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Artificial Neural Network (ANN) Based Formability Prediction Model for 22MnB5 Steel under Hot Stamping Conditions
Published in Kakandikar Ganesh Marotrao, Anupam Agrawal, D. Ravi Kumar, Metal Forming Processes, 2023
Amarjeet Kumar Singh, K. Narasimhan
Forming Limit Diagram (FLD) is used to determine formability of sheet metal component. It is graphical representation of fail and safe region of sheet metal during forming. It depends on temperature, strain rate, thickness of sheet, strain path etc. In this work temperature and strain rate effects were analyzed under hot stamping conditions. Gleeble-3800 was used to conduct experiment in order to determine FLD in drawing region. In order to predict limiting strain, thickness based necking criterion was used [4]. To determine formability in drawing region simple tensile geometry was modified in shape such that it can produce plane strain condition as shown in Figure 1.5. To measure strain circular shape grid with diameter size of 1.5 mm and 2 mm center to ends distance between neighbor grids were engraved on surface of sheet with the help of laser marking machine as shown in Figure 1.6. After deformation four types of distorted grid were observed namely safe grid (before necking), critical grid (at point of necking), cracked or failed, neighbor to critical grid. Calculation of major and minor strain for FLD were done with help of critical grid.
Advances in Sheet Metal Stamping Technology: A Case of Design and Manufacturing of a Car Door Inner Panel Using a Tailor Welded Blank
Published in Pankaj Agarwal, Lokesh Bajpai, Chandra Pal Singh, Kapil Gupta, J. Paulo Davim, Manufacturing and Industrial Engineering, 2021
Tushar Y. Badgujar, Satish A. Bobade
Some of the standardised sheet metal forming operations that are used to measure formability are i) stretch forming (Panda et al. 2007), e.g. hemispherical punch test and ii) deep drawing, (Patel, Shah, and Shah 2012), etc. Formability is also estimated by analytical methods such as i) the height of the form specimen in the Dome test (Lee et al. 2009), ii) the strain distribution across the deformed blank (i.e. forming behaviour), 3) the forming limit diagram (FLD) based on the strain measured, (Cikmis, Pepelnjak, and Hasanbegovic 2010; Ravi Kumar 2002), and more. In these methods, the sheet metal is required to deform until necking occurs or when the metal reaches its forming limit. All materials have a forming limit, which is defined as the maximum uniform strain adjacent to a localised neck or tear in a deformed specimen. The forming limit diagram method is a more common method used in the industry for measuring the formability of materials (Chan, Chan, and Lee 2003).
Strain based and stress based fracture forming line for single point incremental forming
Published in Alka Mahajan, Parul Patel, Priyanka Sharma, Technologies for Sustainable Development, 2020
Y.R. Prajapati, A.M. Gohil, B.A. Modi, K.V. Sheth
A Forming Limit Diagram (FLD) is used in metal forming processes to predict forming behaviour of a sheet metal. The Forming Limit Diagram attempts to expose a graphical description of material failure tests. To prepare the FLD, different geometrical shapes which are capable to generate different straining conditions, are prepared using single point incremental forming process. In order to determine that a given region has failed, circle grid is marked on a sheet metal blank before deformation. After deformation through the process, deformed circle which takes the shape of ellipse are measured. Measured points are marked on FLD. From a number of such points forming limit curve(FLC) is generated, which divides the FLD into safe and failure region. Generated FLC can be used to predict the failure of the newly designed component for a given material and thickness of the blank. Stress based forming limit diagram is obtained from the results of strain based Forming Limit Curve. When strain-based FLD is converted into the forming limit stress diagram, the resulting stress based diagram is negligibly affected by changes to the various strain paths. This phenomena makes stress based Forming Limit Stress Diagram (FLSDs) an alternative to strain based FLDs for the prediction of failure.
Manufacturing methods for metallic bipolar plates for polymer electrolyte membrane fuel cell
Published in Materials and Manufacturing Processes, 2019
Oluwaseun Ayotunde Alo, Iyiola Olatunji Otunniyi, HCvZ Pienaar
The most commonly used tool for evaluating the formability of sheet metal is the forming limit diagram (FLD).[262] Numerical simulation methods (such as FEA) that are used to predict the failure probability of sheet metallic materials depend on a failure criterion that identifies the material’s maximum forming capacity.[263] This criterion is either described by the cancellation of the material composite in the form of a crack or by the local thinning in the direction of the sheet thickness. The FLD considers both criteria.[263] Within the FLD, the forming limit curve (FLC) denotes the onset of necking leading to crack initiation as the FL.[262] Currently, established methods for determining the FLC have some limitations. The standardized evaluation method[264] is position-dependent and does not consider the strain development over time. Merklein et al.[265] and Volk and Hora[266] proposed time-dependent methods that consider the strain development over time. However, these methods are limited in their evaluation area and may lead to the wrong FL. Also, the time-dependent methods depend on the acquisition rate of the strain measurement system, which tends to introduce a high variance for the FL.[263]