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Activity Funded

Topology optimization and metal additive manufacturing unified to obtain functionally graded material structures

Otimização de topologia e manufatura aditiva unificadas para obter estruturas metálicas com gradiente de funcionalidade

Reference
2022.06903.PTDC
Project Start Date
2023-02-01
Project End Date
2025-01-31
Principal Investigator
Coinvestigator
Scientific Area
Engineering and technology
Funding Program
Concurso de Projetos de I&D em Todos os Domínios Científicos - 2022 - PEX

Abstract

Why can Functionally Graded Material (FGM) be outstanding regarding to homogeneous counterparts? A biomimetic approach suggests the answer, e.g., blood vessel holes in load-bearing bones are not normally involved in structural failures. In fact, naturally occurring graded type materials as bone, exhibiting spatial organized property gradients, excel in mechanical performance. This inspires man-made structures resorting to digital manufacturing technologies, involving topology optimization (TO) and additive manufacturing (AM). A consistent evolution of these novel design and manufacturing tools is the synthesis of materials with specific-oriented structure and functionality. This approach claims an unprecedented potential in which materials can evolve into the bio-inspired paradigm of heterogeneity and gradient mechanical properties [1]. FGM designs can now be materialized through multi-material AM systems. This meets environmental and sustainability challenges by the rational use of resources and energy. FGMs can be created acting on spatial gradients related to either architecture or composition [2]. This project focus on the composition. Remarkable outcomes have been already pointed out, for instance, to mitigate stress concentration [3] or enhancing fracture toughness [4]. In this project, a multidisciplinary methodology will be implemented for the creation of structural specific-oriented FGM parts. The proposed strategy aims at unifying TO and multi-feed Wire Arc AM (WAAM), resorting to full-field identification methods for virtual and experimental verification. This entails scientific research of exploratory nature as the overall idea of having TO and AM unified to produce FGM parts in metal requires some proof-of-concept due to scarce contributions in the field. Hence, one focus on benchmark mechanical stress problems where the goal is stress mitigation on account of proper graded material solutions. The strength-oriented design through TO is sought contrasting with the classical compliance-based TO problem. Despite the proof-of-concept goal here, the developed methodology intends to be general enough to render FGM structural parts in problem-oriented engineering practice. FGMs may be obtained from different advanced manufacturing processes. However, the state-of-the-art of these material synthesis processes is still wrapped in several challenges due to the complexity of FGM structures. The standard ISO 17296-2:2015 [5] prescribes seven different AM processes. In this project, WAAM is claimed as most suitable for producing FGM structural parts and relies here on the expertise of the team members J. Oliveira and T. Santos. It is a direct energy deposition process that uses thermal energy (an electric arc) to melt the feedstock material (wire). A double wire feed WAAM variant will be implemented, using different feedstock metal alloys, allowing a predefined prescription of volume fractions, which can be used to control the microstructure and chemical composition along deposition directions. Other AM processes have been used such as Laser Metal Deposition (LMD) and Selective Laser Melting (SLM). In LMD, however, the gradual spatial variation of different metal powders is not that precise and expedite. SLM is a powerful tool to produce functionally graded cellular materials. However, it is a powder bed-based process that is not flexible to carry on real-time controlling of graded chemical composition in both deposition directions. Besides, it is too time-consuming for producing mid-size or large structural parts. The optimal design of FGMs can be assisted by TO [6]. TO has been the most active research area in structural and multidisciplinary optimization in the past decades [7]. The PI (P. Coelho) has been contributing to this field for almost 20 years and, along with another team member here (F. Conde), has recently made some relevant contributions on the multimaterial setting paving the way for FGM design solutions [8]. FGMs exhibit heterogeneous stress fields requiring a disruptive approach dealing with material parameter characterization by coupling inverse identification methods with full-field deformation measurements [9]. In this strategy, the hypothesis is that spatial gradients of relevant mechanical properties of FGMs can be extracted directly from heterogeneous stress field. This methodology will be implemented using digital image correlation (DIC) [10] combined with the virtual fields method (VFM) and FEM updating (FEMU) procedure [11]. The co-IP (J. Xavier) is an expert in this field. In the short-term, the scientific project impact is advancing the state-of-the-art through the systematization and customization of FGM design and production by WAAM, resorting to DIC for verification. This will be disseminated through peer-reviewed papers and through scientific and digital communication of results to public. At the academia level research fellowships will capture talented young researchers.

Institutions

Main Institutions

  • Universidade Nova de Lisboa Associação para a Inovação e Desenvolvimento da FCT (NOVA.ID.FCT)

Funding 49.985,82 €

Fundação para a Ciência e a Tecnologia (FCT) - Portugal

49.985,82 €