---
_id: '65266'
abstract:
- lang: eng
  text: "<jats:title>ABSTRACT</jats:title>\r\n                  <jats:p>This work
    is concerned with the modeling of a cold‐box sand, a composition of sand grains
    and a resin binder. To this end, experiments are performed, which show the following
    characteristics: localization phenomena in the form of a shear band, softening
    behavior in the force‐displacement curve, and asymmetric behavior for compression
    and tension. To model this complex material behavior, a micromorphic continuum
    is used. In the present contribution, we focus on the linear‐elastic regime and
    demonstrate the identifiability of micromorphic material parameters under deliberately
    induced inhomogeneous deformation states. In addition to the degrees of freedom
    of a classical continuum, the micromorphic model has additional degrees of freedom,
    introduced here in a phenomenological sense to represent kinematically enriched
    deformation modes associated with the granular microstructure. Accordingly, the
    micromorphic fields are not interpreted as a separate physical scale (e.g., “binder”
    vs. “grains”), but as an effective continuum description at the specimen scale.
    This contribution addresses parameter identification for a micromorphic model
    of cold‐box sand, with a clear separation between homogeneous deformation states
    governing classical elastic parameters and inhomogeneous states required to activate
    and identify micromorphic length‐scale parameters. The main challenge lies in
    identifying the micro material parameters. To determine these, the corresponding
    gradient terms in the constitutive formulation must be triggered via properly
    tuned experiments. Micro‐parameter identification is demonstrated using synthetic
    data generated from a boundary‐value problem with inhomogeneous displacement fields.
    The chosen benchmark enables controlled activation of gradient terms and thereby
    renders optimization‐based identification of micromorphic parameters feasible.
    The synthetic example is deliberately chosen to assess feasibility and identifiability
    under controlled conditions, thereby isolating micromorphic identifiability aspects
    from experimental uncertainties. The novelty of the contribution lies in explicitly
    linking micromorphic parameter identifiability to kinematic inhomogeneity, and
    in demonstrating this link within a tractable forward– inverse setting for a linear‐elastic
    micromorphic continuum.</jats:p>"
article_number: e70093
author:
- first_name: Alexander
  full_name: Börger, Alexander
  id: '52037'
  last_name: Börger
- first_name: Rolf
  full_name: Mahnken, Rolf
  last_name: Mahnken
- first_name: Ismail
  full_name: Caylak, Ismail
  id: '75'
  last_name: Caylak
- first_name: Richard
  full_name: Ostwald, Richard
  id: '106876'
  last_name: Ostwald
  orcid: 0000-0003-2147-8444
citation:
  ama: Börger A, Mahnken R, Caylak I, Ostwald R. Aspects of Parameter Identification
    for a Micromorphic Continuum applied to a Cold‐Box Sand. <i>Proceedings in Applied
    Mathematics and Mechanics</i>. 2026;26(2). doi:<a href="https://doi.org/10.1002/pamm.70093">10.1002/pamm.70093</a>
  apa: Börger, A., Mahnken, R., Caylak, I., &#38; Ostwald, R. (2026). Aspects of Parameter
    Identification for a Micromorphic Continuum applied to a Cold‐Box Sand. <i>Proceedings
    in Applied Mathematics and Mechanics</i>, <i>26</i>(2), Article e70093. <a href="https://doi.org/10.1002/pamm.70093">https://doi.org/10.1002/pamm.70093</a>
  bibtex: '@article{Börger_Mahnken_Caylak_Ostwald_2026, title={Aspects of Parameter
    Identification for a Micromorphic Continuum applied to a Cold‐Box Sand}, volume={26},
    DOI={<a href="https://doi.org/10.1002/pamm.70093">10.1002/pamm.70093</a>}, number={2e70093},
    journal={Proceedings in Applied Mathematics and Mechanics}, publisher={Wiley},
    author={Börger, Alexander and Mahnken, Rolf and Caylak, Ismail and Ostwald, Richard},
    year={2026} }'
  chicago: Börger, Alexander, Rolf Mahnken, Ismail Caylak, and Richard Ostwald. “Aspects
    of Parameter Identification for a Micromorphic Continuum Applied to a Cold‐Box
    Sand.” <i>Proceedings in Applied Mathematics and Mechanics</i> 26, no. 2 (2026).
    <a href="https://doi.org/10.1002/pamm.70093">https://doi.org/10.1002/pamm.70093</a>.
  ieee: 'A. Börger, R. Mahnken, I. Caylak, and R. Ostwald, “Aspects of Parameter Identification
    for a Micromorphic Continuum applied to a Cold‐Box Sand,” <i>Proceedings in Applied
    Mathematics and Mechanics</i>, vol. 26, no. 2, Art. no. e70093, 2026, doi: <a
    href="https://doi.org/10.1002/pamm.70093">10.1002/pamm.70093</a>.'
  mla: Börger, Alexander, et al. “Aspects of Parameter Identification for a Micromorphic
    Continuum Applied to a Cold‐Box Sand.” <i>Proceedings in Applied Mathematics and
    Mechanics</i>, vol. 26, no. 2, e70093, Wiley, 2026, doi:<a href="https://doi.org/10.1002/pamm.70093">10.1002/pamm.70093</a>.
  short: A. Börger, R. Mahnken, I. Caylak, R. Ostwald, Proceedings in Applied Mathematics
    and Mechanics 26 (2026).
date_created: 2026-04-01T04:52:34Z
date_updated: 2026-04-01T04:54:17Z
department:
- _id: '9'
- _id: '952'
- _id: '321'
doi: 10.1002/pamm.70093
intvolume: '        26'
issue: '2'
language:
- iso: eng
publication: Proceedings in Applied Mathematics and Mechanics
publication_identifier:
  issn:
  - 1617-7061
  - 1617-7061
publication_status: published
publisher: Wiley
quality_controlled: '1'
status: public
title: Aspects of Parameter Identification for a Micromorphic Continuum applied to
  a Cold‐Box Sand
type: journal_article
user_id: '85414'
volume: 26
year: '2026'
...
---
_id: '65491'
abstract:
- lang: eng
  text: "<jats:title>Abstract</jats:title>\r\n                  <jats:p>The micropolar
    continuum is a special case of a micromorphic material model and has additional
    degrees of freedom in the form of microrotations compared to the classical continuum.
    With the micropolar model, size effects can be considered and the boundary value
    problem can be regularized when localization effects occur. In order to map the
    microrotations, an additional strain measure and an additional stress are introduced.
    For simulation of plasticity, it is possible to define one yield function, and
    thus one plastic multiplier as well as one equivalent plastic strain occur. This
    approach is known as the single-surface plasticity approach. The macro- and micro-stresses
    are coupled in a common flow function. On the other hand, there is the so-called
    double-surface plasticity when one yield function, one plastic multiplier, and
    one equivalent plastic strain, respectively, are introduced for each of the macro-
    and micro-variables. The coupling of the macro- and micro-variables is established
    by a possible coupling of both yield functions. The purpose of this paper is to
    compare both approaches and to identify similarities and differences.</jats:p>"
article_number: '94'
author:
- first_name: Alexander
  full_name: Börger, Alexander
  id: '52037'
  last_name: Börger
- first_name: Rolf
  full_name: Mahnken, Rolf
  last_name: Mahnken
citation:
  ama: Börger A, Mahnken R. Single-surface and double-surface plasticity for micropolar
    continuum. <i>Archive of Applied Mechanics</i>. 2026;96(5). doi:<a href="https://doi.org/10.1007/s00419-026-03049-w">10.1007/s00419-026-03049-w</a>
  apa: Börger, A., &#38; Mahnken, R. (2026). Single-surface and double-surface plasticity
    for micropolar continuum. <i>Archive of Applied Mechanics</i>, <i>96</i>(5), Article
    94. <a href="https://doi.org/10.1007/s00419-026-03049-w">https://doi.org/10.1007/s00419-026-03049-w</a>
  bibtex: '@article{Börger_Mahnken_2026, title={Single-surface and double-surface
    plasticity for micropolar continuum}, volume={96}, DOI={<a href="https://doi.org/10.1007/s00419-026-03049-w">10.1007/s00419-026-03049-w</a>},
    number={594}, journal={Archive of Applied Mechanics}, publisher={Springer Science
    and Business Media LLC}, author={Börger, Alexander and Mahnken, Rolf}, year={2026}
    }'
  chicago: Börger, Alexander, and Rolf Mahnken. “Single-Surface and Double-Surface
    Plasticity for Micropolar Continuum.” <i>Archive of Applied Mechanics</i> 96,
    no. 5 (2026). <a href="https://doi.org/10.1007/s00419-026-03049-w">https://doi.org/10.1007/s00419-026-03049-w</a>.
  ieee: 'A. Börger and R. Mahnken, “Single-surface and double-surface plasticity for
    micropolar continuum,” <i>Archive of Applied Mechanics</i>, vol. 96, no. 5, Art.
    no. 94, 2026, doi: <a href="https://doi.org/10.1007/s00419-026-03049-w">10.1007/s00419-026-03049-w</a>.'
  mla: Börger, Alexander, and Rolf Mahnken. “Single-Surface and Double-Surface Plasticity
    for Micropolar Continuum.” <i>Archive of Applied Mechanics</i>, vol. 96, no. 5,
    94, Springer Science and Business Media LLC, 2026, doi:<a href="https://doi.org/10.1007/s00419-026-03049-w">10.1007/s00419-026-03049-w</a>.
  short: A. Börger, R. Mahnken, Archive of Applied Mechanics 96 (2026).
date_created: 2026-04-23T11:55:35Z
date_updated: 2026-04-23T11:56:38Z
department:
- _id: '9'
- _id: '952'
- _id: '321'
doi: 10.1007/s00419-026-03049-w
intvolume: '        96'
issue: '5'
language:
- iso: eng
publication: Archive of Applied Mechanics
publication_identifier:
  issn:
  - 0939-1533
  - 1432-0681
publication_status: published
publisher: Springer Science and Business Media LLC
quality_controlled: '1'
status: public
title: Single-surface and double-surface plasticity for micropolar continuum
type: journal_article
user_id: '85414'
volume: 96
year: '2026'
...