Vector-like Quarks at the Origin of Light Quark Masses and Mixing

We show how a novel fine-tuning problem present in the Standard Model can be solved through the introduction of a single flavour symmetry G, together with three $Q = - 1/3$ quarks, three $Q = 2/3$ quarks, as well as a complex singlet scalar. The symmetry G is extended to the additional fields and it is an exact symmetry of the Lagrangian, only spontaneously broken by the vacuum. Specific examples are given and a phenomenological analysis of the main features of the model is presented. It is shown that even for vector-like quarks with masses accessible at the LHC, one can have realistic quark masses and mixing, while respecting the strict constraints on process arising from flavour changing neutral currents (FCNC). The vector-like quark decay channels are also described.Comment: 25 pages, no figure

Recent Advances on Coated Milling Tool Technology—A Comprehensive Review

The milling process is one of the most used processes in the manufacturing industry. Milling, as a process, as evolved, with new machines and methods being employed, in order to obtain the best results consistently. Milling tools have also seen quite an evolution, from the uncoated high-speed steel tool, to the now vastly used, coated tools. Information on the use of these coated tools in recent scientific researches was collected. The coatings that are currently being researched are going to be presented, highlighting some novel advances in the nanocomposite and diamond coatings area, as these coatings are seeing a growing use in the industry, with very satisfactory results, with performance and tool-life increase. Wear mechanism of various types of coatings are also a popular topic on recent research, as the cutting behavior of these coated tools provides valuable information on the tool’s-life. Furthermore, analysis of these mechanisms enables for the selection of the best coating type for the correct application. Recently, the employment of coated tools paired with sustainable lubrication methods as seen some use. As this presents the opportunity to enhance the coated tool’s and the process’s performance, obtaining better results, in terms of better tool-life and better surface finish quality, in a more sustainable fashionThis research was funded by ON-SURF Project, grant number NUP POCI-01-0247-FEDER-024521.info:eu-repo/semantics/publishedVersio

Recent Advances in Turning Processes Using Coated Tools—A Comprehensive Review

Turning continues to be the largest segment of the machining industry, which highlights the continued demand for turned parts and the overall improvement of the process. The turning process has seen quite an evolution, from basic lathes using solid tools, to complex CNC (Computer Numerical Control) multi-process machines, using, for the most part, coated inserts and coated tools. These coatings have proven to be a significant step in the production of high-quality parts and a higher tool life that have captivated the industry. Continuous improvement to turning coated tools has been made, with many researches focusing on the optimization of turning processes that use coated tools. In the present paper, a presentation of various recently published papers on this subject is going to be made, mentioning the various types of coatings that have recently been used in the turning process, the turning of hard to machine materials, such as titanium alloys and Inconel, as well as the interaction of these coatings with the turned surfaces, the wear patterns that these coatings suffer during the turning of materials and relating these wear mechanisms to the coated tool’s life expectancy. Some lubrication conditions present a more sustainable alternative to current methods used in the turning process; the employment of coated tool inserts under these conditions is a current popular research topic, as there is a focus on opting for more eco-friendly machining options.info:eu-repo/semantics/publishedVersio

3D finite element analysis and optimization of cap ply production system in the tire industry

30th International Conference on Flexible Automation and Intelligent Manufacturing (FAIM2020) 15-18 June 2020, Athens, GreeceIn automotive industry, tires play a key role. They are a composite structure formed by multiple layers of different materials such as rubber compounds, steel and polyamide cords. Between the tread and steel belts, a cap ply layer is used to restrict the growth of the tire, due to centrifugal forces. Cap ply is produced by using a pultrusion process that impregnates polyamide cords with rubber, resulting in a rubberized strip. When the controlling of the process is incorrect, premature vulcanization or lack of impregnation is often observed. To optimize the production process, CFD (Computational Fluid Dynamics) simulations were performed to study the flow of rubber inside the extrusion head channels by modelling the fluid properties and the domain. Laboratory tests were also conducted to determine the physical and cure properties of the rubber compound used. Crossing the results of the simulations with the laboratory tests was found that the temperature control used was inadequate. Simulations were also supported with the results provided by a temperature sensor controlled by an external device (Arduino). By using a proportional integral derivative controller and changing the setpoints for the thermal resistance, the amount of scrap generated by vulcanized rubber and lack of rubber in the cap ply strips was reduced by 100%.info:eu-repo/semantics/publishedVersio

Numerical simulation of adhesively-bonded T-stiffeners by cohesive zone models

30th International Conference on Flexible Automation and Intelligent Manufacturing (FAIM2021) -15-18 June 2021, Athens, GreeceNowadays, the adhesive bonding method has a strong presence in the most varied industries. The bonding of composite materials with structural adhesives became more relevant in the industry, such as the aeronautical industry, which takes advantage of stiffener structures in composite materials using adhesive bonds. In any area of industry, large-scale application of a particular bonding technique requires reliable tools for the design and prediction of failure. This work evaluates the performance of a structural adhesive (Araldite® 2015) on a T-stiffener with composite adherends composed of an epoxy matrix reinforced with carbon fibers. The aim of the work is to numerically study, by the Finite Element Method (FEM) and Cohesive Zone Models (CZM), the behavior of different T-stiffener configurations under peel loads. A parametric study was carried out, including elastic stress analysis and maximum load (Pm) prediction, considering four geometrical parameters: flat adherend thickness (tP), stiffener thickness (t0), overlap length (LO) and curved deltoid radius (R). A significant effect was found for all studied parameters, on both stress distributions and Pm, enabling to define the optimal joint parameters for the T-stiffeners.info:eu-repo/semantics/publishedVersio

Study of the kinematics of a high-course steering system

30th International Conference on Flexible Automation and Intelligent Manufacturing (FAIM2021) 15-18 June 2021, Athens, GreeceIn a context of mobility disruption, due to the accelerated growth of new technologies and sustainability policies, a new class of vehicles is emerging, depending on the type and its function, requiring new technologies suited to its goal. The autonomous modular platforms emerged, in this scenario, to reduce the time of placing electric vehicles on the market, the complexity of the supply and the total cost of production of the vehicle. To facilitate and adapt maneuverability of vehicles to the future challenges of mobility, this paper presents the study of different solutions for a steering system integrated in a modular platform already existing, that enables the vehicles 360° and 90° movements. The difficulty of developing this project is to find a mechanism that meets all kinematic requirements, without compromising the other systems of control and stability of the movement. Thus, considering the parameters of traction and suspension, possible solutions are developed, subsequently tested with the use of the SolidWorks software. Finally, it is concluded that of the solutions tested, the most satisfactory is the one that presents the best kinematic characteristics allied to the smallest course, despite being one of the solutions with more components.info:eu-repo/semantics/publishedVersio

Evaluation of T-joints in aluminium structures under different geometries

30th International Conference on Flexible Automation and Intelligent Manufacturing (FAIM2021) -15-18 June 2021, Athens, GreeceThe adhesive bonding technique is nowadays very popular in industrial applications, and is gradually replacing other more traditional bonding methods (fastened, welded and riveted joints) due to some advantages. However, its application supposes accurate methods for strength prediction. As a result, the techniques to predict the strength of adhesive joints has highly evolved. The eXtended Finite Element Method (XFEM) is a recent innovation implemented over the (Finite Element Method) FEM that enables crack growth to be modelled. However, its application to adhesive joints is still scarce. This work consists of an experimental and XFEM analysis of aluminium alloy T-joints, adhesively-bonded with three adhesive types. A parametric study is undertaken regarding the curved adherends’ thickness (tP2), with values between 1 and 4 mm. The adhesives Araldite® AV138 (strong but brittle), Araldite® 2015 (less strong but moderately ductile) and the Sikaforce® 7752 (with the smallest strength but highly ductile) were tested. A comparative analysis between the different joints conditions was undertaken by plotting peel (σу) and shear (τxy) stresses. The XFEM predictive capabilities were tested with different damage initiation criteria. It was found that, provided that the modelling conditions are properly set, accurate numerical results can be found.info:eu-repo/semantics/publishedVersio

Geometrical parameter study of adhesively-bonded T-joints by cohesive models

A wide variety of adhesive joints architectures is available, offering several options to the designers, although the most common are single-lap joints (SLJ), double-lap joints, and scarf joints. Additional designs, less used and studied are the stepped-lap, T-joints and tubular joints. T-joints find application in different types of industry, such as aircraft to bond stiffeners to skin and in the cars between the B-pillar and the rocker. This work numerically evaluates the performance of the structural adhesive Araldite® 2015 in an aluminum T-joint, after validation with experimental results. A cohesive zone modelling (CZM) numerical study is carried out to capture the behavior of different T-joints geometrical configurations when subjected to peel loads. The work includes a parametric study, considering maximum load (Pm) and dissipated energy at failure (U) prediction, considering four geometrical parameters: flat adherend thickness (a), T-element thickness (t), overlap length (l) and T-element radius (r). A significant effect on Pm was found for the tested parameters, and the CZM method revealed to be a precious method for studying T joints with precision and accuracy.info:eu-repo/semantics/publishedVersio

Cutting forces and wear analysis of Si3N4 diamond coated tools in high speed machining

Si3N4 tools were coated with a thin diamond film using a Hot-Filament Chemical Vapour Deposition (HFCVD) reactor, in order to machining a grey cast iron. Wear behaviour of these tools in high speed machining was the main subject of this work. Turning tests were performed with a combination of cutting speeds of 500, 700 and 900 m min−1, and feed rates of 0.1, 0.25 and 0.4 mm rot−1, remaining constant the depth of cut of 1 mm. In order to evaluate the tool behaviour during the turning tests, cutting forces were analyzed being verified a significant increase with feed rate. Diamond film removal occurred for the most severe set of cutting parameters. It was also observed the adhesion of iron and manganese from the workpiece to the tool. Tests were performed on a CNC lathe provided with a 3-axis dynamometer. Results were collected and registered by homemade software. Tool wear analysis was achieved by a Scanning Electron Microscope (SEM) provided with an X-ray Energy Dispersive Spectroscopy (EDS) system. Surface analysis was performed by a profilometer

Guidelines for Machine Tool Sensing and Smart Manufacturing Integration

30th International Conference on Flexible Automation and Intelligent Manufacturing (FAIM2021) 15-18 June 2021, Athens, Greece.Nowadays the Industry is becoming increasingly competitive with the emergence of even more advanced technologies. This environment leads the companies to look for a bigger availability of the assets, a higher quality of the products and consequently less costs. Thus, is because of this purpose that Maintenance is becoming even more fundamental. The focus of this paper was to develop a strategy of Predictive Maintenance on a Machine Tool with the aim of reducing the unplanned stops, increasing the productivity and creating the bases for an Industry 4.0 environment in the short term. Thus, a model has been created in order to fulfil this goal. The first step was the selection of the critical component of the machine tool that would be studied. In the next phase the variables that will be monitored were selected and their trigger limits. Finally, the necessary components to monitor this system were chosen. In order to reach the objective, a system of condition-based maintenance where the acoustic emissions and vibration of the bearing of a machine tool were monitor was proposed.info:eu-repo/semantics/publishedVersio