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Item type:Publication, Access status: with files , Simulating brittle fracture with a robust hybrid explicit–implicit solver for staggered phase‐field problems(Wiley, 2024-03); ; ; ; In this work, the robustness of phase‐field fracture simulations is increased by introducing a new hybrid approach to take advantages of both explicit and implicit solvers. Switching to an explicit solver at critical load cases enables us to define a threshold on the maximum number of staggered iterations per load step. Having this threshold would be very useful in complicated FCM problems since we cannot wait for a full convergence of the implicit solver at critical load steps. With the new hybrid method, the problem is implicit as long as the implicit solver can converge within a specified threshold; otherwise, the failed load step will be solved robustly using an explicit approach. The method can resolve the highly nonlinear part of the global load–displacement curve. The superiority of the approach is shown in different benchmark examples.Publicationtype: Conference Paper12 20 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Acceleration of immersed computations of brittle phase‐field fracture utilizing moment fitting schemes(Wiley, 2024-03); ; ; ; Numerical methods play an important role when predicting structural failure in industrial applications. Among various methods, the phase‐field modeling (PFM) seems to be a very promising approach. By introducing an additional phase‐field variable, it can account for crack initiation, crack propagation, dynamic crack branching and more. However, it needs a very fine mesh especially along the propagating crack path. When utilizing boundary‐fitted methods such as the finite element method, this can lead to a large amount of elements and thus, results in huge systems of equations. In order to overcome this issue, immersed methods like the finite cell method (FCM) have been developed, where the mesh is independent of the geometry, which results in a fast and simple pre‐processing. In this work, the FCM is applied to the PFM in order to simulate quasi‐static brittle fracture of structures with complex geometries. Furthermore, the non‐negative moment fitting (NNMF) is employed in order to accelerate the finite cell computations. The proposed methods are tested on a numerical example in order to demonstrate the strength of the NNMF.Publicationtype: Conference Paper35 41 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Accurate integration of trimmed cells based on Bezier approximationIn this work, a new adaptive integration method for simulation of two-dimensional linear elasticity problems is presented. The main benefit of the proposed method is the reduction of the computational cost by lowering the number of integration points required to reach a certain level of accuracy. The main concept of the proposed method is to calculate new weights for trimmed cells employing the advantage of Bezier parametric curves. Within this concept, it is possible to map a square to a triangle with one curved edge where any curved edge is approximated by a parametric Bezier curve. In this way, a new set of Gaussian quadrature points is introduced for each trimmed cell in a fast and robust way. Besides main mapping cases, the integration method includes supplementary cases as well to increase the robustness and generality of the method. In the next step, the proposed method is implemented in a two-dimensional fictitious domain code in MATLAB to solve structural problems. The results will be compared to those obtained through the commercial finite element code ABAQUS. It is shown that the proposed method is accurate and robust.Publicationtype: Conference Paper64 189