Dragos Alexandru Apostol

Dr. Dragos Alexandru Apostol

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Research Focus & Metrics

Academic Career Length

19Years (2008-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 October 2014 in Engineering Fracture Mechanics
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Journal Article
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Liviu  MarsavinaLiviu Marsavina
Liviu Marsavina
DCDan Mihai Constantinescu
Dan Mihai Constantinescu
Emanoil LINULEmanoil LINUL
Emanoil LINUL
DADragos Alexandru Apostol
Dragos Alexandru Apostol
TVTudor Voiconi
Tudor Voiconi
Tomasz SadowskiTomasz Sadowski
Tomasz Sadowski

31 July 2012 in Mechanics of Time-Dependent Materials
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Journal Article
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DADragos Alexandru Apostol
Dragos Alexandru Apostol
DCDan Mihai Constantinescu
Dan Mihai Constantinescu

22 October 2024 in Materials
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Journal Article
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AVAlexandru Vasile
Alexandru Vasile
DCDan Mihai Constantinescu
Dan Mihai Constantinescu
ICIulian Coropetchi
Iulian Coropetchi
SSStefan Sorohan
Stefan Sorohan
DADragos Alexandru Apostol
Dragos Alexandru Apostol
Triply periodic minimal surfaces (TPMSs) constitute a type of metamaterial, deriving their unique characteristics from their microstructure topology. They exhibit wide parameterization possibilities, but their behavior is hard to predict. This study focuses on using an implicit modeling method that can effectively generate novel thin-walled metamaterials, proposing eight shell-based TPMS topologies and one stochastic structure, along with the gyroid acting as a reference. After insights into the printability and design parameters of the proposed samples are presented, a cell homogeneity analysis is conducted, indicating the level of anisotropy of each cellular structure. For each of the designed metamaterials, multiple samples were printed using a stereolithography (SLA) method, using a constant 0.3 relative density and 50 µm resolution. To provide an understanding of their behavior, compression tests of sandwich-type specimens were performed and specific deformation modes were identified. Furthermore, the study estimates the general mechanical behavior of the novel TPMS cores at different relative densities using an open cell mathematical model. Alterations of the uniform topologies are then suggested and the way these modifications affect the compressive response are presented. Thus, this paper demonstrates that an implicit modeling method could easily generate novel thin-walled TPMSs and stochastic structures, which led to identifying an artificially designed structure with superior properties to already mature topologies, such as the gyroid.

1 July 2013 in International Journal of Adhesion and Adhesives
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Journal Article
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MSMarin Sandu
Marin Sandu
ASAdriana Sandu
Adriana Sandu
DCDan Mihai Constantinescu
Dan Mihai Constantinescu
DADragos Alexandru Apostol
Dragos Alexandru Apostol

9 January 2025 in Materials
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AVAlexandru Vasile
Alexandru Vasile
DCDan Mihai Constantinescu
Dan Mihai Constantinescu
AIAndrei-Ioan Indres
Andrei-Ioan Indres
ICIulian Coropetchi
Iulian Coropetchi
SSStefan Sorohan
Stefan Sorohan
DADragos Alexandru Apostol
Dragos Alexandru Apostol
Sandwich structures with triply periodic minimal surface (TPMS) cores have garnered research attention due to their potential to address challenges in lightweight solutions, high-strength designs, and energy absorption capabilities. This study focuses on performing finite element analyses (FEAs) on eight novel TPMS cores and one stochastic topology. It presents a method of analysis obtained through implicit modeling in Ansys simulations and examines whether the results obtained differ from a conventional method that uses a non-uniform rational B-spline (NURBS) approach. The study further presents a sensitivity analysis and a qualitative analysis of the meshes and four material models are evaluated to find the best candidate for polymeric parts created by additive manufacturing (AM) using a stereolithography (SLA) method. The FEA results from static and explicit simulations are compared with experimental data and while discrepancies are identified in some of the specimens, the failure mechanism of the proposed topologies can generally be estimated without the need for an empirical investigation. Results suggest that implicit modeling, while more computationally expensive, is as accurate as traditional methods. Additionally, insights into numerical simulations and optimal input parameters are provided to effectively validate structural designs for sandwich-type engineering applications.

15 November 2023 in Proceedings of the Romanian Academy, Series A: Mathematics, Physics, Technical Sciences, Information Science
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Journal Article
Closed access
RSRareş SAVA
Rareş SAVA
DADragos Alexandru Apostol
Dragos Alexandru Apostol
DCDan Mihai Constantinescu
Dan Mihai Constantinescu
The behavior of triply periodic minimal surfaces (TPMS) structures like Gyroid, Schwarz P and Schwarz D created by using the Rhinoceros 6 software was studied through experimental mechanical compression testing. The topologies were printed using additive manufacturing and the DLP technique in cubic volumes, having dimensions of 25x25x25 mm. They had different unit cell arrangements ranging from one unit cell and going up to 8x8x8 unit cells. The overall weight of the samples was kept approximately constant as the increase of cells number would not affect the weight for each topology. Cubes were subjected to static compression testing and elastic constants were established by using the digital image correlation (DIC) method. Failure patterns have been studied by analyzing the cells’ collapse in compression.