TY - CHAP AU - Fekete, Imre AU - Czinege, Imre ED - Conte, Giuseppe L. ED - Sename, Olivier TI - Parametric Analysis of Metal Matrix Syntactic Foams T2 - Proceedings of 12th International Conference on Mechatronics and Control Engineering PB - Springer Nature Singapore CY - Singapore SN - 9789819664528 T3 - Lecture Notes in Mechanical Engineering, ISSN 2195-4356 PY - 2026 SP - 15 EP - 33 PG - 19 DO - 10.1007/978-981-96-6452-8_2 UR - https://m2.mtmt.hu/api/publication/36366200 ID - 36366200 LA - English DB - MTMT ER - TY - JOUR AU - Lendvai, László AU - Fekete, Imre AU - Rigotti, Daniele AU - Pegoretti, Alessandro TI - Experimental study on the effect of filament-extrusion rate on the structural, mechanical and thermal properties of material extrusion 3D-printed polylactic acid (PLA) products JF - PROGRESS IN ADDITIVE MANUFACTURING J2 - PROG ADDIT MANUF VL - 10 PY - 2025 SP - 619 EP - 629 PG - 11 SN - 2363-9512 DO - 10.1007/s40964-024-00646-5 UR - https://m2.mtmt.hu/api/publication/34849476 ID - 34849476 N1 - Funding Agency and Grant Number: Magyar Tudomnyos Akadmia Funding text: No Statement Available AB - Material extrusion (MEX), also commonly referred to as fused deposition modeling (FDM) or fused filament fabrication (FFF) is currently one of the most commonly used additive manufacturing techniques. The quality of the 3D-printed objects fabricated by MEX methods highly relies on various printing parameters, one of which is the so-called filament extrusion multiplier ( k ). In this study, 3D-printed parts were prepared by MEX technique during which the material feeding rate was adjusted by varying the extrusion multiplier in the range of 97–105% ( k = 0.97–1.05). The fabricated parts were tested for their geometrical, structural, mechanical, and thermal conductivity properties. Based on computed tomographic analysis and scanning electron microscopic images, increasing the k parameter resulted in smaller voids, along with gradually decreasing porosity (from 5.82 to 0.05%). Parallel to the decreasing defects, the thermal conductivity of the parts improved from 0.157 to 0.188 W/mK as determined by light-flash analysis technique. On the other hand, when k was set to ≥ 1.03 the geometrical accuracy declined, the size of the specimens considerably increased relative to the nominal values, especially in the X–Y directions due to excess material getting “squeezed” on the sides of the specimens. This latter phenomenon also resulted in the formation of a number of stress concentration sites, which manifested in the decrease of mechanical properties. Accordingly, the tensile, flexural, and impact strength of the samples improved up to k = 1.03; however, above that it dropped considerably. LA - English DB - MTMT ER - TY - JOUR AU - Lendvai, László AU - Jakab, Sándor Kálmán AU - Fekete, Imre AU - Rigotti, Daniele AU - Pegoretti, Alessandro TI - Effect of filament humidity on the properties of material extrusion 3D-printed acrylonitrile butadiene styrene/hexagonal boron nitride composites JF - EMERGENT MATERIALS J2 - EMERGENT MATER VL - 8 PY - 2025 IS - 8 SP - 6791 EP - 6806 PG - 16 SN - 2522-5731 DO - 10.1007/s42247-025-01108-6 UR - https://m2.mtmt.hu/api/publication/36144057 ID - 36144057 AB - This study investigates the effect of filament moisture content on material extrusion (MEX) 3D-printed composites using acrylonitrile butadiene styrene (ABS) as the polymer matrix and 0–10 vol% hexagonal boron nitride (BN) as reinforcement. ABS/BN composites were prepared through batchwise compounding and extruded into MEX-suitable filaments. The filaments were conditioned at 30 °C and 10% or 90% relative humidity (RH) before/during direct feeding into the 3D printer. Specimens were fabricated with raster angles parallel (0°) and perpendicular (90°) to their length. Micro- and macrostructural analyses using scanning electron microscopy and computed tomography revealed intensive void formation, especially in BN-filled composites 3D-printed from humid filaments. This was attributed to BN acting as a physical barrier, hindering the outgassing of evaporated water during 3D printing. Mechanical properties were evaluated using tensile and Charpy impact tests. Based on the tensile test results, neat ABS was the least sensitive to filament moisture, with tensile strength at 0° raster angle dropping from 40.5 MPa to 36.7 MPa as storage RH was increased from 10 to 90%. For composites with 10 vol% BN loading, tensile strength dropped from 34.1 MPa to 22.3 MPa. Charpy impact strength exhibited similar reductions, ascribed to the porous structure of the BN-filled composites caused by the evaporated moisture. Thermal conductivity was also examined, showing slightly superior performance for samples 3D-printed from filaments stored in less humid conditions. For unfilled ABS, the conductivity slightly decreased from 0.188 to 0.185 W/mK, while for 10 vol% BN-filled composite, it dropped from 0.778 to 0.617 W/mK. LA - English DB - MTMT ER - TY - JOUR AU - Lőrincz, Balázs AU - Nagy, András Lajos AU - Fekete, Imre AU - Hatos, István TI - Determination of Optimal Process Parameters for L-PBF Produced 1.2709 Alloy JF - ENGINEERING PROCEEDINGS J2 - ENGENG PROC VL - 113 PY - 2025 IS - 1 SN - 2673-4591 DO - 10.3390/engproc2025113017 UR - https://m2.mtmt.hu/api/publication/36447656 ID - 36447656 LA - English DB - MTMT ER - TY - JOUR AU - Singh, Tej AU - Fekete, Imre AU - Jakab, Sándor Kálmán AU - Lendvai, László TI - Selection of straw waste reinforced sustainable polymer composite using a multi-criteria decision-making approach JF - BIOMASS CONVERSION AND BIOREFINERY J2 - BIOMASS CONV BIOREFINERY VL - 14 PY - 2024 SP - 21007 EP - 21017 PG - 11 SN - 2190-6815 DO - 10.1007/s13399-023-04132-w UR - https://m2.mtmt.hu/api/publication/33748423 ID - 33748423 N1 - Savaria Institute of Technology, Eötvös Loránd University, Szombathely, 9700, Hungary Department of Materials Science and Engineering, Széchenyi István University, Győr, 9026, Hungary Export Date: 09 January 2025; Cited By: 4; Correspondence Address: L. Lendvai; Department of Materials Science and Engineering, Széchenyi István University, Győr, 9026, Hungary; email: lendvai.laszlo@sze.hu AB - The valorization of straw waste as a sustainable and eco-friendly resource in polymer composites is critical for resource recycling and environmental preservation. Therefore, many research works are being carried out regarding the development of wheat straw-based polymer composites to identify the reinforcing potential of these sustainable resources. In this study, three different sizes of wheat straw fibers (60–120 mesh, 35–60 mesh, and 18–35 mesh) were used, and their different ratios (0, 2.5, 5, 10, and 20% by weight) were systematically investigated for the physical and mechanical properties of polypropylene-based sustainable composites. The results indicated that the evaluated composites’ properties are strongly dependent on the quantity and size of the utilized wheat straw. Therefore, a preference selection index was applied to rank the developed sustainable polymer composites to select the best composition. Various properties of the composite materials were considered as criteria for ranking the alternatives, namely tensile strength and modulus, flexural stress at conventional deflection and flexural modulus, impact strength, density, water absorption, material cost, and carbon footprint. The decision-making analysis suggests the alternative with wheat straw content of 20 wt.% (35–60 mesh size) dominating the performance by maximizing the beneficial criteria and minimizing the non-beneficial criteria, making it the most suitable alternative. This study will significantly help formulation designers to deal with the amount and size issues when developing polymeric composites. LA - English DB - MTMT ER - TY - JOUR AU - Jakab, Sándor Kálmán AU - Singh, Tej AU - Fekete, Imre AU - Lendvai, László TI - Agricultural by-product filled poly(lactic acid) biocomposites with enhanced biodegradability: The effect of flax seed meal and rapeseed straw JF - COMPOSITES PART C: OPEN ACCESS J2 - COMPOS PART C VL - 14 PY - 2024 PG - 11 SN - 2666-6820 DO - 10.1016/j.jcomc.2024.100464 UR - https://m2.mtmt.hu/api/publication/34827091 ID - 34827091 N1 - Department of Materials Science and Engineering, Széchenyi István University, Győr, H-9026, Hungary Savaria Institute of Technology, Faculty of Informatics, Eötvös Loránd University, Budapest, H-1117, Hungary Export Date: 09 January 2025; Cited By: 4; Correspondence Address: L. Lendvai; Győr, H-9026, Egyetem tér 1., Hungary; email: lendvai.laszlo@sze.hu LA - English DB - MTMT ER - TY - JOUR AU - Németh, Attila AU - Ibrahim, Sarah Khaleel AU - Movahedi Rad, Majid AU - Szalai, Szabolcs AU - Major, Zoltán AU - Kocsis Szürke, Szabolcs AU - Jóvér, Vivien AU - Mykola, Sysyn AU - Dmytro, Kurhan AU - Harrach, Dániel AU - Baranyai, Gusztáv AU - Fekete, Imre AU - Nagy, Richárd AU - Csótár , Hanna AU - Klaudia, Madarász AU - Pollák, András AU - Bálint, Molnár AU - Hermán, Bence AU - Kuczmann, Miklós AU - Gáspár, László AU - Fischer, Szabolcs TI - Laboratory and numerical investigation of pre-tensioned reinforced concrete railway sleepers combined with plastic-fiber reinforcement JF - POLYMERS J2 - POLYMERS-BASEL VL - 16 PY - 2024 IS - 11 SN - 2073-4360 DO - 10.3390/polym16111498 UR - https://m2.mtmt.hu/api/publication/34865886 ID - 34865886 N1 - Funding Agency and Grant Number: SIU Foundation's project 'Sustainable railways-Investigation of the energy efficiency of electric rail vehicles and their infrastructure' Funding text: No Statement Available LA - English DB - MTMT ER - TY - JOUR AU - Hatos, István AU - Hargitai, Hajnalka AU - Fekete, Gusztáv AU - Fekete, Imre TI - Effect of Energy Density on the Mechanical Properties of 1.2709 Maraging Steel Produced by Laser Powder Bed Fusion JF - MATERIALS J2 - MATERIALS VL - 17 PY - 2024 IS - 14 SN - 1996-1944 DO - 10.3390/ma17143432 UR - https://m2.mtmt.hu/api/publication/35131120 ID - 35131120 N1 - Export Date: 09 January 2025; Cited By: 0; Correspondence Address: G. Fekete; Department of Material Science and Technology, Audi Hungária, Faculty of Vehicle Engineering, Széchenyi István University, Győr, H-9026, Hungary; email: fekete.gusztav@sze.hu AB - The unusual combination of the fundamentally contradictory properties of high tensile strength and high fracture toughness found in maraging steel makes it well suited for safety-critical applications that require high strength-to-weight materials. In certain instances, additive manufacturing (AM) has produced materials that may be desirable for safety-critical applications where impact toughness is a key property, such as structural parts for the aerospace industry or armor plates for military applications. Understanding the influence of process parameters and defect structure on the properties of maraging steel parts produced via laser powder bed fusion (LPBF) is a fundamental step towards the broader use of AM technologies for more demanding applications. In this research, the impact energy of V-notched specimens made of 1.2709 maraging steel produced by LPBF was determined via Charpy impact testing. Specimens were produced using different processing parameter sets. By combining the process parameters with the porosity values of the parts, we demonstrate that an almost full prediction of the impact properties can be achieved, paving the way for significantly reducing the expenses of destructive testing. LA - English DB - MTMT ER - TY - JOUR AU - Lendvai, László AU - Fekete, Imre AU - Jakab, Sándor Kálmán AU - Szarka, Györgyi Éva AU - Verebélyi, Klára AU - Iván, Béla TI - Influence of environmental humidity during filament storage on the structural and mechanical properties of material extrusion 3D-printed poly(lactic acid) parts JF - RESULTS IN ENGINEERING J2 - RESULT ENGIN VL - 24 PY - 2024 PG - 11 SN - 2590-1230 DO - 10.1016/j.rineng.2024.103013 UR - https://m2.mtmt.hu/api/publication/35422527 ID - 35422527 N1 - Department of Materials Science and Engineering, Széchenyi István University, Egyetem tér 1, Győr, H-9026, Hungary Polymer Chemistry and Physics Research Group, Institute of Materials and Environmental Chemistry, HUN-REN Research Centre for Natural Sciences, Magyar tudósok krt. 2, Budapest, H-1117, Hungary Export Date: 09 January 2025; Cited By: 1; Correspondence Address: L. Lendvai; Győr, Egyetem tér 1., H-9026, Hungary; email: lendvai.laszlo@sze.hu AB - Material extrusion (MEX) is one of the most widely used additive manufacturing techniques these days. This study investigates how the properties of MEX 3D-printed objects depend on the relative humidity (RH) conditions in which filaments are stored before and during the manufacturing process. Poly(lactic acid) (PLA) filament was drawn directly from a humidity-controlled chamber into the MEX 3D printer’s nozzle. For each set of samples, the filaments were conditioned under different RH conditions, ranging from 10% to 90%. The macrostructure of the fabricated products was characterized using computed tomography, revealing increased porosity at higher RH values (from 0.84% to 4.42%). The increased porosity at higher storage RH is attributed to under-extrusion and volatile entrapment due to excess moisture. With growing storage RH, the melt flow rate of PLA also gradually increased, indicating a plasticizing effect of humidity on the biopolymer. Gel permeation chromatography and differential scanning calorimetry analyses were conducted to determine whether hydrolytic chain scission took place when PLA was processed in the presence of excessive moisture. Neither measurement indicated any considerable alteration in molecular integrity and crystalline structure as a function of storage RH. Mechanical tests, however, revealed a reduced load-bearing capacity of the manufactured PLA specimens. Flexural strength decreased from 103.0 to 99.6 MPa, and the impact strength dropped from 18.2 to 16.2 kJ/m2, which is ascribed to the increasing size of pores inside the specimens with increasing storage RH. These findings should be taken into account when designing and processing PLA products by MEX-based additive manufacturing. LA - English DB - MTMT ER - TY - JOUR AU - Lendvai, László AU - Dogossy, Gábor AU - Jakab, Sándor Kálmán AU - Fekete, Imre TI - Foam Injection Molding of Poly(Lactic Acid) with Azodicarbonamide-Based Chemical Blowing Agent JF - ENGINEERING PROCEEDINGS J2 - ENGENG PROC VL - 79 PY - 2024 IS - 1 PG - 6 SN - 2673-4591 DO - 10.3390/engproc2024079044 UR - https://m2.mtmt.hu/api/publication/35503978 ID - 35503978 N1 - Department of Materials Science and Engineering, Széchenyi István University, Győr, H-9026, Hungary Department of Vehicle Manufacturing and Technology, Széchenyi István University, Győr, H-9026, Hungary Export Date: 09 January 2025; Cited By: 0; Correspondence Address: L. Lendvai; Department of Materials Science and Engineering, Széchenyi István University, Győr, H-9026, Hungary; email: lendvai.laszlo@sze.hu LA - English DB - MTMT ER -