Machine Elements Research Articles

Numerical and experimental investigations on a bladeless turbine: Tesla's cohesion-type innovation

The design, numerical simulation, manufacturing, and physical experimentation of Tesla's bladeless centripetal turbine for electrical power production are the topics of this research project. The turbine generates rotational motion in the discs by directing pressurized air and water tangentially across parallel smooth disc surfaces. The fluid speed parameter at the nozzle inlet determines the power generated. To ensure optimal mechanical design parameters, SolidWorks design software, fluid dynamics concepts, and machine element design were employed. The numerical simulation software ANSYS CFX was used. The numerical and qualitative findings of the models and physical experiments coincided well. The study revealed that the power production and turbine efficiency were regulated by the input sources and blade size. Variations in the fluid composition between the discs may additionally have an impact on the outcomes. The researchers investigated the connection between input fluid pressure and turbine efficiency, as well as the number of discs and turbine power. The prototype could generate 76.52 W of electricity at 50 bar pressure and 1.01e+05 Reynolds number. The operation was efficiently simulated using CFD, with only a 9.3% difference between experimental and simulated results. Overall, this research provides an in-depth assessment of Tesla's bladeless centripetal turbine. It verifies the design and numerical simulation methodologies used, as well as identifies the essential aspects impacting turbine performance and efficiency. The findings contribute to a better understanding of the turbine's behavior and give ideas for improving its performance.

Estimating Remaining Useful Life of Cutting Tools in Machining Using an Extended Kalman Filter

Monitoring the condition of the cutting tool and forecasting the evolution of its wear during machining are vital to ensure workpiece quality and the safety of machine elements. The accurate prediction of tool wear is crucial to advance predictive maintenance in machining. This article presents a methodology to estimate the remaining useful life (RUL) of cutting tools. The methodology involves extracting features from vibration signals using discrete wavelet transform (DWT) and computing the concomitant indicators of tool health by applying distance metrics to the features. These indicators have a high correlation with tool wear measurements. The RUL is estimated by fusing these indicators in a support vector regression (SVR) algorithm. The SVR outputs then serve as inputs to an extended Kalman filter (EKF) that employs a rectified linear activation unit (ReLU) function for state evolution, enabling real-time estimation of the RUL. The proposed methodology is demonstrated on the IEEE PHM 2010 dataset, showcasing its reliability and effectiveness in accurately estimating the RUL for cutting tools.

Overcoming Conflicts of Objectives Between Sensory and Mechanical Domain in the Development of Sensor-Integrating Machine Elements Using the Example of Bolts

Overcoming Conflicts of Objectives Between Sensory and Mechanical Domain in the Development of Sensor-Integrating Machine Elements Using the Example of Bolts

Teacher and Student Competence Improvement at SMK Muhammadiyah Karangkobar

Abstract. Vocational High School (SMK) is a Vocational High School that targets the formation of character and skills for its graduates. The learning system in Vocational Schools that includes practical material makes Vocational graduates ready to use and able to work and even create jobs. So that SMK graduates are targeted to be able to contribute to the local economy. Highly contradictory conditions were found at the Muhammadiyah Karangkobar Vocational School, Banjarnegara. Muhammadiyah Karangkobar Vocational School is still overwhelmed by the problem of limited learning support practice equipment. So far the practical Teaching and Learning Process (PBM) has only been carried out by watching videos due to the limited equipment and practical simulators available in schools. Occasionally PBM practices using the private vehicles of students/teachers who are willing to use their vehicles as practice media. This condition is still not optimal because the work done tends to be light work which does not adequately represent the material for the Department. This condition is of course not very good considering that the output of SMK students is skills that should be acquired through a structured and systematic practicum process. The solutions offered in these problems are, firstly, providing support equipment grants in practice, especially periodic maintenance of automotive light vehicles, and electric welding tools and bench work, and secondly, providing training to teachers and students of Muhammadiyah Karangkobar Vocational School on Machine Elements, supplemented with job sheets and preceded by the provision of material in advance. The Muhammadiyah Organization-Based Community Service Program (PPM-Muh) aims to increase the knowledge and skills of teachers and students of SMK Muhammadiyah Karangkobar in carrying out periodic service work and light vehicle tune-ups. The dedication method is carried out through the theoretical provision of engine maintenance through classroom learning, soft skills, demonstrations, and tune-up practical exercises. The targets of this training program are teachers and students of SMK Muhammadiyah Karangkobar.

Development of the information model of the soil cutting process spatially oriented knife of dynamic action

The results of the construction of an information model of the process of soil cutting with straight-furrow oriented knives of dynamic action are given. Bulldozer equipment and its main tasks are considered. A working hypothesis of the movement of the scraper and the vertically oriented knife has been formed. The working hypothesis is based on the fact that the movement of the spatially oriented knife will be carried out longitudinally - translationally, perpendicular to the trajectory of the movement of the working body. The dynamic movement of the knife will be carried out with the help of a self-oscillating hydraulic vibrator, the development of such a solution was implemented at the Department of Construction Machinery of KNUСA, the prerequisites were the work of the team, in particular, prof. Smirnov V.M. regarding the structure of the working body and prof. Baladinsky V.M. regarding the regularities of creating dynamic movements of cutting elements of earth-moving machines. And also, based on the works of Khmara L.A., candidate in connection with the intensification of the mechanization of earthworks in construction. Their vector movement and determination of the angles of application of the main cutting force to the corresponding angle α are presented. After constructing the movement vectors of the working body and the spatially oriented knife, a method of calculating the direction of the cutting force and the deflection angle α was developed. Using vector sums and speed ratios ranging from 10:1, where the spatially oriented knife moves ten times faster than the blade, to 1:10, where the spatially oriented knife moves ten times slower. A graph of the determination of the angle α is plotted depending on the ratio of the blade feeding speeds and the displacement of the spatially oriented knife. The speed ratio is calculated and entered in the speed ratio table according to the angle α and the bulldozer's gear ratio.

Enhancing the lifetime and vacuum tribological performance of PVD-MoS2 coatings by nitrogen modification

As a solid lubricant, MoS2 is used for reducing friction and wear in machine elements under challenging operating conditions. In application, service life is thus a decisive factor that depends on the coating. Here, the effect of gaseous nitrogen modification on the performance of physical vapor deposited MoS2 coatings has been studied under vacuum conditions. The coatings were modified chemically or in their structural design by varying the bias voltage alternately. Tribologically induced changes were identified in short-running and long-running intermittent ball-on-disc tests, while the lifetime was evaluated in ball-on-disc tests until coating failure, with a coefficient of friction value exceeding 0.3 defined as the failure criterion. Furthermore, the microstructure was investigated before and after tribological loading. It appeared from scanning electronic microscopic imaging, that nitrogen modification reduced the initial degree of porosity and material compacting occurred after a short tribological loading. Nanoindentation measurements in the wear track of the compacted coating supported these results by a significant increase in indentation hardness and indentation modulus. Overall, the improvement in lubrication performance due to nitrogen modification led to a significant extension of service life, whereas the chemical and structural modification exhibited the highest service life of the coating.

Fault detection in beam structure using adaptive immune based approach

Different structural and machine elements are used over the ages. These are subjected to various loads like static and dynamic load, temperature, corrosion etc. Due to the above-mentioned reasons, ageing of the structural elements occur. So, to enhance the designed lifetime of any structure continuous maintenance is required. One such method has been proposed in this research work and the proposed method can be employed as an online tool for the fault identification. Here dynamic analysis of structure has been conducted as the forward method to find out the modal natural frequencies related with the damage. Recently with the application of machine learning approaches and the soft computing, the damage can be detected easily. In this methodology, Clonal Section Algorithm (CSA) has been applied to find out the faults (crack locations and depth) in the structure initially. Later one such method has been developed in the concepts of adaptive immune based technique (Adaptive Clonal Section Algorithm-ACSA) which is the combination of an artificial immune (Clonal Selection Algorithm) and Regression Analysis (RA). The use of regression analysis makes the proposed method more adaptive and the residual error in the collection of vibration data is reduced. The mechanism and various steps involved in CSA, RA and ACSA are analyzed here in a precise manner. The key endeavor of this study is the development of ACSA and its implementation to condition monitoring of structure. To authenticate and check the accuracy of both the methods (CSA and ACSA), laboratory tests are carried out. The results obtained from each method are corroborated with other and found to be convergent.

DETEKSI CACAT BANTALAN GELINDING BERBASIS ALGORITMA DECISION TREES DAN PARAMETER STATISTIK

Rolling bearings are a common machine element found in rotary machines. The components in the rolling bearing such as the inner race, outer race, rolling element, and cage are the parts that are often damaged. Traditionally spectrum analysis is used to diagnose bearing defects. However, spectrum analysis is not effectively applied to bearings with early defects because the vibration signal generated is dominated by frequency components from other machine elements, so the frequency of bearing defects cannot be observed. This study proposes an alternative method of detecting bearing defects based on vibration signals using machine learning with a decision tree algorithm. This method is more effective than the spectrum analysis method because machine learning is based on feature extraction and pattern recognition of vibration signal data, therefore, providing classification results directly without further analysis. Vibration signals were recorded using an accelerometer mounted on a bearing housing on a test rig. Nine-time domain statistical parameters and six frequency domain statistical parameters were extracted from the vibration signal and then used as input for decision trees. The results show that the decision trees algorithm gives an accuracy of 94.4% for classifying three rolling bearing conditions using the input of 6 selected frequency domain statistical parameters.

DESIGN AND EXPERIMENTAL ANALYSIS OF A TEST MACHINE TO DETERMINE BUCKLING IN THE RODS OF HYDRAULIC CYLINDER

The issue of buckling is one of the subjects that should be especially emphasized in the design and dimensioning processes of engineering. In the past, this issue was not of much importance in construction and machine elements. Because the strength of the existing materials at that time was low and as a result, they were resistant to buckling due to the large cross-sectional areas of the structure and machine elements. However, in the course of time, the cross-sectional area of the building and machine elements also decreased. As a result of the reduction of the cross-sectional area, besides the advantage of getting rid of large and heavy elements, it also brought the disadvantage of buckling. In our seminar study the buckling caused by fixing the shaft at different stroke and pressure values was determined by 4 comparators and the buckling values on the shaft surface were examined.

Design of a Cost-Effective and Statistically Validated Test Specification with Selected Machine Elements to Evaluate the Influence of the Manufacturing Process with a Focus on Additive Manufacturing

Due to their versatile advantages, the use of additively manufactured components is growing. In addition, new additive manufacturing processes are constantly being developed, so that a wide range of printing processes are now available for metal. Despite the same starting material, the microstructure and thus also the final mechanical properties differ greatly compared to conventional processes. In most cases, only direction-dependent characteristic values from the uniaxial tension are used to qualify a printing process before it is used. The literature, on the other hand, demonstrates that the results are not transferable to other loading conditions. In this work, several engineering tests were integrated into a single test specimen so that they can be determined on the same specimen. The test specimen can be used to test tooth root strength, bending strength, notched bar impact energy, and thread strength depending on the mounting direction, thus representing industrial loading cases. In this study, test specimens were fabricated by conventional manufacturing (machining), L-PBF (Laser Powder Bed Fusion), and WA-DED (Wire Arc Direct Energy Deposition), and the results were compared using statistical methods. Factors to capture manufacturing influence and buildup direction were statistically validated on 316L. The work shows a benchmark with a typical initial microstructure of rolled and milled material, L-PBF, and WA-DED parts on loads close to the application and thus simplifies an industry-oriented evaluation of a new manufacturing process.

Performance Analysis of Polymer Additive Manufactured Gear Bearings

Bearings in general, and in this case rotational bearings, are important elements in many machines. The main objective of this study was to find out the load-bearing capacity of 3D-printed gear bearings under various rotational speeds, test the bearings to failure and estimate their lifetime. An interesting note on the gear bearing is its uncommon geometric configuration, because the rolling elements are gears, which allows for a rolling-sliding motion between the constituting elements, minimizing the sliding effect. The material used is PLA (poly lactic acid), a common thermoplastic polyester, and the printing technology was FDM (fused deposition modeling). Considering the PLA’s temperature sensitivity, this was also monitored but had no influence on the failure of the bearing, as experiments show. The rotational speed range for the experiment is 250–1500 RPM (revolutions per minute) in increments of 250 RPM, and the loads are 18 N (Newton) and 45 N for a gear bearing with 51 mm diameter and 15 mm thickness. The results of this study can be used as a reference for application limitations or to design gear bearings using 3D printing methods.

Special Issue on Recent Progress in Precision Engineering

In recent years, the field of manufacturing has become increasingly diversified and complex to meet various requirements, such as improved manufacturing accuracy, productivity, environmental friendliness, and automation/intelligence in manufacturing sites. Consequently, the fusion of different fields as well as interdisciplinary research has become indispensable for the creation of innovative manufacturing technologies that can realize advanced production systems. This special issue comprises seven outstanding research papers that focus on advanced precision engineering in manufacturing systems, covering the following topics: - Advanced cutting technologies - Advanced machine tools and elements - Surface finishing technologies - Non-traditional machining and additive manufacturing - Nano-scale surface finishing - Advanced surface processing All research papers were originally presented at the 19th International Conference on Precision Engineering (ICPE2022), held in Nara, Japan, in 2022. The editors hope that the research papers included in this special issue will offer valuable insights to readers for their future research in the field of manufacturing technology. Each paper underwent a rigorous peer-review process, and the editors would like to express their deep appreciation for the efforts and excellent work of all the authors and anonymous reviewers who contributed to the realization of this special issue. Finally, it is our sincere hope that the papers in this special issue will further contribute to the advancement of our future society.

Analysis of the Electrical Impedance of Graphite and Silver Graphite Carbon Brushes for Use in the Impedance Measurement of Sensory Utilizable Machine Elements

The ongoing digitalization of processes and products in mechanical engineering is accompanied by an increasing demand for data. In order to provide this data, technical systems are being extended with sensory functions. To supply those sensory functions on rotating elements—such as shafts—with electrical energy, and to be able to transmit signals out of the system, sliding contacts can be used as a cost-effective and established solution. However, if electrical properties of machine elements are utilized for sensing purposes, such as condition monitoring of rolling element bearings by means of impedance measurement, sliding contacts are directly in the measurement path and can thus influence the measured impedance. The aim of this paper is to analyze the impedance of graphite and silver graphite carbon brushes under different rotational speeds, in different positions, and with different carrier frequencies. The material of the carbon brushes as well as the position have significant effects on the impedance behavior. Furthermore, carbon brushes show a significant running-in behavior. The results are discussed, and indications for use in impedance measurements are given. Silver graphite carbon brushes in axial positioning are particularly suitable for impedance measurements of sensory utilizable machine elements. Sufficient running-in time must be considered.

Structural Models for Failure Detection of Moore Finite-State Machines

Fault detection is an important task in the design of fault-tolerant state machines. Structural models of Moore finite-state machines are proposed to detect multiple faults in various elements of the finite-state machine and prevent their negative impact on the controlled object. The structural models under consideration make it possible to detect invalid input and output vectors both in each state and for the entire automaton, invalid code of the current and next state of the automaton, and invalid transitions between states. The costs of implementing the proposed structures by area range on average from 3 to 26%, and the speed of the machine either does not change or even increases by an average of 24–30%. Estimates of the area and performance of the proposed structural models of finite-state machines are given, and recommendations for their practical use are given. It is shown that the choice of a suitable structure allows us not to increase the area, and in some cases even leads to an increase in the performance of the finite-state machine.

Combined effects of magnetic field and surface treatments consisting of shot peening, plasma nitriding and their consecutive application on the friction and wear behavior of a ferromagnetic steel

Machine elements are subjected to electrical and/or magnetic field in their use and this can cause the failure of them. On the other hand, in order to extend their service life, different surface treatments such as shot peening and plasma nitriding are used. In recent years, the sequential application of these treatments has gained more attention because plasma nitriding efficiency is improved and more durable surfaces can be obtained through this method. Surface treated materials are also operated under magnetic field but their tribological performance under magnetic field is still unknown. Understanding the impact of magnetic field and surface treatments on the friction and wear behavior of the materials is the aim of the current investigation. As part of this effort, shot peening operations were performed on AISI 4140 low-alloy steel at the intensities of 16 A, 20 A and 24 A and plasma nitriding were performed at 500 °C for 1 h and 4 h. The reciprocating pin-on-disc wear tests were performed with and without magnetic field application. XRD, SEM, microhardness tester and 3D optical microscope were used for the characterization of the samples. Plasma nitriding, shot peening, and their consecutive application increased the material's wear resistance. Magnetic field application provided further enhancement in wear resistance, as the surfaces of the samples were oxidized and the particles formed during the sliding were removed from the wear zone. Untreated and shot peened samples exhibited adhesive wear, whereas abrasive wear was also observed in plasma nitrided samples. Magnetic field did not change the wear mechanisms of the samples. However, due to surface oxidation and removal of the particles, narrower wear marks were observed in the samples worn under magnetic field compared with the wear marks obtained without applying magnetic field.

Thermo-hydrodynamic Analysis of Multistep Journal Bearing using Computational Fluid Dynamics Simulation

Journal bearing is a machine element that is used to maintain the continuous rotation of the shaft on its axis. The rising demand for efficient and economical journal bearing applications has resulted in increased demand for high-speed machines. An increase in engine speed raises the distribution of pressure, temperature, and vapor volume fraction. Most of the research still only focuses on increasing pressure distribution and load-carrying capacity. However, the value of friction force, temperature distribution, and vapor volume fraction must also be considered such that the lubrication of the journal bearing is close to the real situation. Therefore, the research was conducted by varying the geometry modelling through multistep textures using viscous boundaries and thermo-hydrodynamic lubrication. Owing to the high load and speed usage on multistep journal bearings, research on the effect of eccentricity ratio and inlet and outlet temperatures on the tribological performance of multistep journal bearings was conducted. The analysis has been performed using a multistep journal bearing modelling 3D computational fluid dynamics considering the effect of cavitation on temperature. The results of this study indicate that the use of multistep textures on journal bearings can reduce friction force, temperature, and vapor volume fraction. The variation of the eccentricity ratio shows that a high eccentricity ratio leads to a high three parameters (i.e., friction force, temperature, and vapor volume fraction). Finally, for variations of inlet and outlet temperatures, such parameters are high when the inlet and outlet temperatures are high.

Palm oil as an alternative bio lubricant: A review

Lubrication in mechanical operations involving relative motions of machine elements have been known to facilitate longer techno-economic life span of machine and its components. Lubrication reduces wear and tear of contacting surfaces in relative motion by creating a lubricous layered gap of fluid, powder or semi-solid like grease. Lubricant has also been proven to move heat away from rubbing surfaces to enhance thermal stability of their operations. Various methods, substances and technologies have been adopted to achieve the desired smooth running, minimize frictional losses and improve the thermal stability in the machine members. Mineral oils of long chain hydrocarbon as base oil have really gained ground as an extremely popular choice either in liquid or semi-solid state as lubricant. Recent research has however revealed that mineral oils are non-biodegradable, prone to pollution and hence constitute enormous risks to the environment. This observation and the need for a friendly environment have aroused the curiosity of researchers in the field of tribology and material engineering to the onerous challenge of finding alternative lubricants that will be harmless to the ecosystem and easy disposal of after use. Chief amongst the suggestions made towards the discovery of an environmentally friendly lubricant is the use of vegetable oils of distinct species. The identification of the potential available in vegetable oils has been demonstrated in certain classical operations requiring moderate temperature such as machining and few other cold working operations. This review examines the previous studies regarding the discovery of an alternative machine lubricant from the available vegetative seed oils, particularly palm oil, and suggests ways to improve previous findings and potentials.

Influence of Water Contamination, Iron Particles, and Energy Input on the NVH Behavior of Wet Clutches

The driving comfort and safety of the automotive powertrain are significantly related to the performance, lifetime, and functionality of the lubricant. The presented study focuses on investigating the performance loss of the lubricant due to water contamination resulting from environmental influences and iron particles originating from the wear of different machine elements. The main purpose is to determine critical factors that contribute to the degradation of the lubricant, and increase the tendency to NVH behavior, leading to adverse comfort losses to the respective user. Therefore, this performance loss is evaluated by test rig-based analysis of the friction behavior of wet clutches. Due to physical adsorption, a significant impact of water and iron contamination on the degradation of the lubricant is found, while the influence of the energy input is secondary.

Determination of the KIC Fracture Toughness of the X210Cr12 High-Strength Material

Purpose: It is an important problem that the machines become unusable due to the deformation of the machine elements produced before the planned time. In this study, it was aimed to determine the KIC value of X210Cr12, which is a high strength material. In this way, more accurate load values can be used in the design.Methods: In the experimental study to determine the KIC value, the sample geometry, the crack depth, the load-dependent parameters and calculations and some conformity checks were carried out. Experimental system; KIC consists of 3-point flexure specimens, a press, an electronic circuit capable of detecting the change in load crack opening, and a logger.Findings: In the study, the loads were determined from experimental graphs. Subsequently, load-crack opening values were determined. With these data, the KIC values were calculated as 719,7 and 839,7 MPa.mm1/2 as the minumum and maximum values, respectively.Conclusion: The experimental graphs are in the form of curves that break abruptly with unstable crack propagation without showing plastic deformation. There is no study in the literature on the KIC value of X210Cr12 and it has been determined that it has a low KIC value compared to the high-strength steels studied. It is valuable to determine the KIC value, as fracture problems may occur in designs prepared with the material. The results of the study are data at room temperature.

Matheuristics for scheduling of maintenance service with linear operation cost and step function maintenance cost

We study a problem of scheduling machine maintenance activities in discretized periods, under the constraint that a maximum of one activity can be scheduled for each period. The scheduled maintenance activities will be repeated in a cyclic policy with a given cycle length.The problem is to find a scheduling policy specifying which activity is executed in each period in order to minimize the total cost.Two kinds of costs are assumed: operation and maintenance costs. Both of them depend on the number of periods since the last machine maintenance service. The operation cost occurs during the periods in which a machine is not maintained and increases linearly. The maintenance cost takes place in the periods in which a machine is maintained and is defined as a step function. The steps in the maintenance cost function could be justified by the fact of considering the machine element's substitution when this machine is run for too long without being maintained. This cost structure reduces the gap between the academic problem and the industrial reality.In this paper, the scheduling problem with linear operation cost and step function maintenance cost is defined and formalized. In addition, different matheuristic algorithms are proposed for its resolution. Lower bounds for the objective function are proposed and the computational results show an average deviation from the optimal solution lower than or equal to 3.19%.