Structural Analysis of a Bearingless Rotor Using an Improved Flexible Multibody Model

2013 ◽  
Vol 50 (2) ◽  
pp. 539-550 ◽  
Author(s):  
TaeYoung Chun ◽  
Hanyeol Ryu ◽  
Hae Cho Seong ◽  
SangJoon Shin ◽  
YoungJung Kee ◽  
...  
Keyword(s):  
Structural Analysis ◽  
Multibody Model ◽  
Flexible Multibody

Flexible Multibody Model of Desmodromic Timing System#

2009 ◽  
Vol 37 (1) ◽  
pp. 15-30 ◽  
Author(s):  
S. M. Oliveri ◽  
G. Sequenzia ◽  
M. Calì
Keyword(s):  
Multibody Model ◽  
Timing System ◽  
Flexible Multibody

Flexible Multibody Modeling of a Surgical Instrument Inside an Endoscope

2013 ◽  
Vol 9 (1) ◽  
Author(s):  
Jitendra P. Khatait ◽  
Dannis M. Brouwer ◽  
J. P. Meijaard ◽  
Ronald G. K. M. Aarts ◽  
Just L. Herder
Keyword(s):  
Surgical Instrument ◽  
Force Transmission ◽  
Positional Accuracy ◽  
Multibody Modeling ◽  
Multibody Model ◽  
Beam Elements ◽  
Spatial Beam ◽  
Flexible Multibody ◽  
Input Motion ◽  
Flexible Instruments

The implementation of flexible instruments in surgery necessitates high motion and force fidelity and good controllability of the tip. However, the positional accuracy and the force transmission of these instruments are jeopardized by the friction, the clearance, and the inherent compliance of the instrument. The surgical instrument is modeled as a series of interconnected spatial beam elements. The endoscope is modeled as a rigid curved tube. The stiffness, damping, and friction are defined in order to calculate the interaction between the instrument and the tube. The effects of various parameters on the motion and force transmission behavior were studied for the axially-loaded and no-load cases. The simulation results showed a deviation of 1.8% in the estimation of input force compared with the analytical capstan equation. The experimental results showed a deviation on the order of 1.0%. The developed flexible multibody model is able to demonstrate the characteristic behavior of the flexible instrument for both the translational and rotational input motion for a given set of parameters. The developed model will help us to study the effects of various parameters on the motion and force transmission of the instrument.

Experimental Validation and Updating of the Flexible Multibody Model of a Commercial 3R Planar Manipulator

2011 ◽  
Author(s):  
Stefano Fiorati ◽  
Emiliano Mucchi ◽  
Raffaele Di Gregorio ◽  
Giorgio Dalpiaz
Keyword(s):  
Ad Hoc ◽  
Low Frequency ◽  
Experimental Tests ◽  
Low Speed ◽  
Operational Conditions ◽  
Multibody Model ◽  
Planar Manipulators ◽  
Flexible Multibody ◽  
Modes Of Vibration ◽  
Synthesis Methodology

Serial planar manipulators are diffusely used either as stand-alone machines or as part of more complex cells, and many commercial planar manipulators are available on the market. These commercial machines are mainly destined to accomplish low-speed tasks, and they are designed by taking into account their flexibility at most in the joints. Unfortunately, there are particular installation conditions in which even low-speed tasks can generate low-frequency vibrations that highly interfere with the task. This aspect is highlighted here with reference to a commercial 3R planar manipulator, and how to manage this problem is explained. In this sight, a flexible multibody model is developed where the flexibility of the frame, the manipulator is fixed to, is modeled over the flexibility of the joints, that is introduced as lumped stiffness. In particular, the flexible frame is included in the model by using a Component Mode Synthesis methodology, in which only the natural modes of vibration and the static constrain modes are accounted. The model is validated through an experimental campaign. The experimental tests consist of several modal analyses, together with acceleration and laser Doppler measurements in operational conditions. This methodology allows to provide a model which takes into account the installation conditions, and gives a tool for studying ad-hoc solutions which prevent the occurrence of low-frequency vibrations.

The Dynamic Behavior Induced by Different Wind Turbine Gearbox Suspension Methods Assessed by Means of the Flexible Multibody Technique

2012 ◽  
Author(s):  
Jan Helsen ◽  
Klaas Vanslambrouck ◽  
Frederik Vanhollebeke ◽  
Wim Desmet
Keyword(s):  
Wind Turbine ◽  
Drive Train ◽  
Wind Turbine Gearbox ◽  
Multibody Modeling ◽  
Multibody Model ◽  
Cost Constraints ◽  
Flexible Multibody ◽  
Wind Resource ◽  
Continuous Demand ◽  
Turbine Drive

The continuous demand for increase in power output for new wind parks under strict cost constraints, the greater wind resource at elevation and the desire for fewer machines per Mega-Watt to reduce operations resulted in a demand for bigger turbines. The drive train is an important component in realizing reliable and robust wind turbines. This paper investigates a geared wind turbine. In this type a gearbox is used to convert the low rotor speed to the required high generator speed. In the market several solutions are available to constrain the gearbox in the nacelle. The used configuration significantly determines the gearbox response to rotor loads and the transmission of gearbox vibrations to the turbine. This paper investigates the effectiveness of three configurations: the three point mounting, the double bearing configuration and the hydraulic damper system. The flexible multibody modeling technique can be used to accurately characterize gearbox dynamics. The goal of this work is to use an experimentally validated multibody model of a wind turbine drive train to characterize the ability of the three configurations to minimize the introduction of non-torque loads in the gearbox and the ability to isolate the gearbox vibrations from the rest of the turbine.

scholarly journals On design sensitivities in the structural analysis and optimization of flexible multibody systems

2021 ◽  
Author(s):  
Alexander Held
Keyword(s):  
Structural Analysis ◽  
Multibody Systems ◽  
The Body ◽  
Flexible Multibody Systems ◽  
Adjoint Variable ◽  
Flexible Bodies ◽  
Design Sensitivities ◽  
Flexible Multibody ◽  
Data Files ◽  
Floating Frame

AbstractThe structural analysis and optimization of flexible multibody systems become more and more popular due to the ability to efficiently compute gradients using sophisticated approaches such as the adjoint variable method and the adoption of powerful methods from static structural optimization. To drive the improvement of the optimization process, this work addresses the computation of design sensitivities for multibody systems with arbitrarily parameterized rigid and flexible bodies that are modeled using the floating frame of reference formulation. It is shown that it is useful to augment the body describing standard input data files by their design derivatives. In this way, a clear separation can be achieved between the body modeling and parameterization and the system simulation and analysis.

Design of an Experimental Set-Up to Study the Behavior of a Flexible Surgical Instrument Inside an Endoscope

2013 ◽  
Vol 7 (3) ◽  
Author(s):  
Jitendra P. Khatait ◽  
Dannis M. Brouwer ◽  
Herman M. J. R. Soemers ◽  
Ronald G. K. M. Aarts ◽  
Just L. Herder
Keyword(s):  
Modular Design ◽  
Interaction Force ◽  
Surgical Instrument ◽  
Force Transmission ◽  
Multibody Model ◽  
Displacement Sensors ◽  
Flexible Multibody ◽  
Cell Modules ◽  
Set Up

The success of flexible instruments in surgery requires high motion and force fidelity and controllability of the tip. However, the friction and the limited stiffness of such instruments limit the motion and force transmission of the instrument. In a previous study, we developed a flexible multibody model of a surgical instrument inside an endoscope in order to study the effect of the friction, bending and rotational stiffness of the instrument and clearance on the motion hysteresis and the force transmission. In this paper, we present the design and evaluation of an experimental setup for the validation of the flexible multibody model and the characterization of the instruments. A modular design was conceived based on three key functionalities: the actuation from the proximal end, the displacement measurement of the distal end, and the measurement of the interaction force. The exactly constrained actuation module achieves independent translation and rotation of the proximal end. The axial displacement and the rotation of the distal end are measured contactless via a specifically designed air bearing guided cam through laser displacement sensors. The errors in the static measurement are 15 μm in translation and 0.15 deg in rotation. Six 1-DOF load cell modules using flexures measure the interaction forces and moments with an error of 0.8% and 2.5%, respectively. The achieved specifications allow for the measurement of the characteristic behavior of the instrument inside a curved rigid tube and the validation of the flexible multibody model.

Multibody modeling and vibration testing of 3R planar manipulators: effects of flexible installation frames

Robotica ◽  
2013 ◽  
Vol 31 (8) ◽  
pp. 1209-1220
Author(s):  
Emiliano Mucchi ◽  
Stefano Fiorati ◽  
Raffaele Di Gregorio ◽  
Giorgio Dalpiaz
Keyword(s):  
Ad Hoc ◽  
Low Frequency ◽  
Experimental Tests ◽  
Multibody Modeling ◽  
Low Speed ◽  
Operational Conditions ◽  
Multibody Model ◽  
Planar Manipulators ◽  
Flexible Multibody ◽  
Synthesis Methodology

SUMMARYThis work presents the experimental validation and updating of a flexible multibody model ideated for taking into account installation conditions of industrial serial planar manipulators without resorting to cumbersome modeling. The flexibility of the frame, the manipulator is fixed, is modeled over the flexibility of joints, which is introduced as lumped stiffness. In particular, the flexible frame is included in the model by using the Component Mode Synthesis methodology, in which only the natural modes of vibration and the static constrain modes are accounted. The flexible multibody model has been developed because these commercial machines are mainly used to perform low-speed tasks, and they are designed by taking into account their flexibility at most in the joints. Unfortunately, there are particular installation conditions in which even low-speed tasks can generate low-frequency vibrations that highly interfere with the task. This aspect is considered here, and how to manage this problem is explained by using the developed multibody model. The model is validated through experimental measurements. The experimental tests consist of several modal analyses, together with acceleration and laser Doppler measurements in operational conditions. This methodology takes into account the installation conditions through the model of flexible frame, and gives a tool for studying ad hoc solutions which prevent the occurrence of unwanted low-frequency vibrations.

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