Verification of a Finite Element Model of an Unmanned Aerial Vehicle Wing Torque Box via Experimental Modal Testing

2012 ◽  
Author(s):  
Levent Unlusoy ◽  
Melin Sahin ◽  
Yavuz Yaman
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Unmanned Aerial Vehicle ◽  
Natural Frequencies ◽  
Element Model ◽  
Modal Testing ◽  
Mode Shapes ◽  
Resonance Frequencies ◽  
Aerial Vehicle ◽  
Experimental Modal Testing

In this study, the detailed finite element model (FEM) of an unmanned aerial vehicle wing torque box was verified by the experimental modal testing. During the computational studies the free-free boundary conditions were used and the natural frequencies and mode-shapes of the structure were obtained by using the MSC® Software. The results were then compared with the experimentally obtained resonance frequencies and mode-shapes. It was observed that the frequencies were in close agreement having an error within the range of 1.5–3.6%.

Support-Condition Analyses of Rotating Beams Under Distributed Imbalance Loading

2011 ◽  
Author(s):  
Kai Jokinen ◽  
Erno Keskinen ◽  
Marko Jorkama ◽  
Wolfgang Seemann
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Cross Section ◽  
Cross Sections ◽  
Natural Frequencies ◽  
Element Model ◽  
Mode Shapes ◽  
Constant Cross Section ◽  
Support Condition ◽  
Beam Elements

In roll balancing the behaviour of the roll can be studied either experimentally with trial weights or, if the roll dimensions are known, analytically by forming a model of the roll to solve response to imbalance. Essential focus in roll balancing is to find the correct amount and placing for the balancing mass or masses. If this selection is done analytically the roll model used in calculations has significant effect to the balancing result. In this paper three different analytic methods are compared. In first method the mode shapes of the roll are defined piece wisely. The roll is divided in to five parts having different cross sections, two shafts, two roll ends and a shell tube of the roll. Two boundary conditions are found for both supports of the roll and four combining equations are written to the interfaces of different roll parts. Totally 20 equations are established to solve the natural frequencies and to form the mode shapes of the non-uniform roll. In second model the flexibility of shafts and the stiffness of the roll ends are added to the support stiffness as serial springs and the roll is modelled as a one flexibly supported beam having constant cross section. Finally the responses to imbalance of previous models are compared to finite element model using beam elements. Benefits and limitations of each three model are then discussed.

Hydroelastic Modal Analysis of the Perforated Cylindrical Shell in SMART

2011 ◽  
Author(s):  
Youngin Choi ◽  
Seungho Lim ◽  
Kyoung-Su Park ◽  
No-Cheol Park ◽  
Young-Pil Park ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Dynamic Characteristics ◽  
Natural Frequencies ◽  
Element Model ◽  
Mode Shapes ◽  
Steam Generators ◽  
Structure Interaction ◽  
The Finite Element Model ◽  
Reactor Internals

The System-integrated Modular Advanced ReacTor (SMART) developed by KAERI includes components like a core, steam generators, coolant pumps, and a pressurizer inside the reactor vessel. Though the integrated structure improves the safety of the reactor, it can be excited by an earthquake and pump pulsations. It is important to identify dynamic characteristics of the reactor internals considering fluid-structure interaction caused by inner coolant for preventing damage from the excitations. Thus, the finite element model is constructed to identify dynamic characteristics and natural frequencies and mode shapes are extracted from this finite element model.

Thermal Robustness Assessment of a Rigidized Space Inflatable Boom via Experimental Modal Analysis and Finite Element Modeling

2010 ◽  
Author(s):  
Matthew Daly ◽  
Armaghan Salehian ◽  
Alireza Doosthoseini
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Frequency Response Function ◽  
Good Accuracy ◽  
Natural Frequencies ◽  
Beam Theory ◽  
Element Model ◽  
Modal Testing ◽  
Environmental Temperatures ◽  
Robustness Assessment

The following paper presents the results of a thermal robustness assessment of a rigidized space inflatable boom. Modal testing is performed at three different environmental temperatures; spanning a range of 38°C, with the purpose of characterizing dynamic behavior and assessing changes in bending frequencies. Experimental results show that the natural frequencies of the boom shift only marginally within the tested bandwidth. A finite element model is developed in parallel with experiments to determine compatibility with beam theory. The resulting simulation shows that linear beam theory can be used to predict bending frequencies and frequency response function magnitudes with very good accuracy.

Dynamic Analysis of Flexible Structures Using Component Mode Synthesis

1989 ◽  
Vol 56 (4) ◽  
pp. 874-880 ◽  
Author(s):  
M. De Smet ◽  
C. Liefooghe ◽  
P. Sas ◽  
R. Snoeys
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Degrees Of Freedom ◽  
Flexible Structures ◽  
Element Model ◽  
Component Mode Synthesis ◽  
Mode Shapes ◽  
Flexible Robot ◽  
Preliminary Calculation ◽  
Resonance Frequencies

In this paper a dynamic model of a flexible robot is built out of a finite element model of each of its links. The number of degrees-of-freedom of these models is strongly reduced by applying the Component Mode Synthesis technique which involves the preliminary calculation of a limited number of mode shapes of the separate links. As can be seen from examples, the type of boundary conditions thereby imposed in the nodes in which one link is connected to the others, strongly determines the accuracy of the calculated resonance frequencies of the robot. The method is applied to an industrial manipulator. The reduced finite element model of the robot is changed in order to match the numerically and experimentally (modal analysis) determined resonance data. Further, the influence of the position of the robot on its resonance frequencies is studied using the optimized numerical model.

Modal Testing and Finite Element Calculations for Lightweight Aluminum Panels in Car Carriers

2006 ◽  
Vol 43 (01) ◽  
pp. 11-21
Author(s):  
Junbo Jia ◽  
Anders Ulfvarson
Keyword(s):  
Finite Element ◽  
Natural Frequencies ◽  
Damping Ratio ◽  
Element Model ◽  
Modal Testing ◽  
Structural Behavior ◽  
Mode Shapes ◽  
Maintenance Cost ◽  
Car Suspension ◽  
Aluminum Panels

Due to their characteristics and lower maintenance cost, lightweight aluminum structures have been widely used for manufacturing deck structures. When this type of structure is developed, the natural frequencies for the unloaded deck may increase, while the natural frequencies for loaded decks are most likely to decrease and new problems of vibration and damping may appear. In addition, it has already been shown by the authors that compared to the load effects of normal cargo, the dynamic structural behavior of a vehicle-loaded deck is different due to the participation of vehicle vibrations. The current paper presents a modal analysis by both testing and finite element (FE) calculation for a lightweight deck using aluminum panels. By comparing the results between the unloaded and car-loaded cases, it is shown how vehicle loading influences the dynamic structural behavior of the deck structures. The authors report that an aluminum panel mechanically connected to a steel frame may participate in some mode shapes of vibrations that significantly increase the corresponding damping ratio. The reasonably good agreement between modal testing results and FE calculations validates the finite element model, which may then be used for further dynamic analysis. The authors found that the spring-damping systems of car suspension and tires can interfere in the dynamic transmission of the vehicle mass into the deck structure. The study enables structural engineers interested in the design of car carriers to have a better understanding of how the vehicles parked on decks can influence the dynamic characteristics of the vehicle deck systems.

Updating of an Unmanned Aerial Vehicle Finite Element Model using Experimental Data

2015 ◽  
Author(s):  
Melissa Arras ◽  
Giuliano Coppotelli ◽  
Piergiovanni Marzocca ◽  
Antonio Simone Mezzapesa
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Finite Element Model ◽  
Unmanned Aerial Vehicle ◽  
Element Model ◽  
Aerial Vehicle

On Updating of Finite Element Model Using Optimization Method

1997 ◽  
Author(s):  
Wolfgang G. Luber
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Natural Frequencies ◽  
Normal Modes ◽  
Mathematical Optimization ◽  
Element Model ◽  
Optimization Method ◽  
Mode Shapes ◽  
Initial Structure ◽  
Error Localization

Abstract An error localization and update method is presented which examines the elastic and dynamic behavior of the structure by means of deflections stemming from a discrete load case and from normal mode shapes of the structure respectively as well as the information of the change of natural frequencies. The main objective of the study is to provide an economical and reliable error localization method for aeronautical structures. A finite element model of the elastic structure must be available before testing the real structure to determine the optimal positioning of sensors. The error localization is based on sensitivity methods and on nonlinear mathematical optimization codes. Displacements for selected load cases and normal modes are taken as constraints. Minimum sizing changes with respect to the initial structure is used as objective function. Numerical examples with different structures show that the proposed methods can accurately detect the variations in stiffness in certain cases.

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