Si comunica che mercoledì 2 ottobre 2019, alle ore 11:30, presso il Dipartimento di Ingegneria dell’Università Roma Tre il Prof. Stefan Löhnert (Technische Universität Dresden, Institute of Mechanics and Shell Structures) terrà un seminario dal titolo:
Multiscale Methods for Fracture
Classical numerical multiscale techniques like computational homogenisation or FE2 methods are based on the concept of a representative volume element (RVE). To achieve accurate results the size of the RVE should be chosen appropriately such that the statistical representativeness is given and at the same time the computational effort is reasonable. In case of localisation phenomena such as dominantly growing cracks the classical RVE concept fails. The effective response of the RVE strongly depends on the chosen size of the RVE unless special care is taken about the localisation effect. In this presentation an alternative strategy is presented that can generally be used for localisation phenomena such as crack propagation and local instabilities, i.e. fibre kinking etc. The concurrent multiscale technique is based on the projection of the stresses and stiffness from the fine scale to the coarse scale mesh. Fine scale features such as microcracks or heterogeneities are considered explicitly only within the fine scale domain. Their effect however is implicitly included in the coarse scale simulation. The boundary conditions for each fine scale simulation are pure displacement boundary conditions coming from the coarse scale solution. They are projected onto the boundary of the fine scale domain. Each fine scale domain can be simulated independently and in parallel leading to an efficient technique also for multiple fine scale domains. It is shown that this multiscale projection method leads to converged results independent of the choice of an RVE size.