Прегледај по Аутор "Klobčar, Damjan"
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- СтавкаComparison between Mechanical Properties and Joint Performance of AA 2024-T351 Aluminum Alloy Welded by Friction Stir Welding, Metal Inert Gas and Tungsten Inert Gas Processes(MDPI, 2024-07-05) Milčić, Miodrag; Klobčar, Damjan; Milčić, Dragan; Zdravković, Nataša; Ðurić, Aleksija; Vuherer, TomažThe aim of this work is to study joining Al 2024-T3 alloy plates with different welding procedures. Aluminum alloy AA 2024-T351 is especially used in the aerospace industry. Aluminum plates are welded by the TIG and MIG fusion welding process, as well as by the solid-state welding process, friction stir welding (FSW), which has recently become very important in aluminum and alloy welding. For welding AA2024-T35 with MIG and TIG fusion processes, the filler material ER 4043—AlSi5 was chosen because of reduced cracking. Different methods were used to evaluate the quality of the produced joints, including macro- and microstructure evaluation, in addition to hardness and tensile tests. The ultimate tensile strength (UTS) of the FSW sample was found to be 80% higher than that of MIG and TIG samples. The average hardness value of the weld zone of metal for the MIG- and TIG-produced AA2024-T3511 butt joints showed a significant decrease compared to the hardness of the base metal AA2024-T351 by 50%, while for FSW joints, in the nugget zone, the hardness is about 10% lower relative to the base metal AA2024-T3511.
- СтавкаComparison between Mechanical Properties and Joint Performance of AA 2024-T351 Aluminum AlloyWelded by Friction Stir Welding, Metal Inert Gas and Tungsten Inert Gas Processes(MDPI, 2024) Milčić, Miodrag; Klobčar, Damjan; Milčić, Dragan; Zdravković, Nataša; Ðurić, Aleksija; Vuherer, TomažThe aim of this work is to study joining Al 2024-T3 alloy plates with different welding procedures. Aluminum alloy AA 2024-T351 is especially used in the aerospace industry. Aluminum plates are welded by the TIG and MIG fusion welding process, as well as by the solid-state welding process, friction stir welding (FSW), which has recently become very important in aluminum and alloy welding. For welding AA2024-T35 with MIG and TIG fusion processes, the filler material ER 4043—AlSi5 was chosen because of reduced cracking. Different methods were used to evaluate the quality of the produced joints, including macro- and microstructure evaluation, in addition to hardness and tensile tests. The ultimate tensile strength (UTS) of the FSW sample was found to be 80% higher than that of MIG and TIG samples. The average hardness value of the weld zone of metal for the MIG- and TIG-produced AA2024-T3511 butt joints showed a significant decrease compared to the hardness of the base metal AA2024-T351 by 50%, while for FSW joints, in the nugget zone, the hardness is about 10% lower relative to the base metal AA2024-T3511.
- СтавкаInfluence of Surface Preparation of Aluminum Alloy AW-5754 and Stainless Steel X5CRNI18-10 on the Properties of Bonded Joints(MDPI, 2024) Zdravković, Nataša; Klobčar, Damjan; Milčić, Dragan; Zupančić, Matevž; Žužek, Borut; Milčić, Miodrag; Ðurić, AleksijaAdhesive bonding has proven to be a reliable method of joining materials, and the development of new adhesives has made it possible to use bonding in a variety of applications. This article addresses the challenges of bonding metals such as the aluminum alloy EN AW-5754 and the stainless steel X5CrNi18-10. In this study, the effects of laser cleaning and texturing on the surface properties and strength of two bonded joints were investigated and compared with mechanical preparation (hand sanding with Scotch-Brite and P180 sandpaper). The bonded joints were tested with three different epoxy adhesives. During the tests, the adhesion properties of the bonded surface were determined by measuring the contact angle and assessing the wettability, the surface roughness parameters for the different surface preparations, and the mechanical properties (tensile lap-shear strength). Based on the strength test results, it was found that bonded joints made of stainless steel had 16% to 40% higher strength than aluminum alloys when using the same adhesive and surface preparation. Laser cleaning resulted in maximum shear strength of the aluminum alloy bond, while the most suitable surface preparation for both materials was preparation with P180 sandpaper for all adhesives.
- СтавкаInfluence of Surface Preparation of Aluminum Alloy AW-5754 and Stainless Steel X5CRNI18-10 on the Properties of Bonded Joints(MDPI, 2024) Zdravković, Nataša; Klobčar, Damjan; Milčić, Dragan; Zupančić, Matevž; Žužek, Borut; Milčić, Miodrag; Ðurić, AleksijaAdhesive bonding has proven to be a reliable method of joining materials, and the development of new adhesives has made it possible to use bonding in a variety of applications. This article addresses the challenges of bonding metals such as the aluminum alloy EN AW-5754 and the stainless steel X5CrNi18-10. In this study, the effects of laser cleaning and texturing on the surface properties and strength of two bonded joints were investigated and compared with mechanical preparation (hand sanding with Scotch-Brite and P180 sandpaper). The bonded joints were tested with three different epoxy adhesives. During the tests, the adhesion properties of the bonded surface were determined by measuring the contact angle and assessing the wettability, the surface roughness parameters for the different surface preparations, and the mechanical properties (tensile lap-shear strength). Based on the strength test results, it was found that bonded joints made of stainless steel had 16% to 40% higher strength than aluminum alloys when using the same adhesive and surface preparation. Laser cleaning resulted in maximum shear strength of the aluminum alloy bond, while the most suitable surface preparation for both materials was preparation with P180 sandpaper for all adhesives.
- СтавкаMicrostructure and Fatigue Properties of Resistance ElementWelded Joints of DP500 Steel and AW 5754 H22 Aluminum Alloy(MDPI, 2022) Đurić, Aleksija; Milčić, Dragan; Burzić, Zijah; Klobčar, Damjan; Milčić, Miodrag; Marković, Biljana; Krstić, VladislavThe modern concept of lightweight design (LW) requires the application of different materials in one structure (multi-material structures). The structure of different materials has a good perspective for application in the automotive and aerospace industries but only if it is possible to achieve a quality joint between different materials. The most used technology for joining different materials in the automotive industry is Resistance spot welding (RSW). Due to different mechanical, physical, and chemical properties, the joining of different materials by RSW technology does not provide a quality joint, and accordingly, alternative technologies for joining different materials have emerged. Resistance element welding (REW) was developed to enable joint of different materials. This paper presents the welding of AW 5754 H22 Al alloy (1.0 mm-thick) and DP500 steel (1.5 mm-thick) using novel REW. The peak load, absorption energy, microstructure, microhardness and fatigue strength of the REW joint has been investigated. The joint of the same materials has been done also using conventional RSW to compare some results. The results that will be presented in this paper show that that REW can achieve reliable joining of the two materials at relatively low welding currents compared to RSW. Using REW process with a significantly lower welding current, satisfactory mechanical characteristics of the weld joint can be achieved, so peak load is between 2300–2500 N, displacement is between 2.5–3 mm and the absorption energy is between 3.3–5.7 J. REW joints showed fatigue strength with the fatigue limit of 882 N.
- СтавкаMULTI-OBJECTIVE OPTIMIZATION OF THE RESISTANCE SPOT-WELDING PROCESS PARAMETERS FOR THE WELDING OF DUAL-PHASE STEEL DP500(Institute of Metal Materials and Technologies, 2021) Đurić, Aleksija; Miličić, Dragan; Klobčar, Damjan; Marković, BiljanaResistance spot welding (RSW) is still the most used form of welding in the automotive industry, primarily for welding steel. One of the advanced steels used in the automotive industry is dual-phase steel, so it is important to properly select the welding parameter for these steels. Therefore, this paper presents multi-objective optimization in the RSW welding process of DP 500 steel. The paper considers three different mechanical characteristics i.e., the failure load (F), failure displacement (l) and weld nugget diameter (D), as all these welding characteristics play significant roles in evaluating the quality of spot welding. The results show that the welding current is the most influential parameter with respect to the mechanical characteristics. The effect of welding time on the weld quality is the least significant. The optimal parameters for welding DP 500 steel obtained in this paper are weld current 8 kA, electrode force 4.91 kN and weld time 400 ms.
- СтавкаParameter optimisation and failure load prediction of resistance spot welding of aluminium alloy 57547(2019) Đurić, Aleksija; Klobčar, Damjan; Milčić, Dragan; Marković, BiljanaThis paper will also present single objective optimization and Failure load prediction of Resistance spot welding of Aluminium alloy 57547. The experimental studies were conducted under varying welding currents I, electrode forces F, welding times T, pred preheating currents IA. The settings of welding parameters were determined by using the Taguchi experimental design of L9 Orthogonal array method. For optimization and prediction will be used analysis of Signal-to-Noise (S/N) ratio and Response surface modelling RSM.
- СтавкаRESISTANCE SPOT WELDING OF STEEL SHEET DP500 - INFLUENCE OF THE WELDING CURRENT ON THE MICROHARDNESS AND WELD NUGGET DIAMETER(Sveučilište u Slavonskom Brodu, Strojarski fakultet, 2021) Đurić, Aleksija; Milčić, Dragan; Marković, Biljana; Klobčar, Damjan; Milčić, Miodrag; Mitić, DraganDual-Phase steel has been used in body-in-white in order to reduce the weight and enhance the safety of automobiles. One of the most used technology for joining steel in automotive industry is Resistance spot welding. This paper presnet the analysis of the welding current influence on the microhardness and weld nugget diameter. It will be shown in the paper that the increased hardness of the fusion zones reduces the possibility of the necking in the base metal (i. e. Pull-out Fracture - PF mode), which is not considered as a favorable case.Specimens welded with current of 8 kA showed the best mechanical characteristics, the failure load was approximately 20000 N, the hardness of the fusion zone was approximately 350 HV and during the tensile-shear test they faile in PF mode.
- СтавкаTEHNOLOGIJE SPAJANJA LIMOVA OD ČELIKA I LEGURA ALUMINIJA – PREGLED STANJA(DUZS - Društvo za unapređivanje zavarivanja u Srbiji, Beograd, 2023) Đurić, Aleksija; Milčić, Dragan; Klobčar, Damjan; Marković, Biljana; Milčić, MiodragMultimaterijal dizajn je razvijen kao savremeni koncept dizajna za lake konstrukcije (Lightweight design LW) koji ima za cilj integrisanje različitih vrsta materijala u jednu strukturu. Osnovni problem pri spajanju limova od raznorodnih materijala, prvenstveno čelika i legura aluminijuma, su različita mehanička, fizička i hemijska svojstva materijala koji se spajaju. Kroz ovaj rad biće analizirano stanje tehnike kada su u pitanju savremene tehnologije spajanja limova od čelika i legura aluminijuma. Pod pojmom savremene tehnike spajanja misli se na sve inovativne tehnologije spajanje koje su razvijene ili su značajniju primjenu doživjele u posljednjih nekoliko godina.
- СтавкаWAAM and Other Unconventional Metal Additive Manufacturing Technologies(University of Novi Sad, Faculty of Technical Sciences Department of Production Engineering, 2020) Klobčar, Damjan; Baloš, Sebastian; Busić, Matija; Đurić, Aleksija; Lindič, Maja; Ščetinec, Aljaz; Milutinović, MladomirThe paper presents an overview of metal additive manufacturing technologies. The emphasis is on unconventional emerging technologies with firm background on welding technologies such as Ultrasonic Additive Manufacturing, Friction Additive Manufacturing, Thermal Spray Additive Manufacturing, Resistance Additive Manufacturing and Wire and Arc Additive Manufacturing. The particular processes are explained in detail and their advantages and drawbacks are presented. Attention is made on materials used, possibilities to produce multi-material products and functionally graded materials, and typical applications of currently developed technologies. The state-of-the-art on the Wire and Arc Additive Manufacturing is presented in more detail due to high research interests, it’s potential and widespread. The main differences between different arc additive manufacturing technologies are shown. An influence of processing parameters is discussed with respect to process stability and process control. The challenges related to path planning are shown together with the importance of post-processing. The main advantage of presented technologies is their ability of making larger and multi-material parts, with high deposition rate, which is difficult to achieve using conventional additive technologies.