Atakan Altınkaynak

Istanbul Technical University · Department of Mechanical Engineering

Fused deposition modeling (FDM) is widely utilized in additive manufacturing, with the product quality significantly dependent on the strand cross-section geometry. This paper investigates how process parameters affect strand morphology in FDM-printed parts. This is achieved by monitoring the nozzle's position throughout the printing process and an...

Complex numbers and complex functions are frequently utilized in solving equations of motion in free and harmonic responses of vibration systems. However, certain funda- mental details are sometimes overlooked and many books and articles may present differential equations with inconsistencies, which can confuse meticulous readers. This confusion of...

This paper presents a novel interface technique employing Artificial Neural Networks (ANN) for efficient data transfer between incompressible fluid and deformable solid domains in a partitioned fluid-structure interaction (FSI) framework. Governing differential equations (GDE) with potential flow assumptions are solved to obtain pressure values at...

Hamilton’s principle is one of the most important milestones of analytical mechanics. This principle is valid for fixed mass and discrete material systems in its original form. The seminal work of McIver published in 1973 (McIver in J Eng Math 7(3):249–261, 1973) made this principle applicable to variable mass systems and has been constantly refere...

Delta mechanism is one of the well-known parallel mechanisms used in robotic applications. In this study, the trajectory behavior of a novel Delta mechanism, which was designed and fabricated using layer-by-layer origami method, is investigated utilizing the finite element method (FEM). The mechanism was modeled with the dimensions of the actual fa...

Purpose This paper aims to develop experimentally validated numerical models to accurately characterize the cross-sectional geometry of the deposited beads in a fused filament fabrication (FFF) process under various process conditions. Design/methodology/approach The presented numerical model is investigated under various fidelity with varying com...

Radial Basis Function (RBF) kernels are key functional forms for advanced solutions of higher-order partial differential equations (PDEs). In the present study, a hybrid kernel was developed for meshless solutions of PDEs widely seen in several engineering problems. This kernel, Power-Generalized Multiquadric - Power-GMQ, was built up by vanishing...

This study aims to optimize the nozzle channel geometry and manufacturing parameters to obtain polymer parts with the required dimensional accuracy. For this purpose, samples with 30 strips were printed with an FDM printer. Each strip was measured at 4000 points using image processing method. To investigate the effect of the manufacturing parameter...

In robotics, origami-based design methodology can be used to create small scale parallel mechanisms with easier assembly processes. Delta mechanisms are one of the famous parallel mechanism used mostly in pick and place operations due to their capability to reach high speeds and accelerations. In this work, we present a novel Delta mechanism fabric...

The mechanical and tribological behaviors of the parts manufactured with 3D printing methods differ with variations in the manufacturing parameters. This paper aims to investigate the effect of the layer thickness and layer orientation parameters on the hardness, friction coefficient and wear properties of PLA samples printed by Fused Deposition Mo...

In this paper, a new dynamic model for the vibration analysis of an inward-oriented rotating cantilever beam with extra distributed mass was presented. The derived differential equation of motion was solved using the meshless methods of generalized Multiquadric Radial Basis Function (RBF) and the eigenfrequencies of the system were determined. The...

Bu çalışmada, ağsız yöntemler için radyal özelliğe sahip yeni bir temel fonksiyon önerilmiştir. Önerilen fonksiyon, iki boyutta, dört farklı problemde, ağsız yöntemlerde sıklıkla kullanılan Ters Multikuadrik ve Gauss fonksiyonlarıyla birlikte test edilmiştir. Test problemlerinin üç tanesi 2. mertebeden mühendislik problemlerini içerirken son test p...

Purpose This paper aims to analyze experimentally and numerically the effect of the nozzle temperature and feed rates on the dimensions of the fused deposition modeling (FDM) polymer parts. Design/methodology/approach In total, 30 strips per sample were printed with the same width as the nozzle diameter. The strips were printed with one vertical m...

3D finite element simulation of a FDM printer nozzle region was performed using COMSOL Multiphysics software. The polymer exiting the nozzle of the FDM printer was also included in the simulation in order to capture the dimensional behavior of the polymer. The domain of the simulation consisted of a nozzle, printer table, and the surrounding air. I...

The aim of this study is the identification of the mechanical properties of samples printed by Fused Deposition Modeling (FDM) method. Since the mechanical properties of printed parts are different from primary materials, it is important to determine these differences in order to enhance their practical applications. In this study, Acrylonitrile Bu...

Material characterization of 3D printed PLA parts with different infill rates was performed by standard tensile tests. Three-dimensional finite element simulation of the tensile tests was also performed. For the simulations, a method for reconstructing the CAD model of the printed parts with different infill rates was proposed and numerical simulat...

Bu calismada, onden yuklemeli bir camasir makinesinin sikma asamasi sonlu elemanlar metodu ile modellenerek camasir makinesindeki parcalarin yer degistirmeleri ve parcalar uzerindeki gerilmeler ongorulmeye calisilmistir. Yapilan sayisal modellemede, dengesiz kutlenin etkisiyle olusan merkezkac kuvvet, tambur yuzeyine dinamik olarak etkitilmistir. B...

Finite Element Method (FEM) is a well-developed method to solve real-world problems that can be modeled with differential equations. As the available computational power increases, complex and large size problems can be solved using FEM which typically involves multiple degrees of freedom (DOF) per node, high order of elements and an iterative solv...

The use and development of any technology brings about a rapidly evolving life cycle. The rate at which new technology is developed is a very big challenge for the manufacturers in order to respond to consumer needs, demand and requirements very promptly. Therefore, companies have to be fast, flexible and innovative. Bringing a new product to marke...

For an ABS resin, a three-dimensional finite element simulation of melting and flow in the melting and metering sections of a single-screw extruder was performed using barrel rotation boundary conditions. In the simulations, the flow domain was modeled as a full three-dimensional helical channel with flight clearance. The simulation results were th...

The melting of an ABS resin was simulated using a three-dimensional finite element simulation of the two-phase flow in the compression section of a single-screw extruder. Screw freezing experiments were also conducted to compare the numerical predictions with the corresponding experimental data. Numerical simulations as well as experiments exhibite...

Single-screw extrusion is one of the widely used processing methods in plastics industry, which was the third largest manufacturing industry in the United States in 2007 [5]. In order to optimize the single-screw extrusion process, tremendous efforts have been devoted for development of accurate models in the last fifty years, especially for polyme...

Screw-freezing experiments in a single-screw extruder were conducted with screws having different compression ratios and compression rates for an ABS resin. Three-dimensional finite element simulations of the melting process in the compression section of the extruder were also performed for the compression ratios and compression rates used in the e...

Frictional forces (for temperatures less than the melting or devitrification temperature) and viscous forces (for higher temperatures) have important roles on solids conveying and melting processes in plasticating single-screw extruders. These forces are related to the shear stresses at polymer–metal interfaces. For temperatures at which the fricti...

The surface temperature of the root of the screw is an important factor for solids conveying, melting, and the conveying of molten resin in a single-screw extruder. Screw temperature data, however, are rarely available due to the difficulties in sensor placement and the transfer of electrical signals through rotating shafts. This study measures the...

Frictional f orces (for temperatures less than the melting or devitrification temperature) and shear stress es are key s to the solids conveying and melting processes in plasticating, single -screw extruders. For most processes, the shear stress at the polymer -metal inter face, however, is unknown. This paper will present shear stresses and meltin...

Due to the intensive development of technology, the use of polymers increased rapidly during past five decades. Since polymers are being used in wide variety of fields from industrial applications to commercial products, more technical data about various characteristics of polymers is needed in order to understand the behavior of polymers. In this...

Sensitivity of the melting profile to the screw temperature in a single-screw, plasticating extruder was analyzed using a three-dimensional finite element simulation of the melting process. Numerical predictions are compared with the corresponding experimental data from screw freezing experiments. Against the conventional intuition, the predicted m...

Screw freezing experiments in a single-screw extruder were conducted for an ABS resin. The melting of ABS was also simulated by a full three-dimensional simulation of the two-phase flow in the compression section of the extruder. Numerical simulations as well as experiments exhibit the Maddock melting mechanism. However, numerical predictions and e...