Profile Geometry Research Articles

Analysis and manufacturing of bistable metallic profiles

Bistable metal sheets with a coiled transport geometry and an unfolded profile as second stable state, are of great interest as lightweight components. It is well known that a specific distribution of residual stresses is necessary to enable bistable properties. With the help of numerical FE models, the optimal process parameters for production of such sheets are evaluated. Afterwards, incremental bending and roll forming experiments are conducted in order to analyse possible continuous production methods for bistable metallic profiles. Finally, the influence of bending and rolling radii on bistability and profile geometries in stable states are investigated.

Control of residual stresses in roll forming through targeted adaptation of the roll gap

Roll forming is a continuous manufacturing process, which allows for the economical production of a wide range of profile geometries in large batches. When roll formed profiles are cut to length, process related residual stresses are released. This effect, also known as end flare, results in a deformation of the profile ends at the cut-off. However, typical roll formed profiles like linear guides or cable conduits require high dimensional accuracy having tight manufacturing tolerances to guarantee their functionality. Therefore, during process design and set up, countermeasures have to be applied to minimize end flare. In this paper a countermeasure to reduce end flare by targeted adaptation of the roll gap is presented and application limits are discussed. An explanatory model is developed, which shows the creation and reduction of residual stresses due to the reduced roll gap.

Electrodialysis with asymmetrically profiled membranes: Influence of profiles geometry on desalination performance and limiting current phenomena

Electrodialysis (ED) has recently gained much attention in the wide field of desalination and water treatment. However, energy consumption and capital costs may impair the process competitiveness. In this regard, limiting current density (LCD) and current efficiency (η) are key performance parameters for optimized ED systems. In this work, an experimental campaign was carried out characterizing the performance of ED stacks when adopting asymmetrically profiled membranes. Current–voltage curves were recorded under different operating conditions mimicking the operation of brackish water or seawater desalination units. Results showed that there was a preferable direction of the electric current relative to the membrane profiles, which provided higher values of LCD and of maximum η. Stacks with Overlapped Crossed Filaments profiled membranes performed better than conventional ED stacks with flat membranes and spacers by increasing the LCD (by ~20% under various operating conditions) and the maximum η (e.g., from ~55–65% to ~70–73% at 0.5 – 60 g/l inlet concentrations of diluate and brine, respectively). The specific energy consumption was significantly reduced (even more than 50%). On the contrary, the investigated pillar-profiled membranes exhibited the worst performances. The present results suggest that well-designed profiled membranes can reduce the costs of desalination via ED.

Robust Analysis and Laser Stripe Center Extraction for Rail Images

In this paper, a novel method for the effective extraction of the light stripes in rail images is proposed. First, a preprocessing procedure that includes self-adaptive threshold segmentation and brightness enhancement is adopted to improve the quality of the rail image. Secondly, center of mass is utilized to detect the center point of each row of the image. Then, to speed up the procedure of centerline optimization, the detected center-points are segmented into several parts based on the geometry of the rail profile. Finally, piecewise fitting is adopted to obtain a smooth and robust centerline. The performance of this method is analyzed in detail, and experimental results show that the proposed method works well for rail images.

Multi-condition optimization of a cross-flow fan based on the maximum entropy method

Cross-flow fans are widely used in heating, wind-curtains, and air-conditionings, as well as other ventilation systems. A single or double arc is generally used as the camber line of cross-flow fans, but this design leads to constraints in the geometry of the blade profiles. In this study, the camber line of a cross-flow fan blade was parameterized by five parameters based on the fourth-order Bezier curve. A two-dimensional computational fluid dynamics (CFD) simulation was conducted to predict the aerodynamic characteristics and the internal flow field. It is necessary in multi-condition optimization, to evaluate the relative importance of the performance parameters under different working conditions and determine their weight factors. Here, a novel maximum entropy method (MEM) was proposed to quantify of volume flow rate, because the method avoids the subjectivity in the selection of the weights. Subsequently, a multi-island genetic algorithm (MIGA), combined with numerical simulation, was used to search the global optimum in the given design space. The results indicated that the optimum combination of the structural parameters reduced the blade channel vortex in a particular location of the impeller and changed the position and size of the eccentric vortex. The volume flow rate of the optimized impeller was 4.28% higher at the minimum rotation speeds and 12.87% higher at the maximum rotation speeds.

Roller vibroprotection mechanism with a quasi-zero stiffness section

A new numerical method for designing the profile of the support surface for moving the vibration protection mechanism pressure roller for the operator’s seat in road and construction machines has been developed. The roller vibration protection mechanism of the type under consideration provides for the required force characteristic with a quasi-zero stiffness section of a given long length. This advantage of the roller vibration protection mechanism makes it possible to recommend it for application in vibroprotection systems for road and construction machinery operators. Difficulties in creating such mechanisms are caused by the nonlinear nature of the system of algebra-differential equations that describe the relationship between the static force characteristic and the geometry of the mechanism support profile. That is why it is difficult to obtain a solution in the analytical form of a support surface profile and requires a numerical solution. As an example of the efficiency of the proposed method, we obtained a support surface profile for a roller vibration protection mechanism with a given force characteristic in the form of a three-segment spline with 0.1 meters length quasi-zero stiffness section. The developed method lets us use the specified parameter values as the initial data. In the Simscape Multibody application of the MATLAB system, a simulation model of a dynamic vibration protection mechanism system was developed. It allows simulating movements and studying the modes of this mechanism at the design stage. We give an example of the time dependencies of the mechanism points coordinates obtained using a simulation dynamic model for damped free vibrations.

Initial Geometric Imperfections: A Robust, Closed-Section Cold-Formed Box Profile Application Subject to Local Buckling

Initial geometric imperfections are important for simulating local buckling in numerical models. References are found in the technical literature regarding open-section cold formed profiles. This work presents new procedures applied to a robust and closed-section cold formed profile subject to local buckling, and the use of procedures described in the technical literature already successfully used for open section profiles. The difference of this work in relation to the research already carried out is in the type of profile studied, in the mode of failure of the same and in the form of determination of the initial imperfections. The object of study of this work is a closed-section cold formed box profile with a short length when compared with its cross section and with local buckling failure mode. The strategies used in the present work to consider the initial geometric imperfections were to perform the linear stability analysis using the finite element method to obtain the local buckling mode that represents the deformed box profile geometry, to apply a multiplication factor in the displacements, replace the new geometry node coordinates for all profile nodes to induce the local buckling deformation mode, with model validation through experimental testing and the Effective Width Method (MLE) (ABNT NBR 14762 [1]). Finally, using the results of the collapse load of the experimental trial as a basis, it was possible to compare the results obtained by MLE and MEF. Thus, the presentation of this work used a methodology that describes the local buckling behavior and verified the precepts of the existing norms on the subject, combining theoretical and experimental methods, as they bring a better understanding of the structural problem in question.

Experimental and Numerical Investigation of AA5052-H32 Al Alloy with U-Profile in Cold Roll Forming.

The cold roll forming process is broadly used to produce a specific shape of cold-roll formed products for their applications in automobiles, aerospace, shipbuilding, and construction sectors. Moreover, a proper selection of strip thickness and forming speed to avoid fracture is most important for manufacturing a quality product. This research aims to investigate the presence of longitudinal bow, the reason behind flange height deviation, spring-back, and identification of thinning location in the cold roll-forming of symmetrical short U-profile sheets. A room temperature tensile test is performed for the commercially available AA5052–H32 Al alloy sheets using Digital Image Correlation (DIC) technique, which allows complete displacement and strain data information at each time-step. The material properties are estimated from the digital images using correlation software for tested samples; the plastic strain ratios are also calculated from samples at 0°, 45°, and 90° to the rolling direction. The tested sample’s surface morphology and the elemental analysis are conducted using scanning electron microscopy (SEM) method and energy-dispersive X-ray spectroscopy (EDS) analytical technique combined with element mapping analysis, respectively. The cold roll forming experiments are systematically carried out, and then finite element analysis is utilized to correlate the experiment with the model. The performed cold roll forming numerical model outcome indicates a good agreement with the experimental measurements. Overall, the presented longitudinal strain was observed to influence the geometry profile. The spring-back is also noticed at the profile tail end and is more pronounced at high forming speed with lower strip thickness. Conversely, while the forming speed is varied, the strain and stress variations are observed to be insignificant, and the similar results also are recognized for the thinning behavior.

Nonlinear mechanical model of the shaft of a roll forming mill and parameter identification

Roll forming is a continuous process in which a moving metal sheet passes through numerous pairs of opposing forming rolls. The shafts of the roll forming mill are equipped with these rolls and must be set up and aligned to achieve the required final profile of the sheet. The practically relevant task of predicting the profile geometry of this incremental rolling process with varying characteristics of the metal sheet entering the mill requires an accurate description of the stiffness behavior of the shaft with rolls, which is the most compliant part of the roll forming mill. In this paper, the measured force-deflection characteristic of the shaft without rolls is compared with predictions of various theoretical models, followed by the adoption of the shear deformable beam model of the shaft with nonlinear elastic supports in the bearings. The coefficients of the cubic stiffness characteristics of the rotational springs as well as the effective length between the supports are identified based on the experimental data for the deflections, measured along the shaft for various loading levels. The theoretical predictions are obtained via the nonlinear finite element model of the shaft. The model thus provided shows high accuracy compared with the measurements. The paper’s results serve as a foundation for models to predict the stiffness of shafts with rolls.

A Quantitative Biophysical Principle to Explain the 3D Cellular Connectivity in Curved Epithelia

Epithelial cell organization and the mechanical stability of tissues are closely related. In this context, it has been recently shown that packing optimization in bended/folded epithelia is achieved by a surface tension energy minimization mechanism that leads to a novel cellular shape: the scutoid. However, further cellular and tissue level implications of this new developmental paradigm remain unknown. Here we focus on the relation of this complex cellular shape and the connectivity between cells. We address this problem using a combination of computational, experimental, and biophysical approaches in tubular epithelia. We dissect the contribution of the energetic drivers inducing the complex three-dimensional packing of these tissues. We conclude that tubular epithelia satisfy a novel principle, the “Flintstones’ law”, that links tissue geometry and energetic profiles with the average cellular connectivity in epithelia. Our study unveils a quantitative morphogenetic law with key physiological consequences.

Investigation of the influence of incremental sheet forming process parameters using response surface methodology

New methods in metal forming are rapidly developing and several forming processes are used to optimize manufacturing components and to reduce cost production. Single Point Incremental Forming (SPIF) is a metal sheet forming process used for rapid prototyping applications and small batch production. This work is dedicated to the investigation of the profile geometry and thickness evolution of a truncated pyramid. The influence of process parameters during a SPIF process is also studied. A numerical response surface methodology with a Design of Experiments (DOE) is used to improve the thickness reduction and the effects of the springback. A set of 16 tests are performed by varying four parameters: tool diameter, forming angle, sheet thickness, and tool path. The Gurson-Tvergaard-Needleman (GTN) damage model is used to analyze the damage evolution during material deformation. It is found that the model can effectively predict the geometrical profile and thickness with an error of less than 4%. Furthermore, it is noticed that the forming angle is the most influential parameter on the thickness reduction and springback level. Finally, the damage evolution is demonstrated to be sensitive to the forming angle.

ДО ПИТАННЯ ПРО ВИЗНАЧЕННЯ ГРАНИЧНИХ УМОВ ПРОЦЕСУ ПРОКАТКИ-ВОЛОЧІННЯ У ЗДВОЄНИХ РОЛИКОВИХ ВОЛОКАХ

There is a great demand in the world for steel strip profiles, which are widely used in mechanical engineering, instrument making and other sectors of the national economy. In Ukraine, the production of strip profiles is extremely limited. The production volumes of such products, if a wide range of sizes and brands are required, are relatively small. The creation of large specialized enterprises for the production of strip profiles in these conditions is economically unprofitable, the orientation towards the import of these profiles makes the economic and technological security of Ukraine dependent on foreign suppliers. For the production of high-precision profiles, various combinations of basic shaping and auxiliary processes are used, depending not only on the characteristics of the profile itself and the technical requirements of the supply, but also on the size of the ordered batch and the capabilities of the available equipment. This explains the high complexity of technological design. The aim of the work is to determine the boundary conditions of deformation in double roller dies, which ensure a stable flow of the drawing process according to the criterion of the safety factor of the deformed metal. It was found that when calculating the transitions of drawing strip profiles during deformation of the initial round billet with a diameter of 3.67 mm from steel St.70 with a width to thickness ratio of more than two, the maximum value of the relative reduction per transition should not exceed 40-50 % during deformation without counter tension, and 40 % – with tension. Analytical studies have shown that in the range of working reductions per transition (5-40 %), the safety factor that guarantees the process of metal deformation without breakage and does not allow local constrictions and distortion of the profile geometry is not exhausted. It was found that in the range of working reductions per transition (5-40 %), the deformation process of the initial round billet in a roller die with smooth rollers proceeds without exceeding the permissible values of the drawing forces. It has been determined that with an increase in the relative reduction in the first roller die, the range of working reductions in the second roller die, which affects the stability of the metal drawing process, decreases.

A study on the rotor profile and internal clearances of the gerotor pump used in lubricating system of gas turbine engine

Gerotor pump is widely used in lubrication systems of a gas turbine engine where compactness and reliability is of key importance. In this work, the characteristic of the pump is studied for its application in the lubrication system. The rotor profile geometry of the Gerotor pump and its effect on the flow characteristics such as specific flow rate and flow irregularities is studied. The effect of the rotor geometry on the wear characteristics have also been taken into account by considering Hertz contact stress and the relative sliding velocity between the rotors. A Gerotor pump having fixed geometrical parameters designed based on mathematical 1D model using MatLab and AMESim software used for the profile generation and studying the theoretical flow characteristics. This work is further extended by studying the various internal leakages of the pump. The predicted flow rates obtained from Amesim software were then compared with the experimental results and found close match within 5% deviation. Hence, this methodology can be used to estimate performance and wear parameters. This study can assist pump designers to select geometrical parameters and internal clearances of gerotor pump as per their requirements.

Informatization of the Production Process of Rail Grinding in Transit

The possibility of rail grinding process informational support in a transit based on the new approach application and the rail repair profile geometry forming method is considered. The method for designing repair profiles consists of the rail profile geometric parameters calculating at the technological process design stage, taking into account the specific operating conditions of the track and the actual wear of the rail head. Using this method allows minimal removal of metal from the rail head, taking into account the requirements for contact conditions in the wheel-rail system. The mathematical model has been developed for calculating the geometric parameters of a transverse repair profile. In total, the method for calculating the geometric parameters of the rail profile and the method for calculating the inclination angle of grinding trolleys along the rails surface made it possible to increase the level of informational support in a transit, reduce the efficiency and quality impact on a large number of subjective factors, increase the productivity in a transit. Based on them, a software product was created for the automated calculation of asymmetric rail profiles parameters during grinding. The program can be used on rail grinding trains of the RShP-48 and RR-48 type at the stage of preparation for work and the design of the technological process for rail grinding in the conditions of railway track curved sections.

MODELING AND SIMULATION OF THE VERTICAL AXIS WIND TURBINE BY QBLADE SOFTWARE

The use of wind energy has no harmful effects on the environment. This makes it a clean energy that is a real alternative to the problem of nuclear waste management and greenhouse gas emissions. Vertical axis wind turbines have prospective advantages in the field of domestic applications, because they have proven effectual in urban areas where wind flow conditions are intermittent, omnidirectional, unsteady and turbulent. The wind cannot ensure a regular energy supply without optimising the aerodynamics of the blades. This article presents a reminder about wind energy and wind turbines, especially the VAWT type wind turbines and also gives a presentation on the aerodynamic side of VAWT by studying the geometry and aerodynamic characteristics of the blade profiles with the acting forces and also the explanation of the DMS multiple flow tube model. This work also gives the different simulation methods to optimize the behaviour of the blades from the selected NACA profiles; the analysis first goes through the design of the blades by the design and simulation software Qblade which is used to calculate also the forces on the blade and the coefficients of lift, drag and fineness. At the end of this article we have the DMS simulation of the VAWT turbines, by determining the power coefficient and the power collected by the turbine to select the wind turbine adapted to a well characterized site.

Experimental Identification of Optimized Process Parameters for FSW of AZ91C Mg Alloy Using Quadratic Regression Models

This experimental work aims to devise and establish quadratic regression equations, including various input criteria of a friction stir welding (FSW) technique to predict and determine the responses during the fabrication of AZ91C Mg alloy joints. The input process parameters taken into consideration include the traversing speed of the tool, the speed of rotation of the tool, its pin profile (geometry) and the axial force. A five-level, 4 four-factor composite design (of central nature) was applied, and response surface methodology (RSM) was used to formulate quadratic regression models, to develop 3D response surface charts, and to anticipate the responses for various mechanical properties. The generated quadratic mathematical model was tested and validated using the technique of analysis of variance. Validation experimental trial results outlined in the form of scatter diagrams revealed precedented coincidence with that of the generated models. The AZ91C Mg alloy joints obtained using the tool having taper cylindrical pin geometry employed at 1045 rpm, 1.5 mm/s traversing speed, under the exertion of an axial load of 4.87 kN was found to exhibit improved mechanical properties.

Influence of manufacturing error tolerances on contact pressure in gears

Gear manufacturing always results in some degree of manufacturing errors, i.e. deviations from the desired gear geometry. These errors alter how the gears mesh, typically causing increased contact pressure which in turn shortens service life. It is therefore crucial to choose tolerances such that excessive contact pressure, and especially tip contact, is avoided. With increasing demands due to electrification, this becomes even more important. The aim of this paper is to study how pitch error and profile slope error affect the contact pressure in spur gears sets. The meshing is simulated using a novel simulation approach that uses a parametric description of the reference profile and gear geometry, and a hybrid model for the compliance. The method includes tooth modifications such as tip relief, and uses the true geometry to find contacts. Thus, it also handles contact outside the nominal line of action, including tip contact. The study includes cases where a gear is subjected to both pitch error and profile slope error simultaneously. Numerical examples, relevant to the automotive industry, show the outcome of the simulations. It is shown how simulation-based tolerances for relevant industrial applications can be used to improve manufacturing outcome.

Linear gyrokinetic simulations of reversed shear Alfvén eigenmodes and ion temperature gradient modes in DIII-D tokamak

Global linear gyrokinetic simulations using realistic DIII-D tokamak geometry and plasma profiles find co-existence of unstable reversed shear Alfvén eigenmodes (RSAE) with low toroidal mode number n and electromagnetic ion temperature gradient (ITG) instabilities with higher toroidal mode number n. For intermediate n = [10, 12], RSAE and ITG co-exist and overlap weakly in the radial domain with similar growth rates but different real frequencies. Both RSAE and ITG growth rates decrease less than 5% when compressible magnetic perturbations are neglected in the simulations. The ITG growth rates increase less than 7% when fast ions are not included in the simulations. Finally, the effects of trapped electrons on the RSAE are negligible.

Perfection of rolls sizing in bar & wire rod mill 370/150 to ensure accuracy in rolled product profile

An actual problem of production bars with increased geometry accuracy at existing mill 370/150 at OJSC “BMZ -management company of Holding “BMC” has been reviewed. The object of research was reducing-sizing mill, composed of three finishing stands. The subject of research was rolling process in finishing stands aiming at achieving highly accurate geometry in the finished profile. In the work, based on empirical data, efficiency of existing methods of sizing by statistical method to produce a profile of regular accuracy and highly accurate profile was assessed. By the method of finite elements the rolling processes were simulated, approximated to real conditions by means of numerical modeling. Empiric and theoretic data revealed drawbacks of existing systems of sizing, as well as let determine further direction of research. Analytical description of key factors of rolling affecting creation of profile enabled to come to conclusion that the basis for achieving geometry sizes of transversal profile depends on pressure of steel on to rolls and the inter-stand tension. On this basis the new method of sizing has been developed. On the basis of the new method of sizing, rolling processes at different frequencies of rolls rotation were simulated. The process of mathematical simulation to the maximum approximated to real conditions of rolling. Thanks to this it became possible to obtain reliable results of research, enabling to achieve highly accurate geometry of transversal profile. Obtained results of research are the basis for further study of inter-stand deformation to be followed by experimental rolling at mill 370/150.

A highly efficient and informative method to identify ion transport networks in fast ion conductors

High-throughput analysis of the ion transport pathways is critical for screening fast ion conductors. Currently, empirical methods, such as the geometric analysis and bond valence site energy (BVSE) methods, are respectively used for the task. Geometric analysis method can only extract geometric and topological pathway properties without considering the interatomic interactions, while the BVSE method alone does not yield a geometric classification of the sites and interstices forming the pathway. Herein, we propose a highly efficient and informative method to identify interstices and connecting segments constructing an ion transport network by combining topological pathway network and BVSE landscape, which enables to obtain both the geometry and energy profiles of nonequivalent ion transport pathways between adjacent lattice sites. These pathways can be further used as the input for first-principles nudged elastic band calculations with automatically generated chains of images. By performing high-throughput screening of 48,321 Li-, Na-, Mg- and Al-containing ionic compounds from the Inorganic Crystal Structure Database based on the filter combining geometric analysis and BVSE methods, we obtain 1,270 compounds with connected ionic migration pathways of suitable sizes and low migration energy barriers, which include both previously reported fast ion conductors, and new promising materials to be explored further.