Computational modelling of ankle-foot orthosis to evaluate spatially asymmetric structural stiffness: Importance of geometric nonlinearity

Sumihira, Wataru; Otani, Tomohiro; Kobayashi, Yo; Tanaka, Masao

doi:https://doi.org/10.1177/09544119221114199

Computational modelling of ankle-foot orthosis to evaluate spatially asymmetric structural stiffness: Importance of geometric nonlinearity

Sumihira, Wataru; Otani, Tomohiro; Kobayashi, Yo et al.

Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine, 2022, 236(9), 1357-1364

アクセス数:715件（2025-08-28 18:22 集計）

固定URL: https://hdl.handle.net/11094/88623

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タイトル	Computational modelling of ankle-foot orthosis to evaluate spatially asymmetric structural stiffness: Importance of geometric nonlinearity
著者	著者名 Sumihira, Wataru
	NRID 1000040778990 1000040778990 ORCID 0000-0002-6431-2703 0000-0002-6431-2703 researchmap permalink bigvalley bigvalley Scopus Author ID 55625962900 55625962900 著者名 Otani, Tomohiro
	NRID 1000050424817 1000050424817 ORCID 0000-0003-4358-6294 0000-0003-4358-6294 researchmap permalink yokobayashi yokobayashi Scopus Author ID 55516137200 55516137200 著者名 Kobayashi, Yo
	NRID 1000040163571 1000040163571 著者名 Tanaka, Masao
キーワード等	AFO
	buckling
	corotational triangle element
	dorsiflexion
	large deflection
内容	Wataru Sumihira, Tomohiro Otani, Yo Kobayashi, Masao Tanaka, Computational modelling of ankle-foot orthosis to evaluate spatially asymmetric structural stiffness: Importance of geometric nonlinearity, Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine. pp. 9544119221114199. Copyright © 2022 SAGE Publications. DOI: 10.1177/09544119221114199.
抄録	An ankle-foot orthosis (AFO) constructed as a single piece of isotropic elastic material is a commonly used assistive device that provides stability to the ankle joint of patients with spastic diplegic cerebral palsy. The AFO has asymmetric stiffness that restricts plantarflexion during the swing phase while it is flexible to allow dorsiflexion during the stance phase with a large deflection, including buckling originating from geometric nonlinearity. However, its mechanical implications have not been sufficiently investigated. This study aims to develop a computational model of an AFO considering geometric nonlinearity and examine AFO stiffness asymmetry during plantarflexion and dorsiflexion using physical experiments. Three-dimensional AFO mechanics with geometric nonlinearities were expressed using corotational triangle-element formulations that obeyed Kirchhoff–Love plate theory. Computational load tests for plantarflexion and dorsiflexion, using idealised AFOs with two different ankle-region designs (covering or not covering the apexes of the malleoli), showed that plantarflexion moment–ankle angle relationships were linear and dorsiflexion moment–ankle angle relationships were nonlinear; increases in dorsiflexion led to negative apparent stiffness of the AFO. Both ankle-region designs resisted both plantarflexion and dorsiflexion, and out-of-plane elastic energy was locally concentrated on the lateral side, resulting in large deflections during dorsiflexion. These findings give insight into appropriate AFO design from a mechanical viewpoint by characterising three-dimensional structural asymmetry and geometric nonlinearity.
出版者	SAGE Publications
収録物名	Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine
巻(号)	236(9)
ページ	1357-1364
刊行年月	2022-07-23
言語	英語
ハンドルURL	https://hdl.handle.net/11094/88623
PISSN	09544119
eISSN	20413033
NCID	AA10698285
関連情報 (isVersionOf)	DOI (出版社版) https://doi.org/10.1177/09544119221114199
関連情報 (isIdenticalTo)	PMID 35875899
アクセス権	open access
出版タイプ	Accepted Manuscript
カテゴリ	学術雑誌論文 Journal Article

資源タイプ	学術雑誌論文
ローカル資源タイプ	学術雑誌論文
DCMI資源タイプ	text
DCTERMS.bibliographicCitation	Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine. 2022, 236(9), p. 1357-1364
DC.title	Computational modelling of ankle-foot orthosis to evaluate spatially asymmetric structural stiffness: Importance of geometric nonlinearity
DC.creator	Sumihira, Wataru
	Otani, Tomohiro
	Kobayashi, Yo
	Tanaka, Masao
DC.publisher	SAGE Publications
DC.language' scheme='DCTERMS.RFC1766	英語
DC.type' scheme='DCTERMS.DCMIType	text
DCTERMS.issued' scheme='DCTERMS.W3CDTF	2022-07-23
DC.identifier	https://doi.org/10.1177/09544119221114199
DC.subject	AFO
	buckling
	corotational triangle element
	dorsiflexion
	large deflection
DC.description	Wataru Sumihira, Tomohiro Otani, Yo Kobayashi, Masao Tanaka, Computational modelling of ankle-foot orthosis to evaluate spatially asymmetric structural stiffness: Importance of geometric nonlinearity, Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine. pp. 9544119221114199. Copyright © 2022 SAGE Publications. DOI: 10.1177/09544119221114199.
DCTERMS.abstract	An ankle-foot orthosis (AFO) constructed as a single piece of isotropic elastic material is a commonly used assistive device that provides stability to the ankle joint of patients with spastic diplegic cerebral palsy. The AFO has asymmetric stiffness that restricts plantarflexion during the swing phase while it is flexible to allow dorsiflexion during the stance phase with a large deflection, including buckling originating from geometric nonlinearity. However, its mechanical implications have not been sufficiently investigated. This study aims to develop a computational model of an AFO considering geometric nonlinearity and examine AFO stiffness asymmetry during plantarflexion and dorsiflexion using physical experiments. Three-dimensional AFO mechanics with geometric nonlinearities were expressed using corotational triangle-element formulations that obeyed Kirchhoff–Love plate theory. Computational load tests for plantarflexion and dorsiflexion, using idealised AFOs with two different ankle-region designs (covering or not covering the apexes of the malleoli), showed that plantarflexion moment–ankle angle relationships were linear and dorsiflexion moment–ankle angle relationships were nonlinear; increases in dorsiflexion led to negative apparent stiffness of the AFO. Both ankle-region designs resisted both plantarflexion and dorsiflexion, and out-of-plane elastic energy was locally concentrated on the lateral side, resulting in large deflections during dorsiflexion. These findings give insight into appropriate AFO design from a mechanical viewpoint by characterising three-dimensional structural asymmetry and geometric nonlinearity.
DC.format	88623
citation_title	Computational modelling of ankle-foot orthosis to evaluate spatially asymmetric structural stiffness: Importance of geometric nonlinearity
citation_author	Sumihira, Wataru
	Otani, Tomohiro
	Kobayashi, Yo
	Tanaka, Masao
citation_publisher	SAGE Publications
citation_language	英語
citation_date	2022-07-23
citation_journal_title	Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine
citation_volume	236
citation_issue	9
citation_firstpage	1357
citation_lastpage	1364
citation_doi	https://doi.org/10.1177/09544119221114199
citation_pmid	35875899
citation_public_url	https://hdl.handle.net/11094/88623

Computational modelling of ankle-foot orthosis to evaluate spatially asymmetric structural stiffness: Importance of geometric nonlinearity

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