Guest lecture by Prof. Soric (Zagreb) on multiscale methods

In the framework of the research colloquium of the Institute, Prof. Soric from the University of Zagreb will give a lecture on the topic of multi-scale methods on Wednesday, 19.02.2020 at 14:00 Ihr (Room 3516, Mönchebergstraße 7).

The title of the talk is:

"Damage modeling of heterogeneous materials by means of multiscale computational approach".

Abstracts:

Damage phenomena, macroscopically characterized by decrease in material stiffness or so-called softening, are common in engineering materials and can decrease structural load-carrying capacity, and lead to loss of mechanical integrity. A lot of engineering materials can be treated as heterogeneous, particularly if they are observed at microscale. Geometrical and material properties of the constituents forming microstructure have a significant impact on material behavior. Therefore, in order to assess structural integrity and to predict structural lifetime, an analysis of evolving microstructure is necessary.

Damage responses of both quasi-brittle and ductile materials will be considered using two-scale computational procedures. An efficient quasi-brittle damage model implemented into the finite element formulation employing the nonlocal continuum theory is proposed. The damage enhanced constitutive relations are embedded at the structural macrolevel, while the material stiffness matrices are computed at the microscale using a second-order homogenization procedure. Therein, an appropriate representative volume element (RVE), representing a sample of heterogeneous material, is considered. The ductile damage is modelled at the microlevel employing the gradient-enhanced elastoplasticity, and after the homogenization procedure the state variables are mapped at the macroscale. Here, the first-order computational homogenization scheme is applied. An implicit nonlocal ductile damage model, governing the evolution of damage variable, is comprised. Besides the displacement, the nonlocal equivalent plastic strain measure is discretized over the RVE, and accordingly, the mixed finite element formulation is derived. The macrolevel discretization is performed by means of the regular displacement finite element formulation. All algorithms derived have been implemented into the finite element software ABAQUS. The efficiency and accuracy of the proposed computational strategies will be demonstrated by standard benchmark examples.