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1
Maji, Kuntal. "Parametric Study and Optimization of Pulsed Laser Thermal Micro-Forming of Thin Sheets". International Journal of Manufacturing, Materials, and Mechanical Engineering 9, nr 2 (kwiecień 2019): 47–61. http://dx.doi.org/10.4018/ijmmme.2019040103.
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This article presents the investigations on deformation behavior in precision forming of thin sheet metal by laser pulses using finite element analysis. The temperature and deformation fields were estimated and analyzed in pulsed laser micro-forming of AISI 304 stainless steel sheet of rectangular and circular shape considering the effects of different process parameters such as laser power, spot diameter and pulse on time. Response surface models based on finite element simulation results were developed to study the effects of the process parameters on deformations for the rectangular and circular workpieces. The amount of deformation was increased with the increase in laser power and pulse on time, and it was decreased with the increase in spot diameter. The effects of pulse frequency and sample size on deformations were also explained. Experiments were conducted on pulsed laser micro-forming of stainless-steel sheet to validate the finite element results. The results of finite element simulations were in good agreement with the experimental results.
2
Kim, Young Suk, Duy Tung Do, Dae Cheol Ahn i Dong Woo Shin. "Finite Element Simulations for CFRP Press Forming Process". Key Engineering Materials 651-653 (lipiec 2015): 415–22. http://dx.doi.org/10.4028/www.scientific.net/kem.651-653.415.
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The macro-scale and meso/macro-scale simulations for press forming of CFRP sheet using ABAQUS S/W were both implemented to study the influence fiber orientation on the formability of CFRP sheet. The Hashin damage criterion was used to predict the fiber failure in the forming process. The properties of plain woven fiber fabric were obtained from the tensile test and bias extension test. The forming experiments with rectangular punch were carried out to validate the numerical results.
3
Shotri, Rishabh, Koen Faes, Guillaume Racineux i Amitava De. "Improved Coil Design for Magnetic Pulse Welding of Metallic Sheets". Journal of Manufacturing and Materials Processing 6, nr 6 (16.11.2022): 144. http://dx.doi.org/10.3390/jmmp6060144.
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Magnetic pulse welding of overlapping dissimilar metallic sheets is an emerging technique and usually employs flat electromagnetic coils with rectangular-, H-, I-, and E-shaped cross-sections. The asymmetric cross-section of these coils results in a non-uniform electromagnetic field and in a non-uniform connection in the interface between the overlapping sheets. In this article, the use of a novel O-shaped flat coil is proposed to join an aluminium flyer sheet with a target steel sheet. A finite element-based numerical model is developed to calculate the electromagnetic field, flyer velocity, and its gradual impact onto the target, and the deformations of the sheet assembly. The calculated results with the O-shaped coil show a high-intensity electromagnetic field, the concentration of which decreases radially outwards in a uniform manner. The numerically computed and experimentally measured flyer velocity are found to be in fair agreement. The calculated results show a regularly decreasing impact behaviour between the flyer and target and their resulting deformation. The measured results show the formation of an annular ring-shaped joint profile that is generally found to be stronger compared to that obtained with flat coils with a rectangular cross-section.
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Young, A., D. J. Cartwright i D. P. Rooke. "The boundary element method for analysing repair patches on cracked finite sheets". Aeronautical Journal 92, nr 920 (grudzień 1988): 416–21. http://dx.doi.org/10.1017/s0001924000016559.
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Summary The boundary element method is combined with the method of compatible deformations to obtain stress intensity factors for a cracked sheet reinforced with a repair patch. The method is applied to the analysis of a circular patch over a central crack in a rectangular uniaxially stressed sheet. It is shown that the proximity of the edges of the sheet to the patch edge has a negligible effect on the stress intensity factor of a crack completely under the patch.
5
Zhang, Ling Yun, i Song Xie. "The Numerical Simulation Analysis of the Rectangular Box Straight Springback Law". Applied Mechanics and Materials 401-403 (wrzesień 2013): 946–49. http://dx.doi.org/10.4028/www.scientific.net/amm.401-403.946.
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Abstract. Springback is one of the main factors that affects the quality of sheet metal deep drawing. Due to the springback is inevitable, so to explore the springback law becomes an important content in the process of sheet metal forming. In this paper, the ETA/DYNAFORM finite element software was applied to simulate four different length-width radio model of rectangular box. The simulating data shows that the rectangular box with short straight edge rebounded inward when the central of the long straight edge rebounded outward and near the corner part rebounded inward. The study had a very important guiding significance to the stamping process of rectangular box part and mold design.
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Zhang, X. S. "A tearing mode crack located anywhere in a finite rectangular sheet". Engineering Fracture Mechanics 33, nr 4 (styczeń 1989): 509–16. http://dx.doi.org/10.1016/0013-7944(89)90035-0.
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Bunyan, Tanongsak, Suthep Yiemchaiyaphum i Sansot Panich. "Wrinkling Prediction of Rectangular Cup Deep Drawing Process for Aluminum Alloy Sheets by Using the Modified Yoshida Buckling Test". Key Engineering Materials 856 (sierpień 2020): 143–51. http://dx.doi.org/10.4028/www.scientific.net/kem.856.143.
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Nowadays, the industry has been growing interest in lightweight material for automotive and cookware manufacturing. The formability of sheet material is an important issue in these industries. The wrinkling behavior is one of the most failure in sheet metal forming and is often occurred in deep drawing process in cookware manufacturing. In this work, the developed wrinkling limit curves (WLCs) using experimental and numerical simulation of a modified Yoshida buckling test were precisely used to predict the wrinkling behavior of rectangular cup deep drawing for aluminum alloy sheets grade AA5054-O and AA5052-H32. The Industrial parts, the rectangular cup deep drawing was firstly performed for both investigated aluminum sheets for obtaining the wrinkling initiation on the side wall area of deep drawing parts. Subsequently, the experimental formed parts were carefully measured the draw-in of deformed blank sheets and drawing depth to validate the finite element (FE) model. Then, the FE simulation of the corresponding drawing tests were calculated, by which were implemented with the Hill’48 yield criterion and Swift hardening law to descript anisotropic plastic deformation. As a result, the local principle Major and Minor principle strains of observed wrinkle areas were gathered in the side wall area of the rectangular cup deep drawing test. Finally, the developed WLCs of aluminum alloy sheets were applied to predict the wrinkling formation of the formed deep drawing parts. Comparatively, the influence of different aluminum alloy grades on the WLCs and wrinkling behavior were explicitly investigated.
8
Chen, Qin, i Hui Wu. "Nonlinear Finite Element Analysis on CFRP-Confined Square Concrete Column under Cyclic Lateral Loading". Advanced Materials Research 255-260 (maj 2011): 230–35. http://dx.doi.org/10.4028/www.scientific.net/amr.255-260.230.
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An analog computation of carbon fiber-reinforced polymer (CFRP)-confined rectangular concrete column under cyclic lateral load is carried out using the finite element method (FEM) and is compared with the experimental results. The comparison indicates that the FEM could accurately predict the behavior of CFRP-confined reinforced concrete (RC) column under cyclic lateral loading. The reinforcement mechanism of carbon fiber sheets on RC columns is studied by analyzing the results calculated with FEM such as the stress-strain of carbon fiber sheets, stirrups, and concrete. The effect of axial compression ratio and the number of layers of fiber sheet on the ultimate bearing capacity and displacement ductility of RC column are studied by the finite element analysis. Part of the conclusion, namely, the effect of the number of layers and setting height of fiber sheet on the RC column, offers the reference and basis for further engineering application. template explains and demonstrates how to prepare your camera-ready paper for Trans Tech Publications. The best is to read these instructions and follow the outline of this text.
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Alves, Luis M., Rafael M. Afonso, Carlos M. A. Silva i Paulo A. F. Martins. "Joining by Forming of Tubes to Sheets with Counterbored Holes". Key Engineering Materials 767 (kwiecień 2018): 421–28. http://dx.doi.org/10.4028/www.scientific.net/kem.767.421.
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This paper presents a new joining by forming process for connecting tubes to sheets. The process consists of forming an annular flange with rectangular cross section by partial sheet-bulk of the tube wall thickness and performing the mechanical interlock by upsetting the free tube end against a flat-bottomed (counterbored) sheet hole. The presentation identifies the variables and the workability limits of the process and includes an analytical model to assist readers in the design of the new joints. The new proposed joining by forming process and the corresponding analytical model are validated by experimentation and numerical simulation using finite element analysis. The process allows connecting tubes to sheets made from dissimilar materials at room temperature, avoids the utilization of addition materials or adhesives and produces joints that are easy to disassembly at the end of live, allowing recyclability of the tubes and sheets.
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Yang, D. Y., i Y. J. Kim. "Analysis of Hydrostatic Bulging of Anisotropic Rectangular Diaphragms by the Rigid-Plastic Finite Element Method". Journal of Engineering for Industry 109, nr 2 (1.05.1987): 148–54. http://dx.doi.org/10.1115/1.3187105.
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A variational formulation is derived for the incremental analysis of the nonsteady large deformation of normal anisotropic sheet metal which exhibits a rigid-plastic work-hardening behavior. The associated finite element equations are formulated for the analysis of the hydrostatic bulging process of square and rectangular anisotropic metal diaphragms. The relation between bulging pressure and deformation is studied using the finite element analysis. Instability related with the bulging deformation is analyzed by using the instability criterion for sheet metal. The effect of anisotropy on deformation and instability is investigated and discussed. The theoretical results are shown to be in excellent agreement with the existing experimental results and to be very helpful for a better understanding of the process.
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Filimonov, O. P. "CONCLUSION OF THE STIFFNESS MATRIX OF THE FINITE ELEMENT CONCRETE SLABS". Science and Transport Progress, nr 15 (25.04.2007): 220–24. http://dx.doi.org/10.15802/stp2007/18488.
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The concrete plate with external sheet reinforcing is considered. To the given plate preconditions of the theory of «thin plates» are applied. The order of a conclusion and factors of a matrix of rigidity for a rectangular final element of a considered steel-concrete plate is resulted. In each unit is present on three degrees of freedom. The polynom of 4-th degree with two variables for approximation of movings of points of a plate in a medial surface is accepted.
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Li, Xi Ning, Cheng Yu Jiang i Zhong Qi Wang. "Study for Rectangular Box Drawing of Segmented Variable Blank Holder Force". Materials Science Forum 628-629 (sierpień 2009): 523–28. http://dx.doi.org/10.4028/www.scientific.net/msf.628-629.523.
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The sheet forming simulation of rectangular box was conducted by finite element method (FEM), the forming process experiment, further, was investigated, so as to understand the effect of the form of blank holder and the manner of blank holder force (BHF) on the complicated parts forming. In my study, a kind of low carbon steel was investigated, and its mechanical properties were obtained by simple tension tests. The outermost contour of the blank shape was determined by “one step method”. Furthermore, the finite element model was constructed by ANSYS parametric design language (APDL), which has characteristic of grid meshing by Belytschko-Tsay (BT) shell element, applying anisotropic constitutive equation of Barlat yield criterion, dealing contact by penalty function method and using adaptive mesh algorithm in the simulation process. Then the forming process simulation of rectangular box with segmented variable BHF was conducted. On the basis of analyzing the work principle and technical parameters of XP3CEF-100 hydraulic press, the rectangular box drawing system of segmented VBHF was established, which was made of hydraulic press, rectangular box drawing die of segmented blank holder, hydraulic part of blank holder and control part. Finally the low carbon steel forming tests were fulfilled by the rectangular box drawing system on the basis of the simulation result.
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Jarrar, Firas Salah, i Mohammad Ahmad Nazzal. "Inclination Angle Effect on the Thickness Distribution in a Superplastic Formed Long Rectangular Pan". Materials Science Forum 735 (grudzień 2012): 155–61. http://dx.doi.org/10.4028/www.scientific.net/msf.735.155.
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In the superplastic process, the non-uniformity of the produced part thickness and the possibility of severe thinning are among the major disadvantages. This paper presents a parametric study on the superplastic forming of a Pb-Sn sheet into the shape of a long rectangular pan. A two dimensional plain strain finite element model was used to predict the forming times and thinning profiles of the formed Pb-Sn pan. The effect of varying the sidewall inclination angle was investigated for different friction conditions at the die-sheet interface. Results showed that increasing the side wall inclination angle reduced the forming time and provided a better thickness distribution.
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Lemu, Hirpa G., i T. Trzepieciński. "Study of Material Modeling Strategies for Deformability Analysis of Rectangular Cups". Advanced Materials Research 498 (kwiecień 2012): 243–48. http://dx.doi.org/10.4028/www.scientific.net/amr.498.243.
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A comparative study of different material modeling strategies in deformability analysis of rectangular cups is presented in this paper. The article focuses on application of dynamic explicit and static implicit approaches in Finite Element Methods (FEM) for metal forming simulation where different material models and contact conditions with friction are involved. The simulated results are verified using results from experimental study of the deformation on the same material. Further, a comparison between a quadratic Hill anisotropic yield criterion and von Mises yield criterion with isotropic hardening has been studied. The results confirm that the dynamic explicit method is more efficient in simulating sheet metal forming processes. The study shows also that the finite element analysis undoubtedly gives good approximate numerical results to real processes when the material and friction anisotropy are considered.
15
Brubaker, N. D., i J. Lega. "Capillary-induced deformations of a thin elastic sheet". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 374, nr 2066 (28.04.2016): 20150169. http://dx.doi.org/10.1098/rsta.2015.0169.
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We develop a three-dimensional model for capillary origami systems in which a rectangular plate has finite thickness, is allowed to stretch and undergoes small deflections. This latter constraint limits our description of the encapsulation process to its initial folding phase. We first simplify the resulting system of equations to two dimensions by assuming that the plate has infinite aspect ratio, which allows us to compare our approach to known two-dimensional capillary origami models for inextensible plates. Moreover, as this two-dimensional model is exactly solvable, we give an expression for its solution in terms of its parameters. We then turn to the full three-dimensional model in the limit of small drop volume and provide numerical simulations showing how the plate and the drop deform due to the effect of capillary forces.
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Ren, L. M., S. H. Zhang, G. Palumbo i L. Tricarico. "Warm deep drawing of magnesium alloy sheets — formability and process conditions". Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 222, nr 11 (1.11.2008): 1347–54. http://dx.doi.org/10.1243/09544054jem1114.
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The influence of deformation conditions on the formability of magnesium alloy was systematically investigated using the experimental method and finite element analysis. The research activity aimed to gain further insight into the formability of magnesium alloy AZ31 (aluminium 3 wt per cent, zinc 1 wt per cent) and to have first-hand knowledge of the correlations between the material's properties and the processing parameters. In this work, the mechanical properties of magnesium alloy AZ31 sheet were analysed according to the results of tensile tests. A set of experimental equipment with temperature control was employed to perform warm deep drawing of magnesium alloy AZ31 sheets under various forming conditions. The most important process parameters, including the punch speed, the forming temperature, and the geometrical shape of the blank, were taken into account and optimal values were proposed. Finite element analyses were also performed to evaluate the effects of the process parameters on the formability of rectangular cup drawing and to predict the process defects during the process.
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Sherek, Paul A., Louis G. Hector, John R. Bradley, Paul E. Krajewski i Eric M. Taleff. "Simulation and Experiments for Hot Forming of Rectangular Pans in Fine-Grained Aluminum Alloy AA5083". Key Engineering Materials 433 (marzec 2010): 185–95. http://dx.doi.org/10.4028/www.scientific.net/kem.433.185.
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Accurate numerical simulation capability is critical to the development and implementation of hot forming technologies. Numerical simulations were developed for gas-pressure forming of commercial, fine-grained aluminum-magnesium (AA5083) material into deep pan shapes at 450°C. These simulations utilize a material constitutive model recently developed for fine-grained AA5083 materials as a user-defined routine in commercial Finite Element Method (FEM) software. Results from simulations are compared against data from gas-pressure forming experiments, which used the same forming conditions and die geometries. Specifically, local sheet thinning and radius of curvature in edges and corners are compared between simulation and experiment. Numerical simulations are in good agreement with experiments for local sheet thinning of up to 50%. For locations where sheet thinning exceeds 50%, simulations predict less thinning and larger formed radii than observed in experiments. It is likely that cavitation, which is not accounted for in simulations, plays a significant role in causing a decrease in simulation prediction accuracy for thinning values greater than 50%. This study demonstrates a simulation capability that is potentially of significant practical use for predicting the hot gas-pressure forming of fine-grained AA5083 material.
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Fagundes, Daniel Almeida. "Electrostatic potential of a rectangular uniformly charged plate: exact solution and limiting cases". European Journal of Physics 43, nr 1 (23.11.2021): 015203. http://dx.doi.org/10.1088/1361-6404/ac362f.
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Abstract In this paper I derive the exact solution to the electrostatic potential of a rectangular uniformly charged plate with charge density, σ, along the symmetry axis passing through its center, at distance z. The analytical solution generalizes recently obtained formulae for the special case of a square plate. Moreover, given the generality of the solution I obtain a set of limiting and particular cases well-known in the literature, such as: (i) the finite square plate; (ii) an infinite charged sheet; (iii) a 1D finite charged rod; (iv) a 1D infinite charged rod; (v) a single charge at the origin. I also discuss possible benefits of using these results in the context of teaching electrostatics in university physics classes, in the form of challenging exercises to be worked out in groups, and as a helpful tool to emphasize the power of limits and approximations in physics.
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Magrinho, JPG, CMA Silva, MB Silva i Paulo AF Martins. "Formability limits by wrinkling in sheet metal forming". Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 232, nr 8 (5.04.2016): 681–92. http://dx.doi.org/10.1177/1464420716642794.
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This paper presents a new combined experimental and theoretical methodology for determining the formability limits by wrinkling in sheet metal forming. The methodology is based on the utilization of rectangular test specimens clamped along its narrower sides and compressed lengthwise and is aimed at replicating the physics behind the occurrence of wrinkling in deformation regions submitted to in-plane compression along one direction. The methodology draws from a previous development in the field of flexible roll forming, and the overall objectives are to enhance and improve its methods and procedures and to provide a new level of understanding on the onset of wrinkling in sheet metal forming. Experimentation and finite element modelling of cylindrical deep-drawing without blank holder combined with the utilization of the space of effective strain vs. stress triaxiality are employed to discuss the applicability and validity of the new proposed methodology for determining the formability limits by wrinkling.
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Peiravi, Mohammad Mohsen, Pooya Pasha i Davood Domairry Ganji. "Hydro Magnetic Effect on Thread Stretching Surface with Mounted Obstacles in Porous Medium". WSEAS TRANSACTIONS ON HEAT AND MASS TRANSFER 16 (12.07.2021): 95–105. http://dx.doi.org/10.37394/232012.2021.16.12.
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In this paper, Finite element Model is applied for investigation of fluid flow over a stretching sheet in existence of magnetic field. Finite element method is applied to find the influence of melting heat transfer on fluid flow behavior over a stretching sheet in presence of magnetic field. we investigated the flow of fluid flowing through the fins plate under the influence of the magnet. The fins were on the board and the end of the plate. In the case of chamfer fins, the maximum temperature variation is observed. In this fins, the maximum temperature of T = 2.5 and minimum temperature is T = 3. in general, we conclude that the temperature flow around the rectangular fins has a maximum value than 2 other modes. In triangular fins, the fluid temperature vector around the fins has more intensity than other modes and the temperature gradient around it is larger than the previous one and the fluid flow at the end of the plate also has more temperature than the Rectangular fins. The maximum amount of fluid concentration has been observed around the first fin of chamfer mode in range of X=0.05 to X=0.1. In general, the fluid concentration around the triangular fins is higher than other modes. the maximum amount of fluid concentration is found in the triangular fins on the surface. Their concentration from the first fin reaches a value of 2.5 and in the last fin at a value of 1.4.
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Balasubramanian, M., K. Ramanathan i Ke Zhu. "Finite Element Modeling and Numerical Simulation of Superplastic Forming of 8090 Al-Li Alloy in a Rectangular Die". Advanced Materials Research 487 (marzec 2012): 116–21. http://dx.doi.org/10.4028/www.scientific.net/amr.487.116.
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Superplasticity is a physical phenomenon associated with certain polycrystalline materials which exhibit very high tensile elongation prior to fracture under particular conditions of strain rate and temperature. Aluminium alloy undergoes superplastic elongation in the order of a few thousands percent in elongation with low flow stresses. Superplastic forming processes can provide products with integral structure, light weight and superior strength, all of which are of particular importance for aerospace and automotive components. In the present study an analytical model was developed for a rectangular component by considering constant strain rate. This paper attempts to explore the superplastic behaviors of 8090 Al-Li alloy sheet into a rectangular die using blow forming technique. This has been done by a simple theoretical model and by numerical simulation using standard finite element code ABAQUS. The numerical and analytical results agree reasonably well for both the analytical and theoretical values with regard to variation in pressure and time.
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Tsamaphyros, G., i E. E. Theotokoglou. "Crack approaching perpendicularly the boundary of a rectangular sheet: An integral equation and finite element solution". Theoretical and Applied Fracture Mechanics 5, nr 3 (czerwiec 1986): 173–79. http://dx.doi.org/10.1016/0167-8442(86)90004-2.
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Liu, Pan, Tae Wan Ku i Beom Soo Kang. "A Study on Initial Blank Design to Minimize Earing in Multi-Stage Deep Drawing Process for Rectangular Cup Using High Strength Steel Material". Advanced Materials Research 652-654 (styczeń 2013): 1971–75. http://dx.doi.org/10.4028/www.scientific.net/amr.652-654.1971.
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Multi-stage deep drawing process for rectangular cups with extreme aspect ratio using finite element analysis is performed. The process is mainly consists of four forming stages including blanking, drawing, ironing and trimming. However, main deformation of the rectangular cup is completed during the drawing-ironing procedure. Tool design and blank modification for the multi-stage deep drawing process are presented. To consider the deep drawing and the ironing operations, the multi-stage deep drawing process is applied to obtain the rectangular cup by using each numerical simulation models from first to fifth drawing. Based on the design results of the initial blank, the multi-stage deep drawing process is performed, but it is shown that severe earing phenomenon is occurred at the upper flange part. To solve the severe deformation at the upper flange due to normal anisotropy of the used sheet material, initial blank modification is carried out. The simulation results for the rectangular cup are compared with the final configuration before and after the modification of the blank shape. The predicted result is confirmed that the modified blank shape not only improve the quality of a deep-drawn product but also reduce the cost of production.
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Peroni, Lorenzo, i Martina Scapin. "Experimental analysis and modelling of the strain-rate sensitivity of sheet niobium". EPJ Web of Conferences 183 (2018): 01014. http://dx.doi.org/10.1051/epjconf/201818301014.
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The niobium is currently used for the construction of the superconducting radio frequency (RF) Crab Cavity for the particle accelerator LHC at CERN in Geneva. An alternative technique to traditional forming methods is the electrohydraulic forming (EHF), in which ultrahigh-speed deformation of blank sheets is performed by using shockwaves electrically induced in water. A big effort is made for the analysis of the forming processes by FEM simulations, which require the definition of an appropriate flow stress material model. With this aim, in the present work, a testing campaign was performed in tension on sheet specimens with a rectangular cross-section at different strain-rates, up to 103 s-1. The obtained results showed the material is strongly sensitive to strain-rate, as expected for a pure BCC metal. The data, were processed via a reverse engineering procedure, based on finite element simulations of the experimental tests. This methodology allowed the identification of a tabular flow stress model (MAT_224 implemented in LSDYNA) for the prediction of the material behaviour as a function of the plastic strain, strain-rate and temperature.
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Fadhel, Essam Z. "NUMERICAL OPTIMIZATION OF SANDWICH COMPOSITE STRUCTURE UNDER FLEXURAL LOAD". IRAQI JOURNAL FOR MECHANICAL AND MATERIALS ENGINEERING 18, nr 4 (5.01.2019): 616–27. http://dx.doi.org/10.32852/iqjfmme.v18i4.224.
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The structures of a sandwich composite have been utilized in the aerospace industry andengineering applications. Prediction of a theoretical composite construction's flexuralproperties is important for efficient composite products design. In this investigation, fourdifferent core shapes were used in the fabrication of the sandwich frames with constantvolume of sandwich composite structure in each case; these are hexagonal, rectangular,triangular and circular. The effect of core stiffeners number was studied to finding the beststiffeners number which gives the highest properties in strength using the finite elementanalysis.The material of the each face sheet is consisting from epoxy with four layers of a wovenfiberglass laminate construction, and the core stiffener material consists from epoxy matrixwith carbon fiber, the fiber volume fraction was 60% for both skins and core composites.The analysis of the three point bending load with a value of (10 kN) conducted byconstructing a finite element model, explained that the best shape of core was rectangularwhich give less deflection value of (11.939 mm) from the other shapes, for the sameproperties of material and constant core volume in each case. Also, it was determined theoptimum stiffeners number, for the rectangular core, was five stiffeners in longitudinaldirection and twelve stiffeners in transverse direction, gives strengthen structure.
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Nanu, Neculai, Gheorghe Brabie i Maria Bologan. "Influence of the Blankholder Force on the Accuracy of the Rectangular Drawn Parts Made from Steel Sheets". Applied Mechanics and Materials 371 (sierpień 2013): 143–47. http://dx.doi.org/10.4028/www.scientific.net/amm.371.143.
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In the case of sheet metal forming process one of the most important phenomena that affect the dimensional and shape accuracy of the formed parts is the part springback after the tools removing. The springback phenomenon depends, on the one hand by the material mechanical parameters (especially Youngs modulus, anisotropy coefficient, yield stress) and on the other hand by the process parameters and tools geometry. Therefore in order to control the springback for a given material, the influence of the process parameters or tools geometry must be know. The aim of the present paper is to investigate the effect of blankholder force (as process parameter) on the springback parameters in the case of rectangular parts made from steel sheets. The investigations were made both experimentally and by finite element simulation. The springback parameters of the obtained parts were determined by using the ATOS system and ATOS software that allows the virtual reconstruction of the part shape in order to measure the springback parameters. Both experimental and simulation tests shown that the use of a high value of blankholder force leads to the increase of the drawn part accuracy.
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Xia, Wei, Huan Yang i Jian Min Zeng. "Research on Methods of Sheet Blank Shape Optimization for Drawing of Complex Special-Shaped Boxes". Advanced Materials Research 399-401 (listopad 2011): 1826–31. http://dx.doi.org/10.4028/www.scientific.net/amr.399-401.1826.
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The reasonable blank shape is very important for drawing forming quality of sheet. In this paper, the blank shape is obtained by inverse calculation based on final drawing workpiece, with finite element software. The optimal blank contour is determined by modifying the 3D models of final drawing workpiece and comparing with forming quality of the different inverse calculated blank shapes, according to the stress and the material flow law in drawing process. The results show that, in the case of the given shapes of workpiece, the blank shapes with high precision can be obtained, the formability becomes better, and the number of drawing forming can be reduced by using the method. The method may also contribute to the drawing of large and medium-sized panels, rectangular boxes and special-shaped parts.
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Mei, Han, Lihui Lang, Kangning Liu i Xiaoguang Yang. "Evaluation Study on Iterative Inverse Modeling Procedure for Determining Post-Necking Hardening Behavior of Sheet Metal at Elevated Temperature". Metals 8, nr 12 (10.12.2018): 1044. http://dx.doi.org/10.3390/met8121044.
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The identification of the post-necking strain hardening behavior of metal sheet is important for finite element analysis procedures of sheet metal forming process. The inverse modeling method is a practical way to determine the hardening curve to large strains. This study is thus focused on the evaluation of the inverse modeling method using a novel material performance test. In this article, hot uniaxial tensile test of a commercially pure titanium sheet with rectangular section was first conducted. Utilizing the raw data from the tensile test, the post-necking hardening behavior of the material is determined by a FE-based inverse modeling procedure. Then the inverse method is compared with some classical hardening models. In order to further evaluate the applicability of the inverse method, biaxial tensile test at elevated temperatures was performed using a special designed cruciform specimen. The cruciform specimen could guarantee that the maximum equi-biaxial deformation occurs in the center section. By using the inverse modeling procedure, the hardening curves under biaxial stress state are able to be extracted. Finally the stress-strain curves obtained from the two experiments are compared and analysis studies are provided.
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Zhang, X. S. "A finite rectangular sheet with a pair of edge cracks excited by a normal anti-plane shear wave". Engineering Fracture Mechanics 35, nr 6 (styczeń 1990): 1037–42. http://dx.doi.org/10.1016/0013-7944(90)90131-y.
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Milinazzo, F., Marvin Shinbrot i N. W. Evans. "A mathematical analysis of the steady response of floating ice to the uniform motion of a rectangular load". Journal of Fluid Mechanics 287 (25.03.1995): 173–97. http://dx.doi.org/10.1017/s0022112095000917.
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In this article, we considered the steady response of an infinite unbroken floating ice sheet to the uniform motion of a rectangular load. It is assumed that the ice sheet is supported below by water of finite uniform depth. The ice displacement is expressed as a Fourier integral and the method of residues is combined with a numerical quadrature scheme to calculate the displacement of the surface. In addition, asymptotic estimates of the displacement are given for the far field and for the case where the aspect ratio of the load is large. The far-field approximation provides a good description of the surface displacement at distances greater than about one or two wavelengths away from the load. The behaviour of the steady solution at the two critical speeds Um, where the phase speed takes on its minimum, and Ug, the speed of gravity waves on shallow water, observed in Schulkes & Sneyd (1988) for an impulsively started line load is examined to see if these speeds are critical for two-dimensional loads. Unlike the steady part of the solution in Schulkes & Sneyd (1988), the solution is everywhere finite at the critical speed Ug. However, at the load speed Um, the solution is unbounded. At all load speeds the change in surface displacement is greatest near the load. A comparison with the experimental observations of Takizawa (1985) is made. Our calculations show a significant dependence of the amplitude of the ice displacement on the aspect ratio of the load. For wide loads the surface deflection has much more structure than does the surface displacement corresponding to loads of smaller aspect ratios.
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Alves, LM, RM Afonso, CMA Silva i PAF Martins. "Joining sandwich composite panels to tubes". Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 233, nr 7 (27.03.2018): 1472–81. http://dx.doi.org/10.1177/1464420718763463.
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This paper proposes a new joining by forming process for connecting metal–polymer sandwich composite panels to metallic tubes. The process involves forming an annular flange with rectangular cross-section by partial sheet-bulk of the tube wall thickness and performing the mechanical interlocking by upsetting the free tube end against the sandwich composite with a flaring punch. The presentation addresses the main process variables and workability limits, and the overall conclusions are supported by experimentation and finite element analysis. Results show that the new proposed joining by forming process has potential to be used in mass production contributing, therefore, to extend the application of metal–polymer sandwich composites to structural components.
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Li, Jinbo, Xiaohui Chen, Xiao Chen, Hao Liu i Xianlong Liu. "Deep drawing of a rectangular cup with a small radius at the bottom circular arc by employing a locally-thickened plate". Manufacturing Review 9 (2022): 16. http://dx.doi.org/10.1051/mfreview/2022015.
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A rectangular cup with a small radius at the bottom circular arc is a common sheet metal structure in aerospace components. However, when aluminum alloy plates are used for deep drawing of this type of rectangular cups, the wall thickness around the bottom circular arc is severely decreased. Hence, in this paper, locally-thickened plates were adopted for deep drawing of aluminum alloy rectangular cups with a relatively small radius at the bottom circular arc. The effect of thickening parameters of a locally-thickened plate on the radius at the bottom circular arc and the forming load was investigated by employing finite element simulations and deep drawing experiments. The results indicate that a smaller radius at the bottom circular arc is obtained by increasing the angle or reducing the thickness of the thickened convex rib of a plate. Moreover, the aforementioned is achieved when the side length of the thickened convex rib is equal to the punch width. The forming load is closely related to the thickening parameters of a locally-thickened plate. A small radius of 5 mm at the bottom circular arc was successfully obtained by optimizing the thickening parameters. Furthermore, the forming load during the deep drawing was significantly reduced.
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Shahnazari- Aval, Hossein, Mirsattar Meshinchi-Asl i Mahmoud Mehramuz. "Numerical Modelling of TEM Fields by the Edge-Based Finite Element Method Using Tetrahedral Element for Central Rectangular Loops". Nexo Revista Científica 34, nr 04 (28.10.2021): 1180–99. http://dx.doi.org/10.5377/nexo.v34i04.12647.
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In this study, we have implemented an edge-based finite element method for the numerical modeling of the transient electromagnetic method. We took the Helmholtz equation of the electric field as the governing equation for the edge-based finite element analysis. The modeling domain was discretized using linear tetrahedral mesh supported by Whitney-type vector basis functions. We inferred the equations by applying the Galerkin method. The system of equation was solved using a corrected version of the Bi Conjugate Gradient Stabilized Method (BiCGStab) algorithm to reduce the computational time. We obtained numerical solution for electric field in the Laplace domain; then the field was transformed into the time domain using the Gaver-Stehfest algorithm. Following this, the impulse response of the magnetic field was obtained through the Faraday law of electromagnetic induction as it is considerably more stable and computationally more efficient than inversion using the Fourier Transform. 3D geoelectric models were used to investigate the convergence of the edge-based finite element method with the analytic solution. The results are in good agreement with the analytical solution value for two resistivity contrasts in the 3D geoelectric brick model. We also compared the results of tetrahedral elements with the brick element in the 3D horizontal sheet and 3D conductive brick model. The results indicated that these two elements show very similar errors, but tetrahedral reflects fewer relative errors. For the low resistivity geoelectric model, numerical checks against the analytical solution, integral-equation method, and finite-difference time-domain solutions showed that the solutions would provide accurate results.
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Bernai-Aguilar, Yudiesky, Richard Urama, Jose R. Marty-Delgado i Okoye Celestine N. "Development of Intelligent Control of Optimum Parameters in Deep Drawing of Sheet Metal Using Genetic Algorithm and Finite Element Methods". Advanced Materials Research 690-693 (maj 2013): 2280–90. http://dx.doi.org/10.4028/www.scientific.net/amr.690-693.2280.
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The main purpose of this work is to develop an intellectualized control technique on the deep drawing of rectangular pan made of AISI 304 DDQ stainless steel using genetic algorithm and finite element methods. These control methods are employed in order to investigate the most significant parameters in sheet metal forming process such as drawing force, with a view of optimizing these parameters. The genetic algorithm is used for the optimization purpose to minimize the force of the deep drawing process and to investigate the roles of other parameters. Experimental results show that these combinations of control system can cover a wide range of both materials and influential forming parameters automatically. The results further confirm that the developed system is effective and valid alternative for quick responsible control system with high flexibility.
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Abe, Y., J. Watanabe i Kenichiro Mori. "Stamping of One-Piece Automobile Steel Wheels from Tube". Key Engineering Materials 344 (lipiec 2007): 427–33. http://dx.doi.org/10.4028/www.scientific.net/kem.344.427.
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A multi-stage stamping process of one-piece automobile steel wheels from tubes was developed to decrease the loss of material for the blanking. In this process, the tube is nosed into a cup with a central hole, and then the taper bottom and side wall of the cup are formed into disk and rim portions of the wheel, respectively. The tube is produced by bending a rectangular sheet into a tube and by welding both edges of the bent sheet to prevent the loss of material for the blanking. The stamping sequence of the one-piece wheels was designed by finite element simulation. The central hole of the cup was decreased to a desired diameter of the hub hole without buckling and wrinkling by a 5-stages nosing operation. The taper bottom of the cup was reversely drawn, and then was flared without folding by 2 stages. The wall thickness of the formed wheel was thick and thin in the disk and rim portions, receptively, and thus the requirement of strength of wheels is satisfied. A one-piece wheel having a hub hole was successfully formed by the designed sequence in a miniature experiment.
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Vatulia, G. L., A. O. Lovska, S. S. Myamlin i Ye S. Krasnokutskyi. "Substantiation of the Design Features of Sandwich Panels for Container Wall Lining". Science and Transport Progress, nr 1(101) (28.03.2022): 55–63. http://dx.doi.org/10.15802/stp2023/280009.
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Purpose. The main purpose of this work is to substantiate the design features of sandwich panels for the manufacture of container walls of size 1SS. Methodology. To ensure the strength of the container walls, it is proposed to use sandwich panels as their components. This involves the manufacture of a sandwich panel from two metal sheets, between which a material with energy-absorbing properties is placed. This solution helps to improve the strength of the container by reducing its load. To determine the thickness of the panel sheet, the corresponding calculations were performed using the Bubnov-Galerkin method. It is taken into account that the sheet is a thin-walled plate subjected to an evenly distributed load. To improve the stiffness of the sheet, it is proposed to make it corrugated. The analysis of the corrugations has led to the conclusion that it is most appropriate to use corrugations with a rectangular configuration. Findings. The strength of the sandwich panel was calculated. The spatial model of the sandwich panel was created in the SolidWorks software package, and the strength calculation was performed in SolidWorks Simulation, which implements the finite element method. The calculations took into account the most unfavorable loading mode of the container during rail transportation - shunting impact. The calculation was performed on the example of the container's end wall, since it is the wall that is subjected to the highest loads in the event of a shunting collision with a platform car. The strength calculations showed that the maximum stresses in the sandwich panel made of corrugated sheets are about 258 MPa, which is 16% lower than the permissible stresses. The maximum displacements in the sandwich panel assemblies occur in its middle part and are equal to 3.1 mm. Originality. The design of the sandwich panels that form the end walls of the container is scientifically substantiated. The rational configuration of the corrugations of the sandwich panel sheets is determined. Practical value. The study will contribute to the development of recommendations for the design of modern modular-type vehicle structures and improve the efficiency of the transport industry.
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Bernspång, Lars, Tag Hammam, Kjell Mattiasson, Erik Schedin, Arne Melander i Alf Samuelsson. "Verification of an explicit finite-element code for the simulation of the press forming of rectangular boxes of coated sheet steels". Journal of Materials Processing Technology 39, nr 3-4 (listopad 1993): 431–53. http://dx.doi.org/10.1016/0924-0136(93)90174-5.
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Qi, Chang, Shu Yang, Dong Wang i Li-Jun Yang. "Ballistic Resistance of Honeycomb Sandwich Panels under In-Plane High-Velocity Impact". Scientific World Journal 2013 (2013): 1–20. http://dx.doi.org/10.1155/2013/892781.
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The dynamic responses of honeycomb sandwich panels (HSPs) subjected to in-plane projectile impact were studied by means of explicit nonlinear finite element simulations using LS-DYNA. The HSPs consisted of two identical aluminum alloy face-sheets and an aluminum honeycomb core featuring three types of unit cell configurations (regular, rectangular-shaped, and reentrant hexagons). The ballistic resistances of HSPs with the three core configurations were first analyzed. It was found that the HSP with the reentrant auxetic honeycomb core has the best ballistic resistance, due to the negative Poisson’s ratio effect of the core. Parametric studies were then carried out to clarify the influences of both macroscopic (face-sheet and core thicknesses, core relative density) and mesoscopic (unit cell angle and size) parameters on the ballistic responses of the auxetic HSPs. Numerical results show that the perforation resistant capabilities of the auxetic HSPs increase as the values of the macroscopic parameters increase. However, the mesoscopic parameters show nonmonotonic effects on the panels' ballistic capacities. The empirical equations for projectile residual velocities were formulated in terms of impact velocity and the structural parameters. It was also found that the blunter projectiles result in higher ballistic limits of the auxetic HSPs.
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Simlandi, Sudip, Nilkanta Barman i Himadri Chattaopadhyay. "Behaviour of Semisolid Slurry Flows through a Channel". Solid State Phenomena 256 (wrzesień 2016): 146–52. http://dx.doi.org/10.4028/www.scientific.net/ssp.256.146.
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In case of metal sheet forming of alloys in semisolid state, modelling of the process is very essential to predict flow behaviour, temperature distribution of the alloy etc. towards improvement of the product quality and to reduce manufacturing costs. Accordingly, the present work develops a model to predict the behaviour during metal sheet forming of an Al-alloy (A356) in semisolid state. The semisolid alloy passes through a rectangular channel having small depth and larger width. The alloy in semisolid state is cooled from the top at a controlled rate. In the model, the respective flow field is represented by the momentum conservation equation. The non-Newtonian behaviour of the semisolid slurry is incorporated considering the Herschel–Bulkley model. The agglomeration and de-agglomeration phenomena of the suspended particles under shear are represented using a time dependent structural parameter. The temperature field is predicted considering the transient energy conservation equation, and hence the fraction of solid is continuously updated. The solution considers an apparent viscosity of the semisolid alloy as a function of structural parameter, shear stress and shear rate. The governing equations are finally solved by finite difference method. The work predicts velocity, temperature and liquid fraction distribution of the semisolid slurry.
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Fan, Boyu, Cecilia Huertas-Cerdeira, Julia Cossé, John E. Sader i Morteza Gharib. "Effect of morphology on the large-amplitude flapping dynamics of an inverted flag in a uniform flow". Journal of Fluid Mechanics 874 (10.07.2019): 526–47. http://dx.doi.org/10.1017/jfm.2019.474.
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The stability of a cantilevered elastic sheet in a uniform flow has been studied extensively due to its importance in engineering and its prevalence in natural structures. Varying the flow speed can give rise to a range of dynamics including limit cycle behaviour and chaotic motion of the cantilevered sheet. Recently, the ‘inverted flag’ configuration – a cantilevered elastic sheet aligned with the flow impinging on its free edge – has been observed to produce large-amplitude flapping over a finite band of flow speeds. This flapping phenomenon has been found to be a vortex-induced vibration, and only occurs at sufficiently large Reynolds numbers. In all cases studied, the inverted flag has been formed from a cantilevered sheet of rectangular morphology, i.e. the planform of its elastic sheet is a rectangle. Here, we investigate the effect of the inverted flag’s morphology on its resulting stability and dynamics. We choose a trapezoidal planform which is explored using experiment and an analytical theory for the divergence instability of an inverted flag of arbitrary morphology. Strikingly, for this planform we observe that the flow speed range over which flapping occurs scales approximately with the flow speed at which the divergence instability occurs. This provides a means by which to predict and control flapping. In a biological setting, leaves in a wind can also align themselves in an inverted flag configuration. Motivated by this natural occurrence we also study the effect of adding an artificial ‘petiole’ (a thin elastic stalk that connects the sheet to the clamp) on the inverted flag’s dynamics. We find that the petiole serves to partially decouple fluid forces from elastic forces, for which an analytical theory is also derived, in addition to increasing the freedom by which the flapping dynamics can be tuned. These results highlight the intricacies of the flapping instability and account for some of the varied dynamics of leaves in nature.
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Vu, Viet, Yan Beygelzimer, Roman Kulagin i Laszlo Toth. "Mechanical Modelling of the Plastic Flow Machining Process". Materials 11, nr 7 (16.07.2018): 1218. http://dx.doi.org/10.3390/ma11071218.
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A new severe plastic deformation process, plastic flow machining (PFM), was introduced recently to produce sheet materials with ultrafine and gradient structures from bulk samples in one single deformation step. During the PFM process, a part of a rectangular sample is transformed into a thin sheet or fin under high hydrostatic pressure. The obtained fin is heavily deformed and presents a strain gradient across its thickness. The present paper aims to provide better understanding about this new process via analytical modelling accompanied by finite element simulations. PFM experiments were carried out on square commercially pure aluminum (CP Al) billets. Under pressing, the material flowed from the horizontal channel into a narrow 90° oriented lateral channel to form a fin sheet product, and the remaining part of the sample continued to move along the horizontal channel. At the opposite end of the bulk sample, a back-pressure was applied to increase the hydrostatic pressure in the material. The experiments were set at different width sizes of the lateral channel under two conditions; with or without applying back-pressure. A factor called the lateral extrusion ratio was defined as the ratio between the volume of the produced fin and the incoming volume. This ratio characterizes the efficiency of the PFM process. The experimental results showed that this ratio was greater when back-pressure was applied and further, it increased with the rise of the lateral channel width size. Finite element simulations were conducted in the same boundary conditions as the experiments using DEFORM-2D/3D software, V11.0. Two analytical models were also established. The first one used the variational principle to predict the lateral extrusion ratio belonging to the minimum total plastic power. The second one employed an upper-bound approach on a kinematically admissible velocity field to describe the deformation gradient in the fin. The numerical simulations and the analytical modelling successfully predicted the experimental tendencies, including the deformation gradient across the fin thickness.
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Risch, Patrick, Dorothea Helmer, Frederik Kotz i Bastian E. Rapp. "Analytical Solution of the Time-Dependent Microfluidic Poiseuille Flow in Rectangular Channel Cross-Sections and Its Numerical Implementation in Microsoft Excel". Biosensors 9, nr 2 (24.05.2019): 67. http://dx.doi.org/10.3390/bios9020067.
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We recently demonstrated that the Navier–Stokes equation for pressure-driven laminar (Poiseuille) flow can be solved in any channel cross-section using a finite difference scheme implemented in a spreadsheet analysis tool such as Microsoft Excel. We also showed that implementing different boundary conditions (slip, no-slip) is straight-forward. The results obtained in such calculations only deviated by a few percent from the (exact) analytical solution. In this paper we demonstrate that these approaches extend to cases where time-dependency is of importance, e.g., during initiation or after removal of the driving pressure. As will be shown, the developed spread-sheet can be used conveniently for almost any cross-section for which analytical solutions are close-to-impossible to obtain. We believe that providing researchers with convenient tools to derive solutions to complex flow problems in a fast and intuitive way will significantly enhance the understanding of the flow conditions as well as mass and heat transfer kinetics in microfluidic systems.
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Nzokou, François, Brian Morse, Jean-Loup Robert, Martin Richard i Edmond Tossou. "Water wave transients in an ice-covered channel". Canadian Journal of Civil Engineering 38, nr 4 (kwiecień 2011): 404–14. http://dx.doi.org/10.1139/l11-010.
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Many studies show that the propagation of a breakup water surge in impeded rivers (ice cover present) differs from the unimpeded case. Some of the differences are due to ice sheet breaking into pieces as the wave travels downstream while others are due to the effect of a fissured but otherwise intact ice cover’s resistance to motion. This is the subject of this paper: water waves that are sufficiently strong to break the cover away from the banks but not strong enough to create transverse cracks. Although some analytical solutions exist for the propagation of these transients for simple cases, for the first time in the literature, this paper introduces numerical solutions using a FEM model (HYDROBEAM) that simulates this interaction using the one-dimensional Saint-Venant equations appropriately written for rivers having an intact fissured floating ice cover coupled with a classic beam equation subject to hydrostatic loads (often referred to as a beam on an elastic foundation). The governing equations are numerically expressed and are solved using a finite element method (FEM) for the hydrodynamic and ice beam equations separately. A coupling technique is used to converge to a unique solution at each time step (for more information on the numerical characteristics of the model, see companion paper presented by the authors in this issue). The coupled model, gives a first and unique opportunity to compare the simplified analytical solutions to the full numerical solutions. A parametric analysis is herein presented that quantifies the impact of the ice cover's presence and stiffness on wave attenuation and wave celerity as well as to quantify tensile stresses generated in the ice sheet as a function of ice properties (thickness and strength) and channel shape (rectangular and trapezoidal). In general, for rectangular channels, it was found that the simplified analytical solutions are quite representative of the phenomenon namely that short wave transients are affected by the cover’s stiffness but long waves (>400 m) are not.
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Shishmarev, Konstantin, Tatyana Khabakhpasheva i Kristina Oglezneva. "Steady-State Motion of a Load on an Ice Cover with Linearly Variable Thickness in a Channel". Journal of Marine Science and Engineering 11, nr 5 (13.05.2023): 1045. http://dx.doi.org/10.3390/jmse11051045.
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The paper considers the visco-elastic response of the ice cover in a channel under an external load moving with constant speed along the center line. The channel has a rectangular cross-section with a finite depth and width. The fluid in the channel is inviscid and incompressible and its motion is potential. The fluid is covered by a thin sheet of ice frozen to the channel walls. The ice thickness varies linearly symmetrically across the channel, being lowest at the center of the channel and highest at the channel walls. Ice deflections and strains in the ice cover are independent of time in the coordinate system moving with the load. The problem is solved numerically using Fourier transform along the channel and the method of normal modes across the channel. The series coefficients for normal modes are determined by truncation for the resulting infinite systems of linear algebraic equations. The ice deflections and strains in the ice plate are investigated and compared to the case of constant mean ice thickness. It is shown that even a small variation of the ice thickness significantly changes the characteristics of the hydroelastic waves in the channel.
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Ho, Chii-Dong, Hsuan Chang, Chih-Wei Yeh, Choon-Aun Ng i Ping-Cheng Hsieh. "Optimizing Device Performance of Multi-Pass Flat-Plate Solar Air Heaters on Various Recycling Configurations". Energies 16, nr 6 (8.03.2023): 2568. http://dx.doi.org/10.3390/en16062568.
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Various external-recycle configurations of multi-pass flat-plate solar air collectors were studied theoretically to examine the optimal thermal performance under the same working dimension and operation conditions. An absorber plate and insulation sheet were implemented horizontally and vertically, respectively, into an open rectangular conduit to conduct a recycling four-pass operation, which the device lengthens the air flow channel and increases the air mass flow rate within the collector, and thus, a more heat transfer efficiency is obtained. Four recycling types with different external-recycle patterns were introduced and expected to augment the heat transfer rate due to the turbulent convective intensity through four subchannels in the present study. Coupling energy balances into one-dimensional modeling equations were derived by making the energy-flow diagram within a finite element, which the longitudinal temperature distributions for each subchannel were obtained. The theoretical predictions show that the improved four-pass device is accomplished due to the multiple heating pathways over and under the absorber plate, from which the turbulence intensity augmentation results in the heat transfer rate as compared to that in the device without inserting the absorber plate and insulation sheet (say a downward-type single-pass solar air collector). The theoretical results also show that the external-recycle configuration (say Type C in the present study) acts as an optimal collector thermal efficiency and leading to a beneficial design in multi-pass solar air collectors for improving heat-transfer rate and increasing resident time under the same operation conditions. Theoretical predictions show a higher heat-transfer efficiency for the present recycling configurations up to a maximum 115% device enhancement in comparison to that of a single-pass device. Examination of implementing the absorber plate and insulation sheet on the heat-transfer efficiency enhancement as well as the hydraulic dissipated power increment were also delineated, and deliberated the suitable external-recycle configuration with respect to an economic consideration.
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Thuillier, Sandrine, Shun-Lai Zang, Julien Troufflard, Pierre-Yves Manach i Anthony Jegat. "Modeling Bake Hardening Effects in Steel Sheets—Application to Dent Resistance". Metals 8, nr 8 (30.07.2018): 594. http://dx.doi.org/10.3390/met8080594.
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This study is dedicated to the experimental characterisation and phenomenological modeling of the bake hardening effect of a thin steel sheet, to predict the static dent resistance and perform an experimental validation on a bulged part. In a first step, rectangular samples are submitted to a thermo-mechanical loading to characterise the bake hardening magnitude in tension. A three-step procedure is considered, involving first a pre-strain in tension up to several values followed by unloading. Secondly, a heat treatment during a fixed time and a given temperature is performed, and finally, a reloading in tension in the same direction as the pre-strain is applied. Then, a specific device is developed to perform dent tests on a bulged specimen, to evaluate the influence of bake hardening on the dent resistance. A three-step procedure is also considered, with a pre-strain applied with a hydraulic bulge test followed by a heat treatment and then static dent test at the maximum dome height. An original phenomenological model is proposed to represent the yield stress increase after the heat treatment and the second reloading. Material parameters are identified from the tensile tests and are input data to a finite element model. The numerical prediction of the load evolution during the dent test is then compared with experimental data and shows an overall good correlation.
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Loginov, Yu N., A. Yu Volkov i B. I. Kamenetsky. "Analysis of non-equal-channel angular pressing scheme applied for obtaining magnesium sheet in cold state". Izvestiya Vuzov Tsvetnaya Metallurgiya (Proceedings of Higher Schools Nonferrous Metallurgy, nr 1 (22.02.2019): 59–66. http://dx.doi.org/10.17073/0021-3438-2019-1-59-66.
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Deformation patterns of rolling, equal-channel angular pressing and non-equal-channel angular pressing were evaluated. It is noted that when rolling, it is difficult to transfer a circular section preform into a rectangular section with a small thickness. This problem cannot be solved using equal-channel angular pressing. In connection with this, it is proposed to use a non-equal-channel angular pressing pattern to study the cast structure of magnesium. An experimental procedure based on cold extrusion of cylinders with a diameter of 42 mm and a height of 40 mm is described. The strip at the outlet was 40 mm in width and 1 mm in thickness. The percentage reduction of the preform material determined by the ratio of areas was 96 % with a draw ratio of 17. The specific pressures on the punch at the beginning ofthe extrusion process were 1200—1300 MPa, and extrusion force was 1670—1800 kN. The preform was cut into lengths that were rolled at a room temperature into 50 and 10 pm thick foils without intermediate annealing. Rolling was carried out on the Duo mill with a percentage reduction of 12—20 % at an average speed of 0,1 m/s. 20 passes were performed with a total relative reduction of 95 % to make the 50 pm thick foil. The results of computer simulation by the finite element method demonstrated that the constant value of the deformation degree is achieved at a rather considerable distance from the front end estimated as 50 times the thickness of the strip. The deformation rate field was calculated to determine the configuration of the deformation center. Energy costs were estimated. As a result of the completed set of calculated and experimental work, it was possible to establish the following — it is possible to produce a thin sheet preform from a cylindrical cast magnesium blank in one operation at a room temperature. The sheet blank has a level of ductility sufficient for subsequent sheet rolling. The sheet blank obtained in the proposed process has a high level of plastic deformation elaboration created due to the forming pattern with the high level of elongation and shear deformation. Despite the high level of pressure that must be applied to create a comprehensive compression scheme taking into account the lack of the need to heat the preform, energy costs are no higher than in traditional treatment processes.
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Steckiewicz, Adam. "Efficient Transfer of the Medium Frequency Magnetic Field Using Anisotropic Metamaterials". Energies 16, nr 1 (28.12.2022): 334. http://dx.doi.org/10.3390/en16010334.
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This paper introduces a novel waveguide intended for the spatial transfer of alternating magnetic fields. Instead of ferromagnetic material, an air core was proposed, while the cladding was realized using anisotropic metamaterial, built of the resonators and a paramagnetic composite. Since prior works regarding magnetic field transfer concentrated on static or high frequency fields, the proposed device complements the range of medium frequencies (several to hundreds of kilohertz). The three-dimensional model of the 50 cm long and 20 cm wide rectangular structure with metamaterial cladding was made in COMSOL and computed using the finite element method. Multi-turn inductors were considered and homogenized by the current sheet approximation, while an optimization solver was used to identify an optimal design of the waveguide. The analysis was made with respect to different resonators and permeability of the paramagnetic material. Additionally, the frequency response of the structure was determined. On these bases, the dependencies of the mean energy density and magnetic field intensity at the output of the waveguide were characterized. It was shown that discussed structure was able to provide an efficient transfer of the magnetic field between two ports. Thus, this device can be used to extend the distance of the wireless power transfer, especially between devices isolated by a thick barrier (e.g., wall), in which the meta-structure may be embodied.
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Mary, S. Arul, i S. Vignesh Raja. "Numerical Studies on Composite Deck Slab With Floor Openings". Proceedings of the 12th Structural Engineering Convention, SEC 2022: Themes 1-2 1, nr 1 (19.12.2022): 69–75. http://dx.doi.org/10.38208/acp.v1.475.
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Openings in slabs are provided mainly for service works. According to the purpose of the services, the size of the openings was classified as small, medium, and large. The provision of openings in a composite slab was not addressed in design codes like EC-4 and IS 11384. Normally the Longitudinal shear interaction is the influencing factor in determining the capacity and elastic rigidity of a composite slab which may be affected by the presence of openings. In the market, there are various forms of embossment/indentation available to enhance the interlocking at the interface of the Cold Form Steel decking sheet and the topping concrete thereby an increased longitudinal shear resistance can be achieved at the interface. In this numerical study, Among the various type of embossments, combined types of embossments (rectangular and chevron) are considered then the m and k values are determined with the help of the Penalty Friction interaction approach and the same was verified with the known experimental values for a solid slab. In addition, Finite Element [FE] models with various sizes of floor openings were created under the guidelines of SCI publication P300 and SDI Technical Guidance on Deck Damage and Penetrations. The effects of those openings located in the high shear region and no shear region are studied. The simulated load-deflection responses of various FE floor opening models were compared.
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Pan, Bo, Dajun Tao, Baojun Ge, Likun Wang i Peng Hou. "Analysis of Eddy Current Loss of 120-kW High-Speed Permanent Magnet Synchronous Motor". Machines 10, nr 5 (8.05.2022): 346. http://dx.doi.org/10.3390/machines10050346.
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Pulse width modulation current harmonics and space harmonics are some of the major factors affecting the rotor eddy current loss of the high-speed permanent magnet motor. In this study, based on the principle of the equivalent current sheet, a two-dimensional motor model in a rectangular coordinate system was established. Considering the armature reaction, the end effect, and the current harmonics generated by variable frequency power supply, the eddy current loss of the rotor at different frequencies was analyzed and calculated using the analytical and finite element methods (FEM). When the frequency is between 200 Hz and 600 Hz, the variation trend of the rotor eddy current loss with a frequency obtained by analytical calculation and FEM analysis is roughly the same, and the error is still within a reasonable range. However, as the frequency continues to increase, the error between the two becomes larger and larger. Furthermore, based on the two-dimensional FE model, the influence of the sleeve material, the thickness, and the composite structure on the rotor eddy current loss were studied and analyzed. It was found that adding a graphene shielding layer between the permanent magnet and the sleeve can effectively shield the harmonic magnetic field, greatly reduce the eddy current loss of the permanent magnet, and effectively prevent the temperature of the permanent magnet from being too high, which is conducive to the continuous and stable operation of the high-speed permanent magnet motor.