Research

21 pages, 30299 KiB

Open AccessArticle

Neural Network-Based Multi-Objective Optimization of Adjustable Drawbead Movement for Deep Drawing of Tailor-Welded Blanks

by Parviz Kahhal, Jaebong Jung, Yong Chan Hur, Young Hoon Moon and Ji Hoon Kim

Materials 2022, 15(4), 1430; https://doi.org/10.3390/ma15041430 - 15 Feb 2022

Cited by 7 | Viewed by 1570

Abstract

To improve the formability in the deep drawing of tailor-welded blanks, an adjustable drawbead was introduced. Drawbead movement was obtained using the multi-objective optimization of the conflicting objective functions of the fracture and centerline deviation simultaneously. Finite element simulations of the deep drawing [...] Read more.

To improve the formability in the deep drawing of tailor-welded blanks, an adjustable drawbead was introduced. Drawbead movement was obtained using the multi-objective optimization of the conflicting objective functions of the fracture and centerline deviation simultaneously. Finite element simulations of the deep drawing processes were conducted to generate observations for optimization. The response surface method and artificial neural network were used to determine the relationship between variables and objective functions; the procedure was applied to a circular cup drawing of the tailor-welded dual-phase steel blank. The results showed that the artificial neural network had better prediction capability and accuracy than the response surface method. Additionally, the non-dominated sorting-based genetic algorithm (NSGA-II) could effectively determine the optima. The adjustable drawbead with the optimized movement was confirmed as an efficient and effective solution for improving the formability of the deep drawing of tailor-welded blanks. Full article

(This article belongs to the Special Issue Numerical and Experimental Investigations in Metal Forming)

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16 pages, 7364 KiB

Open AccessArticle

Simulation and Experimental Study on Roll-Forming Limit of Cup

by Baohong Zhang, Shengpeng Ning, Zeng Wei, Yali Duan, Xubin Li and Yongbiao Yang

Materials 2022, 15(4), 1279; https://doi.org/10.3390/ma15041279 - 09 Feb 2022

Viewed by 1463

Abstract

Roll forming can improve the material utilization rate and production efficiency of cups with a curved rotary profile, but there is no basis for the determination of forming limit. The DEFORM-3D software was used to simulate the roll forming of cups. The influence [...] Read more.

Roll forming can improve the material utilization rate and production efficiency of cups with a curved rotary profile, but there is no basis for the determination of forming limit. The DEFORM-3D software was used to simulate the roll forming of cups. The influence of the billet wall thickness and bottom thickness, coefficient of friction, radius of roller, and the fillet radius of the punch on the forming limit was studied, and the damage value and velocity vector were analyzed. The results showed that the forming limit of the billet’s wall thickness in roll forming for a cup is about 62%. With the increase of the ratio of the formed cup’s wall thickness to the billet’s bottom thickness, the forming limit of wall thickness will be slightly reduced. A larger radius of roller, fillet radius of punch, and friction coefficient between punch and billet and a smaller friction coefficient between roller and billet are good for decreasing the damage value and improving the roll-forming limit. According to the numerical simulation results, the roll-forming limit diagram of cups is established, and the accuracy of the forming limit diagram is verified by experiments. Full article

(This article belongs to the Special Issue Numerical and Experimental Investigations in Metal Forming)

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21 pages, 41828 KiB

Open AccessArticle

Development of the Platform for Three-Dimensional Simulation of Additive Layer Manufacturing Processes Characterized by Changes in State of Matter: Melting-Solidification

by Dmytro S. Svyetlichnyy

Materials 2022, 15(3), 1030; https://doi.org/10.3390/ma15031030 - 28 Jan 2022

Cited by 5 | Viewed by 2094

Abstract

A new platform for three-dimensional simulation of Additive Layer Manufacturing (ALM) processes is presented in the paper. The platform is based on homogeneous methods—the Lattice Boltzmann Method (LBM) with elements of Cellular Automata (CA). The platform represents a new computer-based engineering technique primarily [...] Read more.

A new platform for three-dimensional simulation of Additive Layer Manufacturing (ALM) processes is presented in the paper. The platform is based on homogeneous methods—the Lattice Boltzmann Method (LBM) with elements of Cellular Automata (CA). The platform represents a new computer-based engineering technique primarily focused on Selective Laser Melting (SLM) technology. Innovative computational strategies and numerical algorithms for simulation and analysis of entire powder bed-based technology with changes in state of matter (melting-solidification) are presented in the paper. The models deal mainly with heat transfer, melting and solidification, and free-surface flow. Linking LBM and CA into a complex holistic model allows for complete full-scale simulations avoiding complicated interfaces. The approach is generic and can be applied to different multi-material powder bed-based SLM processes. A methodology for the adaptation of the model to the real material (Ti-6Al-4V alloy) and processing parameters is presented. The paper presents the first quantitative results obtained on the platform and shows the ability of the model to simulate and analyze a very complex technology, entirely without a complicated interface between the sub-models. It solves the large-scale problem connected with computer-aided design and analysis of new multi-passes and multi-materials processes. Full article

(This article belongs to the Special Issue Numerical and Experimental Investigations in Metal Forming)

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27 pages, 21103 KiB

Open AccessArticle

Prediction of Behaviour of Thin-Walled DED-Processed Structure: Experimental-Numerical Approach

by Miroslav Urbánek, Josef Hodek, Daniel Melzer, Martina Koukolíková, Antonín Prantl, Jaroslav Vavřík, Michal Brázda, Petr Martínek, Sylwia Rzepa and Jan Džugan

Materials 2022, 15(3), 806; https://doi.org/10.3390/ma15030806 - 21 Jan 2022

Cited by 7 | Viewed by 1501

Abstract

Additive manufacturing (AM) becomes a more and more standard process in different fields of industry. There is still only limited knowledge of the relationship between measured material data and the overall behaviour of directed energy deposition (DED)-processed complex structures. The understanding of the [...] Read more.

Additive manufacturing (AM) becomes a more and more standard process in different fields of industry. There is still only limited knowledge of the relationship between measured material data and the overall behaviour of directed energy deposition (DED)-processed complex structures. The understanding of the structural performance, including flow curves and local damage properties of additively manufactured parts by DED, becomes increasingly important. DED can be used for creating functional surfaces, component repairing using multiple powder feeders, and creating a heterogeneous structure with defined chemical composition. For thin parts that are used with the as-deposited surface, this evaluation is even highly crucial. The main goal of the study was to predict the behaviour of thin-walled structures manufactured by the DED process under static loading by finite element analysis (FEA). Moreover, in this study, the mechanical performance of partly machined and fully machined miniaturized samples produced from the structure was compared. The structure studied in this research resembles a honeycomb shape made of austenitic stainless steel AISI 316L, which is characterized by high strength and ductility. The uncoupled damage models based on a hybrid experimental-numerical approach were used. The microstructure and hardness were examined to comprehend the structural behaviour. Full article

(This article belongs to the Special Issue Numerical and Experimental Investigations in Metal Forming)

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20 pages, 5543 KiB

Open AccessArticle

Effect of Tool Geometry Parameters on the Formability of a Camera Cover in the Deep Drawing Process

by Thanh Trung Do, Pham Son Minh and Nhan Le

Materials 2021, 14(14), 3993; https://doi.org/10.3390/ma14143993 - 16 Jul 2021

Cited by 3 | Viewed by 1610

Abstract

The formability of the drawn part in the deep drawing process depends not only on the material properties, but also on the equipment used, metal flow control and tool parameters. The most common defects can be the thickening, stretching and splitting. However, the [...] Read more.

The formability of the drawn part in the deep drawing process depends not only on the material properties, but also on the equipment used, metal flow control and tool parameters. The most common defects can be the thickening, stretching and splitting. However, the optimization of tools including the die and punch parameters leads to a reduction of the defects and improves the quality of the products. In this paper, the formability of the camera cover by aluminum alloy A1050 in the deep drawing process was examined relating to the tool geometry parameters based on numerical and experimental analyses. The results showed that the thickness was the smallest and the stress was the highest at one of the bottom corners where the biaxial stretching was the predominant mode of deformation. The problems of the thickening at the flange area, the stretching at the side wall and the splitting at the bottom corners could be prevented when the tool parameters were optimized that related to the thickness and stress. It was clear that the optimal thickness distribution of the camera cover was obtained by the design of tools with the best values—with the die edge radius 10 times, the pocket radius on the bottom of the die 5 times, and the punch nose radius 2.5 times the sheet thickness. Additionally, the quality of the camera cover was improved with a maximum thinning of 25% experimentally, and it was within the suggested maximum allowable thickness reduction of 45% for various industrial applications after optimizing the tool geometry parameters in the deep drawing process. Full article

(This article belongs to the Special Issue Numerical and Experimental Investigations in Metal Forming)

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22 pages, 12260 KiB

Open AccessArticle

Analysis of Hot Stamping Tool Cooling System—A Case Study

by Piotr Danielczyk and Ireneusz Wróbel

Materials 2021, 14(11), 2759; https://doi.org/10.3390/ma14112759 - 23 May 2021

Cited by 4 | Viewed by 2740

Abstract

One of the important steps in the design of hot stamping tools is the analysis of their cooling system. This article presents an authorial, two-stage approach to solving this problem. The first stage consisted of a series of simulations of the hot stamping [...] Read more.

One of the important steps in the design of hot stamping tools is the analysis of their cooling system. This article presents an authorial, two-stage approach to solving this problem. The first stage consisted of a series of simulations of the hot stamping process in the Autoform package, with initial selection of shape and arrangement of cooling channels. These results allowed for the design of the tool for which the coupled thermal-flow analysis was carried out. The correctness of the adopted design assumptions has been confirmed by experimental tests. A trial series of drawpieces made in production conditions meet the requirements for hardness, mechanical properties, and appropriate microstructure. The presented procedure has become the practice of the drawpiece producers. Full article

(This article belongs to the Special Issue Numerical and Experimental Investigations in Metal Forming)

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15 pages, 5404 KiB

Open AccessArticle

Development of Measurement Equipment and Experimental and Numerical Simulation Studies for Warm Forming Limits of High-Strength Steel

by Qiang Yu, Jin Liang, Qiu Li and Chengyao Li

Materials 2021, 14(9), 2373; https://doi.org/10.3390/ma14092373 - 02 May 2021

Cited by 3 | Viewed by 1706

Abstract

This paper describes the research and development of a set of measurement equipment for the warm forming limits of high-strength steel based on the Nakazima bulging test method and the digital image correlation method. The equipment could provide an argon shield and a [...] Read more.

This paper describes the research and development of a set of measurement equipment for the warm forming limits of high-strength steel based on the Nakazima bulging test method and the digital image correlation method. The equipment could provide an argon shield and a water-cooling atmosphere, as well as two heating options: heating the specimen, dies, and environment to the test temperature simultaneously or heating the specimen to the test temperature at a higher speed than that for the dies and environment. The equipment was applied to measure the forming limit curves for high-strength DP600 steel at room temperature and at the temperature of 300 °C to verify its performance. The DYNAFORM software was then applied for the digital simulation of the bulging test method. A new limit-strain-fitting method was proposed to eliminate the impact of the distorted grid on the digital simulation process. The change trend of the forming limit curve acquired in the test had sound consistency with the test results. Full article

(This article belongs to the Special Issue Numerical and Experimental Investigations in Metal Forming)

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19 pages, 39162 KiB

Open AccessArticle

Simulation and Experimental Study of Dynamical Recrystallization Kinetics of TB8 Titanium Alloys

by Wenwei Zhang, Qiuyue Yang, Yuanbiao Tan, Min Ma, Song Xiang and Fei Zhao

Materials 2020, 13(19), 4429; https://doi.org/10.3390/ma13194429 - 05 Oct 2020

Cited by 9 | Viewed by 1731

Abstract

The dynamic recrystallization (DRX) behavior in the hot working of TB8 titanium alloy was studied by using the experiment and finite element simulation (FEM) method. The results showed that the DRX behavior of TB8 titanium alloys was drastically affected by the hot processing [...] Read more.

The dynamic recrystallization (DRX) behavior in the hot working of TB8 titanium alloy was studied by using the experiment and finite element simulation (FEM) method. The results showed that the DRX behavior of TB8 titanium alloys was drastically affected by the hot processing parameters. The rising deformation temperature and reducing strain rate led to an augmentation in the grain size (

d_{D R X}

) and volume fraction (

X_{D R X}

) of DRX grains. In view of the true stress–strain curves gained from the experiment, the

d_{D R X}

and

X_{D R X}

models of DRX grains were constructed. Based on the developed models for DRX of TB8 titanium alloy, the isothermal forging process of the cylindrical samples was simulated by the DEFORM-3D software. The distributions of the effective strain and

X_{D R X}

for DRX were analyzed. A comparison of the

d_{D R X}

and

X_{D R X}

of DRX grains in the central regions of the samples between the experimental and FEM results was performed. A good correlation between the experimental and simulation results was obtained, indicating that the established FEM model presented good prediction capabilities. Full article

(This article belongs to the Special Issue Numerical and Experimental Investigations in Metal Forming)

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