Application-Oriented Digital Image Correlation for the High-Speed Deformation and Fracture Analysis of AISI 1045 and Ti6Al4V Materials

Lars Gerdes; Sebastian Berger; Jannis Saelzer; Pascal Franck; Ramon Helwing; Andreas Zabel; Frank Walther

doi:10.3390/applmech3040068

Applied Mechanics (Oct 2022)

Application-Oriented Digital Image Correlation for the High-Speed Deformation and Fracture Analysis of AISI 1045 and Ti6Al4V Materials

Lars Gerdes,
Sebastian Berger,
Jannis Saelzer,
Pascal Franck,
Ramon Helwing,
Andreas Zabel,
Frank Walther

Affiliations

Lars Gerdes: Chair of Materials Test Engineering (WPT), Faculty of Mechanical Engineering, TU Dortmund University, Baroper Str. 303, 44227 Dortmund, Germany
Sebastian Berger: Institute of Machining Technology (ISF), Faculty of Mechanical Engineering, TU Dortmund University, Baroper Str. 303, 44227 Dortmund, Germany
Jannis Saelzer: Institute of Machining Technology (ISF), Faculty of Mechanical Engineering, TU Dortmund University, Baroper Str. 303, 44227 Dortmund, Germany
Pascal Franck: Chair of Materials Test Engineering (WPT), Faculty of Mechanical Engineering, TU Dortmund University, Baroper Str. 303, 44227 Dortmund, Germany
Ramon Helwing: Chair of Materials Test Engineering (WPT), Faculty of Mechanical Engineering, TU Dortmund University, Baroper Str. 303, 44227 Dortmund, Germany
Andreas Zabel: Institute of Machining Technology (ISF), Faculty of Mechanical Engineering, TU Dortmund University, Baroper Str. 303, 44227 Dortmund, Germany
Frank Walther: Chair of Materials Test Engineering (WPT), Faculty of Mechanical Engineering, TU Dortmund University, Baroper Str. 303, 44227 Dortmund, Germany

DOI: https://doi.org/10.3390/applmech3040068
Journal volume & issue: Vol. 3, no. 4
pp. 1190 – 1205

Abstract

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In order to achieve realistic simulations of the chip formation, high quality input data regarding the flow stress and damage behavior of the materials are required. The split Hopkinson pressure bar (SHPB) test setup for the characterization of highly dynamic material properties offers a suitable method for generating high strain rates, similar to those in the chip formation zone. However, the strain measurement in SHPB is usually performed by means of strain gauges. This leads to an unreliable evaluation of strain rate and flow stress/shear flow stress in the case of an inhomogeneous material deformation, since this method presents the total strain whilst excluding local deformations. Inhomogeneous deformations are induced deliberately in special shear specimens, as they are also observed in the investigated cylindrical specimens. The present work deals with this issue by providing two additional measurement techniques, which are applied in SHPB tests for cylindrical specimens made of AISI 1045 and Ti6Al4V. To enable a local strain resolution, digital image correlation (DIC) is applied to high-speed images of the deformation process. In order to allow for the detection of shear bands in the specimens, a deep-learning-based approach is presented. The two measurement methods (strain gauges and DIC) are compared and discussed. In particular, the findings regarding the inhomogeneous deformation of Ti6Al4V allow for future improvements in the result quality of SHPB tests. The presented algorithm shows promising predictions for shear band detection and creates the basis for an automated evaluation of shear sample results, as well as an AI-based pre-selection of frames for the DIC evaluation of SHPB tests.

Published in Applied Mechanics

ISSN: 2673-3161 (Online)
Publisher: MDPI AG
Country of publisher: Switzerland
LCC subjects: Technology: Engineering (General). Civil engineering (General)
Website: https://www.mdpi.com/journal/applmech

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