Mechanical Engineering / Makina Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/4129

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  • Book Part
    Citation - WoS: 1
    Citation - Scopus: 1
    A Historical Review of Polyhedral Linkages
    (Springer, 2024) Kiper, Gökhan
    Polyhedral linkages are linkages that resemble polyhedral shapes at different configurations. This paper summarizes the necessary geometrical fundamentals of polyhedral geometry and presents a historical and critical review of the polyhedral linkage designs available in the literature. Basic definitions of polyhedral geometry and operations are needed to comprehend and design polyhedral linkages. First, early works on polyhedral linkages are presented, where flexible polyhedra with rigid faces and flexible edges are issued. The final part is reserved to conformal polyhedral linkages, which go through shape transformations while plane, dihedral and solid angles are preserved. Conformal polyhedral linkages are examined in four categories: 1) Jitterbug-like linkages with screwing polygonal links connected to each other with dihedral angle preserving links, 2) polyhedral linkages with planar kinematic chains in radial motion planes, 3) polyhedral linkages with planar kinematic chains on faces, that are connected to each other with dihedral angle preserving links, and 4) other conformal polyhedral linkages. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2024.
  • Book Part
    Scherengestänge als elemente adaptiver morphologien
    (Birkhäuser, 2020) Akgün, Yenal; Maden, Feray; Gür, Şebnem; Kiper, Gökhan; Korkmaz, Koray; Aktaş, Engin; Yar Uncu, Müjde
    Zu allen Zeiten haben Menschen versucht, flexible Gebäude zu bauen, die sich ständig verändernden Anforderungen und Umweltbedingungen anpassen. Die Einbeziehung von Bewegung in die Architektur ist der Versuch, auf veränderliche Umstände mit neuen Lösungen zu reagieren. Das Konzept der Bewegung ist in der Tat nicht neu für die Architektur. Die Wurzeln gehen bis in die Antike zurück. Einfache, mit flexiblen Außenhäuten gebaute Nomadenzelte können als das erste Beispiel für adaptive Strukturen angesehen werden, die zum Schutz vor extremen Umweltbedingungen dienten.1 Die zum Abdecken des Daches im Colosseum von Rom verwendeten Leinwandbahnen sind ein weiteres Beispiel. Sie bildeten Markisen, die nicht nur Sonnenschutz boten, sondern für die Zuschauer durch ihr Durchhängen zur Mitte hin auch eine Brise einfingen.
  • Book Part
    An Experimental Setup and Procedure for Stiffness Evaluation of Robot Manipulators
    (Springer, 2021) Görgülü, İbrahimcan; Paksoy, Erkan; Carbone, Giuseppe; Dede, Mehmet İsmet Can
    In this paper, an experimental test setup for stiffness evaluation of a spatial parallel mechanism is introduced. The parallel mechanism used in this study is R-CUBE mechanism. In the test setup, a highly rigid gantry-type manipulator’s end-effector is coupled with the R-CUBE’s mobile platform. As the gantry manipulator is actuated the resultant reaction forces/moments are measured via a force\torque sensor. Subsequently, compliant displacements of R-CUBE are measured by using a coordinate measuring machine. The obtained results are presented and discussed in this paper. © 2021, The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG.
  • Book Part
    Citation - WoS: 1
    Citation - Scopus: 1
    Calibration Study of a Continuously Variable Transmission System Designed for Phri
    (Springer, 2020) Mobedi, Emir; Dede, Mehmet Ismet Can
    Variable stiffness actuators (VSAs) have been used in many applications of physical human-robot interfaces (pHRI). A commonly employed design is the spring-based VSA allowing the user to regulate the output force mechanically. The main design criteria of these actuation systems are the adjustment of output force independent from the output motion, and shock absorbing. In our recent work, we implemented certain modifications on the two-cone friction drive continuously variable transmission system (CVT) so that the CVT can be employed in pHRI systems. Subsequently, the optimized prototype is developed. In this study, we introduce the prototype of this new CVT systems, and its force calibration tests. The results indicate that the manufactured CVT is capable of displaying the desired output force throughout its transmission ratio range within a tolerance.
  • Book Part
    Citation - WoS: 3
    Citation - Scopus: 4
    Design and Optimization of Fiber Composites
    (Elsevier, 2017) Aydın, Levent; Artem, Hatice Seçil
    In engineering, design, and optimization processes are very important issues to establish sustainable engineering systems. Compared to isotropic materials, it is necessary to deal with more complicated mathematical models that address the material anisotropy for fiber-reinforced composites. Due to the unique characteristics of fiber-reinforced composite materials such as different directional properties, interlaminar stresses, less notch sensitivity, and having positive and negative coefficients of thermal expansion, they require more material constants for characterization of the hygrothermomechanical responses. Therefore, the design process of composites for the effort required or the benefit desired has to be systematic, which includes innovative approaches to synthesize alternative solutions. In this regard, the main goal of all such attempt is relevant to reach minimizing the effort required or to maximize the desired benefit.
  • Book Part
    Citation - WoS: 4
    Citation - Scopus: 4
    Mechanics of Fiber Composites
    (Elsevier, 2017) Aydın, Levent; Artem, Hatice Seçil; Öterkuş, Erkan; Gündoğdu, Ömer; Akbulut, Hamit
    The objective of this chapter is to emphasize the context in which the mechanics of fiber composites is examined. Constitutive equations describing the stress-strain relations, micromechanics and acromechanics approaches for mechanical analysis are reviewed. Since interfacial mechanics of composites is of primary importance in discussing the material behavior, this concept is also presented with its constitutive and governing equations. Finally, at the end of the chapter, strength failure theories for orthotropic materials and dynamic behavior of composites are discussed.
  • Book Part
    Citation - Scopus: 2
    Improved Usability of a Low-Cost 5-Dof Haptic Device for Robotic Teleoperation
    (Springer, 2019) Ateş, Gizem; Brunetti, Luca; Bonfè, Marcello
    The paper describes the design and application of a low-cost haptic device with five degrees of freedom (5-DOF), all of which are fully actuated for force/torque haptic display. The device is realized using two Novint Falcons, commercially available haptic devices with only translational DOF. The paper focus on the practical issues related to the use of such a haptic device as a robotic teleoperation master and provides solutions to improve its usability during an application inspired by surgical robotics, namely the teleoperated insertion of a needle into a soft tissue. Experiments demonstrate the usefulness of force feedback and virtual fixtures on both translation and orientation degrees of freedom. © 2019, CISM International Centre for Mechanical Sciences.
  • Book Part
    Citation - Scopus: 2
    Computation Time Efficient Stiffness Analysis of the Modified R-Cube Mechanism
    (Springer, 2019) Görgülü, İbrahimcan; Dede, Mehmet İsmet Can
    Parallel manipulators are known to be more stiff than the serial manipulators. However, modeling the stiffness for parallel manipulators are difficult compared to serial manipulators due to the constrained structure and passive joints. In addition, computation of the stiffness model for parallel manipulators are exhausting since it requires an iterative solution algorithm due requirement of force-position convergence of all serial chains connecting to the same mobile platform. Direct solutions are faster however, they lack in accuracy. In this study, direct solution is preferred for real-time application and analytic stiffness model of the modified R-CUBE mechanism is obtained by using Virtual Joint Method (VJM). The finite element (FE) model is constructed and simulated to validate the analytical model. Then, a combination of external wrenches $$\pm 5$$ N in various directions are applied on the mobile platform in both FE and VJM in some critical poses. Finally, the computed numerical results are listed and compared along with their computation times. © Springer Nature Switzerland AG 2019
  • Book Part
    Scissor Linkages in the Design of Adaptive Morphologies
    (Walter de Gruyter GmbH, 2019) Akgün, Yenal; Maden, Feray; Gür, Şebnem; Kiper, Gökhan; Korkmaz, Koray; Aktaş, Engin; Yar Uncu, Müjde
    Scissor linkages are capable of forming various expandable structures. Architects can benefit from this type of linkage especially for designing adaptive, movable, transformable shell structures and deployable beam-like structures. Product designers may benefit as well. The two different methods described here convey the basic design approaches. The unit-based method is very effective for obtaining primary geometries like a dome, arch, circle or line, using serial multiplications and arrays of one of the scissor unit types presented here. The loop assembly method is more convenient when a final form, be it straight or free-form, is the main point of departure. In this case, unlike in the unit-based method, it is not necessary to opt for a specific scissor unit type and its dimensional constraints from the beginning. Designers can choose a type and number of loops and then define the scissor units following the loop sides. Since deployability is guaranteed by applying this method, the architect is free to choose the loop type most suitable for the functional needs and aesthetic concerns of the specific design. With the loop assembly method all loop alternatives can be assembled to scissor structures, their possible motions can be tested and evaluated in a short time, whereas the unit-based method is limited to a single type of motion that a specific unit can provide.
  • Book Part
    Citation - Scopus: 5
    An Experimental Test Procedure for Validation of Stiffness Model: a Case Study for R-Cube Parallel Mechanism
    (Springer, 2019) Görgülü, İbrahimcan; Dede, Mehmet İsmet Can; Carbone, Giuseppe
    Haptic device manipulators are used for generating haptic feedback. This feedback is composed of force which is regulated with respect to motion information. Accurate generation of the feedback requires exact position acquisition of the end-effector. Due to the compliant bodies of a manipulator, a stiffness model is needed to predict this position. Previously, Virtual Joint Method was adopted to obtain the stiffness model of an R-CUBE parallel haptic mechanism. In this paper, experimental test setup and experimental procedure are described for validating this stiffness model, its engineering feasibility and soundness of the proposed model.