Load Distribution Coefficient Research Articles

Research on friction and meshing efficiency of ADC12-POM gear pair considering off-line meshing

Metal-plastic gear pairs, due to their combination of the advantages of both materials, have been widely promoted and applied in many industries. However, research on their transmission performance is not yet complete, especially regarding the tribological properties of metal-plastic gear pairs. The study focus on ADC12-POM gear pairs. Based on the principle of potential energy, the study considers significant elastic deformation during POM meshing, resulting in obvious off-line meshing. Consequently, the study establishes a stiffness model for ADC12-POM gear pairs with off-line meshing. Using this stiffness model and a load distribution model, to calculate the tooth surface load distribution coefficient for the gear pairs. Building upon previous research on friction coefficient models, the study develop a friction coefficient model that accounts for off-line meshing and compare it with the friction coefficient model that does not consider off-line meshing. To validate the accuracy of the friction coefficient model, the study design and create an efficiency test rig for ADC12-POM gear pairs, conducting theoretical and experimental studies on gear mesh efficiency. The study analyzes the distribution of mesh efficiency along the meshing line and its relationship with the friction coefficient. By comparing experimental measurements with theoretical calculations, the study verifies the proposed friction coefficient model, providing a theoretical basis for the study of metal-plastic gears.

A comprehensive sliding wear prediction method for planetary roller screw mechanism

The thread-pairs wear has a significant role in the transmission accuracy, operational stability and service life of planetary roller screw mechanism (PRSM). Nevertheless, the previous literatures still lack the investigation on the wear evolution of roller, nut and screw. Hence, an accumulative wear depth (AWD) prediction model is proposed for PRSM with reciprocating motion. The presented model is validated by the measured wear phenomena of thread pairs and the experimental results in the literature. The equivalent sliding wear experiment of PRSM is designed and the sliding wear coefficient of PRSM material is obtained by the equivalent sliding wear experiment. Considering the thread profile error caused by AWD of roller, nut and screw, the load distribution (LD) and sliding velocities on screw-roller (SR) and nut-roller (NR) sides are calculated. More importantly, the interactions between the AWD, LD and sliding velocity are investigated. Furthermore, the effects of axial load on the AWD, sliding velocities in contact regions and load distribution coefficient are analyzed.

Improved theoretical calculation method for the transverse load distribution of wide bridges considering torsion and distortion

An improved theoretical calculation method was proposed to determine the transverse load distribution of airport and highway bridges under heavy loads using the rigid-joint girder (RJG) method. The effects of torsion, distortion, and vertical inclination of the adjacent box girder joints under an eccentric heavy load were considered. The coefficients and influence lines of a taxiway bridge and a highway bridge were calculated using the proposed method, the RJG method, and the modified RJG methods. The accuracies of the three methods were evaluated by the refined finite element model, and the cosine similarity and peak deviation rate were used as quantitative indices. The results showed that the cosine similarity obtained from the proposed method for the taxiway bridge was 0.996 compared with the finite element method (FEM). The maximum peak deviation rate of the transverse load distribution coefficient for the proposed method was 14.88 % and obviously lower than 34.74 % for the RJG method. For the highway bridge, the cosine similarity of the influence line derived from the proposed method was 0.995, and the maximum peak deviation rate of the transverse load distribution coefficient for the proposed method was 6.66 % and lower than 16.14 % for the RJG method. The results indicate that the proposed method can be used to calculate the transverse load distribution of wide box girder bridges accurately and efficiently.

Numerical modeling and experimental validation of power loss and efficiency in an electric-drive axle system

Power loss and efficiency are pivotal performance metrics significantly impacting the quality of electric-drive axles. This study outlines a numerical method for determining the electric-drive axle system power loss, which includes gear meshing, gear churning, and bearing power losses. Power loss from gear meshing was calculated by analyzing load distribution and friction coefficient. The frictional loaded tooth contact analysis method was employed to ascertain the load distribution during gear meshing. A formula based on a weighting function was utilized to compute the friction coefficient. The finite element method was used to verify the gear load distribution and meshing power loss. Subsequently, empirical formulas were used to calculate the gear churning and bearing power losses. To substantiate the proposed numerical method, an experimental apparatus was employed to measure the power loss and efficiency of an electric-drive axle under various operating conditions. The experimental study demonstrated a strong correlation between the numerical and calculated results. These findings suggest that the proposed method can be an effective tool in predicting the power loss and efficiency of electric-drive axles.

Improving a procedure of load balancing in distributed IoT systems

The object of this research is the process of load balancing in distributed Internet of Things (IoT) systems. Within this work, a complex of problems related to efficient load distribution has been addressed. The authors conducted an analysis of existing load-balancing approaches and their drawbacks and proposed an enhanced architecture for the MQTT broker. Additionally, methods and algorithms for load balancing were developed based on multi-criteria server monitoring. Furthermore, the authors created a mathematical model to assess the uniformity of load distribution in the system and introduced a corresponding metric – the load distribution coefficient. In order to evaluate the proposed load balancing methods, a series of experiments were conducted, including the simulation of a distributed IoT system with non-deterministic load. The main goal of these experiments was to assess the uniformity of MQTT load distribution by the broker. The results of the experiments confirmed the hypothesis of improved load distribution efficiency through multi-criteria monitoring-based balancing. The utilization of the proposed load-balancing methods allowed for a more efficient utilization of computational resources. It was found that when using the proposed methods, in the case of non-deterministic load in the IoT system, the load distribution coefficient on average exceeded the corresponding indicator of existing methods by 70 %. In addition, the value of this coefficient for the proposed methods remains virtually unchanged throughout the experiment, which is evidence of the stable operation of the system as a whole. The results obtained can be useful in the development of modern IoT systems.

Study on Friction Characteristics of ADC12-POM Gear Pair

In a transmission system, the cooperative utilization of metal small gears and plastic large gears not only significantly reduced the system weight and noise levels, but also harmonized strength and longevity between the gears of varying sizes. Nevertheless, the existing research on metal-plastic friction remains insufficient. This study focused on the ADC12-POM gear pair, conducted sliding friction tests between polyoxymethylene (POM) plastic balls of different diameters and ADC12 metal plates using a self-made reciprocating friction and wear testing machine. The friction coefficients between the ADC12-POM sliding pairs were evaluated under different load and velocity conditions, and subsequent nonlinear regression analysis using the IBM SPSS software yielded an initial calculation model for the friction coefficients at the contact surfaces of the ADC12-POM gear pair. By analyzing the Engagement characteristics of gears, we calculated the variations in curvature radius, relative sliding velocity, and load distribution coefficient during the Engagement process. This enabled us to establish a computational model for determining the tooth surface friction coefficient of the ADC12-POM gear pair. Furthermore, we derived the relationship between Engagement efficiency and the friction coefficient and conducted experimental investigations to assess the efficiency of gear Engagement. The deviation between the theoretically calculated Engagement efficiency and the experimental results was approximately 2%, thereby confirming the feasibility of the friction coefficient calculation model.

Study on Lateral Distribution Coefficients of Hollow Slab Bridges After Reinforced by Pasted Steel Plates

This paper adopts a new method of pasting steel plate to restore the transverse connection of hollow slab bridge, so that the strengthened bridge can meet the requirements under the state of serviceability. The original beam of the concrete hollow slab with a span of 8m from the Suizhong to Shenyang section of Jing-Shen highway was reinforced by a method of pasting steel plates. In the test the eccentric load condition was loaded and the abaqus software was used for numerical calculation after the reinforcement. Based on the theory of load transverse distribution coefficient of bridge structure, different calculation methods were used to obtain the transverse load distribution coefficient of the strengthened test beam, and it is verified that the hinged plate method can be used to calculate the hollow slab beam strengthened with steel plate. In addition, combined with previous calculations, test results and numerical analysis, this paper discusses the restoration effect of the new type of pasted steel plate reinforcement method on the bridge lateral connection. The results show that the hinged plate method can be used to calculate the load lateral distribution coefficient of hollow slab beams strengthened by pasted steel plates. therefore, the pasted steel plate reinforcement method can effectively restore the horizontal connection between the hollow slabs and meet the use of bridge structures.

Effect of structural parameters and load states on PTRB’s load distribution

The planetary thread roller bearing (PTRB), as a new type of ball bearing, has the advantages of high-power density, no need to be used in pairs or combinations, and the ability to carry axial-radial combined load and bidirectional axial load. Its load distribution characteristics serve as the basis for building PTRB’s performance models, such as dynamic load rating, static load rating, and friction torque. In this paper, PTRB’s structure and the transmission paths of force were briefly introduced, and the elastic deformation of the threaded roller, inner ring, and outer ring was analyzed on the basis of the Hertz theory and Hooke’s law. Next, the methods for calculating the compressive deformation of shaft when PTRB was under different load states were presented. In view of the nonlinear relation between force and elastic deformation as well as the compatibility equation, the theoretical model of PTRB’s load distribution was set up accordingly. There was a discrepancy between the variation trends and values of load distribution under four axial load states, with a larger load distribution coefficient at the contact point closer to the flange. With the increase of load from 10 to 30 kN, the increase rates of the axial and radial load distribution coefficients were ≯1.2%, so that the load distribution coefficient could be approximately deemed as an inherent characteristic of PTRB. Within the value range of each structural parameter, the variation of the pitch diameter of threaded roller had the most significant effect on axial load distribution coefficient, with a variation rate of 7%; the variation of the number of threaded rollers had a significant effect on radial load distribution coefficient, with a variation rate of 37%; the variation of the remaining structural parameters had a minimal effect on load distribution coefficient, with a variation rate of ≯3%. When a follow-up optimization design is conducted on the performance of PTRB with a fixed dimension, and the contact angle, number of thread teeth per roller, and pitch diameter of threaded roller are deemed as design variables, the load distribution coefficient can be set as a constant value, and the number of threaded rollers can be set as the maximum value to simplify the optimization design process of PTRB’s performance and improve the optimization design efficiency.

Study on Dimensionless Mid-tower Stiffness of Three-Tower Self-Anchored Suspension Bridges Based on an Analytical Approach

Different from the earth-anchored suspension bridges, both the main cable and the stiffening girder significantly contribute to the stiffness of self-anchored suspension bridges. Meanwhile, the mid-tower effect is also non-negligible when extending the traditional self-anchored suspension bridges to the multi-tower system. This study derives a load distribution coefficient to include the coupling effect between the main cable and girder based on displacement compatibility conditions. The load distribution coefficient determines the live-load deflection of the girder and the cable forces on both sides of the mid-tower, corresponding to the lower and upper bound of the mid-tower stiffness. This study also proposed an analytical approach to determine the feasible dimensionless range of the mid-tower stiffness for three-tower self-anchored suspension bridges. The nonlinear finite element method is utilized to validate the accuracy of the analytical model, and a parametric analysis is carried out to examine the effects of different parameters, including the live-load ratio suffered by the main cable, the geometric and loading parameters, the cable-girder connections, and the tower-girder connections, on the range of dimensionless mid-tower stiffness. The results demonstrate that the feasible stiffness range of mid-tower depends on more parameters, including the live-load ratio supported by the main cable, the dead-to-live load ratio, the sag-to-span ratio, and the cable-girder connections, compared with three-tower earth-anchored suspension bridges.

Research on Multiobjective Optimization Design of Meshing Performance and Dynamic Characteristics of Herringbone Gear Pair Under 3D Modification

Abstract Herringbone gear transmission system is widely used in high-speed overloaded fields such as ships. Tooth deformation and installation error, which can cause meshing impact, load mutation, and load uneven, will seriously affect dynamic performance of the whole transmission system. Modification technology is the most effective way to achieve damping and noise reduction. In this article, we propose a three-dimensional (3D) modified tooth surface by grinding wheel along axial to the spiral rise and along radial to the parabolic movement based on the grinding principle and a multiobjective ant lion optimizer model for optimizing meshing performance and dynamic characteristics of herringbone gear transmission system and analyze the impact of optimized modifications of tooth profile, axial, and three dimension on meshing performance, loaded transmission error, load distribution coefficient and meshing impact, meshing stiffness, and vibration acceleration by the example. The results show that the 3D modification of optimization can not only eliminate the contact between the tooth side edge and tooth top edge but also eliminate the influence of installation error on contact performance. The root mean square values of the relative comprehensive vibration acceleration of tooth profile modification, axial modification, and 3D modification are reduced by 30.11%, 49.24%, and 61.41% compared with the standard, respectively. The 3D modification can greatly reduce tooth vibration, reduce resonance peak, and achieve the goal of noise reduction.

TRACTION QUALITIES OF THE DRIVING WHEELS WHEN ROLLING THEM ALONG ONE TRACK

During rectilinear motion of a wheeled tractor on a deformable surface, its rear wheels move along the track formed by the front ones. The amount of soil compaction can be different depending on its physical and mechanical properties, the dimensions of the front wheels of the tractor, the weight load falling on the front axle, and the like. Accordingly, the traction abilities of the rear drive wheels will also be different. This circumstance should be taken into account when designing wheeled tractors, especially tractor-tractors with two driving axles, in which a change in any of the factors listed above, for example, the distribution of the load along the axles, affects not only the compaction of the surface on which the rear wheels move, but and on the traction qualities of the front. In the course of the research, it was found that with a decrease in the load distribution coefficient below 0.5, the role of the rear wheel, which is capable of developing a greater traction force than the front wheel at the same load, in the formation of the total traction force, decreases. Therefore, the total traction force of the driving wheels becomes lower. With an increase in this coefficient above 0.5, the amount of preliminary soil compaction by the front wheel decreases; as a result, the ability of the rear wheel to develop more traction than the front wheel under the same load is reduced. The greatest traction force of two driving wheels moving along the same track is achieved with the same weight loads. Thus, the position of the center of gravity of a tractor with four driving wheels of the same size should be chosen in such a way that the load on the front and rear wheels is equalized at the rated pull on the hook. When conducting research on a field prepared for sowing, with an active semi-trailer with different load distribution between the rear axle of the tractor and the axle of the semi-trailer, it was found that the center of gravity of the active semi-trailer can be selected in the same way as for the inactive one, i.e. taking into account the influence of the semi-trailer on traction performance. The dependences obtained in the work make it possible to analyze the traction qualities of several driving wheels when they roll along one track. With their help, it is possible to identify the effect of surface compaction on the traction qualities of the rear moving front wheels; the influence of load distribution along the axles of the driving wheels on their total traction force, etc.

Effect of Load Distribution Coefficient on Three-Tower Cable-Stayed Bridge with Crossing Cables

Effect of Load Distribution Coefficient on Three-Tower Cable-Stayed Bridge with Crossing Cables

Modeling of contact load distribution of planetary threaded roller bearing based on deformation coordination

Planetary threaded roller bearing (PTRB) mainly consists of an outer ring, an inner ring, and rollers and all these parts have multiple annular threads. The PTRB is used in heavy loading linear transmission mechanisms because of its high-power density. It has been designed mainly to bear the axial load, and its load carrying capacity is determined by the contact load distribution characteristics of the threads in the axial direction. In this study, axial static stiffness model of the PTRB was developed to obtain the deformation of threaded teeth, threaded contact zone, and shaft sections. Based on the coordination of the above-mentioned deformations, contact load distribution of PTRB was calculated. Moreover, the contact load distribution coefficient was proposed to evaluate the distribution regularity of contact load. The validity of the proposed mathematical model was verified by the results of finite element simulation. Finally, the effects of external load, pitch, and number of threaded teeth on the contact load distribution regularity were analyzed.

Load balancing strategy in software defined network by improved whale optimization algorithm

From the recent study, it is observed that even though cloud computing grants the greatest performance in the case of storage, computing, and networking services, the Internet of Things (IoT) still suffers from high processing latency, awareness of location, and least mobility support. To address these issues, this paper integrates fog computing and Software-Defined Networking (SDN). Importantly, fog computing does the extension of computing and storing to the network edge that could minimize the latency along with mobility support. Further, this paper aims to incorporate a new optimization strategy to address the “Load balancing” problem in terms of latency minimization. A new Thresholded-Whale Optimization Algorithm (T-WOA) is introduced for the optimal selection of load distribution coefficient (time allocation for doing a task). Finally, the performance of the proposed model is compared with other conventional models concerning latency. The simulation results prove that the SDN based T-WOA algorithm could efficiently minimize the latency and improve the Quality of Service (QoS) in Software Defined Cloud/Fog architecture.

Load distribution factor along the power transmission lines as a factor in choosing a voltage class

Gas fields differ from industrial enterprises by long power transmission lines with low electrical loads (low density), which grow many times during the life cycle. Power supply to gas well clusters is carried out according to the scheme - “main circuit with one through line with transformer substations distributed along the line”. The distribution of transformer substations along the transmission line affects the voltage loss, and, consequently, the choice of voltage class. The purpose of the research is to quantify the distribution of transformer substations along the power line to develop a mathematical model for calculating the optimal voltage class. To achieve this goal, the following tasks are solved: five power supply schemes are built for gas well clusters; electric moments are calculated for each scheme; the load distribution coefficient is determined. The problems were solved using an experimental-theoretical method (analysis and synthesis) and a software product – Mathcad. As a result, the coefficient is calculated in the work - for even load distribution, when placing the entire load at the end of the line and when placing the load at the beginning of the line.

Load Distribution Coefficient of Node of Lattice Beam Based on Two-Parameter Elastic Foundation Model

According to the force characteristic of lattice beam, used the Two-parameter elastic foundation model to deduce the answer of internal forces of concentrated force on the finite-length beam, and calculate load distribution coefficient of node, then get the internal forces of lattice beam, used the analytical solution combined with practical engineering, and compared with numerical solution of simulation of ABAQUS finite element software, to verify the correctness of theoretical solution, and analyze its deficiency.

Parametric Design on Solving the Maximum Deformation of Traction Helical Gear on Locomotive

The helical gear for locomotive traction has a popular application in the locomotive transmission system due to its excellent transmission performance. The maximum amount of deformation needs to be taken into consideration when performing the tooth profile modification on helical gear. The tooth profile design and corresponding calculation process tend to be tedious since the variation of the contact ratio of gear might lead to the change of logarithm in meshing tooth. In this paper, starting from the effect of the contact ratio on the logarithm of meshing teeth, the mesh-stiffness of helical gear can be solved by cross-section deformation formula based on the similarity of helical gear and spur gear. And then the general calculation formula governing the variation on the length of contact line is derived regarding the moment when gear tooth just engages. On the basis of actual production requirements, the solution equation for inter-tooth load distribution coefficient is derived. As a result, the general mathematical model for maximum deformation of helical gear which can perform parameterized calculation is established. The theory provides a significant theoretical guide in the field of tooth profile modification on locomotive traction helical gear.

Performance optimization for a novel combined cooling, heating and power-organic Rankine cycle system with improved following electric load strategy based on different objectives

In this paper, a novel combined cooling, heating and power-organic Rankine cycle system is proposed. The purpose of the system is to enrich the approach of energy cascade utilization by using different grades of waste heat flexibly. In addition, an improved following electric load strategy for the system is introduced, which could control the prime mover and organic Rankine cycle to share electric demand. To explore the optimization potential of the system under the new strategy, several configuration parameters and operation parameters are synergistically optimized by using enumeration method. Herein, the optimization variables are rated capacity of prime mover, exhaust smoke temperature, exhaust smoke distribution coefficient and cooling load distribution coefficient. The optimization objectives are annual total cost saving, primary energy consumption saving, carbon dioxide emission reduction and comprehensive benefit. The results indicate that the optimal values of above objectives are 38.11%, 21.05%, 47.61% and 35.38%, respectively. Moreover, the variable characteristics, the system performance indexes and the energy dispatch for different objectives are compared and analyzed. To enhance the system flexibility, the variables are further optimized according to the load characteristics of different seasons by using genetic algorithm. The results show that the optimal values of above objectives are further increased by 4.8%, 10.7%, 3.7% and 5.9% respectively. The change of exhaust smoke temperature is conducive to improve the heat utilization efficiency in winter. These findings could promote the sustainable development of the integrated system.

Research on Meshing Characteristics of Shearer Walking Wheel Based on Rigid-Flexible Coupling

Frequent failure of the walking wheel seriously restricts the performance of the whole shearer. To reduce the failure rate and improve the working performance of the walking wheel, the meshing characteristics of the tooth pin are researched. The dynamic state equations of the walking wheel and the contact force model of tooth pin meshing are established. The rigid-flexible coupling simulation model of tooth pin meshing is built. The load distribution characteristics of the walking wheel are analyzed, as well as the effects of impact load amplitude and duration. Results show that the curve of the longitudinal load distribution coefficient (Kβ) of the contact area is W-shaped, with a maximum of 1.325 at the moment of a single tooth contact. The end of the transition curve is the most serious position of the longitudinal load imbalance at the tooth root. In addition, on the impact moment,Kβtends to decrease and maximum stress obviously increases with the increase in impact load under 40%; the material at the contact position will fail under an extra 39% instantaneous impact load. Furthermore, with the impact load of 30%, the influence of load impact duration under 0.5 s on the meshing characteristics of the walking wheel is relatively faint. The results provide some guidance for the design optimization of the walking wheel and provide a reference for improving the reliability of the shearer.

Simulation of power supply systems with external faults and methods for increase of residual voltage at terminals of power receivers

The article discusses the effect of the remoteness of the place of a three-phase short circuit on the depth of the voltage dip depending on the load on the synchronous generators and synchronous motors. A series of experiments was carried out where the length of the 110 kV overhead power line varies, at the end of which a short circuit occurs, as well as the load distribution coefficient of a synchronous machine with higher than normal field-forcing ratio and the influence of these parameters on the level of residual voltage among large industrial consumers. The efficiency of using synchronous machines with a higher than normal field-forcing ratio of the excitation is estimated, and their stability under a sharp increase in loads, which cause voltage changes during the transition process and cause rotor vibrations, accompanied by magnetic losses due to the occurrence of eddy currents in the rotor core, is considered. The results of simulation presented in the Simulink are a MATLAB-based graphical programming environment for modeling, simulating and analyzing multi-domain dynamical systems.