Experimental Modeling Using Pseudo Mode Shape Method

2013 ◽  
Vol 328 ◽  
pp. 552-557
Author(s):  
Ta Chung Yang ◽  
Ying An Tsai
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Rigid Body ◽  
Mode Shape ◽  
Timoshenko Beam ◽  
Experimental Validation ◽  
Modal Testing ◽  
Response Functions ◽  
Beam Elements ◽  
Rigid Body Modes

The foundations of most large industrial machines are complicated in configuration and shape that result in difficulties of modal testing and finite element modeling. Pseudo Mode Shape Method (PMSM) needs only the measurements of frequency response functions at the joint interfaces of the substructure and the mother structure to develop the equivalent dynamic matrices (called the pseudo matrices) of mass, damping, and stiffness of the substructure, which greatly simplifies the modeling procedure of the complicated substructure. Experimental validation of PMSM was conducted by modeling the foundation of a rotor-bearing-foundation system. The foundation is regarded as the substructure and modeled by PMSM. The rotor is the mother structure and modeled by finite element method using 3D Timoshenko beam elements. The effects of rigid body modes of PMSM in this experiment are also investigated.

scholarly journals Analysis of Timoshenko beam with Koch snowflake cross-section and variable properties in different boundary conditions using finite element method

2021 ◽  
Vol 13 (11) ◽  
pp. 168781402110609
Author(s):  
Hossein Talebi Rostami ◽  
Maryam Fallah Najafabadi ◽  
Davood Domiri Ganji
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Boundary Conditions ◽  
Natural Frequency ◽  
Cross Section ◽  
Timoshenko Beam ◽  
Natural Frequencies ◽  
Variable Properties ◽  
The Third ◽  
Koch Snowflake

This study analyzed a Timoshenko beam with Koch snowflake cross-section in different boundary conditions and for variable properties. The equation of motion was solved by the finite element method and verified by Solidworks simulation in a way that the maximum error was about 2.9% for natural frequencies. Displacement and natural frequency for each case presented and compared to other cases. Significant research achievements illustrate that if we change the Koch snowflake cross-section of the beam from the first iteration to the second, the area and moment of inertia will increase, and we have a 5.2% rise in the first natural frequency. Similarly, by changing the cross-section from the second iteration to the third, a 10.2% growth is observed. Also, the hollow cross-section is considered, which can enlarge the natural frequency by about 26.37% compared to a solid one. Moreover, all the clamped-clamped, hinged-hinged, clamped-free, and free-free boundary conditions have the highest natural frequency for the Timoshenko beam with the third iteration of the Koch snowflake cross-section in solid mode. Finally, examining important physical parameters demonstrates that variable density from a minimum value to the standard value along the beam increases the natural frequencies, while variable elastic modulus decreases it.

A Model for the Prediction of Form Errors in Face Milling and Turning

1999 ◽  
Author(s):  
Luc Masset ◽  
Jean-François Debongnie ◽  
Sylvie Foreau ◽  
Thierry Dumont
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Cutting Forces ◽  
Experimental Validation ◽  
Industrial Applications ◽  
Face Milling ◽  
The Finite Element Method ◽  
Form Errors ◽  
Error Computation ◽  
Element Method

Abstract A method is proposed for predicting form errors due to both clamping and cutting forces in face milling and turning. It allows complex tool trajectories and workpiece geometries. Error computation is performed by the finite element method. An experimental validation of the model for face milling is presented. Two industrial applications are produced in order to demonstrate the capabilities of the method.

Computer-Aided Modelling of Cloth Deformation

1996 ◽  
Author(s):  
Y. F. Zhao ◽  
S. T. Tan ◽  
T. N. Wong ◽  
W. J. Chen
Keyword(s):  
Finite Element Method ◽  
Exact Solution ◽  
Finite Element ◽  
Rigid Body ◽  
Present Method ◽  
Geometric Constraint ◽  
Computationally Efficient ◽  
Large Rotation ◽  
Developable Surfaces ◽  
Computer Aided

Abstract A constrained finite element method for modelling cloth deformation is developed. The bending deformation and the geometric constraint of developable surfaces of the cloth objects are considered. The representation of large rotation and the motion of rigid body are described using the current coordinates with the geometric constraint. The effectiveness of the present method is verified by comparing the thread deformation with the exact solution of catenary. Several examples are given to show that the proposed method converges quickly and is thus computationally efficient.

scholarly journals The experimental validation of a numerical model for the receptance prediction

2019 ◽  
Vol 286 ◽  
pp. 01007
Author(s):  
A. Zougari ◽  
J. MartÍnez
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Model ◽  
Experimental Validation ◽  
Parametric Design ◽  
Experimental Methodology ◽  
Railway Track ◽  
Experimental Result ◽  
Ballasted Track ◽  
Ansys Parametric Design Language

The traditional ballasted track with wooden sleepers covers today most railway lines constructions, including the tracks of tram and metro or the industrial railway branching. In this work, we present an experimental methodology to validate a numerical model based on finite element method, the model was previously well defined using the ANSYS Parametric Design Language (APDL) and adapted to represent a classical ballasted track. The obtained result of the analysis is expressed as a frequency response of the track and it is compared to the experimental result from measurements made on the metropolitan classical railway track of Barcelona.

Blade Vibration Stress Determination Method Based on Blade Tip Timing Simulator and Finite Element Method

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Xiaojie Zhang ◽  
Yanrong Wang ◽  
Xianghua Jiang ◽  
Shimin Gao
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Mode Shape ◽  
Fem Analysis ◽  
Axial Direction ◽  
Stress Determination ◽  
Modal Shape ◽  
Shape Information ◽  
Vibration Stress ◽  
Blade Tip

Abstract Blade tip timing (BTT) measurement technology is more widely used to determine the vibrational stress of rotating blades and play an important role for blade service life prediction. The dynamic blade displacements can be measured by tip timing sensors, and then be converted to blade stress by the modal shape information from finite element method (FEM) analysis. However, there are always two uncertainties between the measured displacements by BTT and the modal shape by FEM analysis. First, the effective positions detected by sensors may shift from where they expected due to the deformation of the blade. This deviation may yield calibration factors with deceptions, which will present an inaccurate correlation for the blade stress level and the tip displacement. Second, when vibrating, blade tip would actually oscillate around the equilibrium position both in circumferential and axial direction, while the sensors can only detect the movements along the circumference direction and neglect the other. This causes the measured displacements to be different from the actual displacements. To deal with these two problems, a novel method based on the vibration amplitudes of blade tip along axial direction is proposed to identify the effective detected position. The vibration stress of the whole blade then can be determined by linking the modified displacements to the mode shape information from finite element (FE) predictions. This method is validated by a numerical BTT simulator, which is trying to simulate the actual testing process of BTT measurement. Both synchronous and asynchronous vibrations are discussed to illustrate the applicability of this method. Moreover, sensitivity analysis is performed to identify the uncertainties from the vibration amplitude and mode shape inaccuracies. Results demonstrate the great potential of the method for vibration stress determination.

Dynamic Stability of Timoshenko Beams by Finite Element Method

1976 ◽  
Vol 98 (4) ◽  
pp. 1145-1149 ◽  
Author(s):  
J. Thomas ◽  
B. A. H. Abbas
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stability Analysis ◽  
Shear Deformation ◽  
Dynamic Stability ◽  
Timoshenko Beam ◽  
Dynamic Instability ◽  
Rotary Inertia ◽  
Timoshenko Beams ◽  
Buckling Loads

A Finite Element model is developed for the stability analysis of Timoshenko beam subjected to periodic axial loads. The effect of the shear deformation on the static buckling loads is studied by finite element method. The results obtained show excellent agreement with those obtained by other analytical methods for the first three buckling loads. The effect of shear deformation and for the first time the effect of rotary inertia on the regions of dynamic instability are investigated. The elastic stiffness, geometric stiffness, and inertia matrices are developed and presented in this paper for a Timoshenko beam. The matrix equation for the dynamic stability analysis is derived and solved for hinged-hinged and cantilevered Timoshenko beams and the results are presented. Values of critical loads for beams with various shear parameters are presented in a graphical form. First four regions of dynamic instability for different values of rotary inertia parameters are presented. As the rotary inertia parameter increases the regions of instability get closer to each other and the width of the regions increases thus making the beam more sensitive to periodic forces.

Change of modal parameters due to crack growth in a tripod tower platform

1993 ◽  
Vol 20 (5) ◽  
pp. 801-813 ◽  
Author(s):  
Yin Chen ◽  
A. S. J. Swamidas
Keyword(s):  
Finite Element ◽  
Frequency Response ◽  
Response Function ◽  
Frequency Response Function ◽  
Experimental Results ◽  
Modal Testing ◽  
Modal Parameters ◽  
Response Functions ◽  
Frequency Response Functions ◽  
Strain Frequency

Strain gauges, along with an accelerometer and a linear variable displacement transducer, were used in the modal testing to detect a crack in a tripod tower platform structure model. The experimental results showed that the frequency response function of the strain gauge located near the crack had the most sensitivity to cracking. It was observed that the amplitude of the strain frequency response function at resonant points had large changes (around 60% when the crack became a through-thickness crack) when the crack grew in size. By monitoring the change of modal parameters, especially the amplitude of the strain frequency response function near the critical area, it would be very easy to detect the damage that occurs in offshore structures. A numerical computation of the frequency response functions using finite element method was also performed and compared with the experimental results. A good consistency between these two sets of results has been found. All the calculations required for the experimental modal parameters and the finite element analysis were carried out using the computer program SDRC-IDEAS. Key words: modal testing, cracking, strain–displacement–acceleration frequency response functions, frequency–damping–amplitude changes.

Non-linear thermal analysis of light concrete hollow brick walls by the finite element method and experimental validation

2006 ◽  
Vol 26 (8-9) ◽  
pp. 777-786 ◽  
Author(s):  
J.J. del Coz Díaz ◽  
P.J. García Nieto ◽  
A. Martín Rodríguez ◽  
A. Lozano Martínez-Luengas ◽  
C. Betegón Biempica
Keyword(s):  
Finite Element Method ◽  
Thermal Analysis ◽  
Finite Element ◽  
Experimental Validation ◽  
The Finite Element Method ◽  
Non Linear ◽  
Hollow Brick ◽  
Element Method
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