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Main Authors: Mäkinen, Tero, Taloni, Alessandro, Costantini, Giulio, Della Torre, Davide, Donnini, Riccardo, Zapperi, Stefano
Format: Preprint
Published: 2026
Subjects:
Online Access:https://arxiv.org/abs/2604.01858
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author Mäkinen, Tero
Taloni, Alessandro
Costantini, Giulio
Della Torre, Davide
Donnini, Riccardo
Zapperi, Stefano
author_facet Mäkinen, Tero
Taloni, Alessandro
Costantini, Giulio
Della Torre, Davide
Donnini, Riccardo
Zapperi, Stefano
contents We study the mechanical response of quasi-brittle polymethyl methacrylate (PMMA) specimens containing controlled random distributions of laser-cut holes. Tensile tests combined with digital image correlation reveal a nearly linear decrease of the Young's modulus with porosity, but with a softening rate far exceeding classical effective medium theory and the Hashin-Shtrikman bound. The extrapolated critical porosity at which the modulus vanishes is well below the 2D percolation threshold, indicating that ideal cylindrical void models fail to capture the observed behavior. Microscopy shows irregular pore geometries and frequent coalescence, which effectively act as crack-like defects and strongly enhance compliance. The rupture stress distributions are well described by a Weibull model accounting for both load-bearing area reduction and stress concentration at hole edges. Digital image correlation reveals heterogeneous but non-localized deformation, with strain increasingly correlated with the hole pattern, indicating a growing influence of defect-induced stress concentrations. These results highlight the dominant role of defect morphology in governing stiffness degradation and fracture statistics in porous quasi-brittle materials.
format Preprint
id arxiv_https___arxiv_org_abs_2604_01858
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Elastic softening and fracture in randomly perforated solids
Mäkinen, Tero
Taloni, Alessandro
Costantini, Giulio
Della Torre, Davide
Donnini, Riccardo
Zapperi, Stefano
Materials Science
We study the mechanical response of quasi-brittle polymethyl methacrylate (PMMA) specimens containing controlled random distributions of laser-cut holes. Tensile tests combined with digital image correlation reveal a nearly linear decrease of the Young's modulus with porosity, but with a softening rate far exceeding classical effective medium theory and the Hashin-Shtrikman bound. The extrapolated critical porosity at which the modulus vanishes is well below the 2D percolation threshold, indicating that ideal cylindrical void models fail to capture the observed behavior. Microscopy shows irregular pore geometries and frequent coalescence, which effectively act as crack-like defects and strongly enhance compliance. The rupture stress distributions are well described by a Weibull model accounting for both load-bearing area reduction and stress concentration at hole edges. Digital image correlation reveals heterogeneous but non-localized deformation, with strain increasingly correlated with the hole pattern, indicating a growing influence of defect-induced stress concentrations. These results highlight the dominant role of defect morphology in governing stiffness degradation and fracture statistics in porous quasi-brittle materials.
title Elastic softening and fracture in randomly perforated solids
topic Materials Science
url https://arxiv.org/abs/2604.01858