Power Transmission Components Research Articles

Microstructure and tribological properties of solid lubricant-doped CMT-WAAMed Stellite deposits

AbstractA large share of the world’s total energy consumption is used to overcome friction. Therefore, low friction wear-resistant materials are needed. Solid lubricants are solid-phase materials that can reduce friction at different temperatures between two surfaces sliding against each other without the need for a grease or liquid oil medium. In this study, Cold Metal Transfer Wire Arc Additive Manufacturing (CMT-WAAM) was used to deposit solid lubricant (WS2, MoS2, CaF2) doped hypoeutectic Stellite alloy. Fabricated deposits possessed crack- and pore-free microstructures consisting of γ-Co and M7C3 carbide eutectics embedded with chromium sulfides and microhardness values of ~ 530 HV1. They were also tested in self-mated unidirectional sliding wear tests in dry conditions at room temperature (RT) and at 300 °C in an air atmosphere. The results showed that the dynamic coefficient of friction (COF) decreased ~ 27% at RT and ~ 21% at 300 °C without losing the wear properties. During sliding wear tests severe strain hardening occurred and γ-Co was found to transform to ε-Co. The developed deposits can be used as hard facings or 3D printed components in applications that require good sliding wear properties at different temperatures such as metal forming tools, power transmission components, valves, and internal parts of combustion engines.

Thermal and thermochemical treatments against fretting failure applied to power transmissions

Some power transmission components are subject to the fretting corrosion failure mode, which results in rapid wear of mating surfaces or premature fatigue crack initiation. Fretting corrosion is generated by micro-movements of surfaces in contact. In mechanical transmissions, it is found in particular on shrink-fit connections (bearing rings, for example) and on key and spline connections when they are misaligned or not with the well design fit.The sectoral board for mechanical transmissions and rolling bearings and CETIM is investigating the potential of technical solutions (materials, heat treatment, lubrication, etc.) to prevent fretting. This article presents a study of the impact of thermal and thermochemical heat treatments of steels used in power transmissions on the appearance, morphology and intensity of corrosion fretting.Among the materials and heat treatments commonly used in mechanical transmissions (NF EN 683, ISO 6336-5), the following variants were studied: through-hardened steels (42CrMo4, 100Cr6), surface-hardened steels (42CrMo4), case-hardened steels (20MnCr5) and nitrided steels (42CrMo4). These variants are compared using a standardized ASTM G204 test, which involves oscillating a pressurized, lubricant-free pin (100Cr6) on a plate (the tested variant) for 24 hours. The peak-to-peal slip amplitude range is set at 50µm or 100µm. Tangential forces during testing, then the volume loss of pin and plate after testing, were measured, analysed and compared. The experimental study reveals wear resistance and depend on heat and thermochemical treatment as well as slip amplitudes. Through hardened 100Cr6 has better fretting resistance than nitrided 42CrMo4 for 50µm amplitude, but the results are completely reversed at 100µm amplitude.

High-performance laser power converts for wireless information transmission applications.

Laser Power Converters (LPCs) are components of the laser wireless power transmission (LWPT) system receiving laser power. This paper proposes a comprehensive test method that employs continuous, pulse-pause, and short-time techniques to evaluate the performance of six-junction GaAs LPCs operating with an optical input at 808 nm. Additionally, we investigate the performance of LPCs with different areas and achieve a conversion efficiency over 60%. Furthermore, we apply LPCs with varying areas to wireless information transmission and successfully achieve a response time of 1.7 µs.

A periodic anomaly detection framework based on matrix profile for condition monitoring of planetary gearboxes

As the core power transmission component of mechanical equipment, planetary gearboxes unavoidably experience faults due to harsh working environments and continuously heavy loads. Therefore, to ensure safe operation of the equipment and reduction of maintenance costs, condition monitoring of planetary gearboxes is critical. Anomaly detection provides a potential approach to overcome the limitations of traditional signal processing technologies and deep learning methods. However, since the monitoring signal of planetary gearboxes contains various harmonics and periodic impulses, current unsupervised anomaly detection methods are difficult to achieve a satisfactory result for the monitoring signal. To overcome the above problem, a novel periodic anomaly detection framework is put forward for planetary gearboxes condition monitoring based on matrix profile (MP). In this work, a periodic anomaly detection method, namely matrix profile guided multiple residuals average (MPGMRA), is first introduced to detect periodic impulses caused by the local damage. Then, to better extract the weak periodic impulses, an adaptive parameter selection strategy based on impulse-to-noise ratio (INR) is proposed. At last, both simulated signal and experimental data from a planetary gearbox are analyzed to demonstrate the applicability of the proposed framework, and the correlation kurtosis (CK) is introduced to evaluate the magnitude of the periodic fault component. The results manifest that this framework is able to recognize the condition of planetary gearboxes successfully and the performance based on CK can be improved by 5.4 times.

Prestress Modal Analysis under Assembling Error of Diaphragm Disc Coupling

The high-speed and high-torque diaphragm disc coupling used in coal machine-driven systems is the critical power transmission component, especially in high-speed and heavy-duty shafting. The dynamic rotor characteristics are significant. In the case of external excitation in the installation or working process of diaphragm coupling, it is inevitable to have axial deviation, angular misalignment, and radial misalignment error. Therefore, analyzing the prestress mode under the assembly error of diaphragm disc coupling is crucial. The finite element model of diaphragm plate coupling was established using ABAQUS software. The accessible way under critical speed, the mode under axial dislocation, and radial dislocation were analyzed. The results show that the assembly error of the diaphragm disc coupling will affect the first and second-order natural frequencies in a specific range but will not cause resonance.

Power transformer oil temperature prediction based on empirical mode decomposition-bidirectional long short-term memory

Power transformers are crucial components of power transmission and transformation networks. Their operational status has a direct impact on the reliability of power supply systems. As such, the security and stability of power systems depend heavily on the state of transformers within them. The oil temperature of a transformer is a critical indicator of its working condition. Accurately and rapidly predicting transformer oil temperature is therefore of significant practical importance for ensuring the safe and effective operation of power systems. To address this prediction problem, this article proposes a transformer oil temperature prediction method based on empirical mode decomposition-bidirectional long short-term memory (EMD-BiLSTM). The time series of oil temperature is first cleaned before being processed. Next, the EMD algorithm is used to decompose the time series into relatively stable components. The BiLSTM neural network is then utilized to predict the complex nonlinear long-term series. The proposed method is evaluated using the open data set Electricity Transformer Temperature (ETT)-small. Experimental results show that the EMD-BiLSTM model outperforms traditional LSTM, BiLSTM, EMD-BP, and Wavelet Transform-Bidirectional Long Short-Term Memory (WT-BiLSTM) methods, demonstrating that it is an effective and accurate prediction method for transformer oil temperature.

FEA modelling and environmental assessment of a thin-walled composite drive shaft

Fibre reinforced plastics (FRP) composites have been widely used in the automotive industry with the primary focus on reduced mass. However, there are relatively few reports on their application on power transmission components, such as drive shafts. This paper explores the feasibility of replacing the traditional structural steel by light weight FRP composites in a drive shaft. Three FRP composites are considered against a steel drive shaft; basalt/epoxy, carbon/epoxy, and CNT (carbon nanotubes) reinforced carbon/epoxy composites. The mechanical performance was analysed by finite element analysis (FEA) tool and classical laminate theory (CLT), while the environmental performance was evaluated by life cycle assessment (LCA) method. The study shows that with careful design a composite drive shaft can outperform the mechanical performance of a steel shaft (up to 90% mass saving, and 50% higher Factor of Safety). The study found steel shafts were preferable to FRP shafts based on embodied energy (steel total embodied energy 150MJ, FRP +325MJ). Reductions in carbon footprint from reduced emissions due to weight savings meant a carbon/epoxy shaft was preferable to a steel shaft. Two new material indices were suggested which can be used to select materials based on minimum embodied energy and global warming potential.

Health Index Analysis of Transmission System Components

Optimizing maintenance strategies for power transmission components is crucial to prevent failure in the system while maintaining and enhancing the overall economic efficiency. Condition-based maintenance can fulfill this and in the present paper health index-based efficient condition assessment is applied as an essential input to this type of maintenance. A method for the calculation of the health index of primary transmission system components is presented and discussed. Condition-based assessment is utilized for developing a calculation method for evaluating the health index at different levels in the system. The health index of each component is calculated by using the Weighting and Scoring Method. Several factors affecting the condition of different equipment are considered in the algorithm including environmental effects, mechanical stress, and accessibility issues. The special focus is on assigning a numeric value to the health of individual sub-components of the equipment to plan the condition-based predictive maintenance of power system components. The data indicate that in contrast to considering the health index of the entire system, making decisions considering the individual componet health indices can result in a more reliable operation.

Renewable Energy Technologies in the Global South: Sub-Saharan Africa Trends and Perspectives

Sub Saharan Africa (SSA) and other parts of the Global South are richly endowed with renewable energy resources (RERs) that are grossly untapped. The integration of these resources, such as hydro, wind, solar, and biomass will facilitate the desired net zero-CO2-emissions economy. If these RERs are adequately harnessed, the perennial power supply challenges in the region will be resolved, and the negative power supply narrative changed. Presently, a greater percentage of the population without access to electricity live in the Global South with SSA having the highest share. This inadequacy has been attributed to many factors, which include lack of connection to the national grid; lack of adequate technical capacities to design and manufacture efficient power generation and transmission components and systems; insufficient funds; unreliable, limited, and poor energy data. A comprehensive study of the renewable energy potential (REP) and technologies in the Global South is imperative to the management, regulation, and policies concerning energy, in this era of energy transition (ET). This study presents - a summary of REP of SSA; statistical analysis of the proposed and installed RE capacity across the region; and discussion on the pressing need for renewable energy integration (REI) to mitigate climate change. In addition, to develop RE schemes to facilitate greater access to clean, affordable, and adequate energy supply. Actualization of the integration of RERs into the national portfolio will promote CO2 reduction and improve the socio-economic benefits to the populace in both rural and urban areas of SSA and the Global South generally. Keywords— Renewable energy system; Net-zero-CO2 emissions, renewable energy in Global South; hydro; wind; solar; biomass

Contactless Mechanical Power Transmission Through the High-T c Superconducting Pinning Effect.

Mechanical power transmission (MPT) components are almost indispensable for every engineering equipment with motions. In order to satisfy some rigorous requirements, such as contamination free and zero leakage in the mixing process of biomedical solutions, a contactless MPT mode was proposed in this study based on the high-Tc superconducting flux pinning mechanism. It makes the stirring container with the driven part inside that can be totally isolated from the external environment. The physical principle of superconducting flux pinning effect was discussed firstly to explore a feasible structural scheme, which can completely restrain all the six degrees of freedom (DOFs) by the linkage of magnetic flux lines. Then, a measurement device was established to verify and investigate the proposed contactless MPT mode. The motion can be transferred synchronously from the superconducting driving part to the permanent magnet driven part since they are unified as an integrity through the pinned flux lines. The influence of driving speed, cooling clearance, and magnet arrangement on the transmitted torque was analyzed. The verified contactless MPT mode also has the advantages of self-stability and overload protection, which can avoid the drawbacks of traditional permanent magnetic transmission mode.

Investigation of cycle time behavior in the robotic grinding process

The production of power transmission components such as gears and bearing rings involves precision finishing of highly specialized and dedicated precision grinding machine tools. Six degree-of-freedom (6-dof) articulated arm industrial robots are less expensive and more versatile than precision grinding machines because they can be readily reconfigured for a variety of production tasks including precision grinding of free-form surfaces. However, the high compliance of such robots poses a challenge in high-precision operations, particularly as it relates to the overall cycle time of the process. The paper presents an analysis of the effects of robot compliance and grinding parameters on the cycle time of a precision grinding process. Specifically, a process model for robot-workpiece interaction and grinding process cycle time is developed. This model is used to analyze the behavior of a face grinding process cycle. The results show that for a given robot stiffness, minimizing the face grinding cycle time requires the process to be operated at the highest achievable wheel speed and infeed rate with a wheel of higher hardness. The paper also shows that a 6-dof robot offers the flexibility of modifying the Cartesian stiffness at the end effector by varying the robot pose, which is difficult to achieve in conventional grinding machines. This capability, along with the process cycle time model, permits optimization of process cycle times for precision grinding of surfaces, including free-form surfaces, using 6-dof robots.

Simplified and Precise Design of Crossflow Turbine Power Transmission Components

Despite the merits of small hydropower (SHP), coupled with the perennial inadequate and unreliable electricity supply in SSA, the huge SHP potential in the region is hugely untapped. This is largely attributed to the lack of adequate technical components for the development of SHP turbines, which are: technical personnel, and production facilities in the region. The hydraulic power possessed by flowing water in SHP resources can be harnessed and transformed into usable electrical energy via the deployment of a hydro turbine plant. Commonly used hydro turbines include crossflow (CFT), Pelton, Turgo, and Francis turbines. Amongst these turbines, CFT is mostly applied in low head sites and has efficiency ranging from 70–85%. The CFT power transmission subsystem is considered vital to its performance; the shaft, which transmits the generated motion to drive the alternator, is the most critical part of the CFT transmission subsystem and it requires careful design and production processes. This study centres on the development of a simplified systematic design process for power transmission shaft, pulley, and belt, to facilitate CFT power generation efficiency. .Further, the study is geared towards boosting CFT technology capacity domestically for the benefit of local production. The hydrological properties of the Ayiba SHP site in Osun state, Nigeria, were adopted for this work as a case study. The head and power for this resource are 11.8 m and 122.4 kW, respectively, and are served as the fundamental parameters for the design of the power transmission subsystem. The design computation shows that a shaft of diameter 65 mm and a D-type of V-belt with a corresponding pulley will be required to transmit the generated turbine power to the alternator. A 3-D model was created based on the design values and this was used to validate the integrity of the shaft by static stimulation. The simulation result, which is based on von Mises was satisfactory as the highest stress obtained in the shaft was 205 N/mm2; resulting in a 2.6 factor of safety.

Study on failure of transmission shaft based on finite element and fracture analysis technology

Due to the harsh driving environment, the power transmission components of military vehicles are subjected to long-term alternating loads and sudden impact loads. A failure analysis of the transmission shaft of a military truck was carried out. By constructing a mechanical simulation analysis model of the transmission shaft, the dynamic response of the structure under alternating stress and impact load is solved. Then the cause and mechanism of drive shaft failure were analyzed. Using fracture analysis technology to discuss the phenomenon of bearing sleeve cracking, circlip rupture and flange fork deformation. It indicates that caused by overload, foreign matter between the shaft and the needle etc., which ultimately leads to the failure of the universal joint transmission. Finally, the optimal design of the drive shaft is proposed.

Thermo-mechanical coupling effect on surface residual stress during ultrasonic vibration-assisted forming grinding gear

Abstract Gears are important motion and power transmission components and enhancing their machining accuracy and performance. In this work, a novel processing of ultrasonic vibration-assisted forming grinding gear (UVAFGG) is proposed, which involves the superimposition of ultrasonic vibration on the gear, and the thermo-mechanical coupling effect on surface residual stress is explored as well. Firstly, based on the local contact geometry relationship for forming grinding, the three-dimensional (3D) distribution model of the heat flux density along the tooth profile is established. In addition, the mathematical relationship models between the grinding force, grinding heat, residual stress, and grinding parameters are also given. Then, the effect of grinding parameters such as spindle speed and ultrasonic amplitude for the characteristics of residual compressive stress accumulation is obtained by comparing the single factor experimental and finite element simulation results. It is found that under the action of ultrasonic vibration, the grinding heat and grinding force reduce by 38.7% and 40.5 % and 40.5 %, respectively. The surface residual compressive stress gradually decreases with the increase in spindle speed, while with the increase in ultrasonic amplitude, it increases first and then decrease. Comparing with the conventional grinding gear (CGG), the average rate of increase of the surface residual compressive stress under the both parameters is 17.8 %–31.3 % and 20 % respectively. Meanwhile, the residual compressive stress along involute shows a negative correlation with the increase in the rolling angle. At the same time, the experimental and simulation results agree well with the theoretical model. In conclusion, the results of this study provide a novel process technology for gear machining, and a reference for the investigation on residual stress during UVAFGG.

Critical fault diagnosis method of small components of power transmission based on optimizational YOLOv3 algorithm

In order to solve the problem that the image recognition algorithm in UAV (Unmanned Aerial Vehicle) inspection of power transmission has low recognition rate for small, indiscoverable and high-risk component failures, this paper proposes a critical fault diagnosis method based on the optimizational YOLOv3 algorithm. We add SPP net under the basic framework of the original YOLOv3 and extract multi-scale depth features in the same convolutional layer which can transform all the input images into a uniform size and solve the problem caused by different input image sizes and formats. An optimizational scale prediction framework of YOLOv3 is proposed, which expands the original three-scale prediction frameworks to four scales and carries out multi-scale integration. This improvement is used to strengthen the feature extraction of small and indiscoverable fault. The optimizational algorithm is verified by using the dataset of electrical components of transmission system in the actual scene which have small and indiscoverable faults. The results show that the optimizational YOLOv3 improves the recognition rate of the selected categories by 3.98% on average, and increases the recognition rate of the small size and indiscoverable fault by 11.95% on average.

Seismic performance evaluation of 72.5 kV GIS for design verification (I) - Seismic test

Gas insulated switchgear (GIS) is one of the key components of power transmission and distribution (T&D) systems for providing stable electrical power. Even in the event of a disaster such as an earthquake, the electrical power system should maintain structural safety without losing inherent function. In this study, seismic performance evaluation for 72.5 kV high voltage GIS was conducted using the analysis method. As the first step, a seismic analysis for 1 bay of GIS was done and the analysis model was updated by comparing with the test data like natural frequencies, acceleration and stress. Next step, a seismic analysis of whole GIS of the substation was conducted for seismic performance evaluation according to the IEEE standard. The calculated stress from the analysis compared with the allowable stress and the analysis was repeated until satisfying the criteria after changing the design. Several design changes were made during this process. As a result, the seismic performance of this 72.5 kV GIS of the substation was certified according to IEEE Std. 693-2005.

Design and Implementation of Gsm Enabled Remote Sensor for Monitoring Power Transformer Operation

Transformer is one of the most vital components of power transmission and distribution infrastructure. In a developing country such as Nigeria, majority of the growing population of the people are still grappling with gross inadequate and epileptic power supply. Only about 4000MW of electricity is available for distribution (by load shedding) due to decay in existing infrastructure. The aim of this work is to apply modern technology to prevent further decay of the equipments particularly the transformer which is very expensive. This article involves the design and implementation of a device to monitor and detect the operating condition of a transformer with emphasis on power distribution transformers. A module embedded Global System for Mobile communication (GSM) enabled device is designed to monitor load currents and temperature, using a micro-controller and sensor. The monitored values are processed and recorded in the system memory which is programmed with some predefined instructions to detect any abnormal working condition of the transformer so that the GSM module can send a Small Message Signal (SMS) to designated mobile telephones containing information about the fault, base on the programmed instructions into the micro-controller. This will help the power distribution company respond swiftly to abnormalities that may lead to catastrophic failures and subsequent system short down. It is a fully automated device capable of reducing the risk of transportation and human errors associated with manual transformer inspection and testing. The device was tested and it responded very well to fulfill the set objectives.

Design of an Effective Double-Rotor Machine With Robust Mechanical Structure

Power split system is the key power transmission component in hybrid electric vehicles (HEVs). This paper presents a new consequent-pole inserted permanent magnet (PM) double-rotor machine., which is suitable as the power split system for HEV. The key is to insert the interior radical magnetized PM with the same polarity into the rotor's iron core., so the mechanical structure of the proposed machine is more robust. Also., the working principle is analyzed., and the structure is optimized. In addition., the performances of the conventional machine and proposed type are quantitatively compared. The result shows that proposed machine has more advantages to be applied for the power split system in HEVs.

Assessment of Possessed Generic Green Skills for Green Jobs of Electrical Installation and Maintenance Work Graduates of Technical Colleges in Nigeria

The purpose of this study is to uncover employers’ assessment of possessed generic green skills for green jobs of electrical installation and maintenance work graduates of technical college in Nigeria. The study used 120 out of 140 employers of technical College Graduates in Adamawa State. The instrument used for the data collection was a questionnaire. Mean and standard deviation were used to analyze research data. The hypothesis was tested at 0.05 level of significance. The findings reveal that, in the rewinding of electrical machines modules of electrical installation and maintenance work, technical college graduates have adequate skills to work in the industry except in few areas like: conduct of preventive maintenance and testing faults in electrical filing machines’ winding, the ability to locate faults in electrical filing machines’ winding, carrying out insulation resistance test, interpreting drawings of electrical equipment where they showed averagely adequate and slightly adequate skills. Similarly, from the data obtained and analyzed, the result indicates that the graduates have adequate skills in industrial installation except in few areas like: Ability to handle power transmission equipment and components, maintain simple power tools, to test simple power tools, to interpret drawings of electrical equipment, to read symbols. Therefore, the researchers concluded that technical college graduates have adequate technical skills for green jobs and to work in the industries.

Failure mode analysis of a 1.9 turbo diesel engine crankshaft

This paper reports a failure mode analysis of a 1900 cm3 turbo diesel engine of a well-known commercial brand. The engine is a supercharged diesel engine with turbocharger, producing a maximum power of 81 kW; it was produced in 1999 and collapsed at 120,000 km without warning. A fracture occurred at the crankpin n°1 of the crankshaft in the region of web-fillet. Crankshafts are mechanical power transmission components with complex geometries and experience multiaxial stress states in main journals and crankpins. The objective of this work is to determine the root cause that led to the crankshaft collapse. A fractographic, metallographic, and numeric analysis were performed to understand the crankshaft failure mode and its mechanical mechanisms. Results show that the crankshaft failure resulted from a fatigue process governed by normal stresses raised by two possible processes, namely, a notch in the crack initiation spot, or the crankshaft misalignment.