Xavier Oliver Olivella

Two-scale topology optimization in computational material design: an integrated approach

Summary In this work, a new strategy for solving multiscale topology optimization problems is presented. An alternate direction algorithm and a precomputed offline microstructure database (Computational Vademecum) are used to efficiently solve the problem. In addition, the influence of considering manufacturable constraints is examined. Then, the strategy is extended to solve the coupled problem of designing both the macroscopic and microscopic topologies. Full details of the algorithms and numerical examples to validate the methodology are provided.

Model Order Reduction in computational multiscale fracture mechanics

Nowadays, the model order reduction techniques have become an intensive research eld because of the increasing interest in the computational modeling of complex phenomena in multi-physic problems, and its conse- quent increment in high-computing demanding processes; it is well known that the availability of high-performance computing capacity is, in most of cases limited, therefore, the model order reduction becomes a novelty tool to overcome this paradigm, that represents an immediately challenge in our research community. In computational multiscale modeling for instance, in order to study the interaction between components, a di erent numerical model has to be solved in each scale, this feature increases radically the computational cost. We present a reduced model based on a multi-scale framework for numerical modeling of the structural failure of heterogeneous quasi-brittle materials using the Strong Discontinuity Approach (CSD). The model is assessed by application to cementitious materials. The Proper Orthogonal Decomposition (POD) and the Reduced Order Integration Cubature are the pro- posed techniques to develop the reduced model, these two techniques work together to reduce both, the complexity and computational time of the high-delity model, in our case the FE2 standard model

Crack path field and strain injection techniques in dynamic fracture simulations

Dynamic fracture phenomena are studied employing low cost computational tools based on Finite Elements with Embedded strong discontinuities (E-FEM). Fracture nucleation and propagation are accounted for through the injection of discontinuous strain and displacement modes inside the finite elements. The Crack Path Field technique is employed to compute the trace of the strong discontinuity during fracture propagation. Unstable crack propagation and crack branching are observed upon increasing loading rates. The variation in terms of crack pattern and energy dissipation is studied and a good correlation is found between the maximum experimental crack speed and maximum dissipation at the onset of branching. Comparable results are obtained against simulations employing supraelemental techniques, such as phase-field and gradient damage models, considering coarser discretizations which can differ by two orders of magnitude.