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| Author(s): |
Andre Luis Ferreira da Silva
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Escola Politécnica (EP/BC) |
| Defense date: | 2024-11-25 |
| Examining board members: |
Emilio Carlos Nelli Silva;
Hélio Emmendoerfer Junior;
Alfredo Gay Neto;
Daniel Milbrath de Leon;
Anderson Pereira
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| Advisor: | Emilio Carlos Nelli Silva; Luís Antônio Guimarães Bitencourt Júnior |
| Abstract | |
The popularity of fiber-reinforced materials has led to the development of new additive manufacturing technologies that allow for the tailoring of fiber orientation according to results obtained from optimization techniques. While much work has been done to optimize fiber orientation, the critical issue of stress yield criteria must be addressed. This work presents a novel approach to solving the Topology Optimization problems for isotropic concrete-type materials and composite materials reinforced with fibers considering stress constraints. The proposed method, NDFO-adapt, addresses the challenges of optimizing material distribution, fiber angle, and the penalization field to explore a wider solution space and discover previously unachievable local minima. This approach reduces the reliance on a heuristic selection of continuation methods, leading to more robust and efficient optimization. Furthermore, this work introduces the concept of treating the penalization of the material model used to distribute material within the domain and the variable from the threshold projection technique as design variables. An automatic penalization scheme is developed by incorporating these variables into the optimization process, effectively leveraging the algorithm. The amount of gray in the structure is then used to define a new move limits scheme and update the lower bounds for the penalization and projection variables. The critical issue of stress constraint is addressed by using the Augmented Lagrangian method. Additionally, a mesh refinement scheme based on the FEniCS project is proposed, allowing for adaptive refinement of the mesh to reduce the computational cost of the optimization process. The work also introduces a new constitutive equation for fiber-reinforced concrete that accounts for fracture propagation. Based on a phase-field approach, this equation implicitly captures behaviors such as fiber bursting, the interaction between fibers and concrete, and fiber slip within a simplified variational framework. Additionally, a new objective function is proposed for optimizing fiber orientations in fiber-reinforced concrete. Numerical examples are provided to illustrate the proposed methods performance and effectiveness. This research offers significant insights and contributions to topology optimization of fiberreinforced materials with stress constraints and optimization of fiber orientation in fiberreinforced concrete, with potential applications in various industries for designing efficient and durable structures. (AU) | |
| FAPESP's process: | 20/07557-4 - Design of fiber-reinforced composite structures by using topology optimization |
| Grantee: | André Luis Ferreira da Silva |
| Support Opportunities: | Scholarships in Brazil - Doctorate |