Numerical verification on formability of metallic alloys for skin structure using multi-point die-less forming

Abebe, Misganaw; Park, Ji-Woo; Kim, Jeong; Kang, Beom-Soo

doi:10.1007/s12541-017-0034-3

Cited by 8 publications

(4 citation statements)

References 13 publications

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“…With the rapid development of manufacturing industry, the market demand for three-dimensional sheet metal is increasing. Automotive skins, hull outer panels, human skull prostheses, building plates and so forth are all composed of three-dimensional sheet metals with different shapes and sizes [1][2][3][4]. Single piece and small batch production is the current popular production mode.…”

Section: Introductionmentioning

confidence: 99%

Prediction of Longitudinal Curvature Radius of 3D Surface Based on Quadratic Relationship between Strain and Coordinates in Continuous Roll Forming

Gao

Sun

et al. 2020

Metals

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Continuous roll forming (CRF) is a new method for the rapid forming of three-dimensional (3D) surfaces developed in recent years, and the significant advantage of CRF compared with traditional die forming is that the longitudinal dimension of the sheet metal is not limited. By controlling the curvature radius and gap shape of upper and lower bending rolls, three-dimensional parts with different shapes and sizes can be precisely formed. When the elastic deformation is ignored during the forming process, the transversal curvature radius of the three-dimensional surface is consistent with the radius of the roll gap centerline. Therefore, the calculation of longitudinal curvature radius is the key to improve the accuracy of the 3D surface in CRF. In this paper, the basic principle of CRF is described. The modified formulas for calculating the longitudinal curvature radius of convex and saddle surfaces based on the quadratic relationship between the strain and coordinates are deduced in detail, and the corresponding design method of the roll gap is derived. Furthermore, the mathematical equations of convex and saddle surfaces are given. Through numerical simulation and theoretical analysis, it is found that the relative errors of the longitudinal centerline radius are reduced from 13.67% before modification to 4.35% after modification for a convex surface and 6.81% to 0.41% for a saddle surface when the transversal curvature radius is 800 mm and the compression ratio is 5%. The experimental and measured results indicate that the shapes of formed parts are more consistent with the target parts after modification, which further proves the applicability of the modified formulas.

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Section: Introductionmentioning

confidence: 99%

Prediction of Longitudinal Curvature Radius of 3D Surface Based on Quadratic Relationship between Strain and Coordinates in Continuous Roll Forming

Gao

Sun

et al. 2020

Metals

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“…The most obvious advantages of this process being its economy and enhanced productivity, as various mold forms can be created using a single piece of equipment, unlike conventional press forming. Considerable research has been conducted on the multi-point forming process [5][6][7], but some disadvantages of this forming technique have been observed, particularly dimples and wrinkles in the sheet metal due to the discontinuous mold surface [8,9]. Additionally, in this technique, the size of the product is limited by the size of the forming apparatus, as it is not possible to form a product larger than the experimental machine itself.…”

Section: Introductionmentioning

confidence: 99%

Development on a Prediction Model for Experimental Condition of Flexibly Reconfigurable Roll Forming Process

Park

Kim

Kang

2019

Metals

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Flexibly-reconfigurable roll forming (FRRF) is a novel sheet metal forming technology by which sheet metal is shaped into a desired curvature using reconfigurable rollers and gaps. FRRF is conducive to producing multi-curvature surfaces by controlling the longitudinal strain distribution. However, it is difficult to predict the forming results since FRRF technology forms a secondary surface from the primary curvature. This study investigates the use of regression analysis as a basis for a model that can predict the longitudinal curvature of sheet metal. The following variables were considered as input parameters: Maximum compression value, radius of curvature in the transverse direction, and initial blank width. Regression model samples are obtained by performing experiments using FRRF equipment whilst the experimental design was generated by a three-level, three-factor full factorial design. The experimental surfaces are of a convex and of a saddle-type shape, with a total sample size of 54. Through regression analysis it has been shown that the longitudinal curvature can be expressed by means of a quadratic equation. The matching quadratic function was verified with R-squared values and root-mean-square errors, whilst the normality of the sample data was also verified. To apply the model to the actual forming process, the regression model was converted to deduce the compression characteristics for forming the target surface. Throughout the study, the proposed analytical procedure was validated, and a statistical formula for estimating the longitudinal curvature produced by the FRRF apparatus established.

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“…It outperforms other surrogate modeling techniques due to its unique characteristics of spatiotemporal modeling. In particular, regarding materials forming, a lot of research based on kriging model technique has been conducted (e.g., [ 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 ]). Tuo et al [ 24 ] proposed a kriging model based on a nonstationary Gaussian process that integrates the outputs of different mesh densities in finite element analysis and provides approximation to the exact solution, and then applied the model in casting simulation.…”

Section: Introductionmentioning

confidence: 99%

“…Ambrogio et al [ 33 ] designed a metamodelling technique by integrating the design of the experimental statistical method and the kriging one and validated the feasibility of the proposed method for the crucial problem of localized thinning in the sheet metal forming process. Abebe et al [ 34 ] applied an ordinary kriging model-based prediction technique to find the wrinkling and dimple occurrence limit on metallic alloys multi-point dieless forming. Tutum et al [ 35 ] employed the kriging surrogate method for thermochemical simulation of the pultrusion process.…”

Section: Introductionmentioning

confidence: 99%

Temperature Uncertainty Analysis of Injection Mechanism Based on Kriging Modeling

et al. 2017

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A kriging modeling method is proposed to conduct the temperature uncertainty analysis of an injection mechanism in squeeze casting. A mathematical model of temperature prediction with multi input and single output is employed to estimate the temperature spatiotemporal distributions of the injection mechanism. The kriging model applies different weights to the independent variables according to spatial location of sample points and their correlation, thus reducing the estimation variance. The predicted value of the kriging model is compared with the sample data at the corresponding position to investigate the influence of the temperature uncertainty of the injection mechanism on the injection process including friction. The results indicate that the significant error is observed at a few sample points in the early injection due to the impact of the uncertainty facts. The variance mean and standard deviation obtained by the model calibrated by experimental samples reduce largely in comparison to those obtained from the initial kriging model. This study indicates that model calibration produces more accurate prediction.

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Numerical verification on formability of metallic alloys for skin structure using multi-point die-less forming

Cited by 8 publications

References 13 publications

Prediction of Longitudinal Curvature Radius of 3D Surface Based on Quadratic Relationship between Strain and Coordinates in Continuous Roll Forming

Prediction of Longitudinal Curvature Radius of 3D Surface Based on Quadratic Relationship between Strain and Coordinates in Continuous Roll Forming

Development on a Prediction Model for Experimental Condition of Flexibly Reconfigurable Roll Forming Process

Temperature Uncertainty Analysis of Injection Mechanism Based on Kriging Modeling

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