Bilgin Kaftanoglu

Deformation Analysis of Deep-Drawing by a Finite Element Method

A finite element method is developed to study the elastic-plastic deformation of sheet materials in the presence of large strains and large displacements. It is based on updated Lagrangian type formulation and membrane shell theory. The sheet is assumed to be isotropic and rate insensitive which obeys J2 flow theory. The work-hardening characterstics of material and Coulomb friction between the sheet metal and forming tools are incorporated. The method is used for modelling partial deep-drawing with the appropriate boundary, conditions. Numerical solutions are compared with the experimental results.

Multisensor controlled robotic tracking and automatic pick and place

A multisensor controlled robotic tracking and automatic pick and place system is presented in this paper. The system is designed for recognizing and tracking an object which is selected from multiple objects that are unknown and randomly placed on a moving conveyor belt, using a vision, infrared and encoder sensors in the feedback loop. The robot tracks the parts and transfers them to the proper pallets. We address the use of vision system for identifying and locating objects on a moving conveyor belt, besides we address the use of vision, infrared and encoder sensors for dynamically servoing a manipulator for object tracking, grasping and placing. Laboratory experiments are presented to demonstrate the performance of this system.

Robot end-effector based sensor integration for tracking moving parts

The paper presents a cost-efficient end-effector based infrared proximity sensor integration system and the implementation of a fuzzy logic control algorithm. End-effector sensor outputs are incorporated in a fuzzy logic control algorithm to make the robotic manipulator grasp objects on a moving conveyor belt. The robot movements are going to be the result of the comparative measurements made by the sensors after the motion of the moving target is predicted and the gripper is brought into a zone close to the object to be grasped by the application of a vision system.

Dynamic Load and Root Stress Analysis of Spur Gears

Summary Dynamic loads on spur gears are calculated by using an analytical model based on torsional vibrations of gears, and dynamic load variations during a mesh cycle of a tooth are determined. Tooth profile modifications, profile and pitch errors are included in dynamic load calculations. Variable stiffnesses of gear teeth, which are required for dynamic load calculations, and tooth root stresses resulting from dynamic loads are found by using the finite element method. Calculated tooth root stresses are used in fatigue failure analysis.

A Three-Node Shear-Flexible Hybrid-Stress Finite Element for the Analysis of Laminated Composite Plates

A cost-effective, shear-flexible hybrid-stress element is developed for lami nated composite plates based on the Yang-Norris-Stavsky theory. The element is triangular and has vertex nodes only. The nodal variables are three displacements and two indepen dent normal rotations of C° type. The assumed stress field is linear. The assumed displace ment field is based on the anisoparametric interpolations in which the rotations and in- plane displacements are linear and the transverse displacement is quadratic. The element is invariant and non-locking. The results of the numerical studies show that the present el ement converges rapidly and monotonically in all thickness regimes.

A Cutting Force Estimator for CNC Machining Centers

Abstract This study presents a cutting force estimator topology for feed drives of CNC vertical machining centers to compute the machining forces accurately. The estimator employs recursive discrete Fourier transform to not only estimate inertial forces on the system but also to filter effectively the noise components in the measurements. The accuracy of the estimator is compared to that of a Luenberger observer while the overall performance of the estimator is evaluated through an experimental study. The paper also discusses its inherent limitations.

Moving part recognition and automatic pick and place using an industrial robot

Robotics research continuously seeks to improve productivity in manufacturing automation. In the last several years, more and more efforts have been put in the integration of multiple sensors into robot systems. The goal is to make robots more adaptive and flexible in unstructured or frequently changing environments, and to enable robots to execute intelligent tasks. Thus the robot productivity as well as applicability can be improved. The object of this study is to develop a multisensor controlled robotic tracking and automatic pick and place system. The system is designed for recognizing and tracking an object which is selected from multiple objects that are unknown and randomly placed on a moving conveyor belt, using a vision, infrared and encoder sensors in the feedback loop. The robot tracks the parts and transfers them to the proper pallets.

Computer-Aided Optimal Design Strategy of Power Transmission Systems

Abstract A mechanical power transmission system consists of mainly shafts, gears and bearings, where each machine element can be optimally designed. However in a power transmission system each design variable such as pitch diameters of gears and diameters of bearings have certain constraints. These constraints effect the design of the other member like the shaft. A design strategy is developed for the optimal integrated design of a mechanical power transmission system including the constraints of each member and with the view to satisfy a global optimum for the system.

Computer-Aided Modelling of Tube-Drawing

Summary An interactive procedure on the computer is developed for the modelling of the tube-drawing process through an axisymmetrical die. The shape can be conical, circular or any general shape such as a polynomial which can be optimized to reduce the applied force. Material model is such that strain-hardening, plastic anisotropy can be incorporated. High-temperature and strain-rate effects can be simulated. Thickness changes can be predicted and the drawing loads, die pressure distributions taking into account the back pull can be calculated. The user can enter the geometrical, material and process parameters on an interactive basis. The die profile type can also be chosen graphically. Then the developed algorithm including the material model and the integration of the differential equations will calculate the pressure distributions on the die, thickness distributions on the tube and the drawing force. These results can also be displayed graphically on the screen. The agreement between experiment and theory is satisfactory.

Computer Aided Modeling of Deep-Drawing

Deep-drawing operations are performed widely in industrial applications. It is very important for efficiency to achieve parts with no defects. In this work, a finite element method is developed to simulate deep-drawing operation including wrinkling. A four nodded five degree of freedom shell element is formulated. Isotropic elasto-plastic material model with Von Mises yield criterion is used. By using this shell element, the developed code can predict the bending behavior of workpiece besides membrane behavior. Simulations are carried out with four different element sizes. The thickness strain and nodal displacement values obtained are compared with results of a commercial finite element program and results of previously conducted experiments.