rss_2.0Acta Mechanica et Automatica FeedSciendo RSS Feed for Acta Mechanica et Automatica Mechanica et Automatica 's Cover Engineering of Parts with Asymmetrical Properties Using Replacement Materials<abstract> <title style='display:none'>Abstract</title> <p>Reverse engineering (RE) aims at the reproduction of products following a detailed examination of their construction or composition. Nowadays, industrial applications of RE were boosted by combining it with additive manufacturing. Printing of reverse-engineered elements has become an option particularly when spare parts are needed. In this paper, a case study was presented that explains how such an approach can be implemented in the case of products with asymmetric mechanical properties and using replacement materials. In this case study, a reverse engineering application was conducted on a textile machine spare part. To this end, the nearest material was selected to the actual material selection and some mechanical tests were made to validate it. Next, a replacement part was designed by following the asymmetric push-in pull-out characteristic. Finally, the finite element analysis with Additive Manufacturing was combined and validated experimentally.</p> </abstract>ARTICLE2022-07-13T00:00:00.000+00:00Influence of Imperfect Interface of Anisotropic Thermomagnetoelectroelastic Bimaterial Solids on Interaction of Thin Deformable Inclusions<abstract> <title style='display:none'>Abstract</title> <p>This work studies the problem of thermomagnetoelectroelastic anisotropic bimaterial with imperfect high-temperature conducting coherent interface, whose components contain thin inclusions. Using the extended Stroh formalism and complex variable calculus, the Somigliana-type integral formulae and the corresponding boundary integral equations for the anisotropic thermomagnetoelectroelastic bimaterial with high-temperature conducting coherent interface are obtained. These integral equations are introduced into the modified boundary element approach. The numerical analysis of new problems is held and results are presented for single and multiple inclusions.</p> </abstract>ARTICLE2022-07-13T00:00:00.000+00:00Analytical and Numerical Analysis of Injection Pump (Stepped) Shaft Vibrations Using Timoshenko Theory<abstract> <title style='display:none'>Abstract</title> <p>The free transverse vibrations of shafts with complex geometry are studied using analytical methods and numerical simulations. A methodology is proposed for evaluating the results of a natural transverse vibration analysis as generated by finite element (FE) models of a shaft with compound geometry. The effectiveness of the suggested approach is tested using an arbitrarily chosen model of the injection pump shaft. The required analytical models of the transverse vibrations of stepped shafts are derived based on the Timoshenko thick beam theory. The separation of variables method is used to find the needed solutions to the free vibrations. The eigenvalue problem is formulated and solved by using the FE representation for the shaft and for each shaft-simplified model. The results for these models are discussed and compared. Additionally, the usefulness of the Myklestad–Prohl (MP) method in the field of preliminary analysis of transverse vibration of complex shaft systems is indicated. It is important to note that the solutions proposed in this paper could be useful for engineers dealing with the dynamics of various types of machine shafts with low values of operating speeds.</p> </abstract>ARTICLE2022-07-01T00:00:00.000+00:00Experimental and Numerical Small Punch Tests of the 14Cr ODS Ferritic Steel<abstract> <title style='display:none'>Abstract</title> <p>Nowadays, various small specimen test techniques have gained wide popularity and appreciation among researchers as they offer undoubtful benefits in terms of structural material characterisation. This paper focuses on small punch tests (SPTs) performed on small-sized disc specimens to assess the mechanical properties of 14Cr oxide dispersion strengthened (ODS) steel. A numerical model was established to support experimental data and gain deeper insight into complex strain states developing in a deformed specimen. Modern evaluation procedures were discussed for obtaining mechanical properties from the small punch force-deflection response and were compared with the literature. Applicability and universality of those relations at different test conditions were also studied. It appeared that different ball diameters used had negligible influence on yield point but strongly affected ultimate strength estimation. It was found that friction belongs to decisive factors determining strain distribution in samples, as dry conditions increase the peak strain and move its location farther from the punch pole.</p> </abstract>ARTICLE2022-07-01T00:00:00.000+00:00Simulation Evaluation of the Influence of Selected Geometric Parameters on the Operation of the Pneumatic Braking System of a Trailer with a Differential Valve<abstract> <title style='display:none'>Abstract</title> <p>This article presents simulation models of trailer air brake systems in configurations without a valve and with a differential valve, thus demonstrating the rationale for using a valve to improve system performance. Simplified mathematical models using the lumped method for systems without and with a differential valve are presented. The proposed valve can have two states of operation depending on the configuration of relevant parameters. These parameters can include the length of the control pipe, the throughput between chambers in the control part of the valve and the forcing rise time. Based on the calculations, it was found that the differential valve with large control pipe lengths can reduce the response time of the actuator by 42.77% relative to the system without the valve. In the case of transition of the valve to the tracking action, this time increases only by 9.93%. A force rise time of 0.5 s causes the transition of the valve from the accelerating action to the tracking action, with 9.23% delay relative to the system without a valve. The calculations can be used in the preliminary assessment of the speed of operation of pneumatic braking systems and in the formulation of guidelines for the construction of a prototypical differential valve. In conclusion, it is suggested to use a mechatronic system enabling smooth adjustment of the flow rate between chambers of the control system of the differential valve.</p> </abstract>ARTICLE2022-07-01T00:00:00.000+00:00A New Method of the Positioning and Analysis of the Roughness Deviation in Five-Axis Milling of External Cylindrical Gear<abstract> <title style='display:none'>Abstract</title> <p>Five-axis milling is a modern, flexible and constantly developing manufacturing process, which can be used for the machining of external cylindrical gears by means of cylindrical end mills and special disc mills on universal multi-axis machining centres. The article presents a new method of positioning the tip and the axis of the end mill and the disc cutter in order to ensure a constant value of deviation of the theoretical roughness <italic>R<sub>th</sub></italic> along the entire length of the tooth profile. The first part presents a mathematical model of the five-axis milling process of the cylindrical gear and an algorithm for calculating the <italic>R<sub>th</sub></italic> deviation values. The next section describes the positioning of the end mill and the disc cutter. Then, a new method for the empirical determination of the distribution of the involute root angle <italic>Δui</italic> and the data description by means of the interpolation function are presented and described. In the conducted numerical tests, the influence of the geometrical parameters of the cylindrical gear on the deviation <italic>R<sub>th</sub></italic> is determined, assuming a constant <italic>R<sub>th</sub></italic> value in the five-axis milling process.</p> </abstract>ARTICLE2022-06-15T00:00:00.000+00:00An Overview of Heat Transfer Enhancement Based Upon Nanoparticles Influenced By Induced Magnetic Field with Slip Condition Via Finite Element Strategy<abstract> <title style='display:none'>Abstract</title> <p>The mathematical model of heat generation and dissipation during thermal energy transmission employing nanoparticles in a Newtonian medium is investigated. Dimensionless boundary layer equations with correlations for titanium dioxide, copper oxide, and aluminium oxide are solved by the finite element method. Parameters are varied to analyze their impact on the flow fields. Various numerical experiments are performed consecutively to explore the phenomenon of thermal performance of the combination fluid. A remarkable enhancement in thermal performance is noticed when solid structures are dispersed in the working fluid. The Biot number determines the convective nature of the boundary. When the Biot number is increased, the fluid temperature decreases significantly. Among copper oxide, aluminium oxide, and titanium oxide nanoparticles, copper oxide nanoparticles are found to be the most effective thermal enhancers.</p> </abstract>ARTICLE2022-06-15T00:00:00.000+00:00Data Mining Approach in Diagnosis and Treatment of Chronic Kidney Disease<abstract> <title style='display:none'>Abstract</title> <p>Chronic kidney disease is a general definition of kidney dysfunction that lasts more than 3 months. When chronic kidney disease is advanced, the kidneys are no longer able to cleanse the blood of toxins and harmful waste products and can no longer support the proper function of other organs. The disease can begin suddenly or develop latently over a long period of time without the presence of characteristic symptoms. The most common causes are other chronic diseases – diabetes and hypertension. Therefore, it is very important to diagnose the disease in early stages and opt for a suitable treatment - medication, diet and exercises to reduce its side effects. The purpose of this paper is to analyse and select those patient characteristics that may influence the prevalence of chronic kidney disease, as well as to extract classification rules and action rules that can be useful to medical professionals to efficiently and accurately diagnose patients with kidney chronic disease. The first step of the study was feature selection and evaluation of its effect on classification results. The study was repeated for four models – containing all available patient data, containing features identified by doctors as major factors in chronic kidney disease, and models containing features selected using Correlation Based Feature Selection and Chi-Square Test. Sequential Minimal Optimization and Multilayer Perceptron had the best performance for all four cases, with an average accuracy of 98.31% for SMO and 98.06% for Multilayer Perceptron, results that were confirmed by taking into consideration the F1-Score, for both algorithms was above 0.98. For all these models the classification rules are extracted. The final step was action rule extraction. The paper shows that appropriate data analysis allows for building models that can support doctors in diagnosing a disease and support their decisions on treatment. Action rules can be important guidelines for the doctors. They can reassure the doctor in his diagnosis or indicate new, previously unseen ways to cure the patient.</p> </abstract>ARTICLE2022-05-16T00:00:00.000+00:00Design and Analysis of a Novel Concept-Based Unmanned Aerial Vehicle with Ground Traversing Capability<abstract> <title style='display:none'>Abstract</title> <p>Unmanned aerial vehicle (UAV) is a typical aircraft that is operated remotely by a human operator or autonomously by an on-board microcontroller. The UAV typically carries offensive ordnance, target designators, sensors or electronic transmitters designed for one or more applications. Such application can be in the field of defence surveillance, border patrol, search, bomb disposals, logistics and so forth. These UAVs are also being used in some other areas, such as medical purposes including for medicine delivery, rescue operations, agricultural applications and so on. However, these UAVs can only fly in the sky, and they cannot travel on the ground for other applications. Therefore, in this paper, we design and present the novel concept-based UAV, which can also travel on the ground and rough terrain as an unmanned ground vehicle (UGV). This means that according to our requirement, we can use this as a quadcopter and caterpillar wheel–based UGV using a single remote control unit. Further, the current study also briefly discusses the two-dimensional (2D) and three-dimensional (3D) SolidWorks models of the novel concept-based combined vehicle (UAV + UGV), together with a physical model of a combined vehicle (UAV + UGV) and its various components. Moreover, the kinematic analysis of a combined vehicle (UAV + UGV) has been studied, and the motion controlling kinematic equations have been derived. Then, the real-time aerial and ground motions and orientations and control-based experimental results of a combined vehicle (UAV + UGV) are presented to demonstrate the robustness and effectiveness of the proposed vehicle.</p> </abstract>ARTICLE2022-05-16T00:00:00.000+00:00Calculation of the Optimal Braking Force Distribution in Three-Axle Trailers with Tandem Suspension<abstract> <title style='display:none'>Abstract</title> <p>Heavy agricultural trailers can be equipped with a three-axle chassis with a tandem axle set at the rear and one mounted on a turntable at the front. In such trailers, selection of the distribution of braking forces that meet the requirements of the EU Directive 2015/68, with regard to braking, largely depends on the type of tandem suspension used. The requirements for brake force distribution in agricultural trailers of categories R3 and R4 are described. On this basis, a methodology for calculating the optimal linear distribution of braking forces, characteristic of agricultural trailers with air braking systems, was developed. An analysis of the forces acting on a 24-tonne three-axle trailer during braking was performed for five different suspensions of the rear tandem axle. An optimization algorithm using the quasi Monte Carlo method was described, on the basis of which a computer program for selection of the linear distribution of braking forces was developed. The calculations were made for an empty and loaded trailer with and without the weight of the tandem suspension. The most uniform distribution of braking forces was obtained for two leaf spring with dynamic equalization and air suspension, in which the ratio of the braking force of the tandem axle and the total braking force varied between 22.9% and 25.5% for the different calculation variants. A large variation in the braking force distribution was achieved for the two leaf spring suspension, in which the ratio of tandem axle braking force and the total braking force ranged from 2.7% to 6.4% for the leading axle and from 27.8% to 36.2% for the trailing axle. The presented calculation methodology can be used in the initial phase of the design of air braking systems for three-axle agricultural trailers.</p> </abstract>ARTICLE2022-05-16T00:00:00.000+00:00Numerical Study of Transient Elastohydrodynamic Lubrication Subjected to Sinusoidal Dynamic Loads for Rough Contact Surfaces<abstract> <title style='display:none'>Abstract</title> <p>The purpose of this paper is to study the behaviour of transient elastohydrodynamic contacts subjected to forced harmonic vibrations, including the effect of surface waviness for concentrated counterformal point contact under isothermal conditions. Profiles of pressure and film thickness are studied to reveal the combined effects of sinusoidal external load and surface roughness on the lubrication problem. The time-dependent Reynolds’ equation is solved using Newton–Raphson technique. The film thickness and pressure distribution are obtained at different snap shots of time by simultaneous solution of the Reynolds’ equation and film thickness equation including elastic deformation and surface waviness. It is concluded that the coupling effects of the transient sinusoidal external load and wavy surface would result in increase in modulations of the pressure and film thickness profile in comparison to the case where the smooth contact surfaces are subjected to sinusoidal external load.</p> </abstract>ARTICLE2022-04-18T00:00:00.000+00:00Design of Three Control Algorithms for an Averaging Tank with Variable Filling<abstract> <title style='display:none'>Abstract</title> <p>An averaging tank with variable filling is a nonlinear multidimensional system and can thus be considered a complex control system. General control objectives of such object include ensuring stability, zero steady-state error, and achieving simultaneously shortest possible settling time and minimal overshoot. The main purpose of this research work was the modeling and synthesis of three control systems for an averaging tank. In order to achieve the intended purpose, in the first step, a mathematical model of the control system was derived. The model was adapted to the form required to design two out of three planned control systems by linearization and reduction of its dimensions, resulting in two system variants. A multivariable proportional-integral-derivative (PID) control system for the averaging tank was developed using optimization for tuning PID controllers. State feedback and output feedback with an integral action control system for the considered control system was designed using a linear-quadratic regulator (LQR) and optimization of weights. A fuzzy control system was designed using the Mamdani inference system. The developed control systems were tested using theMATLAB environment. Finally, the simulation results for each control algorithm (and their variants) were compared and their performance was assessed, as well as the effects of optimization in the case of PID and integral control (IC) systems.</p> </abstract>ARTICLE2022-04-18T00:00:00.000+00:00On the Nonlocal Interaction Range for Stability of Nanobeams with Nonlinear Distribution of Material Properties<abstract> <title style='display:none'>Abstract</title> <p>The present study analyses the range of nonlocal parameters’ interaction on the buckling behaviour of nanobeam. The intelligent nonhomogeneous nanobeam is modelled as a symmetric functionally graded (FG) core with porosity cause nonlinear distribution of material parameters. The orthotropic face-sheets are made of piezoelectric materials. These kinds of structures are widely used in nanoelectromechanical systems (NEMS). The nanostructure model satisfies the assumptions of Reddy third-order beam theory and higher-order nonlocal elasticity and strain gradient theory. This approach allows to predict appropriate mechanical response of the nanobeam regardless of thin or thick structure, in addition to including nano-sized effects as hardening and softening. The analysis provided in the present study focuses on differences in results for nanobeam stability obtained based on classical and nonlocal theories. The study includes the effect of diverse size-dependent parameters, nanobeams’ length-to-thickness ratio and distributions of porosity and material properties through the core thickness as well as external electro-mechanical loading. The results show a dependence of nonlocal interaction range on geometrical and material parameters of nanobeam. The investigation undertaken in the present study provides an interpretation for this phenomenon, and thus aids in increasing awareness of nanoscale structures’ mechanical behaviour.</p> </abstract>ARTICLE2022-04-18T00:00:00.000+00:00Bearing Fault Detection and Diagnosis Based on Densely Connected Convolutional Networks<abstract> <title style='display:none'>Abstract</title> <p>Rotating machines are widely used in today’s world. As these machines perform the biggest tasks in industries, faults are naturally observed on their components. For most rotating machines such as wind turbine, bearing is one of critical components. To reduce failure rate and increase working life of rotating machinery it is important to detect and diagnose early faults in this most vulnerable part. In the recent past, technologies based on computational intelligence, including machine learning (ML) and deep learning (DL), have been efficiently used for detection and diagnosis of bearing faults. However, DL algorithms are being increasingly favoured day by day because of their advantages of automatically extracting features from training data. Despite this, in DL, adding neural layers reduces the training accuracy and the vanishing gradient problem arises. DL algorithms based on convolutional neural networks (CNN) such as DenseNet have proved to be quite efficient in solving this kind of problem. In this paper, a transfer learning consisting of fine-tuning DenseNet-121 top layers is proposed to make this classifier more robust and efficient. Then, a new intelligent model inspired by DenseNet-121 is designed and used for detecting and diagnosing bearing faults. Continuous wavelet transform is applied to enhance the dataset. Experimental results obtained from analyses employing the Case Western Reserve University (CWRU) bearing dataset show that the proposed model has higher diagnostic performance, with 98% average accuracy and less complexity.</p> </abstract>ARTICLE2022-03-24T00:00:00.000+00:00Behaviour of a Non-Newtonian Fluid in a Helical Tube Under the Influence of Thermal Buoyancy<abstract> <title style='display:none'>Abstract</title> <p>This work is an evaluative study of heat transfer in the helical-type heat exchanger. The fluid used is non-Newtonian in nature and is defined by Oswald’s model. The work was performed numerically by solving each of the Navier–Stokes equations and the energy equation using the package ANSYS-CFX. Following are the aspects that have been dealt with in this paper: the effects of thermal buoyancy, fluid nature and the tube shape on the heat transfer, and the fluid comportment. The interpretation of the obtained results was done by analyzing the isotherms and the streamlines. The mean values of the Nusselt number were also obtained in terms of the studied parameters. The results of this research enabled us to arrive at the following conclusion: the intensity of thermal buoyancy and the nature of the fluid affect the heat transfer distribution but keep the overall rate of heat transfer the same.</p> </abstract>ARTICLE2022-03-24T00:00:00.000+00:00Linear Motion Error Evaluation of Open-Loop CNC Milling Using a Laser Interferometer<abstract> <title style='display:none'>Abstract</title> <p>The usage of computerised numerical control (CNC) machines requires accuracy verification to ensure the high accuracy of the processed products. This paper introduces an accuracy verification method of an open-loop CNC milling machine using a fringe counting of He–Ne laser interferometry to evaluate the best possible accuracy and functionality. The linear motion accuracy of open-loop CNC milling was evaluated based on the number of pulses from the controller against the actual displacement measured by the He–Ne fringe-counting method. Interval distances between two pulses are also precisely measured using the He–Ne interferometry. The linear motion error and controller error can be simultaneously evaluated in sub-micro accuracy. The linear positioning error due to the micro-stepping driver accuracy of the mini-CNC milling machine was measured with the expanded uncertainty of measurement and was estimated at 240 nm. The experimental results show that linear motion error of the open-loop CNC milling can reach up to 50 μm for 200 mm translation length.</p> </abstract>ARTICLE2022-03-24T00:00:00.000+00:00Performance Evaluation of a Single Cylinder Compressed Air Engine: An Experimental Study<abstract> <title style='display:none'>Abstract</title> <p>The quest to reduce dangerous environmental emissions has led to the research and use of alternate and renewable energy sources. One of the major contributors to the dangerous environmental emissions is the automotive industry. The world is, therefore, quickly moving towards hybrid and electric vehicles. An alternate pollution-free automotive engine is a compressed-air engine, which is powered by compressed air and is more efficient than the electric engine since it requires less charging time than a traditional battery-operated engine. Furthermore, the tanks used in compressed-air engines have a longer lifespan in comparison to the batteries used in electric vehicles. However, extensive research is required to make this engine viable for commercial use. The current study is a step forward in this direction and shows the performance analysis of a single-cylinder compressed-air engine, developed from a four-stroke, single-cylinder, 70 cc gasoline engine. The results show that compressed-air engines are economic, environmental friendly and efficient.</p> </abstract>ARTICLE2022-03-24T00:00:00.000+00:00Method for Enhanced Accuracy in Machining Free-Form Surfaces on CNC Milling Machines<abstract> <title style='display:none'>Abstract</title> <p>The present article describes a method for enhanced accuracy in machining free-form surfaces produced on CNC milling machines. In this method, surface patch machining programs are generated based on their nominal CAD model. After the pretreatment, coordinate control measurements are carried out. The obtained results of the measurements contain information on the values and distribution of observed machining deviations. These data, after appropriate processing, are used to build a corrected CAD model of the surface produced. This model, made using reverse engineering techniques, compensates for the observed machining deviations. After regeneration of machining programs, the object processing and control measurements are repeated. As a result of the conducted procedure, the accuracy of the manufacture of the surface object is increased. This article also proposes the introduction of a simple procedure for the filtration of measurement data. Its purpose is to minimise the effect of random phenomena on the final machining error correction. The final part of the article presents the effects of the proposed method of increasing the accuracy of manufacturing on ‘raw’ and filtered measurement data. In both cases, a significant improvement in the accuracy of the machining process was achieved, with better final results obtained from the filtered measurement data. The method proposed in the article has been verified for three-axis machining with a ball-end cutter.</p> </abstract>ARTICLE2022-03-16T00:00:00.000+00:00Modified Laplace Based Variational Iteration Method for the Mechanical Vibrations and its Applications<abstract> <title style='display:none'>Abstract</title> <p>In this paper, we are putting forward the periodic solution of non-linear oscillators by means of variational iterative method (VIM) using Laplace transform. Here, we present a comparative study of the new technique based on Laplace transform and the previous techniques of maximum minimum approach (MMA) and amplitude frequency formulation (AFF) for the analytical results. For the non-linear oscillators, MMA, AFF and VIM by Laplace transform give the same analytical results. Comparison of analytical results of VIM by Laplace transform with numerical results by fourth-order Runge–Kutta (RK) method conforms the soundness of the method for solving non-linear oscillators as well as for the time and boundary conditions of the non-linear oscillators.</p> </abstract>ARTICLE2022-03-16T00:00:00.000+00:00Theoretical and Empirical Improvement of a Fast-Switching Electro-Pneumatic Valve by Using Different Methods<abstract> <title style='display:none'>Abstract</title> <p>In this paper, a non-linear model of a 2–2 way, on–off fast-switching valve is used. The model includes subsystems of electrical, magnetic, mechanical and fluid. Pulse width modulation (PWM) technique is adopted to energise the on–off solenoid valve and allow the air to flow towards the actuator. Since the non-linear behaviour of valve is of great importance, to reduce the delay in performance of switching valves, different approaches are proposed. Furthermore, hysteresis, proportional integrator (PI), optimal model predictive and fuzzy logic controller (FLC) are used and compared. Also, to improve the valve behaviour, an empirical setup based on AVR microcontroller with FLC is implemented. Empirical and simulation results indicate that all proposed control methods have superior performance. However, the fuzzy method is easy to implement in practice.</p> </abstract>ARTICLE2022-03-16T00:00:00.000+00:00en-us-1