Professor Jörg Schröder

Modeling of damage in fiber-reinforced high-performance concrete at low cycle fatigue using a phase-field regularization

Chair of the Institute of Mechanics at Universität Duisburg-Essen

Jörg Schröder is a Professor of Mechanics and was Vice-Rector for Research, Junior Academic staff, and Knowledge Transfer at the University of Duisburg-Essen from 2011-2015 and 2018-2018. He graduated in Civil Engineering from the University of Applied Sciences (FH) Hildesheim/Holzminden (Germany) in 1988. Then he obtained his Diplom-Ingenieur (U) and Doctor-Ingenieur from the University of Hannover in 1992 and 1995, respectively. After holding for five years a Research Assistantship position at Stuttgart University and completing his Habilitation Theses in 2000, he became a Professor of Mechanics at TU Darmstadt. In 2001, he moved to the Department of Civil Engineering at the University of Duisburg-Essen, where he has stayed since then. 2009 – 2014, he has been a member of the Directorate of the Association of Applied Mathematics and Mechanics (GAMM). From 2020-2023 he was the President of GAMM and is now the Vice-President until 2025. He is a member of the Academy of Sciences and Literature Mainz, the German Academy of Science and Engineering „acatech“ and a senator of the German Science Foundation (DFG). Furthermore, he was the spokesperson of the DFG Research Unit 1509, “Functional Materials at Multiple Scales, Continuum Modeling and Experimental Characterization” and of the DFG Priority Programme 1748, “Reliable Simulation Techniques in Solid Mechanics. Development of Non-standard Discretization Methods, Mechanical and Mathematical Analysis”. He is a member of the selection committee for research scholarships of the Alexander v. Humboldt-Stiftung since 2016.

His areas of research interest are computational mechanics, continuum mechanics, and constitutive modeling. Some of his work focuses on the computational treatment of polyconvexity for general hyperelastic and biological materials and the formulation and implementation of mixed finite elements. Furthermore, methods in multiscale modeling (FE²) have been a focus in the last three decades. The latest works deals with the coupling of electro-magneto-mechanical effects and simplified microstructural models based on statistically similar RVEs (SSRVEs). Questions concerning scale transitions of micromagnetic systems and generalized continua with attached classical microstructures (Cauchy continua) are being analyzed. Furthermore, the focus is on phenomenological descriptions of fiber-reinforced modern concretes and their regularisation in the softening range using the phase field method. He is the author of over 300 technical papers, 15 books and serves as Editor-in-Chief of „Archive of Applied Mechanics“ and on the editorial board of several journals.

Abstract

Modeling of damage in fiber-reinforced high-performance concrete at low cycle fatigue using a phase-field regularization

Fiber-reinforced high-performance concrete (HPC) shows a pseudo-ductile material behavior during failure, mainly characterized by complex fiber-matrix interactions. We propose a phenomenological material model to discuss the influence of reinforced fibers, represented by orientation distribution functions (ODF), on the failure process of HPC. Therein, an additive type macroscopic energy function is formulated, superimposing the models of one-dimensional elastoplasticity for the steel fibers and an elastoplastic phase-field fracture model, cf. [1], which can predict the nonlinear behavior of high-performance concrete (HPC) during low-cycle fatigue. We apply the pressure-sensitive Drucker-Prager yield criterion as a basis for pure concrete behavior. A phase field model is used to regularize the softening behavior of the material; otherwise, we can expect a pathological response in the finite element method. Two different data-driven degradation functions are calibrated to model the asymmetric tension-compression behavior of HPC, see [2]. Three-point bending experimental tests at low-cycle using notched beams are performed, and the experimental load-CMOD (crack mouth opening displacement) curves are used to calibrate the proposed numerical model. ODFs approximate different distributions and orientations of reinforced fibers, see [3]. The accuracy of the proposed numerical model is verified by comparing the degradation of stiffness in numerical and experimental results.

[1] C. Miehe, F. Aldakheel, & A. Raina. Phase-field modeling of ductile fracture at finite strains: A variational gradient-extended plasticity-damage theory. International Journal of Plasticity, 84:1-32, 2016.
[2] J. Schroder, M. Pise, D. Brands, G. Gebuhr & S. Anders. Phase-field modeling of fracture in high performance concrete during low-cycle fatigue: numerical calibration and experimental validation. Computer methods in applied mechanics and engineering. Computer methods in applied mechanics and engineering, 398:115181, 2022.
[3] G. Gebuhr, M. Pise, S. Anders, D. Brands & J. Schroder. Damage evolution of steel fiber reinforced high performance concrete in low-cycle flexural fatigue: numerical modeling and experimental validation. Materials, 15:1179, 2022.

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