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Tech."],"published-print":{"date-parts":[[2023,8,16]]},"abstract":"<jats:p>We explore micropolar materials for the simulation of volumetric deformable solids. In graphics, micropolar models have only been used in the form of one-dimensional Cosserat rods, where a rotating frame is attached to each material point on the one-dimensional centerline. By carrying this idea over to volumetric solids, every material point is associated with a microrotation, an independent degree of freedom that can be coupled to the displacement through a material's strain energy density. The additional degrees of freedom give us more control over bending and torsion modes of a material. We propose a new orthotropic micropolar curvature energy that allows us to make materials stiff to bending in specific directions.<\/jats:p>\n          <jats:p>For the simulation of dynamic micropolar deformables we propose a novel incremental potential formulation with a consistent FEM discretization that is well suited for the use in physically-based animation. This allows us to easily couple micropolar deformables with dynamic collisions through a contact model inspired from the Incremental Potential Contact (IPC) approach. For the spatial discretization with FEM we discuss the challenges related to the rotational degrees of freedom and propose a scheme based on the interpolation of angular velocities followed by quaternion time integration at the quadrature points.<\/jats:p>\n          <jats:p>In our evaluation we validate the consistency and accuracy of our discretization approach and demonstrate several compelling use cases for micropolar materials. This includes explicit control over bending and torsion stiffness, deformation through prescription of a volumetric curvature field and robust interaction of micropolar deformables with dynamic collisions.<\/jats:p>","DOI":"10.1145\/3606922","type":"journal-article","created":{"date-parts":[[2023,8,24]],"date-time":"2023-08-24T10:05:30Z","timestamp":1692871530000},"page":"1-24","update-policy":"https:\/\/doi.org\/10.1145\/crossmark-policy","source":"Crossref","is-referenced-by-count":5,"title":["Micropolar Elasticity in Physically-Based Animation"],"prefix":"10.1145","volume":"6","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6818-2953","authenticated-orcid":false,"given":"Fabian","family":"L\u00f6schner","sequence":"first","affiliation":[{"name":"RWTH Aachen University, Aachen, Germany"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4651-7542","authenticated-orcid":false,"given":"Jos\u00e9 Antonio","family":"Fern\u00e1ndez-Fern\u00e1ndez","sequence":"additional","affiliation":[{"name":"RWTH Aachen University, Aachen, Germany"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3920-7765","authenticated-orcid":false,"given":"Stefan Rhys","family":"Jeske","sequence":"additional","affiliation":[{"name":"RWTH Aachen University, Aachen, Germany"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6665-8302","authenticated-orcid":false,"given":"Andreas","family":"Longva","sequence":"additional","affiliation":[{"name":"RWTH Aachen University, Aachen, Germany"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1908-4027","authenticated-orcid":false,"given":"Jan","family":"Bender","sequence":"additional","affiliation":[{"name":"RWTH Aachen University, Aachen, Germany"}]}],"member":"320","published-online":{"date-parts":[[2023,8,24]]},"reference":[{"key":"e_1_2_2_1_1","doi-asserted-by":"publisher","DOI":"10.1007\/s00024-021-02894-w"},{"key":"e_1_2_2_2_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.pepi.2017.04.006"},{"key":"e_1_2_2_3_1","doi-asserted-by":"publisher","DOI":"10.1145\/3340260"},{"key":"e_1_2_2_4_1","doi-asserted-by":"publisher","DOI":"10.1007\/s00466-012-0679-9"},{"key":"e_1_2_2_5_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.cma.2010.05.002"},{"key":"e_1_2_2_6_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.cag.2014.07.004"},{"key":"e_1_2_2_7_1","doi-asserted-by":"publisher","DOI":"10.1145\/3099564.3099578"},{"key":"e_1_2_2_8_1","doi-asserted-by":"publisher","DOI":"10.5555\/1281957.1281987"},{"key":"e_1_2_2_9_1","doi-asserted-by":"publisher","DOI":"10.1145\/2601097.2601116"},{"key":"e_1_2_2_10_1","doi-asserted-by":"publisher","DOI":"10.1145\/3450626.3459942"},{"key":"e_1_2_2_11_1","doi-asserted-by":"publisher","DOI":"10.1145\/3272127.3275011"},{"key":"e_1_2_2_12_1","doi-asserted-by":"publisher","DOI":"10.1145\/502122.502124"},{"key":"e_1_2_2_13_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.wavemoti.2015.09.006"},{"key":"e_1_2_2_14_1","doi-asserted-by":"publisher","DOI":"10.1145\/3528223.3530076"},{"key":"e_1_2_2_15_1","doi-asserted-by":"publisher","DOI":"10.1145\/3099564.3099577"},{"key":"e_1_2_2_16_1","unstructured":"Eug\u00e8ne Cosserat and Fran\u00e7ois Cosserat. 1909. Th\u00e9orie des corps d\u00e9formables. A. Hermann et fils. English translation \"Theory of Deformable Bodies\" available by David H. Delphenich."},{"key":"e_1_2_2_17_1","doi-asserted-by":"publisher","DOI":"10.1098\/rspa.1999.0352"},{"key":"e_1_2_2_18_1","doi-asserted-by":"publisher","DOI":"10.1002\/nme.7188"},{"key":"e_1_2_2_19_1","doi-asserted-by":"publisher","DOI":"10.1111\/cgf.13326"},{"key":"e_1_2_2_20_1","doi-asserted-by":"publisher","DOI":"10.1023\/a:1006517625933"},{"key":"e_1_2_2_21_1","doi-asserted-by":"crossref","unstructured":"V.A. Eremeyev L.P. Lebedev and H. Altenbach. 2012. Foundations of Micropolar Mechanics. Springer Berlin Heidelberg.","DOI":"10.1007\/978-3-642-28353-6"},{"key":"e_1_2_2_22_1","volume-title":"Microcontinuum field theories: I. Foundations and Solids","author":"Eringen Ahmed Cemal","unstructured":"Ahmed Cemal Eringen. 1999. Microcontinuum field theories: I. Foundations and Solids. 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