Dumitru Nedelcu

Prof. Dumitru Nedelcu

Department of Machine Manufacturing Technology, Gheorghe Asachi Technical University of Iași, 61-63 D. Mangeron Blvd., 700050 Iasi, Romania
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Research Focus & Metrics

Academic Career Length

20Years (2007-Present)

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

Representative Publications

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2 January 2021 in Journal of the Brazilian Society of Mechanical Sciences and Engineering
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HDHarshit K. Dave
Harshit K. Dave
BPBrijesh H. Patel
Brijesh H. Patel
SRShilpesh R. Rajpurohit
Shilpesh R. Rajpurohit
APAshish Prajapati
Ashish Prajapati
Dumitru NedelcuDumitru Nedelcu
Dumitru Nedelcu

21 August 2021 in Applied Sciences
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Justina Georgiana MotasJustina Georgiana Motas
Justina Georgiana Motas
Nima E. GorjiNima E. Gorji
Nima E. Gorji
Dumitru NedelcuDumitru Nedelcu
Dumitru Nedelcu
Dermot BrabazonDermot Brabazon
Dermot Brabazon
Quadrini FabrizioQuadrini Fabrizio
Quadrini Fabrizio
The development of environmentally friendly materials has been the focus of many research groups in recent years due to increased harmful effects of plastics on the environment. Bio-based materials are considered a key solution from a sustainable manufacturing perspective. The nano-coating of biopolymer blends with silver nanoparticles is the subject of challenging research projects in line with the EU Directive on environment protection and sustainable manufacturing. Coating biopolymers with silver nanoparticles provides an antimicrobial and antiviral active surface. In this work, we develop silver nanoparticle-coated biopolymer Arboblend V2 Nature pellets. The main goal is to obtain a new material with antibacterial action obtained from the blending of a biopolymer pellets with silver nanoparticles through physical vapor deposition. The study is divided in three steps. The first step represents the silver nano-coating of the Arboblend V2 Nature and the characterization of the coated/raw pellets. The second step involves the injection molding of the silver nano-coated pellets and the characterization of the samples obtained. The last step regards the press molding of the coated pellets in order to obtain thin films, as well as their characterization. The PVD-sputtering technique is used to coat the pellets with silver nanoparticles. This process is especially optimized for coating raw materials with high water content and small-size pellets. The mechanical properties, surface chemical composition and the thermal properties of the both virgin and silver nanoparticle-coated biopolymer pellets are measured and analyzed for mechanical and thermal resistance of the nano-coating layer. Differential scanning calorimetry, scanning electron microscopy, X-ray photoemission spectroscopy and nanoindentation mechanical testing is performed. The calorimetry test detects no significant alteration of the biopolymer produced from the PVD process and confirms the optimized PVD process for nano-coating of the Arboblend V2 Nature pellets with a viable application in nano-silver–biopolymer composite products.

12 April 2020 in Materials
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SMSimona-Nicoleta Mazurchevici
Simona-Nicoleta Mazurchevici
AMAndrei-Danut Mazurchevici
Andrei-Danut Mazurchevici
Dumitru NedelcuDumitru Nedelcu
Dumitru Nedelcu
In order to find new ways to ensure sustainable development on a global level, it is essential to combine current top technologies, such as additive manufacturing, with the economic, ecological, and social fields. One objective of this paper refers to wire manufacture such as Arboblend V2 Nature, Arbofill Fichte, and Arboblend V2 Nature reinforced with Extrudr BDP “Pearl” (BDP—Biodegradable Plastic) in order to replace the plastic materials. After wire manufacture by extrusion, the diameter accuracy was analyzed compared with the Fiber Wood wire using SEM analyses and also EDAX—Energy Dispersive X-ray Analysis and DSC—Differential Scanning Calorimetry analyses were done in order to identify their elemental composition and the phase transitions suffered by the materials during heating. Using the samples obtained through the Fused Deposition Modeling (FDM) method, both crystalline phases and chemical composition information (XRD analysis) were identified, as well was determined the visco-elastic behavior Dynamic Mechanical Analysis (DMA), for the reinforced material and Fiber Wood. The extruded wires have allowed size for the printing equipment, around 1.75 mm with tolerance of ± 0.05 mm. The wire material diagrams, Arboblend V2 Nature reinforced with Extrudr BDP “Pearl” and Fiber Wood following the calorimetric analysis, presented peaks corresponding to material crystallization, while Arbofill Fichte revealed only the melting temperature. The storage module was almost double in case of Arboblend V2 Nature reinforced with Extrudr BDP “Pearl” compared with Fiber Wood and materials’ melting temperatures were confirmed by the analyses carried out.

31 August 2021 in Polymers
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SMSimona-Nicoleta Mazurchevici
Simona-Nicoleta Mazurchevici
Elena CostescuElena Costescu
Elena Costescu
DRDoreen Rapp
Doreen Rapp
Cristian-Dragos VarganiciCristian-Dragos Varganici
Cristian-Dragos Varganici
CCConstantin Cărăușu
Constantin Cărăușu
Dumitru NedelcuDumitru Nedelcu
Dumitru Nedelcu
Biodegradable materials investigation has become a necessity and a direction for many researchers worldwide. The main goal is to find sustainable alternatives which gradually replace plastics based on fossil resources from the market, because they are very harmful to the environment and to overall quality of life. In order to get to the stage of obtaining different functional parts from biodegradable materials, it is necessary to study their properties. Taking into account these shortcomings, this paper aims at the mechanical characterization (DMA—Dynamic Mechanical Analysis) and thermal degradation (thermogravimetric analysis (TGA)) of lignin-based biopolymers: Arboform LV3 Nature®, Arboblend® V2 Nature, and Arbofill® Fichte Arboform® LV3 Nature reinforced with aramid fibers. The tested samples were obtained by using the most common fabrication technique for polymers—injection molding. The obtained results for the DMA analysis showed separate polymeric-specific regions for each material and, based on the tanδ values between (0.37–0.54), a series of plastics could be proposed for replacement. The mechano-dynamic behavior could be correlated with the thermal expansion of biopolymers for temperatures higher than 50/55 °C, which are thermally stable up to temperatures of at least 250 °C.

15 August 2020 in Materials
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Dumitru NedelcuDumitru Nedelcu
Dumitru Nedelcu
SMSimona-Nicoleta Mazurchevici
Simona-Nicoleta Mazurchevici
RPRamona-Iuliana Popa
Ramona-Iuliana Popa
Lohan Nicoleta-MonicaLohan Nicoleta-Monica
Lohan Nicoleta-Monica
DMDemófilo Maldonado-Cortes
Demófilo Maldonado-Cortes
CCConstantin Carausu
Constantin Carausu
It is essential to combine current state-of-the-art technologies such as additive manufacturing with current ecological needs. Due to the increasing demand for non-toxic biodegradable materials and products, human society has been searching for new materials. Consequently, it is compulsory to identify the qualities of these materials and their behavior when subjected to various external factors, to find their optimal solutions for application in various fields. This paper refers to the biodegradable Polylactic acid (PLA)-based filament (commercially known as Extrudr BDP (Biodegradable Plastic) Flax) compared with the biodegradable composite material PLA-lignin filament whose constituent’s trade name is Arboblend V2 Nature as a lignin base material and reinforcement with Extrudr BDP Pearl, a PLA based polymer, 3D printed by Fused Deposition Modeling technology. Certain mechanical properties (tensile strength, bending strength and DMA—Dynamic Mechanical Analysis) were also determined. The tribology behavior (friction coefficient and wear), the structure and the chemical composition of the biodegradable materials were investigated by SEM—Scanning Electron Microscopy, EDX—Energy Dispersive X-Ray Analysis, XRD—X-Ray Diffraction Analysis, FTIR—Fourier Transform Infrared Spectrometer and TGA—Thermogravimetric Analysis. The paper also refers to the influence of technological parameters on the 3D printed filaments made of Extrudr BDP Flax and the optimization those of technological parameters. The thermal behavior during the heating of the sample was analyzed by Differential scanning calorimetry (DSC). As a result of the carried-out research, we intend to recommend these biodegradable materials as possible substituents for plastics in as many fields of activity as possible.

18 October 2024 in Polymers
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ATAnastasios Tzotzis
Anastasios Tzotzis
Dumitru NedelcuDumitru Nedelcu
Dumitru Nedelcu
SMSimona-Nicoleta Mazurchevici
Simona-Nicoleta Mazurchevici
Panagiotis KyratsisPanagiotis Kyratsis
Panagiotis Kyratsis
This work presents an experimental analysis related to 3D-printed carbon-fiber-reinforced-polymer (CFRP) machining. A polyethylene-terephthalate-glycol (PETG)-based composite, reinforced with 20% carbon fibers, was selected as the test material. The aim of the study was to evaluate the influence of cutting conditions used in light operations on the generated surface quality of the 3D-printed specimens. For this purpose, nine specimens were fabricated and machined under a wide range of cutting parameters, including cutting speed, feed, and depth of cut. The generated surface roughness was measured with a mechanical gauge and the acquired data were used to develop a shallow artificial neural network (ANN) for prediction purposes, showing that a 3-6-1 structure is the best solution. Following this, a genetic algorithm (GA) was utilized to minimize the response, revealing that the optimal combination is 205 m/min speed, 0.0578 mm/rev feed, and 0.523 mm depth of cut, contributing to the fabrication of low friction parts and shafts with a high quality surface, as well as to the reduction of resource waste. A validation study supported the accuracy of the developed model, by exhibiting errors below 10%. Finally, a set of enhanced images were taken to assess the machined surfaces. It was found that 1.50 mm depth of cut is responsible for the generation of defects across the circumference of the specimens. Especially, combined with 150 m/min cutting speed and 0.11 mm/rev feed, more flaws are produced.