---
_id: '12358'
abstract:
- lang: eng
  text: "The complex yarn structure of knitted and woven fabrics gives rise to both
    a mechanical and\r\nvisual complexity. The small-scale interactions of yarns colliding
    with and pulling on each\r\nother result in drastically different large-scale
    stretching and bending behavior, introducing\r\nanisotropy, curling, and more.
    While simulating cloth as individual yarns can reproduce this\r\ncomplexity and
    match the quality of real fabric, it may be too computationally expensive for\r\nlarge
    fabrics. On the other hand, continuum-based approaches do not need to discretize
    the\r\ncloth at a stitch-level, but it is non-trivial to find a material model
    that would replicate the\r\nlarge-scale behavior of yarn fabrics, and they discard
    the intricate visual detail. In this thesis,\r\nwe discuss three methods to try
    and bridge the gap between small-scale and large-scale yarn\r\nmechanics using
    numerical homogenization: fitting a continuum model to periodic yarn simulations,
    adding mechanics-aware yarn detail onto thin-shell simulations, and quantitatively\r\nfitting
    yarn parameters to physical measurements of real fabric.\r\nTo start, we present
    a method for animating yarn-level cloth effects using a thin-shell solver.\r\nWe
    first use a large number of periodic yarn-level simulations to build a model of
    the potential\r\nenergy density of the cloth, and then use it to compute forces
    in a thin-shell simulator. The\r\nresulting simulations faithfully reproduce expected
    effects like the stiffening of woven fabrics\r\nand the highly deformable nature
    and anisotropy of knitted fabrics at a fraction of the cost of\r\nfull yarn-level
    simulation.\r\nWhile our thin-shell simulations are able to capture large-scale
    yarn mechanics, they lack\r\nthe rich visual detail of yarn-level simulations.
    Therefore, we propose a method to animate\r\nyarn-level cloth geometry on top
    of an underlying deforming mesh in a mechanics-aware\r\nfashion in real time.
    Using triangle strains to interpolate precomputed yarn geometry, we are\r\nable
    to reproduce effects such as knit loops tightening under stretching at negligible
    cost.\r\nFinally, we introduce a methodology for inverse-modeling of yarn-level
    mechanics of cloth,\r\nbased on the mechanical response of fabrics in the real
    world. We compile a database from\r\nphysical tests of several knitted fabrics
    used in the textile industry spanning diverse physical\r\nproperties like stiffness,
    nonlinearity, and anisotropy. We then develop a system for approximating these
    mechanical responses with yarn-level cloth simulation, using homogenized\r\nshell
    models to speed up computation and adding some small-but-necessary extensions
    to\r\nyarn-level models used in computer graphics.\r\n"
acknowledged_ssus:
- _id: SSU
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Georg
  full_name: Sperl, Georg
  id: 4DD40360-F248-11E8-B48F-1D18A9856A87
  last_name: Sperl
citation:
  ama: 'Sperl G. Homogenizing yarn simulations: Large-scale mechanics, small-scale
    detail, and quantitative fitting. 2022. doi:<a href="https://doi.org/10.15479/at:ista:12103">10.15479/at:ista:12103</a>'
  apa: 'Sperl, G. (2022). <i>Homogenizing yarn simulations: Large-scale mechanics,
    small-scale detail, and quantitative fitting</i>. Institute of Science and Technology
    Austria. <a href="https://doi.org/10.15479/at:ista:12103">https://doi.org/10.15479/at:ista:12103</a>'
  chicago: 'Sperl, Georg. “Homogenizing Yarn Simulations: Large-Scale Mechanics, Small-Scale
    Detail, and Quantitative Fitting.” Institute of Science and Technology Austria,
    2022. <a href="https://doi.org/10.15479/at:ista:12103">https://doi.org/10.15479/at:ista:12103</a>.'
  ieee: 'G. Sperl, “Homogenizing yarn simulations: Large-scale mechanics, small-scale
    detail, and quantitative fitting,” Institute of Science and Technology Austria,
    2022.'
  ista: 'Sperl G. 2022. Homogenizing yarn simulations: Large-scale mechanics, small-scale
    detail, and quantitative fitting. Institute of Science and Technology Austria.'
  mla: 'Sperl, Georg. <i>Homogenizing Yarn Simulations: Large-Scale Mechanics, Small-Scale
    Detail, and Quantitative Fitting</i>. Institute of Science and Technology Austria,
    2022, doi:<a href="https://doi.org/10.15479/at:ista:12103">10.15479/at:ista:12103</a>.'
  short: 'G. Sperl, Homogenizing Yarn Simulations: Large-Scale Mechanics, Small-Scale
    Detail, and Quantitative Fitting, Institute of Science and Technology Austria,
    2022.'
date_created: 2023-01-24T10:49:46Z
date_published: 2022-09-22T00:00:00Z
date_updated: 2024-02-28T12:57:46Z
day: '22'
ddc:
- '000'
- '620'
degree_awarded: PhD
department:
- _id: GradSch
- _id: ChWo
doi: 10.15479/at:ista:12103
ec_funded: 1
file:
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  date_created: 2023-01-25T12:04:41Z
  date_updated: 2023-02-02T09:29:57Z
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has_accepted_license: '1'
language:
- iso: eng
month: '09'
oa: 1
oa_version: Published Version
page: '138'
project:
- _id: 2533E772-B435-11E9-9278-68D0E5697425
  call_identifier: H2020
  grant_number: '638176'
  name: Efficient Simulation of Natural Phenomena at Extremely Large Scales
publication_identifier:
  isbn:
  - 978-3-99078-020-6
  issn:
  - 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
  record:
  - id: '11736'
    relation: part_of_dissertation
    status: public
  - id: '9818'
    relation: part_of_dissertation
    status: public
  - id: '8385'
    relation: part_of_dissertation
    status: public
status: public
supervisor:
- first_name: Christopher J
  full_name: Wojtan, Christopher J
  id: 3C61F1D2-F248-11E8-B48F-1D18A9856A87
  last_name: Wojtan
  orcid: 0000-0001-6646-5546
title: 'Homogenizing yarn simulations: Large-scale mechanics, small-scale detail,
  and quantitative fitting'
type: dissertation
user_id: 8b945eb4-e2f2-11eb-945a-df72226e66a9
year: '2022'
...