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Projeto de investigação
Topology optimization and metal additive manufacturing unified to obtain functionally graded material structures
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Multi-scale topology optimization of structures with multi-material microstructures using stiffness and mass design criteria
Publication . Conde, Fábio M.; Coelho, Pedro G.; Guedes, José M.; DEMI - Departamento de Engenharia Mecânica e Industrial; UNIDEMI - Unidade de Investigação e Desenvolvimento em Engenharia Mecânica e Industrial; Elsevier Science Publisher B.V.
Nowadays, there is a great interest on the part of the automotive and aerospace industry to design environmentally-friendly structures. To that purpose, stiffness-oriented designs are proposed here by extending previous work on multi-scale topology optimization to the multi-material setting reformulating the problem to include appropriately mass constraints and discussing different design domain parametrizations and algorithmic strategies. On the macroscale, the problem of minimizing the compliance subject to a global mass constraint is addressed. On the microstructure scale, the multi-material design is carried out by solving the problem of minimizing the local complementary strain energy density with mass density constraint. As a result, very efficient structures composed of spatially varying porous and multi-material microstructures are obtained. The optimal design of the multi-material microstructure can be done either in a pointwise manner or in larger subdomains, to promote design uniformity. These parametrizations are here compared and discussed. Moreover, two different algorithmic strategies to solve the multi-scale problem are proposed, and their pros and cons discussed. They differ in the way the macro and micro design variables are related and updated. The macro design variables consider the mass density distribution along the structure, while the micro variables define the microstructure's topology using a multi-material SIMP interpolation scheme. The results show very efficient structures with locally optimized multi-material microstructures, which can outperform their single-material counterparts with regards to stiffness while maintaining the same mass. Additionally, the maximum stress verified on multi-material structures tends to be lower than the one obtained in the single-material counterparts.
Minimizing the maximum von Mises stress of elastic continuum structures using topology optimization and additively manufactured functionally graded materials
Publication . Silva, Rui F.; Coelho, Pedro G.; Conde, Fábio M.; Santos, Bernardo R.; Oliveira, João P.; UNIDEMI - Unidade de Investigação e Desenvolvimento em Engenharia Mecânica e Industrial; DEMI - Departamento de Engenharia Mecânica e Industrial; DCM - Departamento de Ciência dos Materiais; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); Elsevier Science B.V., Amsterdam.
The rising cost of natural resources and environmental concerns motivate systematic design and manufacture of more efficient structures. For that purpose, topology optimization has been appealing, as well as working on an enlarged design space to include multi-material solutions. The resulting optimal designs can be materialized using multi-material additive manufacturing. In the present framework, multi-material printed parts or layouts can be envisaged as having better strength properties than single-material counterparts. The maximum von Mises stress is minimized inside a design domain through topology changes and material selection. The selected composite material model encompasses either the classical arrange of two discrete materials with sharp interfaces, or their mixture controlled by the volume fraction of each base material to generate a Functionally Graded Material (FGM). An optimized continuous variation of properties makes the FGM appealing to mitigate stress concentrations. To adequately capture the physics of mixtures considering the FGM's mechanical properties, one uses the RAMP interpolation scheme within the Hashin-Shtrikman bounds. A set of plane stress benchmarks are proposed. It is shown that considerably lower stress peaks on the evaluated structures can be obtained on the account of introducing more than one solid phase, specifically in the case of FGM solutions.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
Concurso de Projetos de I&D em Todos os Domínios Científicos - 2022
Número da atribuição
2022.06903.PTDC