On the second gradient nonlinear spectral constitutive modelling of viscoelastic composites reinforced with stiff fibers

Abstract General novel nonlinear second-gradient spectral constitutive models for rate dependent fiber-reinforced viscoelastic solids that consider bending stiffness are developed. The constitutive models are characterized by spectral invariants, each with a clearer physical meaning compared to the...

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Main Author: M. H. B. M. Shariff
Format: Article
Language:English
Published: Nature Portfolio 2025-07-01
Series:Scientific Reports
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Online Access:https://doi.org/10.1038/s41598-025-05230-7
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author M. H. B. M. Shariff
author_facet M. H. B. M. Shariff
author_sort M. H. B. M. Shariff
collection DOAJ
description Abstract General novel nonlinear second-gradient spectral constitutive models for rate dependent fiber-reinforced viscoelastic solids that consider bending stiffness are developed. The constitutive models are characterized by spectral invariants, each with a clearer physical meaning compared to the classical invariants. Hence, they are experimentally useful if a rigorous experimental curve fitting exercise is used to obtain a specific form of free energy function. The number of complete-irreducible-minimal spectral invariants is significantly less than the number of ‘classical’ complete-irreducible invariants given in the literature, and hence modelling complexity is drastically reduced when a spectral technique is used. Our spectral approach in this paper is different from the classical invariant approach that have been done in the last decades regarding nonlinear solid mechanics. A detailed proof to show that the spherical part of the couple stress is just a Lagrange multiplier, is given. Results for pure bending and, the extension and inflation of a solid cylinder, that could be useful for experiments and numerical validations, are given.
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spelling doaj-art-c333123c0dac43cd8bfcbf8f1ce0cdeb2025-08-20T04:01:34ZengNature PortfolioScientific Reports2045-23222025-07-0115111810.1038/s41598-025-05230-7On the second gradient nonlinear spectral constitutive modelling of viscoelastic composites reinforced with stiff fibersM. H. B. M. Shariff0Department of Applied Mathematics, Khalifa University of Science and TechnologyAbstract General novel nonlinear second-gradient spectral constitutive models for rate dependent fiber-reinforced viscoelastic solids that consider bending stiffness are developed. The constitutive models are characterized by spectral invariants, each with a clearer physical meaning compared to the classical invariants. Hence, they are experimentally useful if a rigorous experimental curve fitting exercise is used to obtain a specific form of free energy function. The number of complete-irreducible-minimal spectral invariants is significantly less than the number of ‘classical’ complete-irreducible invariants given in the literature, and hence modelling complexity is drastically reduced when a spectral technique is used. Our spectral approach in this paper is different from the classical invariant approach that have been done in the last decades regarding nonlinear solid mechanics. A detailed proof to show that the spherical part of the couple stress is just a Lagrange multiplier, is given. Results for pure bending and, the extension and inflation of a solid cylinder, that could be useful for experiments and numerical validations, are given.https://doi.org/10.1038/s41598-025-05230-7Fibre-reinforced solidsNon-linear viscoelasticBending stiffnessSpectral invariants and formulationCouple stress
spellingShingle M. H. B. M. Shariff
On the second gradient nonlinear spectral constitutive modelling of viscoelastic composites reinforced with stiff fibers
Scientific Reports
Fibre-reinforced solids
Non-linear viscoelastic
Bending stiffness
Spectral invariants and formulation
Couple stress
title On the second gradient nonlinear spectral constitutive modelling of viscoelastic composites reinforced with stiff fibers
title_full On the second gradient nonlinear spectral constitutive modelling of viscoelastic composites reinforced with stiff fibers
title_fullStr On the second gradient nonlinear spectral constitutive modelling of viscoelastic composites reinforced with stiff fibers
title_full_unstemmed On the second gradient nonlinear spectral constitutive modelling of viscoelastic composites reinforced with stiff fibers
title_short On the second gradient nonlinear spectral constitutive modelling of viscoelastic composites reinforced with stiff fibers
title_sort on the second gradient nonlinear spectral constitutive modelling of viscoelastic composites reinforced with stiff fibers
topic Fibre-reinforced solids
Non-linear viscoelastic
Bending stiffness
Spectral invariants and formulation
Couple stress
url https://doi.org/10.1038/s41598-025-05230-7
work_keys_str_mv AT mhbmshariff onthesecondgradientnonlinearspectralconstitutivemodellingofviscoelasticcompositesreinforcedwithstifffibers