Abstract in English:

Abstract Modeling hydraulic fracturing requires capturing the interaction between fluid flow and solid deformation, which leads to complex crack patterns, especially in materials that are heterogeneous at a given scale. At the microscale, such materials can be described as multiphase media with distinct mechanical properties, where damage initiates and may be significantly affected by internal pressure. This work models pressure-driven fracture propagation in heterogeneous materials using a phase-field approach. Representative volume elements with random particle distributions are generated through a take-and-place strategy and subjected to tensile tests within a phase-field framework. Internal pressure is incorporated by coupling it to the gradient of the phase-field variable, enabling the simulation of pressurized crack propagation. A numerical study evaluates the influence of pressure magnitude and aggregate volume fraction on the fracture response. Results demonstrate the ability of the approach to reproduce pressurized crack patterns in quasi-brittle media, providing a consistent and computationally effective approach for future multiscale analyses.

Abstract in English:

Abstract Folding wingtips (FWTs) offer an innovative solution to reconcile aerodynamic efficiency gains of higher aspect ratio wings with airport gate restrictions. Analyzing these adaptive structures requires modeling geometric nonlinearities induced by large displacements, which traditional linear models fail to capture. This study expands the computationally efficient Flexible Multibody Rayleigh-Ritz (FMBRR) framework to analyze highly flexible structures with articulated parts. The methodology couples a linear structural model for local deformation with flexible multibody dynamics to capture global geometric nonlinearities through rigid connections. Novel contributions of this work include a torsional formulation and revolute-joint constraints specifically developed to model the FWT. Results for a highly flexible cantilever beam and an articulated structure demonstrate that the FMBRR framework accurately predicts static and dynamic nonlinear behaviors, significantly reducing computational costs compared to fully nonlinear models without losing fidelity.