying distribution engineering networks in tight urban conditions. Problem. The main disadvantages of the method are the low accuracy of the trajectory and the significant stress in the soil after its compaction, which can lead to the destruction of adjacent underground objects. The first disadvantage is solved by controlling the trajectory of the soil-piercing working body. To solve the second question, it is necessary to know and take into account the specifics of the formation of communication cavities in the soil with an asymmetric tip, which is used for this purpose. Goal. The aim of the work is to establish the regularity of the process of soil puncture by the soil-piercing working body with an asymmetric tip in the form of a cylinder cut at an angle. Methodology. The approaches adopted in the work to solve this goal are based on the theories of deep soil cutting, scientific foundations of soil mechanics, their normative physical and mechanical properties and the law of conservation of soil mass before and after compaction. Results. The calculated dependences for determining the size of the destructive zone from the elastic-plastic deformation of the soil during its puncture by an asymmetric tip with a frontal surface in the form of a beveled cylinder and the pressure of the deformed soil on underground objects are obtained. It is established that the maximum size of the destruction zone and its pressure on underground objects will occur in solid sand. With a tip diameter of 0.3 m, their values can reach 5 m and 0.245 MPa, respectively. Originality. The obtained regularities of soil puncture by a working body with an asymmetric tip in the form of a beveled cylinder made it possible to get an idea of the influence of its deformed state on adjacent communications depending on geometric parameters of the tip and physical and mechanical properties of soils. Practical value. The obtained results can be recommended in the design and determination of technological capabilities of installations for static soil puncture.
The task of improving the educational process, improving the quality of education in the field of engineering and the effective use of technical methods and tools in the design and modernization of construction equipment using computer software is the most pressing modern task. The emphasis in education, which is transferred to the independent work of the student without changing the approaches and methods of teaching disciplines, and even more so specialized subjects, has a negative impact on the quality of the future specialist. Especially in such a difficult time, when you have to completely switch to distance learning, it is extremely necessary to change the approach to learning, especially in senior courses. The creation of complex complexes and machines is accompanied by a significant number of intermediate tasks. The use of the whole complex of construction equipment is mainly used in various technological operations and with the use of various replaceable work equipment. Modern pace of road construction dictates high requirements for modern technology, one of the important parameters of which is the utilization rate of the machine over time. When performing technological operations, the load from the ground is transmitted through the main working body to all elements of the suspension mechanism of the working equipment. The use of software allows you to preview any activity during the simulation allows you to check for security, reduce costs, and sometimes find new ways to implement, without conducting expensive tests. To do this, it is necessary to pre-model the node, unit, module, which will interact in a complex system. The use of modeling will assess the appearance of the finished product and its structural elements. At the moment, the development of objects of any kind cannot but be accompanied by the creation of a 3D model. This process will allow you to analyze the accuracy of all components that will interact when installed on a designed or existing machine.
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