Integral and Gradient-enhanced Non-local Frameworks for Size-dependent Ductile Failure

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Ünsal İ. E., Erdoğan C., Yalçınkaya T.

4th International Workshop on Plasticity, Damage and Fracture of Engineering Materials, İstanbul, Türkiye, 24 - 26 Eylül 2025, ss.58, (Özet Bildiri)

  • Yayın Türü: Bildiri / Özet Bildiri
  • Basıldığı Şehir: İstanbul
  • Basıldığı Ülke: Türkiye
  • Sayfa Sayıları: ss.58
  • Orta Doğu Teknik Üniversitesi Adresli: Evet

Özet

In ductile materials, strain localization can lead to the initiation and propagation of damage. When a local, coupled damage model is used, the size of the localized damage zone depends on the spatial resolution of the finite element (FE) mesh, introducing inherent mesh sensitivity. To address this issue, nonlocal frameworks regularize the damage-driving variable and mitigate mesh dependence [1]. Numerous approaches have been proposed to introduce nonlocality within coupled ductile damage and fracture frameworks [2]. In this study, two widely used approaches from the literature are implemented via user subroutines in Abaqus and compared with respect to mesh objectivity. The nonlocal counterpart of a local variable is obtained using two strategies: (i) an averaging scheme applied after each solution increment to nonlocalize the equivalent plastic strain or the damage variable (termed integral-type approach), and (ii) the solution of a Helmholtz-type equation using built-in coupled temperature-displacement elements by analogy with the steady-state heat equation (termed gradient-enhanced approach). The performance of these two approaches is compared in terms of achieving mesh-independent solutions. References

[1] Peerlings R.H.J., Geers M.G.D., de Borst R., Brekelmans W.A.M. (2001). A critical comparison of nonlocal and gradient-enhanced softening continua. International Journal of Solids and Structures, Vol. 38, pp. 7723–7746

[2] Bergo S., Morin D., Hopperstad O.S. (2021). Accurate modelling of the elastic behavior of a continuum with the discrete element method. International Journal of Solids and Structures, Vol. 219, pp. 134–150