scholarly journals Experimental and theoretical investigations on sensing and dynamic characteristics of PVDF thin film

2020 ◽  
Vol 37 ◽  
pp. 1-12
Author(s):  
Yu-Chih Lin ◽  
Yu-Hsi Huang ◽  
Chien-Ching Ma ◽  
Chun-Kai Chang
Keyword(s):  
Steady State ◽  
Dynamic Characteristics ◽  
Polyvinylidene Fluoride ◽  
Dynamic Properties ◽  
Speckle Pattern ◽  
Laser Doppler Vibrometer ◽  
Piezoelectric Element ◽  
Electronic Speckle Pattern Interferometry ◽  
Element Analysis ◽  
Transient Dynamic

Abstract This research investigates both the steady-state and transient dynamic characteristics of polyvinylidene fluoride (PVDF), which is one of the most commonly used piezoelectric polymers. In steady-state vibration, the visible resonant mode fringe patterns are obtained using the amplitude-fluctuation electronic speckle pattern interferometry experiment, and the point-wise displacement data are measured by laser Doppler vibrometer–dynamic signal analysis. Finite element analysis is also performed, and the numerical results are compared with the experimental ones for the steady-state vibration. In a transient dynamic experiment, the history of dynamic impact generated by a steel ball is measured by the PVDF, and the experimental results are compared with the theoretical results obtained by the Hertz contact law. The comprehensive information about steady-state and transient dynamic properties of PVDF membranes obtained in this study is expected to contribute to the further development of the PVDF piezoelectric element.

scholarly journals Experimental and Numerical Investigation of Resonance Characteristics of Novel Pumping Element Driven by Two Piezoelectric Bimorphs

2019 ◽  
Vol 9 (6) ◽  
pp. 1234 ◽  
Author(s):  
Yu-Chih Lin ◽  
Yu-Hsi Huang ◽  
Kwen-Wei Chu
Keyword(s):  
Speckle Pattern ◽  
Laser Doppler Vibrometer ◽  
Impedance Analysis ◽  
Vibration Characteristics ◽  
Mode Shapes ◽  
Electronic Speckle Pattern Interferometry ◽  
Element Analysis ◽  
Visible Displacement ◽  
Piezoelectric Bimorphs ◽  
Phase Motion

This paper describes the vibration characteristics of a dual-bimorph piezoelectric pumping element under fluid–structure coupling. Unlike the single bimorph used in most previous studies, the proposed device comprises two piezoelectric bimorphs within an acrylic housing. Amplitude-fluctuation electronic speckle pattern interferometry (AF-ESPI) was used to examine the visible displacement fringes in order to elucidate the anti-phase as well as in-phase motions associated with vibration. Analysis was also conducted using impedance analysis and laser Doppler vibrometer (LDV) based on the measurement of point-wise displacement. The experimental results of resonant frequencies and the corresponding mode shapes are in good agreement with those obtained using finite element analysis. The gain of flow rate obtained by the anti-phase motion of the dual-bimorph pumping element is larger than both those obtained by in-phase motion and the single bimorph pumping element. This work greatly enhances our understanding of the vibration characteristics of piezoelectric pumping elements with two bimorphs, and provides a valuable reference for the further development of bionic pump designs.

Application of ESPI in the Vibration Analysis of Turbine Blading

1995 ◽  
Author(s):  
Robert X. Wang ◽  
Graham M. Chapman
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Vibration Analysis ◽  
Speckle Pattern ◽  
Vibration Measurement ◽  
Simplified Model ◽  
Electronic Speckle Pattern Interferometry ◽  
Coupled Modes ◽  
Element Analysis ◽  
Turbine Blading

Abstract This paper reports on the application of Electronic Speckle Pattern Interferometry (ESPI) technique in vibration measurement of turbine blading. Using the time-averaged mode of ESPI, the first six modes of a turbocharger blade with airfoil profile were identified. The effect of the complicated profile of the blade was established by studying simplified model blades. Coupled modes were identified and successfully separated. Experimental results are compared with those obtained using finite element analysis.

Dynamic Characteristics and Finite Element Model Updating of Micromachined Torsion Structures

2013 ◽  
Vol 284-287 ◽  
pp. 1831-1835
Author(s):  
Wei Hsin Gau ◽  
Kun Nan Chen ◽  
Yunn Lin Hwang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Finite Element Model ◽  
Model Updating ◽  
Speckle Pattern ◽  
Element Model ◽  
Mode Shapes ◽  
Electronic Speckle Pattern Interferometry ◽  
Finite Element Model Updating ◽  
Element Analysis

In this paper, two experimental techniques, Electronic Speckle Pattern Interferometry and Stroboscopic Interferometry, and two different finite element analysis packages are used to measure or to analyze the frequencies and mode shapes of a micromachined, cross-shaped torsion structure. Four sets of modal data are compared and shown having a significant discrepancy in their frequency values, although their mode shapes are quite consistent. Inconsistency in the frequency results due to erroneous inputs of geometrical and material parameters to the finite element analysis can be salvaged by applying the finite element model updating procedure. Two updating cases show that the optimization sequences converge quickly and significant improvements in frequency prediction are achieved. With the inclusion of the thickness parameter, the second case yields a maximum of under 0.4% in frequency difference, and all parameters attain more reliable updated values.

Modeling and Measurement of Residual Stresses along the Process Chain of Autofrettaged Components by Using FEA and Hole-Drilling Method with ESPI

2013 ◽  
Vol 768-769 ◽  
pp. 79-86 ◽  
Author(s):  
Horst Brünnet ◽  
Dirk Bähre ◽  
Theo J. Rickert ◽  
Dominik Dapprich
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Residual Stresses ◽  
Speckle Pattern ◽  
Residual Stress Distribution ◽  
Electronic Speckle Pattern Interferometry ◽  
Hole Drilling ◽  
Element Analysis ◽  
Hole Drilling Method ◽  
Drilling Method

The incremental hole-drilling method is a well-known mechanical measurement procedure for the analysis of residual stresses. The newly developed PRISM® technology by Stresstech Group measures stress relaxation optically using electronic speckle pattern interferometry (ESPI). In case of autofrettaged components, the large amount of compressive residual stresses and the radius of the pressurized bores can be challenging for the measurement system. This research discusses the applicability of the measurement principle for autofrettaged cylinders made of steel AISI 4140. The residual stresses are measured after AF and after subsequent boring and reaming. The experimental residual stress depth profiles are compared to numerically acquired results from a finite element analysis (FEA) with the software code ABAQUS. Sample preparation will be considered as the parts have to be sectioned in half in order to access the measurement position. Following this, the influence of the boring and reaming operation on the final residual stress distribution as well as the accuracy of the presented measurement setup will be discussed. Finally, the usability of the FEA method in early design stages is discussed in order to predict the final residual stress distribution after AF and a following post-machining operation.

Vibration Control in Turbomachinery Blading Using Lacing Wires

1995 ◽  
Author(s):  
Robert X. Wang ◽  
Graham M. Chapman
Keyword(s):  
Finite Element ◽  
Vibration Control ◽  
Dynamic Characteristics ◽  
Vibration Analysis ◽  
Finite Element Modelling ◽  
Speckle Pattern ◽  
Electronic Speckle Pattern Interferometry ◽  
Element Modelling ◽  
Wire Vibration ◽  
Theoretical Results

Abstract In turbomachinery practice the use of inter-blade coupling is an accepted procedure. The use of lacing wires in highly stressed short blading introduces damping and also modifies the vibration characteristics of the blading. This paper reports on a study into the dynamic characteristics of single blades with a lacing wire. Vibration analysis is carried out using finite element modelling. The theoretical results are verified using Electronic Speckle Pattern Interferometry technique (ESPI).

Interpretation of Experimental and Theoretical Data for Prediction of Mode Shapes of Vibrating Turbocharger Blades

1988 ◽  
Vol 110 (1) ◽  
pp. 53-58 ◽  
Author(s):  
G. M. Chapman ◽  
X. Wang
Keyword(s):  
Natural Frequencies ◽  
Speckle Pattern ◽  
Theoretical Data ◽  
Mode Shapes ◽  
Electronic Speckle Pattern Interferometry ◽  
Experimental Investigations ◽  
Exhaust Gas ◽  
Element Analysis ◽  
Design Engineers ◽  
Vibration Excitation

The blading in large turbochargers is subjected to vibration excitation originating from pulsations in the exhaust gas stream coupled with the blade pass frequencies. The amplitude of vibrations induced are a source of concern to design engineers as they can seriously affect the operation of the turbocharger. This paper discusses theoretical and experimental investigations aimed at identifying the natural frequencies and the associated mode shapes for a single turbocharger blade. Modal Analysis, Electronic Speckle Pattern Interferometry (ESPI), and Finite Element Analysis are all used in an attempt to categorize the modal patterns.

scholarly journals Vibration Prediction and Quality Control of a Centrifugal Impeller

1993 ◽  
Author(s):  
Michael Hudson ◽  
Geoffrey H. Ballans ◽  
Soritis Georgomanos
Keyword(s):  
Quality Control ◽  
Speckle Pattern ◽  
Accurate Determination ◽  
Centrifugal Impeller ◽  
Electronic Speckle Pattern Interferometry ◽  
Production Environment ◽  
Modal Shape ◽  
Element Analysis ◽  
Vibration Prediction

A multi-disciplinary approach was used to investigate and control the vibration of a 1.7MW gas turbine Impeller. Three techniques were used. First, determination of natural frequencies by Spectral Analysis of an impulse on the impeller. Second, Electronic Speckle-pattern Interferometry (ESPI) to assertain the modal shape of each natural frequency. Finally, 3-dimensional finite element analysis (3DFEA) of the whole impeller. The analyses were synthesized to give an accurate determination of modal shapes and frequencies at test conditions and validate the 3DFEA. Effect of modifications could be predicted with confidence by the 3DFEA. A single parameter was found which linked dimension to resonant frequency in disc mode vibration. A test was developed which gave a predictive technique for vibration quality control in a production environment.

Study on the Effect of Prestress to the Dynamic Characteristics of Truss String Structure

2010 ◽  
Vol 163-167 ◽  
pp. 2571-2575
Author(s):  
Yao Zhi Luo ◽  
Ruo Fei Tong
Keyword(s):  
Dynamic Characteristics ◽  
Dynamic Properties ◽  
High Strength ◽  
Space Structure ◽  
Modal Parameters ◽  
Element Analysis ◽  
String Structure ◽  
New Type ◽  
Testing Experiment ◽  
Affect Factor

Truss string structure (TSS) is a new type of large-span space structure which is composed of upper spatial truss and bottom high-strength cables with vertical supports. For certain upper truss, the main affect factor of dynamic characteristics of a TSS are prestress of the cables, pole number, rise-span ratio and vertical span ratio. In modal parameters, modal frequencies is the most direct and easily observed parameter, which largely reflects the stiffness of the structure and plays an important role in the dynamic response of the structure. In this paper, the mode testing experiment and finite element analysis is executed, to study the changes of the lower modal frequencies in different prestressed cables and to study the influence of the prestress to the dynamic properties of TSS.

A Study on Measurement of Welding Residual Stress Using ESPI System

2006 ◽  
Vol 324-325 ◽  
pp. 859-862 ◽  
Author(s):  
Kyung Su Kim ◽  
Seung Bok Choi ◽  
Jang Hyun Lee ◽  
Seong Mo Park ◽  
Beom Il Kim ◽  
...  
Keyword(s):  
Residual Stresses ◽  
Speckle Pattern ◽  
Three Dimensional ◽  
Welding Residual Stress ◽  
Electronic Speckle Pattern Interferometry ◽  
Fe Model ◽  
Analysis Model ◽  
Element Analysis ◽  
The Difference ◽  
Welding Procedure

In this study, an experimental method has been studied to measure the residual stresses on a specimen with I-groove weldment. The specimens were extracted from I-groove weldment which was joined by SAW (Submerged Arc Welding) with CO2 shield gas. A FEA (Finite Element Analysis) model was developed for the estimation of the residual stresses for the specimen. Measurements were carried out using ESPI(Electronic Speckle Pattern Interferometry) system which can measure the strain distribution on the surface of specimen. The residual stresses were estimated by the value of strain measured by ESPI system. Strain gages were added to evaluate the accuracy of ESPI system. In addition, a three-dimensional FE model was used to estimate the residual stresses generated by the welding procedure. A thermal elasto-plastic analysis was performed by the FEA. The stresses measured by the experiments were compared with the results of FEA. Also, discussed are the difference and agreement between the stresses obtained by experiments and FEA, respectively.

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