bluuebunny/crossref_metadata_2025 huggingface dataset:
Injection Molding Simulation for Part Manufacture with Polystyrene
Authors: Tzetzis Dimitrios , Sofianidis Ioannis , Kyratsis Panagiotis
Published: November 2015

Being able to predict potential defects is a very important aspect of the manufacturing process. The simulation of the injection molding process enables mold and part designers to perform tests during design and development stage and therefore results in a more cost effective and efficient production cycle. This study examines the injection molding simulation of a polystyrene plastic part. The simulation analyzes how melted plastic flows through a mold in order to identify manufacturing defects, while it offers a wide range of simulation parameters and optimizations. Injection molding of the plastic part with the processing guidelines given from the simulation procedure proved successful in the actual manufacturing process. In particular, a significant number of simulations were conducted so that their effect to the final product could be identified. Applying different parameters and optimizations led to several defective parts and identified problems into the process. Common injection molding issues like the short shot occurrence, determining the best injection location or studying the pressure at end of packing had to be addressed by adjusting the simulation parameters and analyzing the results produced. After the procedure's completion it became obvious that the initial processing parameters had to be optimized as otherwise would result in extra manufacturing costs and in delays of production.
Minimization of Sheet Thickness Variation and other Defects of the Mini Drawn Parts Using the Genetic Algorithms Method
Authors: Brabie Gheorghe , Chirita Bogdan
Published: November 2015

Thickness variation is a major defect of the drawn parts made from sheet metals that influences the intensity of part defects. In the case of mini deep drawing, the sheet thickness variation along parts profile has the following effects on the drawn part geometry: increases the non-uniformity of the part diameter variation; influences the values of springback parameters (part edge radius deviations and angle of wall inclination); influences the intensity of wrinkling; causes the part cracking and fracture. Hence, the main objective in the mini scale deep drawing processes must be to increase the drawn part accuracy by minimizing the thickness variation in the drawn parts, i.e. to minimize the values of thinning and thickening. The present paper analyses the results of investigations made to minimize the thickness variation and hence to increase the accuracy of the mini drawn parts by determining the optimal values of the working parameters from the application of the Genetic Algorithms method.
Analysis of the Sheet Wrinkling Variation and Causes in the Case of Mini Drawn Parts
Authors: Brabie Gheorghe , Chirita Bogdan
Published: November 2015

The present paper analyses the results of investigations concerning the size and effects of sheet wrinkling in the case of mini cylindrical drawn parts made from aluminium alloy sheets. The wrinkling occurs in the mini drawn part walls when the blankholder is missing from the die structure or it is driven with an excessive force. By comparing to macro scale processes, the manufacturing of mini parts usually involves new concepts concerning the establishment of the following parameters: tool clearances, tool dimensional parameters, blank dimensions, working process parameters etc. In the case of mini deep drawing such objectives cannot be simply achieved by reducing the process from macro to mini scales. The present work was devoted to study the particularities of the wrinkling that occur during mini deep drawing processes and affect the quality of the mini drawn parts. The experimental investigations were performed using a mini tool having the following main components: punch with a flat bottom, die and an annular blankholder plate. The tool was installed on a mini deep drawing device having the following main components: mobile grip - connected to machine mobile head; fixed grip; helical spring - used to regulate the blankholder force and placed between the fixed grip plate and punch support. The simulation was performed using the DynaForm software and the applied criterion of plasticity was the Barlat 89 criterion.
The Influnce of Some Parameters on the Quality of Deep Drawing of Cylindrical Cups without a Blank Holder
Authors: Chiorescu Dan , Nagîț Gheorghe , Dodun Oana
Published: November 2015

Deep drawing is one of the most important processes for forming sheet metal parts. Besides its importance as a forming process, cup drawing also serves as a basic test for the sheet metal formability. This article investigates the influence of the die punch clearance, the average velocity in the active stage and the lubrication on the deep drawing quality expressed by the thickness evenness on the finished product surface. In order to minimize the number of experimental trials, a fractional factorial design was developed together with an orthogonal array, thus analyzing the contribution of the three parameters under study to the quality of the deep drawing process. Using TAGUCHI’s signal-to-noise ratio, we determine that ram velocity has a major influence, followed by the clearance between the active elements, while the contribution of lubrication is negligible. The results of the research are useful in developing a sensible design of experiments.
Experimental Research of Effective Cutting Speed Influence on Surface Roughness in Ball End Milling of C45 Material with Hardness 54 HRC
Authors: Ravai-Nagy Sandor , Paşca Ioan , Lobontiu Mircea , Banica Mihai
Published: November 2015

In the context of the increasingly frequent use of curved surfaces in the design of products surrounding us, ball end mills are at present the only usable tools in the cutting of complex surfaces, either concave or convex. This aspect, once correlated with the need to reduce the surface roughness, which means an increase in the cost of processing, directs our research to those on the milling with ball end mill. In this way we can identify the optimum cutting data in terms of costs to ensure the prescribed surface roughness. The paper is based on a set of experiments on the correlation of roughness with the parameters of the cutting process, for the C45 material treated with heat at 54HRC. The paper presents a part of a complex industrial research in this area and is complementary to the published works [1, 2]
Aluminum Flow Simulation to Severe Plastic Deformation by Multiaxial Forging
Authors: Bejinariu Costica , Cazac Alin Marian , Lazar Petru , Gheorghiu Diana Antonia
Published: November 2015

By plastic deformation processing techniques is possible to achieve parts with complex geometric configuration and superior mechanical characteristics required in many industries such as aerospace, energy, transport etc. These parts are subjected to high loads or involves a special safety in operation and therefore can not be achieved by empirical design techniques. In addition, industrial development requires obtaining parts with smaller dimensional deviations without defects from expensive materials which are manufacturing in smaller series. To cope with these trends in the currently processed by severe plastic deformation is necessary to apply plastic deformation simulation using finite element method. Aluminum flow simulation is necessary for plastic deformation predetermination the total force, which is used to choose the machine deformation. Also through flow simulation aims to determine contact stress material - deformation tools, necessary stress dimensioning tool, in this case the active plate, punch and counterpunch.
Researches on the Colloidal Solutions Applied in the Process of Electrochemical and Electrical Discharge Machining
Authors: Botis Mihaela
Published: November 2015

When machining by electrochemical and electrical discharge machining methods, the working solution plays an important role and this paper presents the results obtained by applying of some mixtures between colloidal and inorganic solutions that will remove the drawbacks of both media and promotes the increasing of the process efficiency.
The Influence of the Quenching Technology on the Dimensional Stability in Time and the Fatigue Resistance of a 100Cr6 (RUL 1) Steel
Authors: Bancescu Nicolai , Dulucheanu Constantin , Severin Traian
Published: November 2015

This paper presents the influences of quenching technologies (classical, with cooling in magnetic field, cryogenic, with cooling in the ultrasonic field) on the dimensional stability in time and the contact fatigue behaviour of some elements of ball bearings made from 100Cr6 (RUL 1) steel. From the analysis of the experimental data obtained it has resulted that the use of ultrasound for martensitic quenching of these steels ensures changes to the properties favorable to elements of ball bearings and may represent an effective way of increasing the quality of bearings; the technology is relatively simple, it does not require substantial constructive changes in the quenching machines and no further investment of large values.
Monitoring and Control of Thermal Expansion Effect on Machining Process of Aluminum Alloy Parts
Authors: Moldovan Ştefan Adrian , Năsui Vasile
Published: November 2015

In this paper we present a technological problem encountered in the machining accuracy of the parts for aerospace made of aluminum alloy extruded profile with length up to 10 meters. Those parts have very tight tolerances and on milling process appear several factors that influence the repeatability of machining processes, the main one being the thermal expansion effect.
Investigation of Surface Accuracy Obtained by RAM Electro Discharge Machining of Small Cylindrical Surfaces
Authors: Beşliu Irina , Coteaţă Margareta , Slătineanu Laurenţiu
Published: November 2015

The paper deals with the investigations of influence parameters of electro discharge machining (EDM) on the shape accuracy of external cylindrical surfaces machined by EDM process. A Sodick AD3L CNC electrode discharge machine was used to perform the EDM tests. In order to obtain the external cylindrical surfaces by RAM EDM copper cylindrical electrodes were used. Different machining setups and dielectric immersion modes were considered. In order to investigate the influence of the machining parameters on the investigated factors a factorial plan of experiments was considered. The preliminary experimental results highlighted the possibilities to obtain small diameter external surfaces of revolution on a ram electrical discharge machine.
Quality Surface Modification for Refractory Stainless Steel by Tungsten Deposition, Using Electro-Spark Deposition Method
Authors: Tugui Catalin Andrei , Vizureanu Petrică , Nejneru Carmen , Perju Manuela Cristina , Axinte Mihai
Published: November 2015

In this paper were analyzed Tungsten electrode depositions using electro-spark deposition method, on stainless steel, used for hydraulic turbine vanes and blades of mixing blades for chemical industry, in order to achieve an improved wear resistance. This deposition method was chosen due to its relatively low cost, easy to achieve, and leads to obtaining thin layers with good adherence to the substrate, and with different thicknesses, depending on the number of deposited layers. The chosen electrode is an alpha character element and generates an increase of the mechanical properties at low and high temperatures for austenitic stainless steels. Tungsten does not modify the corrosion resistance for the stainless steels. The samples were analyzed on scanning electrons microscope (SEM) and also the chemical analysis (EDX) for distinguish the layer-support structure and the elements repartition on the surface and in line.
Research on the Influence of the Orientation of Deposited Material on the Mechanical Properties of Samples Made from ABS M30 Material Using the 3D Printing Method
Authors: Păcurar Răzvan , Păcurar Ancuţa , Radu Sever Adrian
Published: November 2015

The majority of commercially available 3D printers utilize an additive manufacturing (AM) technique known as molten polymer deposition, whereby a solid thermoplastic filament is forced through a computer-driven extrusion nozzle. Even if it sounds simple at a first look, there are a series of factors that significantly influence the mechanical strength of parts manufactured by using the 3D printing method. The present work tries to investigate by using the finite element method and experimental research how the building orientation is influencing the mechanical strength of samples made from ABS M30 material using a Desktop 3D Printer machine that has been originally designed and produced at the Technical University of Cluj-Napoca (TUC-N).
Numerical Analysis of Residual Stresses and Distortions in Aluminium Alloy Welded Joints
Authors: Kik Tomasz , Slovacek Marek , Moravec Jaromir , Vanek Mojmir
Published: November 2015

Simulation software based on a finite element method have significantly changed the possibilities of determining welding strains and stresses at early stages of product design and welding technology development. But the numerical simulation of welding processes is one of the more complicated issues in analyses carried out using the Finite Element Method. A welding process thermal cycle directly affects the thermal and mechanical behaviour of a structure during the process. High temperature and subsequent cooling of welded elements generate undesirable strains and stresses in the structure. Knowledge about the material behaviour subjected to the welding thermal cycle is most important to understand process phenomena and proper steering of the process. The study presented involved the SYSWELD software-based analysis of MIG welded butt joints made of 1.0 mm thickness, 5xxx series aluminium alloy sheets. The analysis of strains and the distribution of stresses were carried out for several different cases of fixing and releasing of welded elements.
Friction Stir Welding of Composite Materials with Metallic Matrix: A Brief Review
Authors: Boşneag Ana , Constantin Marius Adrian , Niţu Eduard , Iordache Monica , Rizea Alin
Published: November 2015

Composite materials with metallic matrix are increasingly require more than traditional materials metallic, being lighter, more reliable and with their superior properties like: rigidity, tensile strength, flexural strength, fatigue strength, modulus of elasticity, hardness, etc. Due to these advantages, above mentioned, this process has largely penetrated industrial environment. Despite these advantages, there are restrictions on their combination through traditional fusion welding methods so that was passed at the solid-state welding processes, respectively at Friction Stir Welding (FSW). Our researches presents in this brief review: some general ideas about composite materials with metallic matrix and Friction Stir Welding process, appearance and benefits, basic information about the process and composite materials welded by this process, shows the current state of the research with respect to behaviour macrostructure, microstructure, microhardness, tensile properties and defects of the welded joint between composite materials with metallic matrix.
Influence of Shielding Gas and Wire Type on the Microparticles Size Generated during MAG Welding Process
Authors: Gheonea Marius Corneliu , Mihailescu Danut , Scutelnicu Elena
Published: November 2015

Exposure of welders to welding fumes and microparticles produced during electric welding can be dangerous and may cause serious maladies. It is important to understand the formation mechanism of microparticles generated during welding process on the one hand and the methods to diminish the risk on the welder’s health on the other hand. Experimental research results related to the assessment of microparticles size, generated during MAG welding process, are presented and discussed in detail in this paper. Rutile flux-cored and low fume metal powder cored wires with 1.2 mm diameter in combination with CO2 shielding gas or M21 gas mixture (Corgon 18) have been used in the investigations. The experimental tests were performed in a special enclosure, equipped with Glass Fiber Filters and a Philips vacuum, with the aim to capture the microparticles developed by the MAG welding process. The microparticles collected during the experimental program have been analysed and measured by electron microscopy method with (SEM/ESEM - EDAX) Quanta 200 microscope. The study showed that low fume metal powder cored wires determined the achievement of smaller microparticles in comparison with rutile flux-cored wires. Finally, several conclusions emerged from the findings of this study are synthetically presented.
Numerical Simulation of Friction Stir Welding of Aluminum Alloys: A Brief Review
Authors: Constantin Marius Adrian , Boşneag Ana , Iordache Monica , Niţu Eduard , Iacomi Doina
Published: November 2015

Friction Stir Welding (FSW) is the latest innovative and most complex process which is widely applied to the welding of lightweight alloys, such as aluminum and magnesium alloys, and most recently, titanium alloys, copper alloys, steels and super-alloys. Friction stir welding is a highly complex process comprising several highly coupled physical phenomena. The experiments are often time consuming and costly. To overcome these problems, numerical analysis has frequently been used in the last ten years. In this paper is presented a brief review of scientific papers in recent years on numerical simulation of Friction Stir Welding of aluminum alloys. The main elements analyzed by FSW simulation, and briefly in this paper are: temperature and residual stress distribution; work tool geometry (size and shape of the pin); distribution of equivalent plastic deformation; main areas resulted after welding; distribution of microstructure (grain size); parameters and optimization of the FSW process.
The Influence of PCB Mounting/Interconnection Technologies into the Design of a Part
Authors: Parvu Alina Lavinia , Dolga Valer
Published: November 2015

The concepts which go out from the design activity are based on high knowledge [1], rules of designing [2] and previous experience. Until the product is closer to the series and after in the final customer environment, many processes have to be followed. In the development phase (the phase which contains the concept ideas), considering that a separate plastic connector assembled with Aluminum housing has more advantages [4], the current topic which is handled in this paper is to change the material to plastic and establish how the PCB is mounted and positioned inside the housing. More said which the optimal process for this application is. And this is the most challenging step, of choosing the optimal technology for the assembly (in this case 2 assemblies are considered: the PCB with the housing, which is the PCB mounting/ fixation, and the PCB holes with the connector pins, which is the PCB positioning). The material was changed due to higher properties of plastic which in automotive field brings strong added value. As known, in automotive field there are several processes for the mounting of PCB inside the housing like, snapping-on, clamping, screwing and press-fit. To position and to interconnect the PCB holes with the pins, processes like press-fit, spring contact and wave soldering. The selection of the proper process is made by implementing each of the processes requirements into the shape design of the connector, pins and housing.
Study of Grain Motion Parameters on a Sloping Shelf
Authors: Bahadirov Gayrat , Barakaev Nusratilla
Published: November 2015

As it is well known the grain mixture entered for processing, is a mechanical mixture of different components, which can be up to 20% of different impurities. Modern cleaning machines of various modifications do not always provide high quality separation of grain mixture. Imperfection of these machines does not allow get the maximum effect of purification. In order to improve the quality and achieve a more stable and independent processes grain cleaning, it is proposed a new device for cleaning grain. The device comprises a chamber with air aspiration inclined perforated shelves and a boot device. In the study of moving grain particles doped with an inclined perforated shelf is advisable to use the general law of dynamics for the bodies of variable mass. Movement of the selected grains center of mass mixed with particles in the direction of the shelves as described in the fundamental equation of dynamics. While moving mass of particles with a mixture of grains, will be reduced by removing light impurities retracting force of the air flow. This mass is a function of time. Taking into account the reduction of total mass of grain particles, because of impurities reduction the motion equation used in the form of variable mass. There will be the same equations of motion along the other shelves, respectively, the equations are written for the first leg, but with different masses, as well as with other forces retraction.
Effect of Surface Preparation and Passivation Treatment on Surface Topography of Ti6Al4V for Dental Implants
Authors: Strnad Gabriela , Chirila Nicolae , Jakab-Farkas Laszlo
Published: November 2015

The major goal of our research work is to develop an effective and efficient procedure to prepare surfaces with an average surface roughness Ra of 1...2,5 μm and a proper surface topography, as the morphology of dental implant surface is of extreme importance in the process of implant osseointegration. The aim of present research was to elucidate the effect of surface preparation and passivation treatment on topography of Ti6Al4V surfaces for dental implants, and to perform an efficient procedure, in terms of process time. Thirty samples were prepared, some samples were subjected to sand blasting, all samples were acid etched using a dual bath of H2SO4 1n and HCl 1n (1:1) at different temperatures (60°C, 80°C, and 100°C) using different process durations (1 h, 3 h, 6 h, 12 h, and 24 h). After acid etching procedure some samples were passivated in 30% HNO3 at room temperature, for 15 min. Scanning electron microscopy was performed in order to characterize the topography of the surfaces. We found that sand blasting and passivation treatment promotes the formation of a proper surface topography with large, smooth valleys (∼50 μm), different size large peaks (∼30 μm), and micropores (<10 μm) opened on the surface of valleys and peaks, required by a good osseointegration. We showed that the same proper morphology can be achieved by acid etching at different temperatures, using different process duration. The most efficient procedure takes place at 100°C, with process times of 1...3 hours.
A Study on Nanocomposites Behavior at Heating
Authors: Simionescu Tudor Mihai , Minea Alina Adriana
Published: November 2015

Published literature is rich with investigations of mechanical properties of composites, but fewer publications are focused on thermal properties. Several publications addressing different theoretical approaches for predicting thermal conductivity of composite materials have been noted. However, one of the publications has discussed both transverse and axial thermal conductivity of a carbon fiber composite. A non-linear increase in the thermal conductivity was reported with the increase of fiber volume fraction of plain weaves and no theoretical models are able to predict this non-linearity. The result of literature search even further identified the necessity and importance of carrying out further investigations on thermal behavior of composites materials. Thermal conductivity of composites is anisotropic in nature and data about thermal conductivity of resin is known to reduce stresses related to shrinkage of composites during cure and mismatch in thermal expansion coefficients. Before conducting experiments to determine thermal conductivity of various composites, knowledge about effect of different parameters influencing thermal conductivity is essential. This paper deals with an analytical study on few nanocomposites behavior at heating.
Identification of Mechanical Behavior Law Parameters for Polyphenylene Sulphide Composites Reinforced by Glass/Carbon Fibers, Graphite and Polytetrafluoroethylene
Authors: Besnea Maria Aida Cristina , Trufasu Dan Catalin , Cotet Adrian , Andrei Gabriel
Published: November 2015

Mechanical behaviour law for thermoplastic polymers was established on the basis of phenomenological models. This work is intended to examine whether a constitutive equation used for thermoplastic polymers could be applied in case of their composites. G’Sell-Jonas model gave good results when used for the prediction of stress-strain characteristics at high strain rate, for semi-crystalline polymers subjected to mechanical tests. Data obtained through compressive test of polyphenylene sulphide (PPS) composites were processed by a numerical algorithm based on G’Sell-Jonas constitutive equations. Besides, a comparative analysis of experimental results and numerical model was done. The study showed clearly a good agreement between experimental and numerical results.
Strain Analysis of an Epoxy Resin Based Composites – Laboratory and Simulation Comparative Studies
Authors: Sobek Michał , Baier Andrzej , Buchacz Andrzej , Grabowski Łukasz , Majzner Michał
Published: November 2015

In this paper issues of stress analysis of composite materials are presented. The components of composite materials and principles of composition has been discussed. Particular attention was paid to the epoxy resins and the fabrics made from carbon fibers. The article also includes basic information about strain measurements performed on with a resistance strain gauge method. For the purpose of the laboratory tests a series of carbon - epoxy composite samples were made. The main aim of the studies was to compare the results of two different research methods – laboratory and simulation method. During laboratory strain tests described in the paper, a composite samples were loaded with a specified load. Tenmex's delta type strain gauge rosettes were used to measure strain. They were arranged in specific locations on the surface of the samples. Data acquisition procedure were carried out using HBM measurement station. Numerical studies were carried out in a computing environment, Siemens NX 9.0. The results of simulation and laboratory tests were compared and presented in the form of graphs. They allow you to validate the method of laboratory measurements. The results of both research types have shown the percentage difference between them for individual loads applied to each composite.
Neural Network Based Analysis of Tribological Behavior for an Epoxy-Clay Composite System
Authors: Roman Igor , Ciortan Sorin , Birsan Iulian Gabriel
Published: November 2015

Prediction of a polymer properties, based on its composition, is a complex problem with no easy method to obtain directly and accurately results. Among the tribological properties, the friction coefficient and wear rate are the most interesting ones. The epoxy resin based polymers, with clay as filler, shows different properties following the clay concentration. This paper presents an analysis of the properties variation with filler concentration, for a polymer. Due to tribological processes complexity, mechanical and thermal properties must be taken into account. The aim of the study is to find an optimal concentration value, with minimal influence on polymer properties. All value properties will be used in a neural network model in order to optimize and predict composite properties.
Calculus of the Relationship of the Cutting Moment at Drilling of the Stainless Steel X5CrNiMo17-12-2
Authors: Iacob Marius , Blăjină Ovidiu , Vlase Aurelian
Published: November 2015

This article studies the cutting moment at drilling of the stainless steel X5CrNiMo17-12-2. The structure of the cutting moment relation was modified with respect to the relation available in the technical literature for common steels. The tool speed was included in the calculus relation. The experimental data and their subsequent processing represent the original contributions of the authors to the estimation of polytropic exponents and to the assessment in terms of structure of the calculus relation of the cutting moment. The paper also contains graphs with the cutting moment variation depending on the parameters of the cutting technology. The graphs are drawn based on the analytic relationship of the cutting moment, obtained in the article, using the mathematical softwareMaple. The results presented in this study can be taken into consideration in the educational studies and in the theoretical technical research. Also, they can be readily implemented in the manufacturing activity. Our further studies aim these problems for other classes of steels and cutting machining processes.
Chromium Addition Effect on Wear Properties of Cast-Iron Material
Authors: Florea Costel , Bejinariu Costică , Paleu Viorel , Chicet Daniela , Carcea Ioan , Alexandru Adrian , Cimpoesu Nicanor
Published: November 2015

A new cast iron material with a higher Cr content than usual is analyzed by chemical, micro-structural and friction coefficient point of view. The material was obtained by classical melting and the results compared with the experimental results obtained from a standard cast-iron used for applicative disk brake. Four different mechanical solicitation rates were used on the same material surface and the same load. The solicitation regime can be considered as semi-liquid and similar to a raining day experimental conditions. In this paper no thermal considerations were present or discussed. The results present a bigger friction coefficient of the new material and further considerations are necessary for example in a different friction regime.
Smart Alloys for Automotive Bumpers
Authors: Crăciun Radu Cristian , Stanciu Sergiu , Cimpoeşu Ramona , Săndulache Florin , Ursanu Dragos Adela Ioana , Axinte Mihai
Published: November 2015

Bumper beam absorbs the accidental kinetic energy by deflection in low-speed impact and by deformation in high-speed impact. Based on the last years necessity of lighter materials and safer usage of vehicles we try to come with a new class of materials for bumper systems. Analyze of metallic materials is cheaper when the analyze take place on a computer avoiding the metallic loss or energy consume. We present few results obtained in Catia software about the behavior of some metallic materials under external solicitations in function of the mechanical properties of metallic elements, geometry of the element, restrains and solicitation points. Shape memory alloy are smart materials that can use the external mechanical energy damping to thermal energy in bumper applications. In martensite to austenite domain we observe an increase of damping mechanical capacity with possible applications in bumper systems.
On the Simulation of Powered Axles Stick-Slip
Authors: Tudorache Cristina Mihaela , Oprea Razvan Andrei , Stan Cornelia
Published: November 2015

The use of high power railway vehicles requires enhanced control of wheel-rail adherence. When setting the train in motion, driving axles can exhibit torsional vibrations resulting in poor adherence and even axle damage. A significant number of railway authorities safety warnings and accident reports were issued related to the above phenomena. Adhesion saturation and negative slope are the characteristics which lead to self-sustained axial vibration. The aim of the present work is to prove the appropriateness of non-smooth models in the study of the axle torsional stick-slip vibrations which may occur when traction vehicles are set into motion. The model is simple, observes the main friction characteristics and provides the basis for efficient dynamics simulation. An experimental setup comprising a reduced scale wheel set is analyzed in order to validate the model proposed. The friction parameters are then identified using the proposed force-creepage relationship. Validation and verification is further carried out in frequency domain using both steady state and transient manoeuvres. Specific phenomena like discontinuities in the time-history friction force values occur. Validation and verification is carried out in frequency domain using both steady state and transient manoeuvres. From the comparison between the numerical and experimental results, it can be concluded that the setup is modeled accurately. Related problems may be solved using the present method, as it is pointed out in the article.
Screw Ball Actuator Stress Behavior
Authors: Croitorescu Valerian , Tudorache Gheorghe , Stamin Ştefan , Jiga Gabriel
Published: November 2015

The new perspectives with regard to early stage beginning vehicles development introduce the need for using driving simulators also. The objective of this study consists in investigating the stress behavior during driving simulator operation at maximum balance angle. The investigation during functioning of the mechanism (the stresses that occur in the system) starts with the static stress analysis, followed by the investigation for different angular positions from 0° to 10° that are mandatory. The analysis can predict the structural stress level that may become very high and generate deficiencies for the entire assembly while using different materials, including composite materials.
Reverse Task of Mechanical System with Active Reduction of Vibration
Authors: Białas Katarzyna
Published: November 2015

The main purpose of this work is the presentation reverse task of mechanical systems including active elements. This reserve task is known as synthesis of mechanical system. In result of conducted synthesis was received structures and parameters of a discrete model meeting the defined requirements concerning the dynamic features of the system, in particular, the frequency spectrum. The presented approach i.e. a non-classical synthetic method applied in designing mechanical or mechatronical systems, one (as early as at the design and construction stage) may verify future systems. The aim of this paper is also analysis of obtained system to check relationship between basic system and active subsystem reduction vibrations. This active subsystem was consisted from electric elements. In this paper was used a non-classical method of polar graphs and their relationship with algebra of structural numbers. The use of such a method enables the analysis and synthesis of mechanical systems irrespective of the type and number of the elements of such a system. Active elements give better results (in compare with passive elements) in case of reduction of low frequency vibrations. Presented approach simplifies the process of selecting the dynamical parameters of systems in view of their dynamical characteristics. Thanks to the approach, introduced in this paper, can be conducted as early as during the designing of future functions of the system as well as during the construction of the system. Using method and obtained results can be value for designers of mechanical systems with elements reducing vibrations.
Training Mechanical Design for Sustainability through the Development of Systems with End-of-Life Components
Authors: Martinho Alberto , Coteaţă Margareta , Slătineanu Laurenţiu , Gonçalves-Coelho António , Mourão António
Published: November 2015

The goal of this paper is to show that one can teach mechanical design making the students aware about the sustainability issues in mechanical engineering by incorporating obsolete parts. The example herein developed aims at finding viable design solutions by re-using end-of-life components to perform functions that are very similar to the ones for which they were initially designed, with only minor adjustments to make them suitable for their new purposes. A Savonius wind turbine was chosen for our exercise since it is easy to build and assemble, has low manufacturing costs and is appropriate for delivering a small amount of mechanical power.
Friction Torque in Low Loaded Thrust Ball Bearings
Authors: Balan Mihaela Rodica , Tufescu Ana , Benchea Marcelin , Olaru Dumitru
Published: November 2015

The authors investigated experimentally the friction torque in a thrust ball bearing operating at very low axial load and lubricated with mineral oils. The experiments were conducted using spin-down methodology and the results were compared with the theoretical values determined by the SKF methodology for friction torque. The values of the friction torque obtained in the experiments are higher than the analytical values obtained with SKF equations, the differences being explained by the important influence of the friction in balls–cage contacts.
Model for Optimization of the Tool Life and the Cutting Speed for Maximum Productivity at Drilling of the Steel X5CrNiMo17-12-2
Authors: Iacob Marius , Blăjină Ovidiu , Vlase Aurelian
Published: November 2015

The research in the last decade regarding their cutting machinability have highlighted the insufficiency of the data for establishing of the optimum cutting processing conditions and the optimum cutting regime. The purpose of this article is the optimization of the tool life and the cutting speed at the drilling of the stainless steels in terms of the maximum productivity. A nonlinear programming mathematical model to maximize the productivity at the drilling of a stainless steel is developed in this paper. The optimum cutting tool life and the associated cutting tool speed are obtained by solving the proposed mathematical model. The use of this productivity model allows greater accuracy in the prediction of the productivity for the drilling of a certain stainless steel and getting the optimum tool life and the optimum cutting speed for the maximum productivity. The obtained results can be used in production activity, in order to increase the productivity of the stainless steels machining. Finally the paper suggests new research directions for the specialists interested in this field.
Air Conditioning: A Renewable Energy Perspective
Authors: Panaite Carmen Ema , Popescu Aristotel , Dodun Oana , Papakostas Konstantinos
Published: November 2015

Global challenges related to fossil fuels depletion, climate changes and growth of population with a higher comfort demand require a significant change of heating and cooling perspective in the building sector, from currently mainly fossil combustion to renewable energy sources. Solar heating and cooling may have an important role in providing an economically feasible and environmentally sustainable long-term solution to these essential requirements. This paper presents a brief overview on the available solar cooling technologies focus on thermally driven methods. A market study is also carried out and the potential of solar cooling is emphasized.
Optimization Strategies of Peripheral Speeds for Planetary Speed Reducers Used in the Actuation of Industrial Robots
Authors: Butunoi Paul Alin , Stan Gheorghe , Ungureanu Lacramioara
Published: November 2015

Planetary speed reducers are used as the actuating module of the revolute joints for the industrial robots as a result of their specific advantages given by high transmission ratios, efficiencies and reliability. However, planetary speed reducers are currently used with variable high speed electric motors, which leads to increased peripheral speeds for the gears and planet carrier, leading in turn to increased noise during operation. Therefore it becomes necessary to manufacture the gears and planet carrier in an upper precision class, leading to significantly increased costs for the entire planetary transmission. Throughout this paper, novel solutions for planetary speed reducers are proposed, characterized by reduced peripheral speeds of the moving elements. For all the structural variants proposed, the summation method (Svamp’s rule) was applied in order to establish mathematical expressions for the transmission ratios. Subsequently, expressions for the peripheral speeds, corresponding to each moving element were derived, and expressed as a function of the number of revolutions of the input shaft. The method described in this paper was applied for each structural variant proposed, the results obtained being compared and analysed, leading to the optimal variant, characterized by a reduced level of noise and vibrations. Based on the mathematical expressions previously derived, a series of graphical representations of peripheral speeds as a function of the number of revolutions for the input shafts were elaborated for each structural variant proposed. At the same time, some recommendations useful for both designers and manufacturers of planetary speed reducers were made, based on the obtained results.
Floating Hydrostatic Bearings for Numerically Controlled Machine Tools
Authors: Stan Gheorghe
Published: November 2015

The use of hydrostatic guideways in CNC machine-tools is very common as a result of their low friction coefficient. The major problem of hydrostatic guideways represents the recovery of the fluid used in guideways, where the fluid should be protected against mechanical impurities and then led towards the hydraulic aggregate. The floating support described in this paper resolves the collection of fluid by using a closed circuit, without exposing the fluid to mehanical impurities and to a gravitational collecting.
Parametric Design of Gear Hob Cutter
Authors: Stǎnǎşel Iulian , Blaga Florin , Buidoş Traian
Published: November 2015

The gears are some of the most used mechanical transmission due to the advantages its provide: constant transmission ratio, high power transmitted, high efficiency, small size, silent operation, precision kinematic, etc. This causes the wheel to be one of the most valuable machine elements both in terms of accuracy and processing technology as well. From the technological point of view due to high precision and productivity, one of the most methods used is processing with gear hob cutter. Although the tool profile does not depend on the number of teeth on the wheel, but only its module, large diversity of gear requires the design of gear hob cutters tailored to existing needs. As it is known the gear hob cutters are complicated and expensive gear cutting tools, both due to the manufacturing process and in terms of design, requiring a significant amount of calculations, high effort from the designer and consequently results in a large cycle of design. For this reason, the literature and in various websites, there are many studies and research information to optimize the design process and increase accuracy of gear hob cutters.
Experimental Research Regarding Static Rigidity in Transversal Direction of “Narrow“ Modules from Modular Fixtures Structure
Authors: Chitariu Dragoş Florin
Published: November 2015

In the paper a research methodology was developed and used to determine the rigidity in transversal direction of modular fixture structures. The paper presents experimental results regarding the total deformation of modular structure consisting of ”narrow” modules from modular kits. The research conducted showed the different evolution of deformation curves in the case of modular structure, with different shape and different sizes of modules, in the case of similar loads. The experimental results indicate displacements of the entire modular structure alongside the base plate and, also, tilting. The measured deviations of modules from fixture structure may cause "dimensional"/ position deviations (linear displacement of the measurement base) and deviations of shape and orientation-position (angular displacement of the measurement base) of the workpiece during severe machining conditions.
Dynamic Behavior Study of Drill Bush Guide Plates from the Fixtures Structure
Authors: Seghedin Neculai Eugen , Chitariu Dragoş Florin
Published: November 2015

Fixtures are use to ensure the orientation and position of workpiece and cutting tools in machining systems. Drill bush guide / holder or are part of a specific category of elements and mechanisms, found in the fixtures structure: elements for size adjustment and guidance for cutting tools. These drill guide bush/ holder are used for guidance of drills, in order to ensure a certain position of the tool regarding the certain reference elements of the workpiece, or to increase the stiffness of drills, when the tool diameter is reduce, or when the surface of the machined workpiece is inclined. The drill bushes are placed in the fixture body, directly or through drill bush guide plates/ drill bush support plates. The characteristic feature of these bush plates is the console length. Sometimes, the bush guide plates can have large lengths that affect the dynamic stability. The bush guide plates are dynamically excited by the direct contact with the drill of the bush. If the natural frequency of vibration of the plate is equal or higher than the excitation frequency of the machining process, then the resonance phenomenon can appear.
Nature of the Elastic Grinding Tools Working Surface in the Contact Area with the Workpiece
Authors: Mikhailov Alexander , Baykov Anatoly , Navka Ilya
Published: November 2015

Formation of the ground surface is the result of the interaction of the cutting elements of the diamond tool with the material being processed, so the nature of the working surface geometry of the grinding wheel (WSW) has principal value on processed surface quality. One of the main parameters that characterize the geometry of the WSW is the law of the grain distribution vertex in height. However, statistical models do not reflect the real picture of the tool interaction with the material being processed in the modelling process of grinding tool on the elastic ligament used for final operations. In the process of contact with the material being processed each diamond grain is moved with an adjacent block ligament, changing the position of the cutting vertex relative to both the midrange cords level and the other grains vertexes. As a result the nature of the grain vertexes distribution changes and the conditions of interaction with the material being processed change too. Studies have shown that the density distribution in height of diamond grains elastic grinding tool vertexes in a static state can be described by different distribution laws. For practical use in the calculation of the processed surface roughness and processing capacity is sufficient to approximate the distribution in height only the most protruding grains. In the area of contact with the processed material the distribution density of the grains elastic tool in height significantly differs from the static characteristics and is defined by the elasticity degree of the grinding tool ligament and machinability index of the workpiece material. The obtained results can serve as initial data for the calculation of the processed surface roughness.
Optimal Arrangement of Stiffeners Using PSO with Cloning Improvement
Authors: Szczepanik Mirosław
Published: November 2015

In the paper an application of the particle swarm optimizer (PSO) with cloning improvement to optimization problems is presented. Reinfored structures considered in this work are dynamically loaded and analyzed by the coupled boundary and finite element method (BEM/FEM). The method is applied to optimize location of stiffeners in plates using criteria depended on displacements or stresses. Numerical examples demonstrate that the combination of the PSO with the BEM/FEM is an effective technique for solving computer aided optimal design problems, both with respect to accuracy and computational resources.