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3 pages, 198 KiB

Open AccessEditorial

Recent Advances and Applications of Machine Learning in Metal Forming Processes

by Pedro A. Prates and André F. G. Pereira

Metals 2022, 12(8), 1342; https://doi.org/10.3390/met12081342 - 12 Aug 2022

Cited by 3 | Viewed by 1932

Abstract

Machine Learning (ML) is a subfield of artificial intelligence, focusing on computational algorithms that are designed to learn and improve themselves, without the need to be explicitly programmed [...] Full article

(This article belongs to the Special Issue Recent Advances and Applications of Machine Learning in Metal Forming Processes)

Research

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36 pages, 4673 KiB

Open AccessFeature PaperArticle

The Use of Machine-Learning Techniques in Material Constitutive Modelling for Metal Forming Processes

by Rúben Lourenço, António Andrade-Campos and Pétia Georgieva

Metals 2022, 12(3), 427; https://doi.org/10.3390/met12030427 - 28 Feb 2022

Cited by 14 | Viewed by 5467

Abstract

Accurate numerical simulations require constitutive models capable of providing precise material data. Several calibration methodologies have been developed to improve the accuracy of constitutive models. Nevertheless, a model’s performance is always constrained by its mathematical formulation. Machine learning (ML) techniques, such as artificial [...] Read more.

Accurate numerical simulations require constitutive models capable of providing precise material data. Several calibration methodologies have been developed to improve the accuracy of constitutive models. Nevertheless, a model’s performance is always constrained by its mathematical formulation. Machine learning (ML) techniques, such as artificial neural networks (ANNs), have the potential to overcome these limitations. Nevertheless, the use of ML for material constitutive modelling is very recent and not fully explored. Difficulties related to data requirements and training are still open problems. This work explores and discusses the use of ML techniques regarding the accuracy of material constitutive models in metal plasticity, particularly contributing (i) a parameter identification inverse methodology, (ii) a constitutive model corrector, (iii) a data-driven constitutive model using empirical known concepts and (iv) a general implicit constitutive model using a data-driven learning approach. These approaches are discussed, and examples are given in the framework of non-linear elastoplasticity. To conveniently train these ML approaches, a large amount of data concerning material behaviour must be used. Therefore, non-homogeneous strain field and complex strain path tests measured with digital image correlation (DIC) techniques must be used for that purpose. Full article

(This article belongs to the Special Issue Recent Advances and Applications of Machine Learning in Metal Forming Processes)

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15 pages, 1560 KiB

Open AccessArticle

Strip Steel Surface Defects Classification Based on Generative Adversarial Network and Attention Mechanism

by Zhuangzhuang Hao, Zhiyang Li, Fuji Ren, Shuaishuai Lv and Hongjun Ni

Metals 2022, 12(2), 311; https://doi.org/10.3390/met12020311 - 10 Feb 2022

Cited by 24 | Viewed by 2760

Abstract

In a complex industrial environment, it is difficult to obtain hot rolled strip steel surface defect images. Moreover, there is a lack of effective identification methods. In response to this, this paper implements accurate classification of strip steel surface defects based on generative [...] Read more.

In a complex industrial environment, it is difficult to obtain hot rolled strip steel surface defect images. Moreover, there is a lack of effective identification methods. In response to this, this paper implements accurate classification of strip steel surface defects based on generative adversarial network and attention mechanism. Firstly, a novel WGAN model is proposed to generate new surface defect images from random noises. By expanding the number of samples from 1360 to 3773, the generated images can be further used for training classification algorithm. Secondly, a Multi-SE-ResNet34 model integrating attention mechanism is proposed to identify defects. The accuracy rate on the test set is 99.20%, which is 6.71%, 4.56%, 1.88%, 0.54% and 1.34% higher than AlexNet, VGG16, ShuffleNet v2 1×, ResNet34, and ResNet50, respectively. Finally, a visual comparison of the features extracted by different models using Grad-CAM reveals that the proposed model is more calibrated for feature extraction. Therefore, it can be concluded that the proposed methods provide a significant reference for data augmentation and classification of strip steel surface defects. Full article

(This article belongs to the Special Issue Recent Advances and Applications of Machine Learning in Metal Forming Processes)

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21 pages, 6107 KiB

Open AccessArticle

A Buckling Instability Prediction Model for the Reliable Design of Sheet Metal Panels Based on an Artificial Intelligent Self-Learning Algorithm

by Seungro Lee, Luca Quagliato, Donghwi Park, Guido A. Berti and Naksoo Kim

Metals 2021, 11(10), 1533; https://doi.org/10.3390/met11101533 - 26 Sep 2021

Cited by 8 | Viewed by 2686

Abstract

Sheets’ buckling instability, also known as oil canning, is an issue that characterizes the resistance to denting in thin metal panels. The oil canning phenomenon is characterized by a depression in the metal sheet, caused by a local buckling, which is a critical [...] Read more.

Sheets’ buckling instability, also known as oil canning, is an issue that characterizes the resistance to denting in thin metal panels. The oil canning phenomenon is characterized by a depression in the metal sheet, caused by a local buckling, which is a critical design issue for aesthetic parts, such as automotive outer panels. Predicting the buckling instability during the design stage is not straightforward since the shape of the component might change several times before the part is sent to production and can actually be tested. To overcome this issue, this research presents a robust prediction model based on the convolutional neural network (CNN) to estimate the buckling instability of automotive sheet metal panels, based on the major, minor, and Gaussian surface curvatures. The training dataset for the CNN model was generated by implementing finite element analysis (FEA) of the outer panels of various commercial vehicles, for a total of twenty panels, and by considering different indentation locations on each panel. From the implemented simulation models the load-stroke curves were exported and utilized to determine the presence, or absence, of buckling instability and to determine its magnitude. Moreover, from the computer aided design (CAD) files of the relevant panels, the three considered curvatures on the tested indentation points were acquired as well. All the positions considered in the FEA analyses were backed up by industrial experiments on the relevant panels in their assembled position, allowing to validate their reliability. The combined correlation of curvatures and load-displacement curves allowed correlating the geometrical features that create the conditions for buckling instability to arise and was utilized to train the CNN algorithm, defined considering 13 convolution layers and 5 pooling layers. The trained CNN model was applied to another automotive frame, not used in the training process, and the prediction results were compared with experimental indentation tests. The overall accuracy of the CNN model was calculated to be 90.1%, representing the reliability of the proposed algorithm of predicting the severity of the buckling instability for automotive sheet metal panels. Full article

(This article belongs to the Special Issue Recent Advances and Applications of Machine Learning in Metal Forming Processes)

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24 pages, 4038 KiB

Open AccessFeature PaperArticle

Application of Machine Learning to Bending Processes and Material Identification

by Daniel J. Cruz, Manuel R. Barbosa, Abel D. Santos, Sara S. Miranda and Rui L. Amaral

Metals 2021, 11(9), 1418; https://doi.org/10.3390/met11091418 - 7 Sep 2021

Cited by 11 | Viewed by 4282

Abstract

The increasing availability of data, which becomes a continually increasing trend in multiple fields of application, has given machine learning approaches a renewed interest in recent years. Accordingly, manufacturing processes and sheet metal forming follow such directions, having in mind the efficiency and [...] Read more.

The increasing availability of data, which becomes a continually increasing trend in multiple fields of application, has given machine learning approaches a renewed interest in recent years. Accordingly, manufacturing processes and sheet metal forming follow such directions, having in mind the efficiency and control of the many parameters involved, in processing and material characterization. In this article, two applications are considered to explore the capability of machine learning modeling through shallow artificial neural networks (ANN). One consists of developing an ANN to identify the constitutive model parameters of a material using the force–displacement curves obtained with a standard bending test. The second one concentrates on the springback problem in sheet metal press-brake air bending, with the objective of predicting the punch displacement required to attain a desired bending angle, including additional information of the springback angle. The required data for designing the ANN solutions are collected from numerical simulation using finite element methodology (FEM), which in turn was validated by experiments. Full article

(This article belongs to the Special Issue Recent Advances and Applications of Machine Learning in Metal Forming Processes)

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11 pages, 712 KiB

Open AccessArticle

Topological Optimization of Artificial Neural Networks to Estimate Mechanical Properties in Metal Forming Using Machine Learning

by David Merayo, Alvaro Rodríguez-Prieto and Ana María Camacho

Metals 2021, 11(8), 1289; https://doi.org/10.3390/met11081289 - 16 Aug 2021

Cited by 12 | Viewed by 2789

Abstract

The ability of a metal to be subjected to forming processes depends mainly on its plastic behavior and, thus, the mechanical properties belonging to this region of the stress–strain curve. Forming techniques are among the most widespread metalworking procedures in manufacturing, and aluminum [...] Read more.

The ability of a metal to be subjected to forming processes depends mainly on its plastic behavior and, thus, the mechanical properties belonging to this region of the stress–strain curve. Forming techniques are among the most widespread metalworking procedures in manufacturing, and aluminum alloys are of great interest in fields as diverse as the aerospace sector or the food industry. A precise characterization of the mechanical properties is crucial to estimate the forming capability of equipment, but also for a robust numerical modeling of metal forming processes. Characterizing a material is a very relevant task in which large amounts of resources are invested, and this paper studies how to optimize a multilayer neural network to be able to make, through machine learning, precise and accurate predictions about the mechanical properties of wrought aluminum alloys. This study focuses on the determination of the ultimate tensile strength, closely related to the strain hardening of a material; more precisely, a methodology is developed that, by randomly partitioning the input dataset, performs training and prediction cycles that allow estimating the average performance of each fully-connected topology. In this way, trends are found in the behavior of the networks, and it is established that, for networks with at least 150 perceptrons in their hidden layers, the average predictive error stabilizes below

4 %

. Beyond this point, no really significant improvements are found, although there is an increase in computational requirements. Full article

(This article belongs to the Special Issue Recent Advances and Applications of Machine Learning in Metal Forming Processes)

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20 pages, 19183 KiB

Open AccessFeature PaperArticle

Machine Learning-Based Models for the Estimation of the Energy Consumption in Metal Forming Processes

by Irene Mirandola, Guido A. Berti, Roberto Caracciolo, Seungro Lee, Naksoo Kim and Luca Quagliato

Metals 2021, 11(5), 833; https://doi.org/10.3390/met11050833 - 19 May 2021

Cited by 16 | Viewed by 4001

Abstract

This research provides an insight on the performances of machine learning (ML)-based algorithms for the estimation of the energy consumption in metal forming processes and is applied to the radial-axial ring rolling process. To define the mutual influence between ring geometry, process settings, [...] Read more.

This research provides an insight on the performances of machine learning (ML)-based algorithms for the estimation of the energy consumption in metal forming processes and is applied to the radial-axial ring rolling process. To define the mutual influence between ring geometry, process settings, and ring rolling mill geometries with the resulting energy consumption, measured in terms of the force integral over the processing time (FIOT), FEM simulations have been implemented in the commercial SW Simufact Forming 15. A total of 380 finite element simulations with rings ranging from 650 mm < DF < 2000 mm have been implemented and constitute the bulk of the training and validation datasets. Both finite element simulation settings (input), as well as the FI (output), have been utilized for the training of eight machine learning models, implemented with Python scripts. The results allow defining that the Gradient Boosting (GB) method is the most reliable for the FIOT prediction in forming processes, being its maximum and average errors equal to 9.03% and 3.18%, respectively. The trained ML models have been also applied to own and literature experimental cases, showing a maximum and average error equal to 8.00% and 5.70%, respectively, thus proving once again its reliability. Full article

(This article belongs to the Special Issue Recent Advances and Applications of Machine Learning in Metal Forming Processes)

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20 pages, 4786 KiB

Open AccessArticle

Novel Prediction Model for Steel Mechanical Properties with MSVR Based on MIC and Complex Network Clustering

by Yuchun Wu, Yifan Yan and Zhimin Lv

Metals 2021, 11(5), 747; https://doi.org/10.3390/met11050747 - 1 May 2021

Cited by 6 | Viewed by 2057

Abstract

Traditional mechanical properties prediction models are mostly based on experience and mechanism, which neglect the linear and nonlinear relationships between process parameters. Aiming at the high-dimensional data collected in the complex industrial process of steel production, a new prediction model is proposed. The [...] Read more.

Traditional mechanical properties prediction models are mostly based on experience and mechanism, which neglect the linear and nonlinear relationships between process parameters. Aiming at the high-dimensional data collected in the complex industrial process of steel production, a new prediction model is proposed. The multidimensional support vector regression (MSVR)-based model is combined with the feature selection method, which involves maximum information coefficient (MIC) correlation characterization and complex network clustering. Firstly, MIC is used to measure the correlation between process parameters and mechanical properties, based on which a complex network is constructed and hierarchical clustering is performed. Secondly, we evaluate all parameters and select a representative one for each partition as the input of the subsequent model based on the centrality and influence indicators. Finally, an actual steel production case is used to train the MSVR prediction model. The prediction results show that our proposed framework can capture effective features from the full parameters in terms of higher prediction accuracy and is less time-consuming compared with the Pearson-based subset, full-parameter subset, and empirical subset input. The feature selection method based on MIC can dig out some nonlinear relationships which cannot be found by Pearson coefficient. Full article

(This article belongs to the Special Issue Recent Advances and Applications of Machine Learning in Metal Forming Processes)

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16 pages, 7552 KiB

Open AccessArticle

Robust Optimization and Kriging Metamodeling of Deep-Drawing Process to Obtain a Regulation Curve of Blank Holder Force

by Maria Emanuela Palmieri, Vincenzo Domenico Lorusso and Luigi Tricarico

Metals 2021, 11(2), 319; https://doi.org/10.3390/met11020319 - 12 Feb 2021

Cited by 15 | Viewed by 2841

Abstract

In recent decades, the automotive industry has had a constant evolution with consequent enhancement of products quality. In industrial applications, quality may be defined as conformance to product specifications and repeatability of manufacturing process. Moreover, in the modern era of Industry 4.0, research [...] Read more.

In recent decades, the automotive industry has had a constant evolution with consequent enhancement of products quality. In industrial applications, quality may be defined as conformance to product specifications and repeatability of manufacturing process. Moreover, in the modern era of Industry 4.0, research on technological innovation has made the real-time control of manufacturing process possible. Moving from the above context, a method is proposed to perform real-time control of a deep-drawing process, using the stamping of the upper front cross member of a car chassis as industrial case study. In particular, it is proposed to calibrate the force acting on the blank holder, defining a regulation curve that considers the material yield stress and the friction coefficient as the main noise variables of the process. Firstly, deep-drawing process was modeled by using commercial Finite Element (FE) software AutoForm. By means of AutoForm Sigma tool, the stability and capability of deep-drawing process were analyzed. Numerical results were then exploited to create metamodels, by using the kriging technique, which shows the relationships between the process parameters and appropriate quality indices. Multi-objective optimization with a desirability function was carried out to identify the optimal values of input parameters for deep-drawing process. Finally, the desired regulation curve was obtained by maximizing total desirability. The resulting regulation curve can be exploited as a useful tool for real-time control of the force acting on the blank holder. Full article

(This article belongs to the Special Issue Recent Advances and Applications of Machine Learning in Metal Forming Processes)

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17 pages, 7863 KiB

Open AccessArticle

Intelligent Recognition Model of Hot Rolling Strip Edge Defects Based on Deep Learning

by Dongcheng Wang, Yanghuan Xu, Bowei Duan, Yongmei Wang, Mingming Song, Huaxin Yu and Hongmin Liu

Metals 2021, 11(2), 223; https://doi.org/10.3390/met11020223 - 27 Jan 2021

Cited by 16 | Viewed by 3271

Abstract

The edge of a hot rolling strip corresponds to the area where surface defects often occur. The morphologies of several common edge defects are similar to one another, thereby leading to easy error detection. To improve the detection accuracy of edge defects, the [...] Read more.

The edge of a hot rolling strip corresponds to the area where surface defects often occur. The morphologies of several common edge defects are similar to one another, thereby leading to easy error detection. To improve the detection accuracy of edge defects, the authors of this paper first classified the common edge defects and then made a dataset of edge defect images on this basis. Subsequently, edge defect recognition models were established on the basis of LeNet-5, AlexNet, and VggNet-16 by using a convolutional neural network as the core. Through multiple groups of training and recognition experiments, the model’s accuracy and recognition time of a single defect image were analyzed and compared with recognition models with different learning rates and sample batches. The experimental results showed that the recognition model based on the AlexNet had a maximum accuracy of 93.5%, and the average recognition time of a single defect image was 0.0035 s, which could meet the industry requirement. The research results in this paper provide a new method and thought for the fine detection of edge defects in hot rolling strips and have practical significance for improving the surface quality of hot rolling strips. Full article

(This article belongs to the Special Issue Recent Advances and Applications of Machine Learning in Metal Forming Processes)

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12 pages, 1194 KiB

Open AccessFeature PaperArticle

Performance Comparison of Parametric and Non-Parametric Regression Models for Uncertainty Analysis of Sheet Metal Forming Processes

by Armando E. Marques, Pedro A. Prates, André F. G. Pereira, Marta C. Oliveira, José V. Fernandes and Bernardete M. Ribeiro

Metals 2020, 10(4), 457; https://doi.org/10.3390/met10040457 - 1 Apr 2020

Cited by 18 | Viewed by 3082

Abstract

This work aims to compare the performance of various parametric and non-parametric metamodeling techniques when applied to sheet metal forming processes. For this, the U-Channel and the Square Cup forming processes were studied. In both cases, three steel grades were considered, and numerical [...] Read more.

This work aims to compare the performance of various parametric and non-parametric metamodeling techniques when applied to sheet metal forming processes. For this, the U-Channel and the Square Cup forming processes were studied. In both cases, three steel grades were considered, and numerical simulations were performed, in order to establish a database for each combination of forming process and material. Each database was used to train and test the various metamodels, and their predictive performances were evaluated. The best performing metamodeling techniques were Gaussian processes, multi-layer perceptron, support vector machines, kernel ridge regression and polynomial chaos expansion. Full article

(This article belongs to the Special Issue Recent Advances and Applications of Machine Learning in Metal Forming Processes)

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