Person: ÇAVDAR, KADİR
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ÇAVDAR
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KADİR
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Publication Effect of atmospheric pressure plasma treatment on the adhesive bonds of metal surfaces(Gazi Univ, Fac Engineering Architecture, 2023-01-01) Kanbir, Öyküm; Taşyakan, Emel; Çavdar, Kadir; ÇAVDAR, KADİR; Mühendislik Fakültesi; Makine Mühendisliği Bölümü; A-4627-2018Purpose: In this study, it is aimed to investigate the effect of atmospheric pressure plasma application on the strength of the adhesive bond of galvanized steels (H300LAD) and non-galvanized steels (H300LA). Theory and Methods: The contact angles of the test samples prepared from galvanized coated and non -galvanized steel material were measured using water drops, and the relative surface tensions were determined with the ink test. These data were compared with the data obtained after the APP application and the effects of the applied plasma treatment on the surface properties were investigated. The test samples prepared by applying different plasma velocities and different adhesives were subjected to the tensile test. With these data obtained, the effects of plasma treatment on the adhesion strength of the materials were evaluated. Results: After the APP treatment, an improvement of approximately 69% in the galvanized material and 34% in the non-galvanized steel material was achieved in the surface wettability. In the (M1 Y2 V3) experimental group, the adhesion strength increased 4.38 times after APP application, and the greatest increase was obtained. The least increase in adhesion strength was obtained in the (M1 Y1 V1) experimental group with an increase of 1.74 times. While it is understood that the adhesion strength increases as the plasma velocity steps up, the most remarkable increase is the 39% increase in adhesion strength obtained by changing the velocity from V1 to V3 in galvanized steel. Conclusion: As a result, it has been understood that the application of APP increases the surface energy for galvanized steel and non-galvanized steel materials, thereby improving the bonding behavior of metals. This difference can be further increased with different experimental parameters. In addition, it has been observed that the plasma velocity is quite effective in changing the surface energy.Publication Effect of the welding parameters on the surface morphology of resistance spot welded AISI 304 stainless steel joints(Walter de Gruyter, 2020-07-01) Çavdar, F. Yıldız; Yaşar, Hüseyin; Çavdar, Kadir; ÇAVDAR, KADİR; Mühendislik Fakültesi; Makina Mühendisliği Bölümü; 0000-0001-9126-0315; A-4627-2018Resistance spot welding is an extensively used production process in the industry. The joint strength of sheet metal parts bonded by resistance spot welding is expected to be sufficient. Furthermore, it is desirable that the appearance of the welding area be acceptable on visible surfaces. In regard to having an adequate surface appearance on the welded area, is necessary to remove the color changes on the unpainted surfaces and to eliminate the indentations caused by the welding pressure. In this study, an objective evaluation was performed using the color measurements of the test samples joined with resistance spot welding. The effects of welding parameters on surface appearance were investigated and the most suitable settings for the appearance of the welded surface were discussed.Publication Investigation of the effect of environment friendly atmospheric pressure cold plasma application on bond strength of pom and pp materials(Gazi Univ, Fac Engineering Architecture, 2023-01-01) Güler, Hikmet; Ayaş, Kadir; Çavdar, Kadir; ÇAVDAR, KADİR; Mühendislik Fakültesi; Makina Mühendisliği Bölümü; A-4627-2018Purpose: Cold atmospheric pressure plasma (CAPP) processes were performed on polypropylene (PP) and polyoxymethylene (POM) polymers with different process speed and distance. Two different types of adhesives applied on these polymers and characterization methods were carried. It was aimed to investigate the effect of CAPP process on surface free energy and bonding strength.Theory and Methods:For CAPP treatment three different plasma process speed and two different distances were carried out on PP and POM materials. Polymers were treated at 0.5, 1, 1.5 cm/s process speed, 1-1.5 mm process distance. Piezobrush (R) PZ2 model atmospheric pressure plasma device, which uses air as the process gas, was used for surface treatments and a device was made by us to control the plasma processing speed. Water contact angle measurements, surface free energy measurement with special inks and tensile test carried out for characterization.Results:It was observed that the tensile strengths of adhesives increase due to increased surface free energy after CAPP process. Varying increases in adhesion strength were observed for each polymer-adhesive pairs after plasma treatments at different speeds and distances. After the CAPP treatment, the water contact angle measurements show that polymer surfaces changed to hydrophilic.Conclusion:The results show that atmospheric pressure plasma treatment is an alternative to other surface energy enhancement methods due to its environmental friendliness, ease of operation and low operating costs. However, it is necessary to continue rapidly in CAPP research for better results and popularization of use in practical applications.Publication Experimental and numerical investigation of sound radiation from thin metal plates with different thickness values of free layer damping layers(Springer Singapore, 2021-04-30) Yılmaz, İlhan; Arslan, Erşen; Çavdar, Kadir; ÇAVDAR, KADİR; Mühendislik Fakültesi; Makine Mühendisliği Bölümü; 0000-0001-9126-0315; A-4627-2018Sound radiation from thin metal plates has consistently been recognized as a severe noise problem. One of the most popular approaches to suppressing this noise is applying viscoelastic layers, also called free layer damping (FLD), on the plate surface, which can damp the structural motion and minimize the radiated sound. The thickness of the FLD is an important parameter. It needs to be optimized for the target acoustic limits through numerical simulations, as the total mass and the costs may rise unnecessarily. This paper investigates the sound radiation from thin metals of particular sizes with different thickness values of FLD. A unique test setup was established to measure vibration and sound for three different sized plates, with each one having three different FLD thicknesses, namely, 0.5 mm, 0.75 mm, and 1 mm. In parallel, vibro-acoustic analyses were performed for the same configurations using the finite element method. The damping of the FLD was defined using the Rayleigh damping model, of which coefficients were obtained through a prediction formula developed earlier by the authors. After validating the model with the test, the effect of FLD on the extended acoustic parameters (radiated sound power, directivity) was also analyzed.Publication Creativity effect with computer program for product designers(Taylor, 2004-06-01) Çavdar, Kadir; Babalık, Fatih C; ÇAVDAR, KADİR; Babalık, Fatih C.; 0000-0001-9126-0315; A-4627-2018; CER-5060-2022The mechanism of human creativity could not be still exactly comprehensible. It was considered that, with the development of the present knowledge management software, the subconscious functions of the human brain could be used efficiently. An extensive computer program can be an incitement element of the new ideas, and brings new creative designs on the paper or screen.With the results of the human brain analyses which seek an answer to "How a trigger-effect could be given to brain", the expectations from the software are mentioned, which have an extensive effect on the subconscious functions of brain. A computer program for engineers and designers in the area of machine acoustics is prepared. In this article, the frame of the knowledge system-GAMAK and a new approach to design of products with low noise are given.Publication The design process of the complex special utility vehicle using the methodical design approach(Japan Soc Mechanical Engineers, 2019-01-01) Borklu, Hüseyin R.; Sezer, H. Kürşad; Çavdar, Kadir; ÇAVDAR, KADİR; Çavdar, Kadir; Mühendislik Fakültesi; A-4627-2018This paper describes the designing and manufacturing process of a complex special utility vehicle (SUV) using the methodical design approach for which the basics were explained decades ago in Germany. The application steps of the design methodology with comprehensive data are clearly outlined and the experiences gained during the project along with the authors' experiences in design research and design practice over 25 years are generously shared. This paper contributes to the methodical approach laid by Pahl & Beitz with an industrial example proving its applicability in real engineering design applications. The proposed solutions for difficulties encountered in the process are especially valuable and applicable for SMEs (small and medium-sized enterprises) in the field. Such details are reported with comprehensive discussions in this paper.Publication Setup for testing the vibration-based loosening of pre-loaded bolted joints(Carl Hanser Verlag, 2019-10-01) Çavdar, F. Yıldız; Bilal, Halil; Güllü, Ramazan; Güler, Birtan; Ciğeroğlu, Ender; Çavdar, Kadir; Solmaz, Erol; Çavdar, F. Yıldız; Bilal, Halil; Guler, Birtan; ÇAVDAR, KADİR; SOLMAZ, EROL; Makine Mühendisliği bölümü; 0000-0001-9126-0315; 0000-0001-9369-3552; HRA-1531-2023; A-4627-2018; A-4627-2018; GPO-9850-2022; EXX-4814-2022In this study, a test setup was designed and manufactured in order to study vibration based self-loosening characteristics of preloaded bolted joints, especially used in the automobile industry. Details of the designed test setup and its operating principles are presented in addition to the test setups available in the literature. Using the test system developed and implementing a design of experiments procedure, first trials were conducted by using the test setup. Under predefined conditions, it is possible to identify when theloosening of bolts occurs and what tightening moment value is required to prevent self-loosening.Publication Determination of the some anthropometric data of Turkish men population(Gazi Üniversitesi, 2014-01-01) Cavdar, Kadir; ÇAVDAR, KADİR; Mühendislik Fakültesi; Makine Mühendisliği Bölümü; 0000-0001-9126-0315; A-4627-2018The technical composition's properties should be appropriate to the physical and mental characteristics of human who will use or produce them. The goal of this research is the estimation of some anthropometric data of Turkish men population. For this goal, anthropometric measurements have been done on 220 male subjects according to the method used for design activities in the automotive industry. On human body, 29 anthropometric parameters have been measured. A multiple regression analysis was conducted to estimate the anthropometric parameters on human body by using two statistical variables, which are stature and weight. According to the results, 17 anthropometric parameters have been formulated depending on stature and weight. The determined formulations can be used especially by automotive industry during design.