Balance laws versus the Principle of Virtual Work and the limited scope of Noll's theorem

Fuente: arXiv
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Main Authors: Rodriguez, Casey, dell'Isola, Francesco
Format: Preprint
Published: 2026
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author Rodriguez, Casey
dell'Isola, Francesco
author_facet Rodriguez, Casey
dell'Isola, Francesco
contents The relationship between balance laws and the Principle of Virtual Work as well as the structure of contact interactions in continua remain foundational issues in Mechanics. In this work, we revisit these issues within the distributional framework emphasized by Paul Germain. We show that while the Principle of Virtual Work implies balance of forces and moments for $n$th-gradient continua, balance laws alone do not suffice to characterize equilibrium for $n \geq 2$. We then reexamine Noll's classical theorem asserting that surface contact forces depend solely on the unit normal to the surface and identify the precise role of his additional assumptions, namely the absence of edge and wedge contact interactions and the boundedness of the surface contact density on the space of oriented surfaces. We demonstrate that these hypotheses fail for general higher-gradient continua. Consequently, the presence of curvature-dependent surface contact forces in such materials does not conflict with Noll's theorem and refutes his claim of their nonexistence.
format Preprint
id arxiv_https___arxiv_org_abs_2603_00327
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Balance laws versus the Principle of Virtual Work and the limited scope of Noll's theorem
Rodriguez, Casey
dell'Isola, Francesco
Classical Physics
The relationship between balance laws and the Principle of Virtual Work as well as the structure of contact interactions in continua remain foundational issues in Mechanics. In this work, we revisit these issues within the distributional framework emphasized by Paul Germain. We show that while the Principle of Virtual Work implies balance of forces and moments for $n$th-gradient continua, balance laws alone do not suffice to characterize equilibrium for $n \geq 2$. We then reexamine Noll's classical theorem asserting that surface contact forces depend solely on the unit normal to the surface and identify the precise role of his additional assumptions, namely the absence of edge and wedge contact interactions and the boundedness of the surface contact density on the space of oriented surfaces. We demonstrate that these hypotheses fail for general higher-gradient continua. Consequently, the presence of curvature-dependent surface contact forces in such materials does not conflict with Noll's theorem and refutes his claim of their nonexistence.
title Balance laws versus the Principle of Virtual Work and the limited scope of Noll's theorem
topic Classical Physics
url https://arxiv.org/abs/2603.00327