Action Of External Forces Research Articles

АНАЛІЗ ІСНУЮЧИХ МОДЕЛЕЙ ВИНИКНЕННЯ НАПРУЖЕНЬ В ТОНКИХ ПЛІВКАХ І ПОКРИТТЯХ

The analysis of existing models of stress in thin films and coatings was carried out. While reaching critical value, stress can lead to defects, cracks, delamination of coating from substrate, etc. The task of prediction and controlling of the direction and magnitude of the stress of coating-substrate system is relevant nowadays regardless of coating and thin films deposition methods. Different types of coatings and thin films are widely used in almost all industries: optics, mechanical engineering, measuring technology, medicine, micro- and nanoelectronics, etc. Development and investigation of new promising methods for the formation of nanostructures, such as nanowires in a plasma environment, requires a sufficient theoretical basis for the origin and growing of stresses. Depending on the mechanism, the causes of stress in thin films and coatings can be: chemical reactions, phase transformations, inclusions and impurities, particle bombardment (the cause of internal stress during coating growing); temperature changes (the cause of thermal stress due to different values of coefficients of thermal expansion of coating and substrate materials); deformation of coating-substrate system, etc. Models of stress development in coatings and thin films can be divided into the following groups: stress that occur at the coating-substrate interface, internal coating stress, and stress at the coating-environment interface. The study presents methods of stress measuring in thin films and coatings. Based on the results of the current research, it can be concluded that the existing models of stress in the process of growth of coatings and films, as well as stress arising under the action of external forces, describe only the causes of the stress and unfortunately do not give an understanding of their complex effect on stress-strain state of coating-substrate system and need further development and improvement. Stress relaxation is also important to obtain new structures and certain properties of coatings. The development of stress management tools can be considered as one of the ways to increase the lifetime of products with coatings and thin films.

Microstructure and mechanical behavior of asphalt mixture based on freeze-thaw cycle

PurposeIn order to unravel the evolution of microstructure characteristics and the change of mechanical properties of bituminous mixture in the freezing and thawing environment in cold region, this study starts from macroscopic experiments and analyzes the changes in mechanical properties of asphalt mixtures before and after freezing and thawing in detail. On this basis, the displacement of key particles in the structure of asphalt mixture under the action of external forces (before and after freezing and thawing) is simulated through the combination macroscopic and microscopic methods.Design/methodology/approachThe climate in China exhibits high complexity and diversity, divided into five zones based on the temperature difference from south to north. Considering that the significant effect of geography and natural climate on the design, construction and maintenance of asphalt pavement, the criterion for the road construction at different areas should be highly different.FindingsThe results show that the mechanical properties of asphalt mixture greatly decrease due to the influence of freeze-thaw, and the displacement of key particles in the structure of asphalt mixture (several representative particle sizes were selected through experiments) is obviously observed because of the action of external force. By analyzing the variation of several key particle sizes after freezing-thawing cycle, the gradation standard of asphalt mixture aggregate suitable for cold area was obtained. The research results have certain theoretical and practical value for the design and application of asphalt mixture in cold area.Originality/valueThe results show that the mechanical properties of asphalt mixture greatly decrease due to the influence of freeze-thaw, and the displacement of key particles in the structure of asphalt mixture (several representative particle sizes were selected through experiments) is obviously observed because of the action of external force. By analyzing the variation of several key particle sizes after freezing-thawing cycle, the gradation standard of asphalt mixture aggregate suitable for cold area was obtained. The research results have certain theoretical and practical value for the design and application of asphalt mixture in cold area.

RETRACTED ARTICLE: Research on application of flexible strain sensor in human motion monitoring

The flexible wearable device is a kind of flexible electronic device, which can be installed on the skin of the human body, follow the activities of human body joints and tissues to produce a variety of deformation, such as extending the body, bending and turning activities, and respond to the movement of the wearer. Composite conductive polymer has excellent extensibility and mechanical properties, as well as very strong flexibility. It can change the resistance in a wide range and under the action of external force, so it can maintain sustainable development in human movement, electronic skin, robot and other fields. Using these new polymer materials as matrix, flexible polymer materials such as graphene and carbon nanotubes as conductive fillers, RGO/TPU strain sensors and PDA/CNTs/EB strain sensors with excellent strain sensitivity were fabricated. It can be found that PDA/CNT/EB has the advantages of large strain amplitude, wide range, high sensitivity, fast reaction rate and high durability/EB conductive composite can monitor people's daily muscle and joint activities, and perform human–computer interaction, which can show very good safety and high accuracy, so that wearable flexible sensor has better ideas and requirements in the design and development process, and wearable sensor has good practical application effect.

ИССЛЕДОВАНИЕ ПЕРЕХОДНОГО ПРОЦЕССАЭКСПЛУАТАЦИИ ПРИ КОНТАКТНОМ ВЗАИМОДЕЙСТВИИ БАРАБАННОЙ ПЕЧИ И ОПОРНЫХ РОЛИКОВ В ANSYSMECHANICAL

At first glance, a rotary kiln is a simple structural object, which is very widespread in the industry of processing and obtaining materials, both for construction and for other purposes. However, behind the external simplicity, there are complex chemical processes, mechanical, subtleties of the control system, the technology of manufacturing large-sized parts that are part of the general assembly and directly issues related to the design and modernization stage. The study of various regularities of mechanical processes associated with the theory of elasticity, kinematics and contact interactions is difficult even separately, especially when the processes run together. Studying the contact interaction of the kiln with roller supports allows to see the anomalous effects that can occur if the design is incorrect. In a specific case, it is necessary to observe how, under the action of external forces, time-varying deformations, displacements, of individual structural elements occur, which are of key functional importance in the operation of the equipment, in conditions of contact interaction of its individual parts, taking into account inertial loads and damping. The study of transition processes with changing force factors in time will allow to obtain the response of the structure to external influences

RETRACTED ARTICLE: Correlation between coastline soil loss rate and artificial intelligence English vocabulary based on GIS system

Under the action of internal and external forces, the material in the soil deviates from its original position, reaches another position through constant movement, and stabilizes. This process is the most common phenomenon in the natural geographic process—soil loss. Soil loss occurs throughout the country, and soil loss not only affects people’s normal agricultural activities but also leads to ecological imbalance. In China, the phenomenon of soil erosion is extremely serious. Almost all regions will have the phenomenon of soil erosion. The total amount of soil erosion is very large, but there are many types of soil erosion reasons. In order to understand the process of soil loss more clearly and protect China’s landforms and water and soil, some scholars have established a soil loss equation. Proposing relevance theory not only brings a whole new dimension to college English vocabulary but also deepens students’ understanding of vocabulary and helps students to remember vocabulary. In the process of teaching, teachers should combine the spelling, comprehension, and use of vocabulary with relevance theory in college vocabulary teaching according to theoretical principles to promote the improvement of college students’ English proficiency and help teachers in English vocabulary teaching. Nowadays, artificial intelligence has been applied to various fields, and the combination of translation technology and artificial intelligence has reached maturity. In college English teaching, it is necessary to combine foreign language learning with the application of technology, which is a brand new challenge for college English teachers. Some teachers and administrators need to change their existing thinking and improve their ability to use artificial intelligence for foreign language teaching according to the requirements of the current environment. Under the action of internal and external forces, the material in the soil deviates from its original position, and reaches another position through constant movement and stabilizes.

Weak solutions to stationary motions of shear thinning fluids with nonhomogeneous Dirichlet boundary conditions

We consider steady flows of shear thinning fluids in bounded domains under the action of external forces and Dirichlet boundary conditions. For a power-law index q∈(2d∕(d+2),3d∕(d+2)], we construct weak solutions to the nonhomogeneous boundary value problem assuming that the boundary data is small enough. Moreover, under the restriction q∈((2d−1)∕d,2), d=2,3, and extra regularity for the boundary data, we construct weak solutions by extending the tangential part of the velocity at the boundary in such a way that it is possible to partially control the inertial term. This imposes restrictions only on the size of the normal component of the boundary data.

Intelligent Discrimination Method Based on Digital Twins for Analyzing Sensitivity of Mechanical Parameters of Prestressed Cables

The information collected on large-span prestressed cables by field sensors is susceptible to interference, which leads to inaccurate collection of structural and mechanical parameters of large-span prestressed cables, resulting in misjudgment of structural safety performance. This paper proposes an intelligent judgment method for improving the sensitivity of analyzing mechanical parameters of prestressed cables based on digital twins (DTs). The safety performance of the structure was evaluated by analyzing the mechanical parameters. First, the information during prestressed cable tensioning is dynamically sensed, thereby establishing a multidimensional model of structural analysis. The virtual model is processed by the model modification rule to improve the robustness of the simulation; thus, a DT framework for the sensitivity judgment of the mechanical parameters of the cable is built. In the twin model, the simulation data of the real structure were extracted. Probabilistic analysis was performed using the Dempster–Shafer(D–S) evidence theory to discriminate the sensitivity of mechanical parameters of each cable node under the action of external forces with high accuracy and intelligence. Sensitivity analysis provides a reliable basis for the safety performance assessment of structures. Taking the wheel–spoke-type cable truss as an example, the application of DTs and D–S evidence theory to the sensitivity determination of cable mechanical parameters under temperature fully verified that the proposed intelligent method can effectively evaluate the safety performance of the actual structure.

Stabilnost smera kretanja poljoprivrednog traktora

The discrepancy between the plow width and the tractor width leads to the asymmetry of plowing units. The geometry of the plowshare surface of the moldboard plow contributes to the generation of lateral forces on the working tool. All this leads to the imbalance of the tool and the deviation of the tractor from straight-line movement during plowing. To maintain straight-line movement, the driver has to adjust the machine every 5-10 meters, which is highly tiresome. To study the causes of lateral slips of the plowing unit, we constructed a mathematical model, which consists of the equations of controlled movement and equations of the tractor's uncontrolled shear under the action of external forces from the plow. The description of the force interaction of the drive with the ground is based on the mathematical theory of friction, taking into account anisotropy and elastic properties in contact. Based on the passive shear model, we constructed a hodograph diagram of the maximum tractor shear force from the side of the working tool. We found that the shear force reaches its maximum friction value only in the case of a translational shear, when its line of action passes through the tractor's center of gravity. In all other cases, the shift (slip) of the tractor is caused by a lower force. We formulated the features and assumptions of the model as applied to caterpillar and wheeled tractors. As a result, we found that, regardless of the direction of the lateral displacement of the plow's traction resistance, the tractor is slipped towards the plowed field. The result of the numerical experiment showed that the main reason for the slip of the wheeled plowing unit is the difference in soils along the sides of the tractor but not the deviation of the plow traction resistance.

ОЦІНКА СТІЙКОСТІ БОКОВИХ ПОРІД У ВУГЛЕПОРОДНОМУ МАСИВІ З УРАХУВАННЯМ ДЕФОРМАЦІЙНИХ ХАРАКТЕРИСТИК ОХОРОННИХ СПОРУД

Purpose. Evaluate the stability of the rocks surrounding the roadways in a coal-rock stratum, taking into account the deformation characteristics of supporting structures. Methodology. To achieve this goal laboratory study of the deformation characteristics of supporting structures located between the simulated roof and floor of the coal seam under uniaxial compression was performed. Results. This study demonstrates that the deformation characteristics of secondary support structures affect the stability of roadway surrounding rocks in a coal-rock stratum. The nature of the deformation of supporting structures under the action of external forces is specified by their stiffness. All other things being equal, when the roof and floor rocks have a constant flexural rigidity, their stability depends on the stiffness of the supporting structures and the direction of the load applied in the tangential (wooden crib supports: 4-point chock, sandwich chock) or radial (vertical timber sets) direction. For the simulated supporting structures with an increase in the compressive load was recorded a simultaneous linear increase in their stiffness and deformation modulus. Moreover, for wooden yielding crib supports, when the load is applying across the wood fibres, the compressed chocks of wooden cribs are compacted, because of which the roof-to-floor convergence is limited. There is no such pattern for rigid structures in the form of vertical timber sets. After the loss of stability of the supporting structure, the deformation modulus decreases, which is accompanied by an increase in the roof-to-floor convergence to the destruction of the construction. It is recommended to refuse to use rigid and fragile secondary support structures. Novelty. The roadways roof stability in the coal-rock stratum is estimated by the maximum relative deformation of the secondary support structures under uniaxial compression using a coefficient characterizing the ratio of the stiffness of the working supporting structure to flexural rigidity of the roof and floor strata. Practical significance. It is necessary to focus on the use of yielding supporting structures to ensure the stability of the immediate roof and floor of mine workings in the coal-rock stratum and the operational condition of the gateroads adjacent to the working face at the extraction site of the coal mine.

Determination of angular stiffness coefficient of the annular seal by experiment-calculation

Hydrodynamic forces in annular seals of centrifugal pumps create a significant effect on the vibrational activity of the rotor as a whole. Theoretical and experimental studies of various authors made it possible to establish the structure of hydrodynamic forces and determine the magnitude of the coefficients of radial forces. The authors of this work obtained quantitative load characteristics of the rotor in an annular seal at specially created laboratory experimental stands at various pressure drops and significant angles of misalignment of the rotor axis relative to the seal axis. Static experiments were also conducted with annular seals of various lengths with a constant differential pressure of the liquid and a fixed angle of misalignment of the rotor axis relative to the axis of the annular seal. The given misalignment angle was obtained as a result of the action of various external forces on the rotor. In addition to static experiments, dynamic rotor tests were carried out. Experimentally obtained amplitude - frequency characteristics of the forced radial - angular oscillations of the rotor, which is dynamically mounted in two symmetrical annular seals. From the experimental characteristics, the critical frequency of the rotor angular oscillations in the seals was determined. According to theoretical formulas, taking into account the value of the coefficient of angular stiffness of the annular seal, the frequency of the natural angular oscillations of the rotor in the annular seals was calculated. A comparison of theoretical and experimental values indicates their good quantitative agreement.

Direktne metode za određivanje čvrstoće ljuske jaja

During the manipulation of hen eggs from the farm to the consumer due to action of external forces and weak mechanical strength of shell, the eggs break. The goal of egg producers is to reduce losses when breaking eggs during the production and placement, and thus increase revenues. Each egg can be damaged by external forces whose values are greater than maximum strength of the egg shell. Direct and indirect methods are used to determine the quality of eggs and shell strength. By direct methods, strength of the shell can be determined on the basis of puncture force measurements, impact forces, quasi-static compression forces and free fall forces on a known surface. In our research, a device was constructed for the realization of experiment and a direct method for determining strength of eggs was applied on the basis of measured breaking force of the shell. The device for measuring strength of eggs by the direct method of puncture eggshell was constructed and applied at the Faculty of Technical Sciences and the Faculty of Agronomy in Čačak. Class "M" hen eggs produced on the "Grbović" farm in the vicinity of Čačak were used in the research. The laying hens are a 41-week-old Isa Brown hybrid. During the research, physical characteristics of hen eggs were determined: length, width, index of shape and weight of eggs, as well as weight of the shell, share of the shell in the total mass of eggs, thickness and puncture force of the shell. The results of research show that the length of egg is 57.00 mm, width 44.59 mm with a coefficient of variation from 2.7 to 1.4%. The thickness of egg shell is on average 0.39 mm, in range from 0.377 to 0.416 mm. The share of shell is 10.54% of average weight of eggs (62.43 g). The quality of the tested eggs was quite uniform because the puncture force of egg shell ranged from 20.35 to 23.97 N. The research results are important for cage construction, design of egg collection equipment, design of egg packaging, and applicable in selection for obtaining new genotypes of laying hens with increased resistance to egg breaking.

Vibration separation of multiple mixed particle curves based on image recognition and machine learning

The motion characteristics of particulate matter are very wonderful. With the development of science and technology, the motion of granular materials has gradually become a hot topic, which has attracted the attention of many scientists and experts. The research of granular matter has gradually become specialized and systematic. With the gradual improvement of the system, a frontier research field particle physics has been formed. Under the combined action of external force and internal force, particles can reflect the properties of fluid, but in the process of flow, it will show different size separation phenomenon from the fluid. The problem of particle separation was formally introduced into the field of physics in 1987. In reality, the existence of particles is not unique. In view of this, the author makes a systematic research and Analysis on the behavior and factors of vibration.

УПРАВЛЕНИЕ ТЕМПЕРАТУРНО-ВЯЗКОСТНЫМ КЛИНОМ В ПОДШИПНИКЕ ЖИДКОСТНОГО ТРЕНИЯ НА ОСНОВЕ АЛГОРИТМА ГЛУБОКОГО ОБУЧЕНИЯ С ПОДКРЕПЛЕНИЕМ

. This paper discusses the possibility of using intelligent systems based on reinforcement learning and deep neural networks to control the lubrication system of a mechatronic fluid friction bearing. The training of the agent of the control system was carried out on a simulation model of a rotary machine, the purpose of training was to reduce energy losses for friction and reduce the level of vibrations under conditions of a random external force action of a periodic nature with a random frequency. The ability to switch modes has reduced the negative effect of the resonance phenomenon. The results of the training demonstrated the effectiveness of using such intelligent systems for the developed mechatronic bearing arrangement.

On the Analytical Modeling of a Resonant Fatigue Testing Rig

The drill string is a common rotating structure extensively used in oil exploration and production. The drill string fails under the long-term action of internal and external pressure, axial force, bending stress and torque in the drilling process. In order to facilitate the study of fatigue life of pipe joints, a light-structural and cost-and-time, efficient resonant bending fatigue test scheme is adopted, an analytical resonant bending fatigue test model is established, and the relationship between the parameters such as pipe length and the natural frequency of the sample is explored. The natural frequency and the zero-displacement position of the first mode of the test sample are predicted. The location of the moving point, the central bending moment and the corresponding normal stress can be used to predict if the test requirements are satisfied.

Semi-analytical model-based research on influencing factors of the spacing of volume fracturing horizontal well in tight oil reservoirs via consideration of imbibition

A mathematical model was established for porous flow of horizontal wells based on the dual-porosity model under consideration of imbibition, which was solved by means of a semi-analytical method to forecast production of multiple wells. Moreover, analysis was carried out to effects of production by those factors such as reservoir energy, abundance (the content of crude oil per unit area of the reservoir), brittleness (the property that the material will break after only producing a small deformation under the action of external force) and well spacing by taking Chang 7 reservoir of ChangQing(CQ) Oil Field (a typical tight oil region in China) as an example. On this basis, an optimal method for spacing of volume fracturing horizontal well in tight oil reservoir was formed under constraints of economic benefits. Our finding indicates that there would be no any optimal well spacing without considering constraints but those factors such as reservoir energy, abundance, brittleness would influence well spacing to bring about parameter optimization considering constraints. As for a complex fracturing area gathered near the wellbore whose reservoir energy, abundance and brittleness are higher, horizontal wells for volume fracturing of tight oil reservoirs shall be distributed in a small well spacing. Additionally, comparison of ChangQing and North American Bakken tight oil reservoirs indicates that the former has lower abundance, reservoir energy and brittleness. While the oil price is $60/barrel, the horizontal well is 1000m long and the well spacing is 400m, the target rate of return can be achievable in tight oil reservoir of CQ Oil Field. However, in case of considering the imbibition, the gain can be obtained while the well spacing is 300m. Our study for optimization of the horizontal well spacing for volume fracturing of tight oil reservoirs provides not only theoretical supports for the porous flow mechanism of tight oil reservoirs but also corresponding technical guidance for petroleum engineers when deploying well patterns.

The estimation of dynamical condition of vibration technological machines at joint action of two external disturbances

The introduction of additional elastic elements into the structure of a vibrating technological machine is considered. The design scheme of a vibrating machine is a mechanical oscillating system with a rigid body on elastic supports. A method for creature mathematical models of technical objects is offered, which makes it possible to evaluate their dynamic state with the introduction of additional ties. For a more detailed analysis of the properties of the system, structural mathematical modeling methods are used. The essence of such approaches is the equivalent of replacing the initial design scheme of a vibrating technological machine with a dynamically equivalent analogue, which is a structural scheme of an automatic control system. It is shown that with the asymmetric introduction of additional elastic elements, it is necessary to develop special methods for the analysis of dynamic stiffnesses. Taking into account the combined action of external force influences shows the possibility of manifestation of new dynamic effects associated with the regimes of dynamic absorbtion of oscillations and the influence of inter-partial ties. Based on the studies and the obtained analytical ratios, a methodological basis for the dynamic synthesis of the parameters of mechanical vibrational systems with the ability to control and control the dynamic state of the working bodies of vibrating technological machines has been developed.

Modeling drag force in ellipsoidal particle suspensions with preferential orientation

High aspect ratio ellipsoidal particle suspensions exhibit preferential orientation under the action of external forces and in the presence of walls. The preferential orientation of the particles has a large effect on the drag force experienced by the suspension. In this paper particle resolved simulations are conducted on ellipsoidal particles of aspect ratio 10 and 2.5 in the Reynolds number range 10 ≤ Re ≤ 200 and solid fractions 0.10 ≤ φ ≤ 0.30. An orientational order parameter −2.0 ≤ S ≤ 1 is used to define the preferential orientation of the suspension. It is shown that in spite of up to 400% variation in mean drag force with S, a simple linear relationship between S = −2 and 1 can describe the variation of drag force. This is a significant finding which establishes that only two data points at S = −2 and 1 are needed to define mean drag at any preferential orientation exhibited by the suspension. It is also shown that the inclination dependent mean drag is quite independent of S at low Reynolds number and solid fraction but shows increasing dependence at higher values.

Study on the Establishment and Optimization of Sandcastle Infrastructure Model

Sand castle was created by the tourists on the beach for fun, then how to set up a stable sand castle under the condition of waves and tidal waves to get the honor of “sandcastles builder” has been their main concern. In this paper, considering the formation principle of sandcastle and the effect of the uncertain factors and the effect on the stability of the sand castle, the sandcastle infrastructure model is established and the 3D geometric model of the sand pile is optimized step by step. We start with sand heap discretization, the impact process of waves and tides is regarded as the external force acting on the sand, and the stress analysis shows that there are three kinds of stress conditions: no external force, one external force and two external forces. Then from the point to surface, the stress energy of the whole layer of sand is analyzed according to the two aspects of energy transfer dissipation and internal force failure dissipation. The optimal bearing capacity plane is approximately pentagon by annealing algorithm. Finally, from the surface to the solid, taking the self-weight of the sand pile, the effective external force action and the seawater erosion action as the constraint conditions, the optimal tilt angle of the plane stack is calculated to be 36.87° by measuring the risk degree of the overlaying slope Angle. Therefore, the oblique pentagonal body with an inclination angle of 36.87° is relatively stable.

Dynamic modeling of cables with external forces applied to the terminal load

Cables are flexible structures often used in underwater applications, mainly related to oil extraction industry. This paper proposes a new dynamic modeling of cables that includes the action of external forces applied to its terminal load in two situations: free terminal load and fixed to the seabed. The continuous cable flexibility is approximated by rigid links connected by fictitious elastic joints that allow elevation, azimuth and torsion movements. External forces applied to the terminal load are considered in two situations: written in the inertial framework and written in the body framework. Generic algorithms are proposed for the automatic generation of models considering any number of links in the discrete approximation of continuous cable’s flexibility. The simulation results were very close to the experimental ones, thus validating the proposed modeling formalism. A software was developed to animate the cable with three-dimensional spatial configuration for viewing the simulation results. These animations showed physically the expected results, as well as a great sense of physical reality.

Preparation and performance of MAX phase Ti3AlC2 by in-situ reaction of Ti-Al-C system

In order to clarify the effects of the proportion of raw powders, heating temperature and holding time on the purity and properties of MAX phase Ti3AlC2, powder mixtures of Ti, Al and C powder with different ratio were prepared by planetary ball mill and heated under different conditions by spark plasma sintering. The microstructures and phase structures of the as-synthesized samples were characterized, the correlation between the mechanical properties and microstructure and fracture mechanism were investigated systematically. The results show that with the proportion of raw powders Ti:Al:C = 3:1.2:2, the sample heated at 1300 °C for 60 min has the highest purity 97.23 wt% of MAX phase. It has a compact and uniform lath-like structure with the length-thickness ratios of 3–5 and excellent comprehensive mechanical properties: the Vickers hardness, bending strength and fracture toughness are 5.26 GPa, 500 MPa and 7.35 MPa∙m1/2, respectively. The experimental results show that among the three factors, the proportion of raw powders has the greatest influence on purity of Ti3AlC2 phase, followed by heating temperature and holding time. The fracture morphologies of the tested samples demonstrate that under the action of external force, extrusion and kink occurred in the layered structures of Ti3AlC2 phase. These two forms of energy dissipation lead to the bending strength and fracture toughness of Ti3AlC2 are higher than that of traditional ceramics.