Naslov
An Approach to Damage Modeling in Heterogeneous Materials Using Strain Gradient Formulation

Autori
Sorić, Jurica ; Putar, Filip ; Lesičar, Tomislav ; Tonković, Zdenko

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
5th International Conference on Material Modeling Book of Abstracts / Dell’Isola, Francesco ; Rizzi, Nicola ; Bertram, Albrecht - Rim, 2017

Skup
5th International Conference on Material Modeling

Mjesto i datum
Rim, Italija, 14.06.2017. - 16.06.2017

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Quasi-Brittle Damage ; C1 Continuity Finite Element ; Strain Gradient Theory ; Heterogeneous Material

Sažetak
The damage phenomenon, macroscopically characterized by the decrease in the elastic material stiffness or so-called softening, is common in all engineering materials and can significantly decrease structural load-carrying capacity, and eventually lead to a complete loss of mechanical integrity. A lot of engineering materials can be treated as heterogeneous, particularly if they are observed at microscale. The geometrical and material properties of the constituents forming the microstructure have a significant impact on the material behavior. Therefore, in order to assess structural integrity and to predict structural lifetime, an analysis evolving microstructure is necessary. In the present contribution, an efficient damage model for quasi-brittle materials implemented into the two-dimensional C1 continuity triangular finite element formulation employing the nonlocal continuum theory is proposed. Th element consists of three nodes and 36 degrees of freedom with the displacement field approximated by the full fifth order polynomial. The nodal degrees of freedom are the two displacements and their first- and second-order derivatives with respect to the Cartesian coordinates. Using the derived formulation, a nonlocal material behaviour is introduced in the model, enabling the preservation of the ellipticity of the boundary value problem when a material softening occurs. The isotropic damage law is embedded in the higher-order stress-strain constitutive relations, which enable the analysis of both homogeneous and heterogeneous materials. In the numerical examples the damage responses of both heterogeneous and homogeneous materials are analyzed and compared. The two benchmark examples exhibiting the mode I and II failure problems are performed. It is observed that the softening behavior depends on the RVE size dictating nonlocal behavior, as well as on the porosity and the average hole radius describing anisotropy of the heterogeneous material. Furthermore, the structural responses of the considered computational models clearly indicate that heterogeneous materials have a much lower load-carrying capacity, as expected. All results are mesh independent. In contrast to the results obtained in the literature, where the conventional implicit gradient damage formulation is adopted, the proposed damage algorithm yields a fully localized deformation without spurious damage growth.

Izvorni jezik
Engleski

Znanstvena područja
Strojarstvo

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