Roller Shaft Research Articles

Characteristics Comparison and Case Study of Traditional Anti-Slip Saddles and Innovative Rolling Saddles in Highway Long-Span Bridges

The cable saddle structure is the main support component for long-span bridges to transmit cable force, which is of great significance for the structural force system. Nowadays, the main cable saddle structures used in long-span bridges are mainly traditional anti-slip saddles and innovative rolling saddles. To clarify the characteristics of the saddles in long-span bridges, the design principles, mechanical properties, and casting process of these two types of saddle structures were researched. A rolling saddle in a bridge project was taken as an example and its mechanical situation in the roller area was investigated. The results showed that the stress concentration phenomenon is prone to occurring in the rolling saddle because of the line contact in the contact area and the rolling saddle is mainly subjected to vertical force. Thus, attention should be paid to the von Mises stress in the contact area between the saddle base and the roller shaft, the lower surfaces of both ends of the roller shaft, and the top surface of the tower, to avoid material damage. Furthermore, the casting process of the anti-slip saddle structure is mature, but also faced with problems due to the welding of thick plates, and urgently needs to be improved and upgraded. The rolling saddle is used with the all-welded casting process, but its technology is relatively immature and the requirements for the roller shaft material performance are strict. The research results can provide a reference for the selection and design of the saddle structure in long-span bridges.

Experimental study on the static rolling friction coefficient of a flat-roller-flat configuration considering surface roughness

The friction-based seismic isolation technology is widely used in structural engineering. Despite the advantages and disadvantages of different types of isolated bearings, the coefficient of friction is a crucial factor that affects the seismic performance and stability of the isolation systems. In this study, a test apparatus with a flat-roller-flat configuration is developed to measure the static rolling friction coefficient (SRFC) of roller shafts. The SRFC under different conditions of normal load, material properties, geometry characteristics, and surface roughness are experimentally studied. The SRFC of the aluminum roller shafts ranges between 0.0020 and 0.0150, while that of the acrylic roller shaft ranges between 0.0028 and 0.0177, under low normal load level. The SRFCs of the roller shafts are positively correlated with the normal load and negatively correlated with their diameters. The surface roughness of the bottom plate significantly affects the SRFC. More precisely, the larger the surface roughness, the larger the SRFC. A theoretical model based on the elastic hysteresis theory is also proposed to predicted the SRFC. It is assumed that the elastic hysteresis loss coefficient (EHLC) is linearly correlated with the surface roughness of the bottom plate. Compared with the experimental results, the values predicted theoretically are within the error of 25 % for 85 % cases.

Синтез механизма привода ремиз

Introduction. Domestic enterprises in various industries use a variety of process equipment, including weaving machines. Modern weaving machines have several unique features, including a close relationship between technical condition, productivity, and product quality. Weaving machines are widely used in the textile industry in Russia and other countries. To produce cotton, silk, wool, linen, and other types of fabrics, appropriate machines are designed, including shuttle, shuttleless, pneumatic, and hydraulic machines. One of the most crucial parts of the machine is the heddle lifting mechanism, which determines the weave pattern and the quality of the fabric produced. The purpose of the work is to reduce the dimensions of the loom by changing the design parameters of the heddle lifting mechanism. The research methods are based on the theory of machines and mechanisms. They enable the development of a method for synthesizing the heddle lifting mechanism and designing a device with reduced dimensions. The paper presents the synthesis and analysis of the Assur group algorithm, which can determine the kinematic characteristics of the mechanism. Results and discussion. Following the proposed methodology, the mechanism design was modified by removing the fixing device from the lever mechanism operating area. This allowed for a reduction in interaxial distances and a change in the kinematic scheme. As a result of the new position of the fixed axes, some levers, the connecting rod, and the angle of the double-arm lever were also altered. The synthesis of the mechanism is proposed to begin with the last Assur group, setting it a specific value for the G-point motion equal to 75 mm. (motion of the fourth heddle shaft). As a limitation, the equality of arcs (chords) E´E = F´F ` was accepted. By assigning these values to the input element for the second-class first-type Assur group and bearing in mind the accepted conditions, the motions for point D were obtained. Thus, the value of the swing angle  of the roller shaft equal to 22.46° was obtained, which is 27.44 mm along the chord. Applying the interpolation principle, we found the initial motion value of 28 mm. Since the loom is planned to produce interlacing fabric patterns using 10 heddles, the design provides for a variable parameter that allows changing the motion of the heddles depending on their location in the depth of the machine. This role was assigned to the lever B03D. A cam pair synthesis was performed after determining the maximum and minimum values of the center of the roller motion. In total, 5 types of laws of motion were considered: straight-line, harmonic, double harmonic, power-law, cycloidal ones. For the center of the roller, the cycloidal law of motion was selected since it better corresponds to the specified conditions. The synthesis's accuracy was confirmed by the constructed cam profile and conducted kinematic studies for the Assur groups.

Синтез схем навантаження силових елементів кулько-гвинтового гідропідсилювача з аксіальною структурою приводу

The well-known design of ball-screw hydraulic power steering is not without flaws - the bearing supports of the output shaft are the most loaded elements of the unit structure, and the elastic deformation of these supports, during operation, is the reason for the depressurization of the sealing system in this area. The purpose of the work is to determine the layout of ball-screw hydraulic power steering with a steering arm, using which it is possible to ensure the maximum beneficial effect from the use of a system of active unloading of the rolling bearings of the shaft sector, increasing the load-bearing capacity and ensuring better tightness. The study is based on the provisions of the theory of resistance of materials. The paper examines and compares the two most common configurations for the location of the steering arm's longitudinal axis relative to the cavity of the gear shaft: coaxial and perpendicular location. To achieve the goal, an analysis of the interaction system of the output shaft of the ball-screw hydraulic power steering with rolling bearings, steering arm, and rack and pinion transmission was carried out for the given two configurations. The operating conditions of the output shaft, under its load, and the reactions of the supports are described by systems of equations. For the purpose of comparative evaluation of the ratio of the reactions of the supports depending on the load and taking into account the real linear dimensions of the parts, a methodology and a number of assumptions have been developed in the work. With the help of the developed methodology, a relative comparison of the layout configurations studied in the work was carried out, taking into account the direction of rotation of the output shaft of the ball-screw hydraulic power steering with the steering arm installed. As a result of the study, the composition of the ball-screw hydraulic power steering with steering arm was determined, which allows to ensure the maximum beneficial effect of the use of the system of active unloading of the rolling bearings of the shaft sector. The use of the steering arm installation scheme, in which the longitudinal axis of the arm is located coaxially relative to the cavity of the gear shaft, creates prerequisites for the development, in the future, of an active system for unloading the rolling bearings at the points of the bearing reactions. Such a system can be implemented, for example, due to the use of hydraulics elements, thereby ensuring an increase in bearing capacity, reducing the load on the output shaft rolling support elements and reducing the impact of this load on the tightness of the unit.

Investigation of Roller Press Surface and Stud Based on FEM Simulation

As an emerging grinding equipment, roller presses are widely used in Cement industry. The current problem with roller press is that the rolls surface is prone to wear and needs to be replaced regularly. This greatly reduces the service life of the roller press and affects the development of the roller press. Therefore, how to reduce the wear on the surface of the roller press and increase the service life of the roller press is an urgent problem that needs to be solved for the current roller press. Current research mainly focuses on the mechanism research of roller press wear and the optimization of rolls surface structure. In this paper, the extrusion force between the stud-lining and the material is calculated by analyzing the stress of the studded rolls under actual working conditions and the compression and rebound characteristics of material layer. The failure modes of studded rolls are mainly divided into two parts. On the one hand, it is fatigue cracking of the roller shaft and stud-lining. On the other hand, it is cracking at the contact between the stud-lining and the stud, and the fracture of the stud. Because the failure modes of the studded rolls are divided into two parts, the studded rolls are divided into two parts for simulation by using ANSYS 18.0 . Firstly, the static analysis is carried out on the roller shaft and the stud-lining, and the distribution cloud diagram of the stress and contact pressure of the roller shaft and the stud-lining is obtained, and the stress concentration area is optimized. After optimization, the contact pressure between the roller shaft and the stud-lining is reduced by about 50%. The maximum equivalent stress of the roller shaft and stud-lining has also been reduced. Secondly, a static analysis was conducted on the stud-lining and studs. Since the stud-lining of the studded rolls are composed of stud holes arranged in a certain order. Therefore, stress concentration is prone to occur around the stud hole. The simulation experiment was carried out by changing the optimization schemes such as the assembly method of the stud and the stud-lining, the distance between the studs, and the length of the stud. To reduce the stress concentration of stud and stud-lining. After optimizing the model of the stud and stud-lining, the maximum equivalent stress of the stud-lining and stud decreased by about 10% and 25% respectively. Through the optimized design of roller shafts, stud-lining and studs. The service life of the studded rolls can be effectively improved and the production cost can be reduced. This can provide a reference for the design of the studded rolls.

Investigation on two-phase flow characteristics and oil capture performance of axial oil scoop in aero-engine

Due to the improvement in the performance of aero-engines and the continuous size reduction, efficient under-race lubrication is becoming more and more important to provide the proper amount of lubricant oil for the main shaft rolling bearings. In this paper, experimental tests and numerical simulations are conducted to investigate the two-phase flow behavior and oil capture performance of the axial oil scoop. It is found that the oil capture efficiency increases with the decrease of injection distance, while the maximum increment of oil capture efficiency is less than 1.5% within the range of 58 mm–128 mm. The measurement results show that the oil capture efficiency first rises to the maximum value of 100% with increasing rotational speed, and then keeps the maximum value constant. Adjusting the oil supply pressure difference can reduce the oil loss and improve the oil capture performance. The oil capture efficiency decreases with increasing jet angle, and the oil capture efficiency corresponding to jet angle of 15° decreases by more than 20% at the rotational speed of 15000r/min. The experimental results are used to develop a corrected discharge coefficient formula based on the rotation coefficient. The predicted results from this formula have a maximum relative error of less than 6%.

Experimental Analysis and Evaluation of Automatic Control System for Evenly Scattering Crushed Straw

In order to improve the solution to the unachieved uniformity of straw throwing, the unachieved qualified rate of coverage and the uneven straw throwing in sowing wheat without a tillage process after the rice harvest, and to change this unsatisfied quality of the straw mulch, a set of automatic control systems for straw throwing and covering was designed innovatively. An STM32 microcontroller was used as the main control unit, and the torque-acquisition system was used to collect the torque of the cutter roller shaft in real time and convert it into the conveying signal of the crushed straw. The control system changes the conveying quantity of broken straw in real time, through the dynamic response. This process realizes the optimal dynamic matching between the conveying amount of crushed straw and the impeller speed. We set up two kinds of tests: a straw-crushing-and-throwing system test bench (T6)6 with an automatic control system and a control test bench (C) without an automatic control system. T1 to T5 are, in turn, 0.85 m/s, 1.0 m/s, 1.15 m/s, 1.30 m/s and 1.45 m/s. For the C test, six test levels of 0.85 m/s (C1), 1.0 m/s (C2), 1.15 m/s (C3), 1.30 m/s (C4), 1.45 m/s (C5) and variable speed test (C6) were also set as control tests. The running time of the test-bed at each test level was 10 s; taking the throwing uniformity of the crushed straw and the rate of coverage as indexes, the rapid effect of the throwing-impeller speed on the test indexes at six levels was studied, and compared with the control test. Based on the great practical needs of this problem, this experiment innovatively realized the automatic regulation of the rotating speed of the scattering impeller at different forward speeds. Although some experimental innovations have been made in this study, the smashing knife (group) of the knife roller shaft will hit the ground during the rotation, which brings uncertainty and certain experimental errors to the real-time monitoring of the torque signals. In the next step, more sensors and intelligent algorithms will be added to the system, to reduce the knife throwing.

Development and Performance Evaluation of a Small Scale Kenaf Fibre Spinning and Reeling Machine

Abstract A developed small scale kenaf spinning and reeling machine was evaluated in this study. The machine uses the principle of the ring spinning technique to produce spun kenaf-yarn (single or double-ply). The machine component includes two 0.5 kW electric motors positioned on a 640×433×10 mm mild steel frame (with speeds of the electric motors controlled by 0.5 kW variable frequency drives), twisting spindle, inlet frustum, feed roller shaft, reeling and spinning shafts, bearings, and a bevel gear. The machine was evaluated using different spinning speeds (90, 100 and 110 rpm), reeling speeds (60, 70 and 80 rpm) and a kenaf sample (Ifeken DI 400). At the spinning and reeling speeds combination of 90 and 80 rev·min−1, the developed machine was able to produce a continuous length of kenaf yarn twisted at 95.5 turns per minute with a production speed of 0.94 m·min−1 at the highest efficiency (88.9%) of the machine. The level of twist of the spun yarn spun provides information on the required twist level for kenaf fibre as deviation from this value was discovered to cause deformation on the spun yarn. This machine was able to reduce the drudgery involved in the production of spun kenaf-yarn and the technology is expected to positively influence kenaf’s growth and utilization in Nigeria.

A Machine Vision-Based Method for Detecting Surface Hollow Defect of Hot-State Shaft in Cross Wedge Rolling

In order to solve the problems of low detection efficiency and safety of artificial surface defects in hot-state cross wedge rolling shaft production line, a machine vision-based method for detecting surface hollow defect of hot-state shafts is proposed. Firstly, by analyzing the high reflective properties of the metal shaft surface, the best lighting method was obtained. And by analyzing the image contrast between image foreground and image background, the most suitable optical filter type in image acquisition was determined. Then, Fourier Gaussian low-pass filtering method is used to remove the interference noise of rolled shafts surface in frequency domain, such as high-light, oxide skin and surface texture. Finally, by analyzing the characteristics of the surface hollow defect area, a defect identification method combining the Otsu threshold method and the adaptive threshold method is proposed to realize the effective extraction of surface hollow defect of rolled shafts. The test results show that the average recognition rate of the method based on machine vision is 95.7%. The results of this paper provide technical support to meet the production requirements of high quality and high performance of cross wedge rolling.

Design and Evaluation of a Mechanical Floor-Standing Jujube Picker

The poor adaptability of existing harvesting machinery and low work efficiency is observed due to the low-level mechanized harvesting of Xinjiang jujube orchards. A mechanical floor-standing jujube picker was designed on the basis of the characteristics of the high fruit drop of the Xinjiang jujube harvest period. The machine can pick up the jujubes, which have been manually collected into strips on the ground. The structure and working parameters of the pickup device are determined in accordance with the pickup principle. The conditions for satisfying the picking operation were analyzed, and the range of motion speed ratio parameters to meet the pickup operation was obtained. Furthermore, the contact process of jujubes on the conveying and separating device was analyzed and studied; the factors affecting the collision damage and conveying the balance of jujubes were analyzed; and the basic structural parameters of the conveying and separating devices were determined. A mechanical floor-standing jujube picker was also fabricated for trial. A three-factor and three-level Box– Behnken test was performed by taking the forward speed of the machine, the speed of the strip brush roller shaft, and the hole pitch height of the profiling rod as factors, and the pickup, breakage, and impurity rates of jujubes as indicators. Results show that when the forward speed of the machine was 0.3 m·s−1, the speed of the strip brush roller shaft was 53 rpm and the hole pitch height of the profiling rod was 60 mm. The jujube pickup rate of the machine was 92.11%, the breakage rate was 2.07%, and the impurity rate was 4.15%. The relative error with the prediction model was less than 8%. Thus, the model is reliable and meets the operational requirements. This study can provide a reference for the mechanical floor-standing jujube picker.

DEM investigation of particle flow in a vertical rice mill: Influence of particle shape and rotation speed

The obscure milling mechanism, causing by diversity of rice grain shape, restricts appropriate selection of processing conditions for improving milling quality of different varieties. On this basis, the rice grain was represented as an axi-symmetric ellipsoid using discrete element method (DEM). Effects of particle shape and roller shaft rotation speed as well as the interplay of both on axial dispersion, radial exchange, spatial orientation and collision characteristics relating to the milling mechanism were analyzed. The results indicated that effects of aspect ratio on the milling uniformity depend on rotation speed, displaying the axial dispersion coefficient and mean effective collision rate increase with increasing aspect ratio in the lower rotation speed, whereas completely opposite in the higher rotation speed. Effects of aspect ratio on the milling intensity are independent of the rotation speed, showing radial ectopia number, variance of orientation distribution and mean collision energy all increase with increasing aspect ratio.

Optimized design of the 4TSQ-2 sugar beet top cutting machine

To solve the problems faced by 4TSQ-2 sugar beet top cutting machine, i.e. large structure, high power consumption and high manufacturing cost, the multi-roller mechanism for leaves removal and fixed-thickness cutting method was studied. Using five-factor and two-level tests, the structure configuration of the leaf removal device was optimized, and the scheme of two roller shafts defoliation, the roller shaft rotation speed of 800 r/min and the forward speed of 0.8 m/s were determined. Through the working process and mechanical analysis of the top cutting device, the cutting device with the slant profiling plate structure characterized by a profiling angle of 25°-45° for the profiling plate and a cutting angle of 20°-40° was studied. With the two-factor and three-level experiments, the profiling angle of profiling plate of the top cutting device was 35°, and the cutting angle was 30°. Compared with the 4TSQ-2 sugar beet top cutting machine before optimization, the structure size of the machine was reduced by 30%, the weight was reduced by 15%, the cost was reduced by 25%, the qualified rate of top cutting wad was increased by 2.6%, and the push over rate of sugar beet was reduced by 0.5%. Besides, each index met the index requirements of beet top cutting harvest. Keywords: beet harvest, leaves cleaning, top cutting, structure, optimization DOI: 10.25165/j.ijabe.20221502.6981 Citation: Wang F Y, Zhang Z Y, Pan Y F, Yun Y L, Wang D W. Optimized design of the 4TSQ-2 sugar beet top cutting machine. Int J Agric & Biol Eng, 2022; 15(2): 111–116.

Steady State Thermal Effect on Static Characteristic of Copper Roller Shaft

The static analysis of a copper roller shaft is performed. The copper roller shaft consists of bushing, pen roll and roller. All of those components g4bconsist of different materials. Thermal steady state and statical analysis is performed in order to investigate the thermal effect of high temperature copper slab on the roller shaft. The copper slab temperature is 1200 OC. Based on this work obtained that the maximum total deformation is 0.0050523 m, maximum equivalent stress is 41600 MPa, maximum life cycle is 1011, total heat flux maximum is 879910 W/m2 and the maximum damage occur in the pen roll component.

Titanium Alloy is Best Material for Roller Shaft in Sugar Mill

In sugar industry, the sugar processing done in different sections, but to increase total crushing per day (TCD) capacity, the milling section takes a vital role in the sugar industry. The sugar industry aims to extract the maximum amount of juice from sugarcane. In the milling section, the processed sugarcane is fed in between the three-roller shaft from the different arrangements, there are different loads applied on each part roller shafts. When load between all rollers varies then there is a chance of bending it is analyzed to check the roller shaft condition. The modeling is done on roller shaft with the help of CATIA V5. After modeling, we analyze the condition of the rollers, when different stress or forces are applied to different sections of the roller shaft it analyzed with the help of Finite element method using ANSYS WORKBENCH software. We were selecting titanium alloy materials for the roller shaft to analyze the variation in results. When comparing the calculated and software-based results using Maximum Shear stress and Total deformation for top, feed, and discharge rollers said the roller shafts are safe to use in the sugar industry and titanium alloy is the best material for these roller shafts.

The DESIGN OF A TRANSMISSION SYSTEM ON A BALL MILL MACHINE TO PROCESS HOMOGENIZATION OF BLACK POWDER USING AN AUTOMATIC SYSTEM

Abstract: In the military world, battle technology has experienced very rapid development, both close-range combat and long-range combat. In long-distance combat the technology that is often used is rocket technology where this rocket technology can paralyze the enemy in large numbers. Black powder is a mixture of potassium nitrate (KNO3), carbon powder (C) and sulfur (S). (Evie Lestariana, LAPAN). The black powder itself functions as an igniter filling material for the propellant combustion process. This research is to design a tool to support the manufacture of black powder in the igniter filling to help the combustion of rockets, especially those owned by the Indonesian Army. This study uses an experimental method using empirical calculations to get a tool with the desired specifications. Before carrying out the calculations, the author collects research data to carry out calculations, the data collected are as follows: 1. Roller shaft rotation: 246 rpm, 2. Roller shaft torque: 4.0697 Nm, 3. Roller shaft diameter: 25 mm, 4. Pulley shaft diameter top: 100mm. The results obtained after carrying out the calculations are the diameter of the driving pulley 98 mm, the belt contact angle against the pulley 174.6º, and the length of the V-belt 453.14 mm, moment of inertia on the gearbox output shaft 1884,8 mm4.

Optimization Design of Extrusion Roller of RP1814 Roller Press Based on ANSYS Workbench

Firstly, the force of an extrusion roller under actual working condition was analyzed while the contact stress between the roller shaft and the roller sleeve and the extrusion force between the roller sleeve and the material were calculated. Secondly, static analysis of the extrusion roller was carried out using ANSYS software, and conclusively, the stress concentration appears at the roller sleeve’s inner ring step. Furthermore, an optimization scheme of the setting transition arc at the step of the contact surface between roller shaft and roller sleeve was proposed, and a simulation test was carried out., Finally, the maximum equivalent stress of the extrusion roller was set at the minimum value of the objective function; the extrusion roller was further optimized by using the direct optimization module in ANSYS Workbench. The results from optimization show that the maximum equivalent stress is reduced by 29% and the maximum deformation is decreased by 28%. It can be seen that the optimization scheme meets the strength and deformation requirements of the extrusion roller design. The optimization scheme can effectively improve the bearing capacity of the extrusion roller and reduce its production cost. This can provide a reference for the design of the roller press.

Research of seeding fulfilled with the help of stud-roller feed

This article is dedicated to increasing the quality of grain seeds distribution in a row using various parameters of the stud roller with new studs bent off to the side rotation, and also contains the results of theoretical and experimental investigations. In the frames of this investigation the optimal parameters of experimental seed wheel were defined, the factors influencing seed feed were identified, the formula of full working volume of seeds, thrown out by feeding mechanism per one rotation of roller, was generated, the following dependencies were detected: dependence of seed feed on quantity of roller studs, seed feed - on frequency of roller shaft rotation and seed feed - on degree of valve opening. The usage of the suggested seed-feeding device will help to reduce traumatization of seeds and pulsation of its flow, to increase equal distribution of seeds in the row.

“Design and Development of Tractor Drawn Subsurface Manure and Seed Applicator”

Organic farming is now recognized as the best known alternative to the conventional agriculture, where cultivation and raising of crops and best quality of food is grown without any harm to the soil health, environmental and to the human being and microorganism present in the soil. Efficient organic nutrient supply to plant in adequate quantities to sustain most plant growth and yield while minimizing the environmental affected by the use of large quantities of inorganic fertilizers and pesticides which reduces the soil characteristics and productivity. Vermicom post is the major alternatives for organic farming with higher plant nutrients. Therefore, a tractor drawn subsurface manure and seed applicator was designed and developed in Farm Machinery and Power Engineering Department, G.B.P.U.A& T Pantnagar, Uttara khand for placement of vermicom post (organic manure) at a depth of 50 to 200 mm below the soil surface. Firstly the frame for vermicom post and seed hopper was fabricated according to the desired capacity of vermicom post manure hopper. Six rectangular orifices were provided for delivery of manure at the middle of the bottom surface of the manure hopper. A counter shaft was fixed on the frame which was driven by the ground wheel and rotated the horizontal screw conveyor shaft of the manure hopper as well as seed hopper shaft by means of chain - sprocket arrangement. The velocity ratios between the ground wheel and the manure and fluted roller shaft were 2:1. The manure hopper shaft and fluted roller shaft were rotated at 14, 35 and 41 rpm when tractor forward speed 2, 4 and 6 km/h, respectively. Two depth control side wheels were provided below the frame to adjust the depth of cut of machine in field operation. A furrow opener was designed to penetrate into the soil at the desired depth and placed the vermicom post and seed below the soil surface.

Numerical simulation approach to predict the abrasion rate of rice during milling

The effect of the rice movement and the forces acting on rice grains during abrasion in a mill is unclear limiting the development of rice milling machines. The aim of this work is to provide a numerical methodology for predicting the abrasion rate of rice to provide the basis for the design and use of rice mills and improving milling quality and efficiency. Here, the milling process was investigated experimentally in a laboratory using a vertical mill to identify the dominant abrasion mechanism and to the analyse of particle size distributions. In order to evaluate the abrasion rate, the effect of rotational speed of the roller shaft on the normal force and the sliding distance between particles and particle-geometry was examined using the discrete element method. Abrasion rate calculated according to the Archard abrasion equation from the simulation results and this agreed well with the experiment results thereby validating the feasibility of numerical-experimental approach. The relationship between rotational speed and abrasion rate was established based on polynomial fitting.

Algorithmic performance constraints for wind turbine condition monitoring via convolutional sparse coding with dictionary learning

We analyze vibration signals from wind turbines with dictionary learning and investigate the relation between dictionary distances and faults occurring in a wind turbine output shaft rolling element bearing and gearbox under different data and compute constraints. Dictionary learning is an unsupervised machine learning method for signal processing, which permits learning a set of signal-specific features that have been used to monitor the condition of rotating machines, including wind turbines. Dictionary distance is one such feature, and its effectiveness depends on an adequate selection of the dictionary learning hyperparameters and the data availability, which typically is constrained in condition monitoring systems for remotely located wind farms. Here we evaluate the characteristics of the dictionary distance feature under healthy and faulty conditions of the wind turbines using different options for the selection of the pretrained dictionary, the sparsity of the signal model which determines the compute requirements, and the interval between data samples. Furthermore, we compare the dictionary distance feature to the typical time-domain features used in condition monitoring. We find that the dictionary distance based feature of a faulty wind turbine deviates by a factor of two or more from the population distribution several weeks before the gearbox bearing fault was reported, using a data sampling interval as long as 24 h and a model sparsity as low as 2.5%.