Nectarios Vidakis

• Mechanical Engineer, PhD
• Professor (Full) at Hellenic Mediterranean University

The motivation of the research was to introduce nanocomposites with the polycarbonate (PC) thermoplastic as the matrix material, with biocidal capabilities and improved mechanical performance for the material extrusion (MEX) additive manufacturing (AM) technique. Such nanocomposites have not been investigated so far. They would exploit the use of t...

This work aimed to evaluate the capacity of recycled fine powder glass (RFPG) to reinforce the mechanical performance and characteristics of polylactic acid (PLA) for use in 3D printing (3DP) applications. Six composites with an RFPG filler quantity of 2.0 wt. % -12.0 wt. % (with a 2.0 step) were evaluated. The raw materials were turned into mixtur...

The extensive utilization of materials in daily life can result in environmental pollution, resource depletion, and numerous other consequences. One approach to mitigate these issues could be adopting recycling techniques for high-consumption materials. In this investigation, Acrylic Styrene Acrylonitrile (ASA) was selected for examination under si...

This study aimed to develop a biochar-modified polyethylene terephthalate glycol (PETG) composite for 3D printing. Biochar prepared from olive tree prunings was compounded with PETG at different loadings and then processed into filaments through a controlled extrusion process. The resultant filaments were used to print test specimens, which were ch...

Poly(methyl methacrylate) (PMMA) is a thermoplastic widely utilized in civilian-, defense-, and medicine-related applications. Therefore, inducing antibacterial properties is an additional asset when infection control is prioritized. To counter this, PMMA was mixed, for the first time, with antibacterial agents (antibacterial blend nanopowder, AP)...

This research focuses on the effect of Antimony Tin Oxide (ATO) filler on high-density polyethylene (HDPE) polymers in 3D printing. Initially, the polymer and filler were blended and melt-extruded into filaments with uniform filler dispersion and fine surface quality. The filaments were used to create 3D-printed specimens according to international...

Biocomposite filaments for material extrusion (MEX) additive manufacturing, particularly those derived from agricultural biomass, have attracted significant research and industrial interest. Biochar is a well-documented reinforcement agent that is used in several polymeric matrices. However, systematic research efforts regarding the quality scores...

The increasing production of solid waste and the lack of valorization options for some of them pose a constant environmental threat. Ferronickel slag (FNS) is a solid waste derived from the smelting of ferronickel alloys and has a low utilization rate worldwide. In this study, FNS was used as an additive for high-density polyethylene (HDPE) thermop...

Structural control techniques can be used to protect engineering structures. By computing instantaneous control forces based on the input from the observed reactions and adhering to a strong control strategy, intelligent control in structural engineering can be achieved. In this study, we employed intelligent piezoelectric patches to reduce vibrati...

In this study, 3D-printed acrylonitrile butadiene styrene (ABS) was investigated using samples manufactured to examine their intriguing properties in defense applications. The overall quality was also assessed. The resulting average roughness (Ra), root mean square (Rz) roughness, actual to nominal geometrical deviation, porosity, and dielectric re...

In this study, medical poly [ε-caprolactone] (PCL) was used as the matrix material for the development of composites, with hydroxyapatite (HAp) particles with angular and spherical shapes employed as additives. Pellets of such composites were created with five different filler concentrations in the range of 0.0 up to 8.0 wt% (2.0 wt. % increase). T...

Herein, silicon nitride (Si3N4) was the selected additive to be examined for its reinforcing properties on high-density polyethylene (HDPE) by exploiting techniques of the popular material extrusion (MEX) 3D printing method. Six different HDPE/Si3N4 composites with filler percentages ranging between 0.0–10.0 wt. %, having a 2.0 step, were produced...

Bioplotting has high potential for the 3D printing of scaffolds and cellular structures. Medical-grade poly(ε-caprolactone) (PCL) is characterized by low 3D printing temperatures and strengths compared to those of common polymers. Thus far, research on PCL in bioplotting has mainly focused on improving its performance through the development of com...

A cyclic economy and sustainability-driven production are key aspects of the industry. Recycled feedstocks are steadily replacing virgin materials to produce parts and as sustainable additives to develop eco-friendly composites. The reinforcing potential of recycled fine powder glass (FPG) on terephthalate glycol (PETG) is investigated. The perform...

This study focused on the production of polypropylene (PP)/silver (Ag) composites via additive manufacturing. This study aimed to enhance the quality of medical-grade PP in material extrusion (MEX) three-dimensional printing (3DP) by improving its mechanical properties while simultaneously adding antibacterial properties. The latter can find extrem...

In this study, we introduce progress in intelligent control for reducing structural vibrations. The field of intelligent control for dampening structural vibrations is evolving rapidly, driven by advancements in materials science, AI, and actuator technology. These innovations have led to more efficient, reliable, and adaptable vibration-control sy...

Robust materials in medical applications are sought after and researched, especially for 3D printing in bone tissue engineering. Poly[ε-caprolactone] (PCL) is a commonly used polymer for scaffolding and other medical uses. Its strength is a drawback compared to other polymers. Herein, PCL was mixed with hydroxyapatite (HAp). Composites were develop...

Additive Manufacturing (AM) can provide customized parts that conventional techniques fail to deliver. One important parameter in AM is the quality of the parts, as a result of the material extrusion 3D printing (3D-P) procedure. This can be very important in defense-related applications, where optimum performance needs to be guaranteed. The qualit...

This study aimed to investigate the potential of antimony-doped tin oxide (ATO) as a reinforcing agent for polyamide 12 (PA12) in 3D printing by examining four mixtures with varying ATO concentrations (2.0 to 8.0 wt.%, with a 2.0 wt.% interval). These mixtures were used to fabricate filaments for the manufacturing of specimens through the material...

Friction stir welding (FSW) was introduced to join parts that are difficult to join using existing methods. Joining polymeric parts using the FSW process is still a challenging task and has not yet been thoroughly investigated. Parameters such as the forces developed in the process are yet to be studied, but they affect the performance of the weld....

The generation of large quantities of waste materials has become a pressing environmental issue that necessitates immediate action. One such industrial byproduct that has garnered attention in recent years is ferronickel slag (FNS), which is a product of the smelting and refining of iron and nickel ores in electric furnaces. This study sought to in...

In this study, titanium nitride (TiN) was selected as an additive to a high-density polyethylene (HDPE) matrix material, and four different nanocomposites were created with TiN loadings of 2.0–8.0 wt. % and a 2 wt. % increase step between them. The mixtures were made, followed by the fabrication of the respective filaments (through a thermomechanic...

The utilization of eco-friendly reinforcing materials and the fabrication of sustainable composites with enhanced mechanical and electrical properties are a subject of great scientific interest. Such research is aiming to be applied in a variety of industrial applications. In this study, polypropylene (PP) was used as a matrix material and combined...

Bioactive, low-cost, and reinforced filaments for additive manufacturing (AM) have proven valuable in medical applications. Herein, for the first time, nanocomposites were compiled through a reduction process, using pharmaceutical-grade polypropylene (PP) as the matrix material, polyvinyl alcohol (PVA) as the reduction agent, and silver nitrate (Ag...

Segment anything model (SAM) proposed by META Artificial Intelligence (AI) has disrupted the space of Deep Learning (DL) and Machine Learning (ML) and claims performance that outrivals conventional Convolutional Neural Networks (CNNs). The well recognized success of foundation models paved the way towards Natural Language Processing (NLP), which in...

This literature review explores the integration of biochar in 3D printing materials, highlighting the enhancements in mechanical and thermochemical properties that biochar composites can offer. Biochar, a byproduct of the thermochemical conversion of biomass, is characterized for its superior porosity, large specific surface area, and carbon richne...

This research focused on developing medical-grade polypropylene (PP)/silver (Ag) nanocomposites for the production of components through material extrusion (MEX) three-dimensional printing (3DP). The objective was to improve the performance of PP by enhancing its mechanical properties and imparting antibacterial characteristics. An industrially sca...

In this study, piezoelectric patches are used as actuators to dampen structural oscillations. Damping oscillations is a significant engineering challenge, and the use of piezoelectric patches in smart structures allows for a reduction in oscillations through sophisticated control methods. This analysis involved H-infinity (H∞) robust analysis. H∞ (...

Acrylonitrile butadiene styrene (ABS) composites were prepared in filament form compatible with the material extrusion (MEX) 3D printing method, using biochar as a filler at various loadings of up to 10.0 wt %. Samples were fabricated to experimentally investigate their mechanical performance. The ABS/biochar composites were characterized using the...

This study outlines a comprehensive strategy for designing and implementing robust controllers tailored for intelligent structures. This study presents a robust control-based structural identification technique that uses the input/output data of the system to construct a state-space mode and frequency domain. To reduce vibrations, a robust controll...

In this study, poly (ethylene terephthalate) (PETG) was combined with Antimony-doped Tin Oxide (ATO) to create five different composites (2.0–10.0 wt.% ATO). The PETG/ATO filaments were extruded and supplied to a material extrusion (MEX) 3D printer to fabricate the specimens following international standards. Various tests were conducted on thermal...

The field of production engineering is constantly attempting to be distinguished for promoting sustainability, energy efficiency, cost-effectiveness, and prudent material consumption. In this study, three control parameters (3D printing settings), namely nozzle temperature, travel speed, and layer height (LH) are being investigated on polyamide 6/c...

Herein, a new generation of printable bio-composite nanofilaments is explored. The aim was to explore the efficiency of Titanium nitride (TiN) as a reinforcing agent for the Fused Filament Fabrication (FFF) 3D printing technique. TiN, a common ceramic in medical devices, in nanopowder form, was used as a polymer enhancer for the also popular medica...

Herein, a research and engineering gap, i.e., the quantitative determination of the effects of the compressive loading rate on the engineering response of the most popular polymers in Material Extrusion (MEX) Additive Manufacturing (AM) is successfully filled out. PLA (Polylactic Acid), ABS (Acrylonitrile Butadiene Styrene), PP (Polypropylene), and...

Polyethylene terephthalate glycol (PETG) and silicon nitride (Si3N4) were combined to create five composite materials with Si3N4 loadings ranging from 2.0 wt.% to 10.0 wt.%. The goal was to improve the mechanical properties of PETG in material extrusion (MEX) additive manufacturing (AM) and assess the effectiveness of Si3N4 as a reinforcing agent f...

The development of efficient and sustainable composites remains a primary objective of both research and industry. In this study, the use of biochar, an eco-friendly reinforcing material, in additive manufacturing (AM) is investigated. A high-density Polyethylene (HDPE) thermoplastic was used as the matrix, and the material extrusion (MEX) techniqu...

n this study, we investigated the performance improvement caused by the addition of copper (Cu) nanoparticles to high-density polyethylene (HDPE) matrix material. Composite materials, with filler percentages of 0.0, 2.0, 4.0, 6.0, 8.0, and 10.0 wt% were synthesized through the material extrusion (MEX) 3D printing technique. The synthesized nanocomp...

Bioabsorbable and biodegradable composites have experienced rapid growth, owing to their high demand in the biomedical sector. Polymer-cellulose nanocrystal (CNC) compounds were developed using a medical-grade poly (ε-caprolactone) (PCL) matrix to improve the stiffness and load-bearing capacity of pure PCL. Five PCL/CNCs filament grades were melt-e...

The demand for 3D-printed high-performance polymers (HPPs) is on the rise across sectors such as the defense, aerospace, and automotive industries. Polyethyleneimine (PEI) exhibits exceptional mechanical performance, thermal stability, and wear resistance. Herein, six generic and device-independent control parameters, that is, the infill percentage...

Polypropylene (PP) composites reinforced with hexagonal boron carbide (B 4 C) nanoparticles were constructed using a Material Extrusion (MEX) 3D printing method. The goal was to provide nanocomposites for MEX 3D printing with enhanced mechanical properties by exploiting the superior properties of the B 4 C additive. The fabricated 3D-printed specim...

By enabling the development of complex structures with adaptable qualities, techniques for additive manufacturing have opened new routes for material development and research. In this research, silicon nitride (Si3N4) ceramic nanoparticles are incorporated into polypropylene (PP) matrices. Various loading levels and standardized test specimens that...

As the use of Additive Manufacturing (AM) expands, the need for materials capable of satisfying the demanding specifications is increasing. This is more intense in the medical field, where specifications are more sophisticated, restricting the choice of compatible materials. Herein, the performance of a medical specification resin (Biomed clear) wa...

In this study, we created an accurate model for a homogenous smart structure. After modeling multiplicative uncertainty, an ideal robust controller was designed using μ-synthesis and a reduced-order H-infinity Feedback Optimal Output (Hifoo) controller, leading to the creation of an improved uncertain plant. A powerful controller was built using a...

Friction stir welding (FSW) as a welding process for polymers is growing steadily, owing to its inheren1t advantages. The developed forces during the joining process are sensitive to the parameters used and affect the quality of the weld in terms of voids and defect formation. This study focuses on the analysis of the effects of four FSW parameters...

High-density polyethylene polymer (HDPE) and carbon black (CB) were utilized to create HDPE/CB composites with different filler concentrations (0.0, 2.0, 4.0, 6.0, 8.0, 10.0, 16.0, 20.0, and 24.0 wt.%). The composites were extruded into filaments, which were then utilized to fabricate 3D-printed specimens with the material extrusion (MEX) method, s...

In this paper, our strategy is to look for locally optimum answers to a non-smooth optimization problem that has been constructed to include minimization goals and restrictions for smart structures’ vibration suppression. In both theoretical analysis and practical implementation, it is widely recognized that designing multi-objective control system...

To simulate a lightweight structure with integrated actuators and sensors, two-dimensional finite elements are utilized. The study looks at the optimal location and active vibration control for a piezoelectric smart flexible structure. Intelligent applications are commonly used in engineering applications. In computational mechanics, selecting the...

The use of bioabsorbable and biodegradable composites in the medical field has experienced significant growth. Cellulose nanofibers (CNF) have been employed to reinforce medical-grade poly[ε-caprolactone], enhancing both its load-bearing capacity and stiffness compared to pure polycaprolactone PCL. The manufacturing process involved a series of ste...

In this study, we successfully address a significant research and engineering gap by quantitatively assessing the impact of varying compressive loading rates on the mechanical behavior of four popular thermoplastic polymers in material-extrusion-based (MEX) 3D printing. Raw powders of polycarbonate (PC), polyethylene terephthalate glycol (PETG), po...

Glass in the type of powder, flakes, and beads was reinforced into a PP matrix and then used for filament production, through a thermomechanical process, in different loadings each (3.0 wt. %, 6.0 wt. %, 9.0 wt. %,), with the aim of optimizing the concentrations. Thermogravimetric and Raman analysis were utilized for the determination of thermal st...

During the past few years, there has been a notable surge of interest in the field of smart structures. An intelligent structure is one that automatically responds to mechanical disturbances by minimizing oscillations after intelligently detecting them. In this study, a smart design that contains integrated actuators and sensors that can dampen osc...

The goal of this paper is to investigate tungsten carbide (WC) as a reinforcement in the popular material extrusion (MEX) additive manufacturing (AM) procedure. The impressive characteristics of WC demonstrate its potential as a valuable additive for commonly used polymeric matrices in MEX 3D printing, offering reinforcement and stabilization prope...

The development of bioactive, multi-functional, and cost-effective nanocomposite filaments for additive manufacturing (AM) is pivotal for the evolution of biomedical and healthcare sectors. Herein, an industrially scalable process is reported, to produce medical grade PA12/AgNP nanocomposites, through in-situ reactive melt-mixing, occurring within...

In this study, innovative nanocomposite materials for material extrusion (MEX) 3D printing were developed using a polypropylene (PP) polymer with tungsten carbide (WC) nanopowder. The raw materials were converted into filaments using thermomechanical extrusion. The samples were then fabricated for testing according to the international standards. E...

The utilization of friction stir welding (FSW) for the joining of polymers and composites is gaining increasing recognition due to its capabilities. In this study, the weldability of 4 mm thick polycarbonate (PC) plates in FSW is examined. Statistical modeling tools were employed to investigate the effect of four control parameters, i.e., rotationa...

Tungsten carbide (WC), a superhard and thermally stable ceramic, is widely used in several industries. Its exceptional features portray WC as a promising reinforcement and stabilizing agent for popular polymeric matrices deployed in material extrusion (MEX) 3D-Printing, such as Acrylonitrile Butadiene Styrene (ABS). This potential was investigated...

Featured Application The findings presented herein can be directly applied for the prediction and optimization of the compressive strength and the energy consumption of parts to be manufactured with the material extrusion 3D printing process with the Polyamide 6 polymer. Abstract Both energy efficiency and robustness are popular demands for 3D-pri...

Silicon nitride (Si3N4) is a well-known bio-ceramic that is widely used for medical and healthcare purposes, due to its biocompatibility and superior chemical, physical and mechanical properties, which make it suitable for implants. Due to its unique features, examining its efficiency as a cost-effective reinforcement agent for thermoplastics in ma...

This study's goal is to utilize robust control theory to effectively mitigate structural oscillations in smart structures. While modeling the structures, two-dimensional finite elements are used to account for system uncertainty. Advanced control methods are used to completely reduce vibration. Complete vibration suppression is achieved using advan...

Currently, energy efficiency and saving in production engineering, including Material Extrusion (MEX) Additive Manufacturing, are of key importance to ensure process sustainability and cost-effectiveness. The functionality of parts made with MEX 3D-printing remains solid, especially for expensive high-performance polymers, for biomedical, automotiv...

The development of sustainable and functional biocomposites remains a robust research and industrial claim. Herein, the efficiency of using eco-friendly biochar as reinforcement in Additive Manufacturing (AM) was investigated. Two AM technologies were applied, i.e., vat photopolymerization (VPP) and material extrusion (MEX). A standard-grade resin...

Cellulose Nanofibers (CNF) are excellent reinforcement agents for biomedical resins in VPP 3D printing. However , the impact of process parameters on CQIs of VPP-fabricated geometries has not been investigated so far. Hence, the effect of CNF loading, Printing Angle (PA), and Layer Thickness (LT) on the porosity and dimensional accuracy of prismati...

Herein, polytetrafluoroethylene (PTFE) is evaluated as a reinforcement agent in material extrusion (MEX) additive manufacturing (AM), aiming to develop nanocomposites with enhanced mechanical performance. Loadings up to 4.0 wt.% were introduced as fillers of polylactic acid (PLA) and polyamide 12 (PA12) matrices. Filaments for MEX AM were prepared...

The influence of nanoparticles (NPs) in zirconium oxide (ZrO2) as a strengthening factor of Polylactic Acid (PLA) and Polyamide 12 (PA12) thermoplastics in material extrusion (MEX) additive manufacturing (AM) is reported herein for the first time. Using a melt-mixing compounding method, zirconium dioxide nanoparticles were added at four distinct fi...

Nanocomposites for Additive Manufacturing (AM) featuring enhanced mechanical properties and antibacterial performance are desirable in the medical and culinary fields. Silver nitrate was introduced as a reinforcement and antibacterial agent in a medical-grade polyamide 12 (PA12) for the preparation of PA12/Ag nanocomposites for the material extrusi...

Herein, the feasibility of joining with the friction stir welding (FSW) process 3D-printed parts made of poly(methyl methacrylate) (PMMA) with extruded PMMA sheets is investigated. A full factorial design method is followed, with two control parameters, i.e., tool rotational and travel speed, and three levels each. The hybrid joints produced were s...

The industrial demand for functional filaments made of bio-sourced, biocompatible, biodegradable, and/or recyclable polymers and composites for material extrusion (MEX) 3D printing is continuously growing. Polylactic acid (PLA), the most popular filament, combines such properties, yet its reinforcement with low-cost, inert, and/or recycled fillers...

Herein, a blend of nanoparticle (NP) inclusions has been arranged at various loadings into a photosensitive resin, while bi-functional three-dimensional (3D) printed specimens were fabricated through a vat photopolymerization process, to elucidate physicochemical mechanisms and synergistic effects, over the filler loading. Energy-dispersive X-ray s...

The current research aimed to examine the thermomechanical properties of new nanocomposites in additive manufacturing (AM). Material extrusion (MEX) 3D printing was utilized to evolve acrylonitrile butadiene styrene (ABS) nanocomposites with silicon nitride nano-inclusions. Regarding the mechanical and thermal response, the fabricated 3D-printed sa...

Unprecedented growth in 3D reality-based capturing devices - such as Terrestrial Laser Scanners (TLS) or Unnamed Aerial Vehicles (UAVs) equipped with high-resolution cameras, followed by photogrammetry 3D metrics reconstruction - has revolutionized the way Architectural, Engineering, and Construction (AEC) sector operates. Building Information Mode...

The cost-effectiveness and the environmental impact of Additive Manufacturing (AM) are nowadays two of the hottest process-related industrial and research topics. Energy efficiency is a strong claim, and so is the demand for durable and functional 3D-printed workpieces. These contradictory aspects usually require flexibility and compromises. Especi...

Optimization of reinforced nanocomposites for MEX 3D-printing remain strong industrial claims. Herein, the efficacy of three modeling methods, i.e., full factorial (FFD), Taguchi (TD), and Box-Behnken (BBD), on the performance of MEX 3D printed nanocomposites was investigated, aiming to reduce the experimental effort. Filaments of medical-grade Pol...

Acrylonitrile butadiene styrene (ABS) is a multipurpose thermoplastic and the second most popular material in material extrusion (MEX) additive manufacturing (AM). It is widely used in various types of industrial applications in the automotive sector, housing, and food processing, among others. This work investigates the effect of seven generic con...

Process sustainability vs. mechanical strength is a strong market-driven claim in Material Extrusion (MEX) Additive Manufacturing (AM). Especially for the most popular polymer, Polylactic Acid (PLA), the concurrent achievement of these opposing goals may become a puzzle, especially since MEX 3D-printing offers a variety of process parameters. Herei...

Challenging issues arise in the design of control strategies for piezoelectric smart structures. Piezoelectric materials have been investigated for use in distributed parameter systems in order to provide active control efficiently and affordably. In the active control of dynamic systems, distributed sensors and actuators can be created using piezo...

The energy efficiency of material extrusion additive manufacturing has a significant impact on the economics and environmental footprint of the process. Control parameters that ensure 3D-printed functional products of premium quality and mechanical strength are an established market-driven requirement. To accomplish multiple objectives is challengi...

Acrylonitrile Butadiene Styrene (ABS) nanocomposites were developed using Material Extrusion (MEX) Additive Manufacturing (AM) and Fused Filament Fabrication (FFF) methods. A range of mechanical tests was conducted on the produced 3D-printed structures to investigate the effect of Titanium Nitride (TiN) nanoparticles on the mechanical response of t...

Sustainability and energy efficiency of additive manufacturing (AM) is an up-to-date industrial request. Likewise, the claim for 3D-printed parts with capable mechanical strength remains robust, especially for polymers that are considered high-performance ones, such as polycarbonates in material extrusion (MEX). This paper explains the impact of se...

Titanium nitride (TiN) is known as an ultra-hard ceramic, mainly deployed in thin hard coating applications for improving the substrate's surface properties. Therefore, investigating its effectiveness as a reinforcement for thermoplastics in material extrusion (MEX) 3D printing (3DP) has great potential for the development of materials with superio...

Material extrusion (MEX) 3D printing fabricates cost-effective functional polymeric parts, while a new class of materials, such as polylactic acid/carbon nanotubes (PLA/CNTs) nanocomposites, have great potential for use in MEX due to their multi-functional performance. MEX advantages include the construction of lightweight specimens with complex ge...

The weldability of 3D printed (3DP), through material extrusion (MEX), of Polyamide 6 (PA6) plates joined with FSW is investigated. FSW has its challenges in polymers, especially for 3D printed parts, while it is used for various industrial applications in the automotive and airspace sector, in joints, and in other types of parts. Herein, a full fa...

Polycarbonate-based nanocomposites were developed herein through a material extrusion (MEX) additive manufacturing (AM) process. The fabrication of the final nanocomposite specimens was achieved by implementing the fused filament fabrication (FFF) 3D printing process. The impact of aluminum nitride (AlN) nanoparticles on the thermal and mechanical...

Material extrusion (MEX), frequently known as fused filament fabrication (FFF), is a material extrusion 3D printing process for fabricating cost-effectively functional polymeric parts. Even if the MEX process fabricates fully dense or lightweight specimens with a relatively complex geometry in a reduced time and cost, it presents some drawbacks in...