Numerical Service Life Calculation Of Forming Tools During Thixoforging Using The Sehitoglu Model

authored by: Bernd Arno Behrens, Kai Brunotte, Hendrik Wester, Alexander Zaitsev, Maiwand Hootak
Abstract: The approach of the most common industry-specific FE-systems for the service life evaluation of forming tools holds some disadvantages. For example, within the decoupled tool analysis, load situations are typically analysed at room temperature and thus, the transient temperature development in the forging die is not considered in the lifetime evaluation. An elastic material behaviour is assumed for the tool component to be analysed. In this way, both deformation and fatigue behaviour are only approximately simulated. However, plastic deformation can occur in critical areas of the tool due to the operationally high tool loads, which can increase during operation and lead to hardening or softening processes in the material. For this reason, neglecting the temperature distribution in the tool makes it impossible to reproduce thermally induced damage processes. Therefore, Sehitoglu's life prediction approach, which is able to take into account thermo-mechanical loads in the tool during thixoforging and to calculate tool life, is presented in this publication. Since, particularly in thixoforming, where the temperatures exceed those of hot forming, the consideration of thermally induced damage plays a decisive role in order to predict the possibly early failure of the tools. Thus, an appropriate numerical design is possible. For this purpose, experimental tests such as low cycle and thermo-mechanical fatigue tests were performed for the parameterisation of the model. By means of optimisation routines, the model's parameters were determined. Subsequently, FE-simulations of a cup backward extrusion process were carried out to calculate tool fatigue along with different damage proportions. Finally, validation of the numerical calculations took place by a comparison with experimental results.
Organisation(s): Institute of Metal Forming and Metal Forming Machines
External Organisation(s): St. Petersburg State Polytechnical University
Type: Conference contribution
Pages: 320-326
No. of pages: 7
Publication date: 27.07.2020
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: Mechanics of Materials, Metals and Alloys, Surfaces, Coatings and Films
Electronic version(s): https://doi.org/10.37904/metal.2020.3484 (Access: Open)
: Details in the research portal "Research@Leibniz University"

BibTeX

@inproceedings{c99d81c74d4a4833897a76bbff2311df,
title = "Numerical Service Life Calculation Of Forming Tools During Thixoforging Using The Sehitoglu Model",
abstract = "The approach of the most common industry-specific FE-systems for the service life evaluation of forming tools holds some disadvantages. For example, within the decoupled tool analysis, load situations are typically analysed at room temperature and thus, the transient temperature development in the forging die is not considered in the lifetime evaluation. An elastic material behaviour is assumed for the tool component to be analysed. In this way, both deformation and fatigue behaviour are only approximately simulated. However, plastic deformation can occur in critical areas of the tool due to the operationally high tool loads, which can increase during operation and lead to hardening or softening processes in the material. For this reason, neglecting the temperature distribution in the tool makes it impossible to reproduce thermally induced damage processes. Therefore, Sehitoglu's life prediction approach, which is able to take into account thermo-mechanical loads in the tool during thixoforging and to calculate tool life, is presented in this publication. Since, particularly in thixoforming, where the temperatures exceed those of hot forming, the consideration of thermally induced damage plays a decisive role in order to predict the possibly early failure of the tools. Thus, an appropriate numerical design is possible. For this purpose, experimental tests such as low cycle and thermo-mechanical fatigue tests were performed for the parameterisation of the model. By means of optimisation routines, the model's parameters were determined. Subsequently, FE-simulations of a cup backward extrusion process were carried out to calculate tool fatigue along with different damage proportions. Finally, validation of the numerical calculations took place by a comparison with experimental results.",
keywords = "Fatigue model, FEA, Process simulation, Thixoforming, Tool life",
author = "Behrens, {Bernd Arno} and Kai Brunotte and Hendrik Wester and Alexander Zaitsev and Maiwand Hootak",
note = "Funding information: Sincere thanks to the German Research Foundation (DFG) for financial support (project number 299534929: “Numerical Calculation of Thermal Die Load and Die Life during Thixoforging of Steel”).; 29th International Conference on Metallurgy and Materials, METAL 2020 ; Conference date: 20-05-2020 Through 22-05-2020",
year = "2020",
month = jul,
day = "27",
doi = "10.37904/metal.2020.3484",
language = "English",
series = "METAL Conference Proceedings",
publisher = "TANGER Ltd.",
pages = "320--326",
booktitle = "METAL 2020 - 29th International Conference on Metallurgy and Materials, Conference Proceedings",
}