Mechanical Engineering / Makina Mühendisliği

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  • Conference Object
    A Comparative Study of Attention-Augmented YOLO Architectures for Defect Detection in Fused Deposition Modelling
    (Institute of Electrical and Electronics Engineers Inc., 2025) Cezayirli, H.; Tetik, H.; Dede, M.I.C.; Phone, W.L.; Alkan, B.
    Additive manufacturing (AM), particularly fused deposition modelling (FDM), facilitates the fabrication of complex geometries with increasing flexibility and efficiency. Ensuring consistent print quality in FDM processes necessitates the development of accurate defect detection mechanisms. Attention-augmented YOLO (You Only Look Once) models have emerged as a promising solution for addressing this challenge. In this study, we systematically benchmark and evaluate the performance of YOLO architectures enhanced with attention mechanisms within the context of FDM 3D printing applications. The models were trained and evaluated using representative defect datasets. The attention-augmented models demonstrate improved detection performance. © 2025 IEEE.
  • Conference Object
    Redundancy resolution options for the twin-it-romans robotic hybrid manufacturing system
    (Springer Science and Business Media B.V., 2025) Gündüz, G.M.; Dede, Mehmet İsmet Can; Kiper, Gökhan; Schmitz, M.; Corves, B.
    The Twinnig Iztech in Robotics Manufacturing System (TWIN-IT-ROMANS) project funded by EU Horizon -Widera-2023-Access-02-01 aims to develop a hybrid manufacturing system that can perform additive and subtractive manufacturing processes and inline quality control using a robotic system. The system will incorporate a 6-degree-of-freedom robot arm and a positioner with 2-degree-of-freedom, which will operate synchronously. This manipulation system is to be designed for performing different manufacturing operations with different degrees-of-freedom requirements. In order to reveal alternative trajectory planning scenarios for this system, this paper presents an initial review of redundancy resolution approaches for kinematically redundant robotic manipulators. First, the four main approaches for redundancy resolution techniques are introduced. Then main studies on energy minimization and stiffness maximization for kinematically redundant robotic manipulators are reviewed. Similar or new approaches are planned to be generated and implemented for the redundant system for hybrid manufacturing. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2025.
  • Conference Object
    Towards Sustainable Manufacturing: a Review and Future Directions in Additive Manufacturing of Fiber-Reinforced Polymer Composites
    (Springer Science and Business Media B.V., 2025) Türkcan, M.Y.; Tetik, Halil; Kurt, B.; Dede, Mehmet İsmet Can; Karaş, B.; Tetik, H.; Shokrani, A.; Dede, M.İ.C.
    The United Nations Sustainable Development Goals (SDGs) provide a global framework for addressing critical challenges such as climate change, resource scarcity and sustainable industrialization. With increasing demand for products and improving quality of life, linear consumption of materials and resources following the “take-make-waste” is no longer possible. As such, innovative solutions are increasingly necessary to enable circular economy in manufacturing. Additive manufacturing (AM) has emerged as a transformative technology in achieving SDGs by enhancing resource efficiency and minimizing waste. Fiber reinforced composites are a promising application of AM, as they offer the potential to optimize material use, reduce labor and support sustainable production practices. However, there is an urgent need for considering circular economy strategies, life cycle assessment (LCA) frameworks and effective recycling at the end of their lifetime. This study examines additive manufacturing systems for fiber-reinforced composites, their environmental impact and exploring the potential contributions of robotic integration in composite manufacturing to enhanced sustainability. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2025.
  • Article
    Enhancing trajectory-tracking accuracy of high-acceleration parallel robots by predicting compliant displacements
    (Cambridge University Press, 2025) Paksoy, Erkan; Dede, Mehmet Ismet Can; Kiper, Gokhan
    For precision-required robot operations, the robot's positioning accuracy, repeatability, and stiffness characteristics should be considered. If the mechanism has the desired repeatability performance, a kinematic calibration process can enhance the positioning accuracy. However, for robot operations where high accelerations are needed, the compliance characteristics of the mechanism affect the trajectory-tracking accuracy adversely. In this paper, a novel approach is proposed to enhance the trajectory-tracking accuracy of a robot operating at high accelerations by predicting the compliant displacements when there is no physical contact of the robot with its environment. Also, this case study compares the trajectory-tracking characteristics of an over-constrained and a normal-constrained 2degrees-of-freedom (DoF) planar parallel mechanism during high-acceleration operations up to 5 g accelerations. In addition, the influence of the end-effector's center of mass (CoM) position along the normal of the plane is investigated in terms of its effects on the proposed trajectory-enhancing algorithm.
  • Article
    Citation - WoS: 1
    Citation - Scopus: 1
    Analysis and Comparison of the Projectile Impact Response of an Electron Beam Melt-Ti64 Body Centered Cubic Lattice-Cored Sandwich Plate
    (Springer, 2025) Erten, H.İ.; Çimen, G.; Yıldıztekin, F.M.; Güden, M.
    Background: One potential application of additively fabricated lattice structures is in the blade containment rings of gas turbine engines. The blade containment rings are expected to be able to absorb the kinetic energy of a released blade (broken blade) in order to protect the engine parts from damaging. Metallic lattice-cored sandwich plates provide a gap (free space) between two face sheets, which helps to arrest the released blade and increases the energy absorption capability of containment rings. Objective: The objective was to investigate numerically the projectile impact response of Body-Centered-Cubic (BCC) Electron-Beam-Melt (EBM) lattice-cored/Ti64 face sheet sandwich plates as compared with that of an equal-mass monolithic EBM-Ti64 plate. Methods: The projectile impact simulations were implemented in LS-DYNA using the previously determined flow stress and damage models and a spherical steel impactor at the velocities ranging from 150 to 500 m s−1. The experimental projectile impact tests on the monolithic plate were performed at two different impact velocities and the results were used to confirm the validity of the used flow stress and damage models for the monolithic plate models. Results: Lower impact stresses were found numerically in the sandwich plate as compared with the monolithic plate at the same impact velocity. The bending and multi-cracking of the struts over a wide area in the sandwich plate increased the energy absorption and resulted in the arrest of the projectile at relatively high velocities. While monolithic plate exhibited a local bent area, resulting in the development of high tensile stresses and the projectile perforations at lower velocities. Conclusions: The numerical impact stresses in the sandwich plate were distributed over a wider area around the projectile, leading to the fracture and bending of many individual struts which significantly increased the resistance to the perforation. Hence, the investigated lattice cell topology and cell, strut, and face sheet sizes and the lattice-cored sandwich plate was shown potentially more successful in stopping the projectiles than the equal-mass monolithic plates. © The Author(s) 2025.
  • Article
    Ağır Ticari Araçlarda Kullanılan Bir Volanın Parametrik Optimizasyon Yöntemiyle Tasarımının İyileştirilmesi
    (2022) Sırmalılar, Mehmet Yalçın; Haktanır, Murat; Saklakoğlu, Nurşen; Eş, Caner
    Otomotiv endüstrisinde rekabetçi olabilmenin anahtarı ürün geliştirmenin ilk aşamalarında üretim maliyetini ve ürün performansını düşünerek daha iyi yapısal tasarımlar elde etmektir. Son yıllarda sonlu eleman analizindeki gelişmeler daha güvenli ve daha ucuz tasarımların oluşturulmasını sağlamış ve bu yeteneği kazanan firmalar önemli avantajlar elde etmiştir. Bu çalışmada Dönmez Debriyaj firmasında seri üretimi yapılan bir volanın malzeme maliyetini azaltmak üzere boyut optimizasyonu gerçekleştirilmiştir. Bilgisayar destekli sonlu elemanlar yöntemi ile volanın çalışma koşulları simüle edilmiş, parametrik optimizasyon yöntemi ile volan için istenen mekanik özellikleri sağlamanın yanı sıra maliyeti en düşük tutacak şekilde optimizasyon yapılmıştır. Bu çalışma sonunda volan ağırlığı 27,956 kg’dan 26,019 kg’a düşürülerek, toplam volan ağırlığından %6,93 azaltma sağlanmıştır ve ilgili volan, analizlerden elde edilen sonuçlar doğrultusunda talaşlı üretim ile revize edilerek üretilmiş ve araç testine tabi tutulmuştur. Bu test sonucunda hiçbir hasarla karşılaşılmamıştır.
  • Conference Object
    Kinematic Design of a Novel Finger Exoskeleton Mechanism for Rehabilitation Exercises
    (Springer international Publishing Ag, 2024) Kiper, Gokhan; Inanc, Emirhan
    The paper presents the kinematic design of a novel low-cost two degree-of-freedom finger exoskeleton mechanism to be used for rehabilitation exercises for post-stroke or injured patients. The first degree-of freedom is for the flexion/extension of metacarpophalangeal joint and is achieved via a planar 4-bar loop. The second degree-of-freedom is for the simultaneous flexion/extension of distal/proximal interphalangeal joints and is achieved via an over-constrained double-spherical 6-bar linkage, where 3 of the links are the phalanges of the finger and 2 of the joints are finger joints themselves. So, the number of extra links are less compared to other designs in the literature. The motion of an index finger is recorded via image processing. The four-bar mechanism part is designed for optimum transmission angle characteristics. The formulation and application of the kinematic synthesis of the 6-bar linkage is presented. The design is verified via a prototype.
  • Conference Object
    Citation - Scopus: 3
    A Continuously Variable Transmission System Designed for Human–robot Interfaces
    (Springer, 2021) Mobedi, Emir; Dede, Mehmet İsmet Can
    Within a predefined limit, continuously variable transmission (CVT) systems can continuously vary the power transmission ratio. The transmission in CVTs is achieved via friction, belt or gear systems. If CVT designs can incorporate backdrivability, independent output position and impedance variation, shock absorbtion, and low mass and inertia, they can be employed in human–robot interfaces. Among various types of CVT designs, the two-cone drive CVT designs have a major drawback since the output torque and position cannot be changed independent of each other. The friction wheel used in this design does not have a holonomic motion capability and causes this inconvenience. In order to overcome this problem, a sphere is used in this work for the CVT design as the transmission element. In addition, it is stated in the literature that common CVT drive systems do not have the capability to be used in cyclic bidirectional motion. In the presented CVT design, a second sphere is added to the system with two springs from the lower part of the cones for pretension in order to solve the bidirectional transmission problem. In this paper, the working principle and conceptual design details of the novel two-cone CVT drive are presented. Experimental results showed that the novel CVT has the capacity to transmit bidirectional power with some accuracy. © 2021, Springer Nature Singapore Pte Ltd.
  • Conference Object
    Determination of Interfacial Heat Transfer Coefficient for a Mixed Convection Heat Transfer in a Vertical Channel Filled With Uniformly Heated Blocks
    (Begell House Inc., 2015) Çelik, Hasan; Mobedi, Moghtada; Manca,O.; Buonomo,B.
    The interfacial convective heat transfer coefficient of a periodic porous medium under mixed convection heat transfer is determined computationally by using volume averaging method. The porous medium consists of square blocks in inline arrangement. The continuity, momentum and energy equations are solved in dimensionless form for a representative elementary volume of porous medium and the velocity and temperature fields for different values of Richardson and Reynolds numbers are obtained. Based on the obtained results, the interfacial convective heat transfer coefficient is calculated by using volume average method. The temperature of the solid phase is considered uniform and different than the inlet temperature. A detailed discussion on the effect of the governing dimensionless parameters (i.e. Reynolds, Richardson numbers, and porosity) on the local and average interfacial Nusselt number is done. It is concluded that the local interfacial convective heat transfer coefficient increases with Reynolds number, however the rate of increase depends on Richardson number and porosity. The study is performed for two values of porosity of 0.51 and 0.94. © 2021, Begell House Inc. All rights reserved.
  • Conference Object
    A Numerical Study on the Determination of the Effects of Pore To Throat Size Ratio on the Thermal Dispersion in Porous Media
    (Begell House, 2014) Özgümüş, Türküler; Mobedi, Moghtada; Özkol, Ünver
    Direct pore-level numerical simulations are widely used to estimate macroscopic properties of fluid flow and heat transfer in porous media. Thermal dispersion is one of the most important macroscopic transport parameters for analyzing convective heat transfer in a porous medium. It should be known in order to predict the macroscopic temperature distribution. In the present study, a microscopic scale analysis is performed for a porous medium with periodic structure. A representative elementary volume is chosen from an infinite medium consists of rectangular rods in inline arrangement. The continuity and momentum equations are solved to obtain flow field and the energy equations for fluid and solid phases are solved to obtain microscopic temperature distributions in two phases. There are velocity and temperature deviations between macroscopic and microscopic local values. Volume averaging method is applied to the computed deviations and thermal dispersion conductivity of porous media is determined. The aim of this study is to analyze the effects of pore to throat size ratio on the longitudinal and transverse thermal dispersion in porous media. The study is performed for representative elementary volumes with different pore to throat size ratios and Reynolds numbers from 1 to 100. The study is performed for high porosity porous media (ε = 0.7 and 0.91). It is shown that the porosity and pore to throat size ratio have more influence on the transverse rather than longitudinal thermal dispersion. © 2014, Begell House Inc. All rights reserved.