Paulo Nigro

Delft University of Technology | TU · 3mE - DCSC

This work consists of a low level analysis, considering assembly instructions, registers, Floating Point Unit and RAM (Random-Access Memory) details, of programming codes used by direct methods of solving linear systems, such as Crout, Cholesky and others, written in high level language, as well as discussing mechanisms that can be used to optimize...

Model Order Reduction (MOR) methods are extremely useful to reduce processing time, even nowadays, when parallel processing is possible in any personal computer. This work describes a method that combines POD (Proper Orthogonal Decomposition) and Ritz vectors to achieve an efficient Galerkin projection which changes during nonlinear solving (online...

Model Order Reduction (MOR) methods are employed in many fields of Engineering in order to reduce the processing time of complex computational simulations. A usual approach to achieve this is the application of Galerkin projection to generate representative subspaces (reduced spaces). However, when strong nonlinearities in a dynamical system are pr...

It is not new that Model Order Reduction (MOR) methods are employed in almost all fields of Engineering in order to reduce the processing time of complex computational simulations. At the same time, Interior Point Methods (IPM), a method to deal with inequality constraint problems ‐ which is little explored in engineering ‐ can be applied in many f...

Single crystal plasticity plays a major role in the analysis of material anisotropy and texture evolution, treats each crystalline grain individually. The polycrystalline material response is obtained upon considering a structure consisting of various individual grains, often also considering interface effects at the grain boundaries. On the indivi...

In this paper, an adaptive reduced order method for small strain elasto-plasticity is discussed. This method works purely online, meaning no preliminary offline calculations have to be conducted. Using a GALERKIN projection, the high-fidelity problem is reduced to a lower vector space. For this, the basis is extracted from an initial POD after the...

In the field of single crystal plasticity, different algorithms exist for the solution of the constitutive equations. They can be grouped into rate independent and rate dependent approaches, where both classes are governed by inherent shortcomings, as discussed in, e.g., [3]. This contribution outlines an algorithmic formulation for single crystal...

In this contribution, a small strain single crystal plasticity framework in the context of an in feasible primal-dual interior point method (IPDIPM) is discussed with a focus on the numerical treatment. Related to rate-independent algorithms in the field of single-crystal plasticity, the use of the IPDIPM to solve the constrained optimization probl...

In this contribution, an online adaptive reduced order model is presented for small‐strain elasto‐plasticity. Using the GALERKIN method, the problem is projected to a lower subspace giving a reduced problem based on the displacement field snapshots. The adaptivity lies in the update of the projection operator, which is carried out in different part...

The paper presents a novel approach for rate‐independent single crystal plasticity based on the Infeasible Primal‐Dual Interior Point Method in a small strain framework. Therein, the principle of maximum dissipation together with the yield functions on the slip systems in the crystal are considered as the constrained optimization problem. The const...