Internal Friction Forces Research Articles

An investigation of heat transfer and optimization of entropy in bio-convective flow of Eyring-Powell nanomaterial with gyrotactic microorganisms

Entropy generation in nanofluid flows is a critical parameter that influences the performance, efficiency, and sustainability of thermal systems. Understanding and optimizing entropy creation can lead to noteworthy advancements in numerous engineering applications, from renewable energy systems to industrial processes and biomedical equipments. The purpose of this article is to examine the entropy produced in the bioconvection flow of Eyring-Powell nanomaterial with gyrotactic microorganisms. The mathematical equations representing the flow are modeled considering the flow towards a porous surface of a cylinder. Together with the effects of the governing parameters, the mass and heat transfer components of the problem are discussed. The thermal effects of different natures are used in a new way. Overall, entropy creation is designed with regard to the second law of thermodynamics. Activation energy, chemical reaction, thermal radiation, and internal friction force effects are accounted for the development of the mathematical model. Coupled non-linear dimensional equations have been altered into ordinary differential equations (ODEs) and then treated using the MATLAB Finite Difference Method (FDM). Consequence of diverse sundry parameters on entropy production, thermal field, mass concentration profile, Bejan quantity, and motile density of microorganisms is deliberated via plots. Through tables, engineering quantities are analyzed. According to the findings, the velocity profile rises as the curvature and Eyring-Powell fluid parameters rise, while it falls when the magnetic parameter is enhanced. Additionally, it is noted that as the curvature variable enhances, the rate of heat transfer and skin friction coefficient decays.

Resistance reduction characteristics analysis of the tee based on field synergy and viscous dissipation

There has been increasing attention on reducing pipe resistance friction losses, particularly those represented by tees, in heating, ventilation, and air conditioning systems to enhance the sustainability of buildings. This paper analyzes the resistance characteristics, flow patterns, and force conditions of tee, identifies the locations with great resistance losses, and proposes a novel tee with an added the U-shaped deflector. The resistance reduction effect of the U-shaped deflector through field synergy and viscous dissipation is also analyzed. The results indicate that the resistance loss of the tee is mainly from the main-branch pipe section, with the maximum velocity gradient on the outer side of the branch and the inner side of the straight pipe. The fluid resistance friction loss in the section taken by the branch pipe is much greater than that in the main pipe section, the fluid resistance friction loss in the section taken by the main pipe is not affected by the pipe diameter ratio, and the internal friction force accounts for 83 %–92 % of the resistance friction loss in the branch pipe section. Adding the U-shaped deflector can improve the synergy of the velocity and pressure gradient fields downstream of branch pipes and straight pipes, and reduce viscous dissipation. The total local resistance loss reduction rate of the novel tee is 83.15 %, the volume weighted average synergy angle is increased by 2.09°, and the viscous dissipation is reduced by 22.9 %.

Dynamic characteristics analysis of a rotor system with loose support considering internal friction in couplings

Along with the rotating machinery advances toward high speeds, the significance of the excitation force of the seal fluid in the rotor system is growing, which can cause serious accidents. Most of the previous research on rotors in rotating machinery has predominantly focused on the effects of misalignment in couplings. In this article, a novel model is proposed, introducing an analytical approach that combines both internal friction in couplings and loosening support faults. Additionally, an analysis and discussion of the vibration characteristics of the rotating system under the influence of internal friction are presented. This method allows for a more comprehensive assessment of the performance of rotors in engineering applications. Assuming that the left support of the rotor is loose, this model focused on how various factors such as rotor speeds, eccentricity, seal disc mass, and left-end support mass affect the labyrinth seal rotor system's dynamic characteristics. Based on the findings, The emergence of internal friction forces advances the chaos of the rotor. It seems that as the rotating speed increases, there will be a small frequency range, resulting in fluid oscillation, and the system stability will be reduced at this time. The improvement in the seal disc's quality has minimal impact on the stability of the left journal, but it will reduce the stability of the seal disc. The increase in the mass of the left end support will increase the stability of the movement at the left journal and reduce the stability of the movement at the seal disc.

Sediment incipient motion on sandy seabed considering relative density effect: Laboratory experiments and mathematical analysis

The threshold of the sediment initial movement is closely related to marine structure scour. In complex marine environment, the relative density of seabed is usually changed by liquefaction and scour that is caused by currents and waves. It affects the scour depth and scour time scale which have been noted recently. However, the effect of relative density on sediment movement was mostly ignored in previous studies. In this paper, a series of tests were conducted to investigate the incipient motion under different relative density conditions on different seabeds. Subsequently, the internal friction force was introduced to describe the relative density effect, and an incipient motion model was built. Accordingly, a unified sediment incipient motion velocity function that considers relative density is proposed. Based on this function, the critical bed shear stress was assessed. A new theory was then evaluated in terms of the critical bed shear stress. Finally, the percentage of internal friction force to the whole resistance was discussed. Results indicated the significance of considering the relative density effect in predicting small-sized sediment movement. The new function provides better prediction accuracy with an acceptable error of 20%. Additionally, the discussion of the internal friction force gives a potential avenue to quantify interparticle force.

Modeling of a screw extruder 3D printer using pellets or crushed polymer waste as the raw material

In this article, the process of moving polymer material in the screw extruder of a 3D printer, which uses granules or crushed polymer waste as raw materials, is chosen as the object of mathematical modeling. It is noted that the modeling of screw extruders is a highly relevant task, as it is an essential tool for optimizing production processes in the polymer industry and other industries where they are used. It allows you to study and optimize the material cylinder's processes thoroughly. It is noted that the modeling of screw extruders for 3D printers, which use granules or shredded plastic waste, is a critical factor in supporting innovation, increasing production efficiency, improving product quality, and developing new technological solutions in various industries. It was noted that during the movement of the material along the channel of the extruder screw, several of its states continuously changed from a solid at the entrance of the channel to a viscous liquid at the exit. In the feed zone, the polymer is solid and moves along the material cylinder due to friction. A physical model was used in the simulation, in which compacted polymer particles do not move relative to each other during movement through the channel. This is because the internal friction forces in the polymer greatly outweigh the friction of the polymer on the steel, and the particles move as a single elastic compressible medium due to the balance of dry friction between the cylinder wall and the screw. The geometrical parameters of the extruder in the feed zone are shown. A diagram of the expanded extruder channel for calculating productivity is given. A diagram of the movement of material in it was drawn up to determine the productivity of the extruder feed zone. A mathematical model of productivity was obtained depending on the diameter of the screw, the frequency of rotation, the depth of the screw channel, and the angle of elevation of the screw line of the screw cutting. The pressure in the extruder channel was calculated. A scheme for calculating the forces acting on the material in the feeding zone is given. A formula was obtained for determining the pressure in the material loading zone from the hopper, which connects the characteristics of the polymer material and the geometric parameters of the loading hopper. Keywords: 3D printer, screw extruder, modeling; polymer material; loading area; bunker; productivity; pressure.

ANALYSIS OF POWER AND ENERGY PARAMETERS OF THE CONVEYOR INFRARED DRYER OF OIL-CONTAINING RAW MATERIALS

Infrared drying of bulk agricultural products is becoming increasingly widespread in processing and food industries due to energy efficiency, compactness of technological equipment, and ease of operation. The purpose of the presented research is to determine the influence of the technological parameters of the process of infrared drying of the moving layer of oil-containing raw materials. An experimental model of a vibro-conveyor dryer and a set of measuring equipment were developed to solve the problems. The scientific novelty of the work is the confirmation that in the conditions of a vibro-liquefied layer of products, unique conditions are created for the constant renewal of heat exchange surfaces and, accordingly, the leveling of the negative thermal radiation effect on the products, the possibility of advancing the product layer along the working zone, reducing the forces of internal friction in the technological mass, which leads to a decrease in energy consumption on the process Laws have been established regarding the effect of the number of thermoradiation blocks, the load on the flexible belt of the wave conveyor, the speed of product advancement on the belt on the dynamics of infrared drying of soybeans and rapeseed. The practical value of the work was the substantiation of the operating modes of thermoradiation drying with the help of a vibrating wave conveyor installation based on the energy saving of the technological impact, high intensification of the process and minimization of the negative effect on the properties of the processed products.

The Precursory 3D Displacement Patterns and Their Implicit Collapse Mechanism of the Ice-Rock Avalanche Events Occurred in Sedongpu Basin Revealed by Optical and SAR Observations

Quantifying the kinematic evolution patterns of mountain glaciers near Yarlung Tsanpo River performs a major role in evaluating the glacial instability and the secondary disasters. For the Sedongpu Basin near the Yarlung Tsanpo River Valley, the dramatic geomorphic landscape variations triggered by the ice-rock avalanche events were visually identified as the dominant texture deficiencies in time-series optical images. To improve the image correlation quality broken by these image texture deficiencies, the Landsat-8/Sentinel-2 optical images were divided into different groups, then a stepwise combination strategy was innovatively proposed to derive the glacier time-series displacement velocities in different temporal stages. The standard deviations (STD) of the optical measurements in the stable area maintained around 0.04 m/yr for the normalized displacement velocity and maintained from 0.6 to 1.7 m for the cumulative displacement time series. The obvious variations in glacier displacement velocity were identified before each collapse event. Subsequently, the offset-tracking procedures were performed on 7 Sentinel-1A Synthetic Aperture Radar (SAR) images to acquire the range and azimuth displacement velocities. To better reveal the dynamic mechanism of the glacier activity, the three-dimensional (3D) glacial displacement velocity was also derived by using optical and SAR results. The precipitation, temperature, and seismic activities were assumed as the main triggering factors of controlling the glacial dynamic mechanism and final collapse events. Additionally, the dynamic mechanism of the active glaciers in Sedongpu Basin conformed to a power law, which was limited by the changes of the internal stress friction force on the sliding base surface. The aim of this study is to shed a light on interpreting the precursory displacement patterns and their implicit failure mechanism of these ice-rock avalanche events with the conventional freely optical and SAR observations.

Simulation and experimental study on the effect of iron on the structure and flow properties of coal ash slag

Slag fluidity is an important parameter affecting the stable operation of the gasifier. Above liquid temperature, slag fluidity is closely related to its structure. In the present study, the effect of iron on the three-dimensional connection state between [SiO4]4- and [AlO4]5- tetrahedrons in the SiO2-Al2O3-FeO-CaO slag system at 1773 K was deeply discussed by applying molecular dynamics (MD) simulation and ring statistics methods, and the slag network structure was divided into three rings with different functions according to the three-dimensional connection state. It was found that Fe2+ operated as a network modifier ion and substituted Si4+ and Al3+ in the slag and combined with O2–, thereby continuously depolymerizing higher-order rings into lower-order rings. This phenomenon simplified slag structure, reduced internal friction force, and improved fluidity. Finally, the ring distribution coefficient (Rdc) was defined and it was found that there was a linear relationship between Rdc and viscosity.

Scientific Study for the Internal Dynamic Friction between Warp and Weft Yarns of Woven Fabrics

Fabrics are typically classified based on their weight, which may vary widely from light, medium to heavy-weight fabrics. On the other hand, weaving machines are also often classified into light, medium, and heavy according to the weight of the woven fabric on them. Although, this classification method of weaving machines may be incorrect in many cases, as there isn’t necessarily a relationship between the weight of the woven fabric and the classification method for weaving machines in general. This is confirmed by the research in our hands. Where the research plan is based on the analysis of the internal friction forces between the warp and the wefts yarns, which are interlaced with each other within the fabric construction. Those internal friction forces have a significant impact on the force needed to beat up the wefts, based on Newton's third law "To every action, there is always opposed an equal reaction: or the mutual actions of two bodies upon each other are always equal and directed to contrary parts". According to the previous mechanical theory, it is expected that the required beating-up force values certainly depend on the number of interlacing rates within the woven construction repeat more than the fabric weight. The research paper revealed several important points, including determining a theoretical basis for calculating the internal friction values between warp and weft yarns within the woven fabric structure based on the warp yarns’ tension during the weaving process. By determining the values of internal friction, it is possible to estimate the values of some mechanical properties of the fabrics. These calculation values can also be used to determine the appropriate machine for the weaving process with high precision.

Study of the motion of modified solid particles in hydratransport systems

The article examines the movement of solid particles, the hydraulic calculations of pipes in the process of movement, the classification of reducing the impact of solid particles on hydrotransport systems. The effect of solid particle magnification on flow rate, pressure loss, speed reduction as a result of the effect of internal friction forces of solid particles, friction in the flow of solid particle hydroarations, pressure loss as a result of the impact of Resistance Forces, internal corrosion process observed in the pipe, increased energy consumption were analyzed using the example of hydrotransport systems Recommendations have been made to solve the problems of speed reduction and pressure loss due to the movement of solid particles in the hydroaration flow through the modification method. The prior and subsequent movement of solid particles in a pipe modification is shown through comparison graphs. Information about the gossipol Tar selected as a modifier is provided.

MATHEMATICAL MODEL OF THE MOVEMENT OF PARTICLES IN A CYLINDRICAL VIBRATING MIXER CONTAINERS

Mixing is the process of bringing different masses of products into close interaction by increasing the contact area in order to obtain the product of the required consistency, to maintain the latter or to evenly distribute impurities in the main volume of products. The process of mixing components with different physical and mechanical properties is realized mainly by creating shear deformations in the entire mass of the product with the help of blades, rotating screws, or other working bodies. At the same time, in order to ensure a uniform distribution of the components, it is necessary to give the particles of the dispersed mass such trajectories that would ensure the greatest probability of their crossing. But the movement of these particles in the volume of the mixture is opposed by the forces of inertia and the forces of dry internal friction (friction of particles against each other) and forces of dry external friction (friction of material particles against the container, blades or other working organs of the mixer), which, as a rule, are on the order of lower than the forces of dry internal friction. In addition, when mixing, it is necessary to overcome the forces of gravity, which try to lower the particles of the material to the bottom, which leads to their delamination. Numerical modeling has been increasingly used in the description of mixing processes of loose materials in recent decades. Numerical modeling is especially convenient when describing the processes of gravity-overflow mixing, when it occurs most actively in a thin layer of material, in which there is a random transition of component particles to the adjacent layer. The article examines the modeling of the movement of particles during the rotating movement of the cylindrical mixer chamber without the use of blade intensifiers and the effect of vibration on the product.

STUDY OF RADIAL SLIDE BEARINGS WITH A FLOATING RING CONSIDERING THE PHYSICAL PROPERTIES OF OIL

Radial slide bearings are typically used in turbochargers (among other applications), owing to their simple design and advantages, such as good heat dissipation from the working zone, high stability of operation and low resistance to motion. The current research is both experimental and theoretical. In a state of static equilibrium, the operation of a bearing can be described using a system of five coupled differential equations. The bearing’s operating parameters are related to the type of oil used. Two types of oil, VG46 and VG68, were used for testing. In accordance with the applicable standard, the tolerance of kinematic viscosity of oils is ±10%. The results imply a significant influence of the oil class and viscosity tolerance on the resistance to motion caused by internal friction forces in the oil. In conclusion, it seems advisable that the calculation procedures currently in use should include the slide bearing design optimisation by taking the resistance to motion in the bearing into account.

Viscometer for investigating the viscosity of magnetic fluid media

The rational application of magnetic fluids in various technical systems requires their stability analysis, hydrodynamic particle size, dissipative processes in the colloid control. The existing viscometers do not fully meet all requirements, in particular, they do not allow research in a magnetic field of given magnitude and certain topography. It is proposed to determine rheological properties of magnetic fluids using rotary viscometer, in which two measuring gaps are structurally designed and filled with studied fluid, which is important for calculating characteristics of low viscosity magnetic media. The device design implements practically homogeneous magnetic field, varying within wide range and directed perpendicular to liquid shear stress. The device allows to steadily maintain shear rate in medium under study, and to determine viscosity with a sufficiently large change. A small magnetic fluid volume is required to estimate rheological characteristics. The accuracy of measurements of the internal friction force, device heating temperature, coaxial cylinders rotation speed and magnetic field inside investigated medium meet the requirements of international standards. Laminar fluid flow process in the device gap is described mathematically. This made it possible to justify the construction geometrical dimensions in order to increase the measurements and determine rheological properties of low-viscosity magnetic materials. The formulas for calculation of Newtonian fluid viscosity coefficient, shear stress and shear rate based on experimental data were obtained.

Non-smooth dynamics of Anti Stick–Slip Tool

This paper investigates non-smooth dynamics of an Anti Stick–Slip Tool (ASST) and its effects on a simulated downhole drilling. An ASST is a mechanical tool mounted on a Bottom Hole Assembly and designed to suppress stick–slip phenomena arising in drill-strings. In this paper the ASST is considered as a non-smooth dynamic system, where the presented modelling accounts for switching between Activated and Non-Activated states and proposes quantitative conditions for observing each state. In this tool, a helical spline couples axial and rotational movements acting together with an internal preloaded spring. The helical spline governs a relative motion of coupled parts and the preloaded spring determines a threshold value for activation of the ASST. The internal friction between coupled components contributes to conversion of excessive loads to a relative motion of two coupled parts. The proposed model describes the effect of internal friction forces on the operation of the tool whilst the tool is subject to nonlinear cutting forces from bit–rock interactions. Prescribed kinematics imposed on the tool allows to simplify the model of entire system and to provide an insight into the complex behaviour of the tool. Nonlinear responses of the developed model for a range of system parameters were numerically simulated to explore the dynamic behaviour of the ASST.

A physical model-neural network coupled modelling methodology of the hydraulic damper for railway vehicles

The dynamic characteristics of the hydraulic damper are time-varying in the complex working environment. To reveal the internal influence mechanism of the boundary conditions on the dynamic performance of the hydraulic damper and take it into account in the multi-body dynamics calculation, the laboratory test of the hydraulic damper is carried out firstly, and it is confirmed that the hydraulic damper has significant frequency-dependent and amplitude-dependent and temperature-dependent characteristics. Then, combining the physical parameter model with the neural network model, an accurate hybrid neural network model of the hydraulic damper is proposed. The physical parameter model considers the damper structure, including orifice, damping valve, rubber joint and the relationship between temperature and viscosity of hydraulic oil. The neural network model describes the personality characteristics of the hydraulic damper, such as oil leakage, the internal friction force and the percentage of entrapped air in oil. Finally, the responses and the dynamic parameters of the hybrid neural network model are calculated and compared with the experimental results by considering various exciting amplitudes and frequencies. The results show that the proposed model can fully simulate the dynamic performance of the hydraulic damper under various operating conditions.

DYNAMIC PROCESSES ANALYSIS IN HIGH-SPEED SPINDLE ASSEMBLIES OF MACHINES TOOL WITH ACCOUNT DIFFERENT TYPES NONLINEARITY

The productivity and accuracy machine parts often depend on the dynamic processes during machine and cutting operation. The increase requirements for machining operation and quality machine parts leads to the need to evaluate and take into account all the capabilities of the technological processing system (TS) to ensure the stability of the cutting process and increase speed. One of the features emergence and existence of self-oscillating processes, the least studied and dangerous in terms of the effect on sustainability ТS is the nonlinearity parameters elastic system of the machine tool and the processes occurring during cutting operation. Therefore, to assess the conditions for implementation of the cutting process with a steady limited amplitude of oscillations, it is necessary to analyze and take into account the main nonlinearities dynamics of the TS. The article considers dynamic processes in high-speed processing systems on the example of high-precision spindle assemblies, with analysis and following review of their different types nonlinearity. The machine tool spindle unit for the case of high-speed processing according to the working conditions approaches the scheme of the rotor system which self-oscillations can be caused by the action of non-conservative circulation-type forces that are not associated with external periodic loads or any resonant relationships: internal friction forces, hydrodynamic forces in sliding bearings and seals, electrodynamic and electromagnetic forces in the electrical components of motor-spindles. It is shown that if the nonlinearity is associated only with internal external friction and coefficients of friction forces do not depend on frequency, the amplitude and frequency of self-oscillations (unlike linear system) will depend only on relationship of friction forces.

Transverse oscillations of the incompressible MHD mode in the visco-resistive plasmas: an explanation of Alfvénic to Landau-type characteristics

ABSTRACT In this paper, we characterize transverse oscillations as either Alfvénic or Landau-type in an incompressible non-ideal magnetohydrodynamic (MHD) fluid. We consider shear viscosity and magnetic diffusivity as dissipation mechanisms to derive a general dispersion relation for the incompressible MHD waves. The solutions of this dispersion relation for k as a function of ω – denoting by the source for any value of θ up to which magnetic tension acts as restoring force and dominates over internal friction forces – result in four roots, as follows. Two roots, which have a high phase velocity $c_{\rm A}\cos\theta $ are identified as almost undamped propagating Alfvén waves. The other two roots, which have a phase velocity $(2c_{\rm A}\cos\theta)/(\sqrt{\eta/\nu} + \sqrt{\nu/\eta})$, result in Alfvénic-type disturbances of a much shorter decay length than the wavelength. In contrast, when internal frictional forces start dominating over magnetic tension (i.e. for the propagation perpendicular to the background magnetic field, where the tension in the magnetic field becomes zero), the solutions of the dispersion are akin to Landau-type transverse oscillations. Transverse waves of this type were initially reported by Landau in an ordinary viscous fluid. However, our study corresponds to MHD visco-resistive fluid. The prediction for these lateral propagating transverse waves to be of Landau type may be very useful to explain the heating of observed filamentary structures across the magnetic field on a very small spatial scale in the solar coronal plasma, wherein the heating rate is directly proportional to the operating frequency of the driver, while its damping length is inversely proportional to the square root of the frequency.

THE EFFECTIVE VISCOSITY OF TRIBOLOGICAL COMPOSITE MATERIAL ULTRAN 630CF

The main methods of forming polymer composite materials based on thermoplastic matrices are injection molding and extrusion. All of them realize the process of viscous flow, in which an internal friction force occurs, characterized by the melt viscosity. This parameter determines the method of processing the material into a product. (Research purpose) The research purpose is to determine the value of the effective viscosity of a composite tribotechnical material ULTRAN 630CF based on polyamide, depending on the temperature and the applied force. (Materials and methods) The samples were granules of ULTRAN 630CF. The rheological properties of ULTRAN 630CF were measured using an extrusion plastometer PTR-LAB-02. The experiment consisted in evaluating the effective viscosity of the material with varying temperatures and operating loads. The heating temperatures of the samples were 250, 270 and 290 degrees Celsius. During the measurements, the melt shear rate varied by installing loads of various weights: 3.8; 5; 7 kilograms. (Results and discussion) Based on the data obtained experimentally, the article presents the calculated viscosity value and a graphical interpretation. With increasing temperatures and loads, the viscosity of the material drops to 6.1 times. The influence of the load value is noticeable only at a temperature of 250 degrees Celsius, which is associated with a viscosity anomaly. At temperatures of 270 and 290 degrees Celsius, the shear stresses are small, the material flows with a constant viscosity. (Conclusions) The viscosity of ULTRAN 630CF decreases linearly with increasing temperatures and loads, which indicates its high stability and a wide range of processing methods: extrusion, injection molding, pressing, 3D printing.

Dynamic contact response of an elastic sphere on a piezoelectric half-space

This paper studies the dynamic contact response of a piezoelectric half-space under the action of an insulating elastic spherical punch. By means of the perturbation method, the dynamic contact pressure distribution is deduced. Utilizing Hankel transform, the dynamic contact displacement is obtained. Combining the elastic spherical punch oscillation and the piezoelectric half-space motion through contact-displacement boundary conditions, the resonant frequency shift of the elastic sphere is derived. Numerical calculations are given to discuss the influences of the material constant, piezoelectric effect, internal friction and static force on the dynamic contact pressure and resonance frequency shift. The results show that the difference between the dynamic and static contact pressures is small at the center of the contact region, while it is large near the edge of the contact region.

Validation of CubeSat tether deployment system by ground and parabolic flight testing

This paper describes the experimental validation of a CubeSat tether deployment design by air-bearing ground test and microgravity parabolic flight test. The tethered CubeSat mission includes two 1U CubeSats with a tape-type tether of 100 m. The tether will be deployed by pull with two CubeSats separating at a desired velocity. Various ground tests were performed to validate the designed separation velocity, estimate the internal friction force, and measure the deployed tether length. Finally, the engineering model of tether deployment system is validated by microgravity parabolic flight testing. The parabolic flight demonstrated the tether deployment system works as expected. By measuring the separation velocity of CubeSats in the parabolic flight, it reveals the internal friction is much less in the microgravity environment than the value measured on the ground.