Rapid Non-Destructive Testing of Ceramic Multilayer Capacitors by a Resonance Method

1988 ◽  
Vol 142 ◽  
Author(s):  
O. Boser ◽  
P. Kellawon ◽  
R. Geyer
Keyword(s):  
Acoustic Waves ◽  
High Speed ◽  
Piezoelectric Materials ◽  
Resonance Method ◽  
Test Method ◽  
Test Set ◽  
Speed Test ◽  
Multilayer Capacitors ◽  
Set Up ◽  
Non Destructive

AbstractA rapid non-destructive test method for ceramic multilayer capacitors made from piezoelectric materials such as barium titanate or lead containing materials is described and evaluated. The test method is based on the internal excitation of standing acoustic waves in the capacitors. The standing waves are severely dampened by defects such as delaminations and pores. An undampened resonance is a good indication of a defect free ceramic multilayer capacitor. This finding was used in a nondestructive test set-up to evaluate about 1,000 capacitors. The test set-up has the potential to test over 100,000 capacitors an hour. Through metallographic (cross section) examination a sorting accuracy of 2% false accepts and 8% false rejects was determined for the high speed test set-up.

Interaction Between Wind Loading and Japanese Slates: Effect on Vibration and Scattering

2008 ◽  
Author(s):  
Satoru Okamoto
Keyword(s):  
Wind Tunnel ◽  
High Speed ◽  
Natural Frequencies ◽  
Basic Mechanism ◽  
Video Camera ◽  
Flow Speed ◽  
Test Method ◽  
Wind Loading ◽  
Natural Mode ◽  
Set Up

A series of wind tunnel tests was conducted on the vibration and scattering behavior of full-sized model of roof tiles, which were used widely for roofings of Japanese wooden dwellings. This study has investigated the nature and source of the vibrating and scattering behavior of roof tiles with the aim of providing a better insight to the mechanism. The roof tiles were set up on the pitched roof in the downstream of the flow from the wind tunnel. The vibrations for the roof tiles were measured by the Laser Doppler Vibrometry and the accelerometer, and the practical natural frequencies of the roof tiles were analyzed by the impulse force hammer test method. The motions of the vibration and scattering were observed by the high-speed video camera. Based on the consideration on the results of the measurements, there is a basic mechanism which can lead to flow-induced vibrations of the roof tiles. This mechanism is similar to that of the so-called fluttering instability, which appears as the self-excited oscillation in the natural mode of the structure at the certain critical flow speed. The values of the frequencies for the oscillating relate to the values of natural frequencies of the vibration.

Effect on Slates by Wind Over Roof of Japanese Residence

2009 ◽  
Author(s):  
Satoru Okamoto
Keyword(s):  
Wind Tunnel ◽  
High Speed ◽  
Natural Frequencies ◽  
Basic Mechanism ◽  
Video Camera ◽  
Flow Speed ◽  
Test Method ◽  
Natural Mode ◽  
Excited Oscillation ◽  
Set Up

A series of wind tunnel tests was conducted on the vibration and scattering behavior of full-sized model of roof tiles, which were used widely for roofings of Japanese wooden dwellings. This study has investigated the nature and source of the vibrating and scattering behavior of roof tiles with the aim of providing a better insight to the mechanism. The roof tiles were set up on the pitched roof in the downstream of the flow from the wind tunnel. The vibrations for the roof tiles were measured by the Laser Doppler Vibrometry and the accelerometer, and the practical natural frequencies of the roof tiles were analyzed by the impulse force hammer test method. The motions of the vibration and scattering were observed by the high-speed video camera. Based on the consideration on the results of the measurements, there is a basic mechanism which can lead to flow-induced vibrations of the roof tiles. This mechanism is similar to that of the so-called fluttering instability, which appears as the self-excited oscillation in the natural mode of the structure at the certain critical flow speed. The values of the frequencies for the oscillating relate to the values of natural frequencies of the vibration.

scholarly journals Dynamic Non-Destructive Evaluation of Piezoelectric Materials to Verify on Accuracy of Transversely Isotropic Material Property Measured by Resonance Method

2020 ◽  
Vol 10 (15) ◽  
pp. 5072
Author(s):  
Yu-Hsi Huang ◽  
Chien-Yu Yen ◽  
Tai-Rong Huang
Keyword(s):  
Material Property ◽  
Isotropic Material ◽  
Piezoelectric Materials ◽  
Resonance Method ◽  
Transversely Isotropic ◽  
Piezoelectric Ceramics ◽  
Resonant Frequencies ◽  
Material Constants ◽  
Non Destructive ◽  
Extension Length

In many engineering applications of piezoelectric materials, the design and prediction of the dynamic characteristics depends on the anisotropic electromechanical material property. Through collecting the complete formula in literature and listing all the prepared specimens, transversely isotropic material constants were obtained and verified by dynamic non-destructive evaluation in the paper. The IEEE (Institute of Electrical and Electronics Engineers) resonance method was applied to measure and calculate the orthotropic material constants for piezoelectric ceramics. Five specimens need to be prepared for the measurements using an impedance analyzer, in order to obtain the resonant and anti-resonant frequencies from the modes of thickness extension, length-extension, thickness-shear extension, length-thickness extension, and radial extension. The frequencies were substituted into the formulas guided on the IEEE standard to determine the elastic, dielectric, and piezoelectric constants. The dynamic characteristics of soft and hard piezoelectric ceramics in the results from the finite element method (FEM), which is analyzed from the anisotropic material constants of the resonance method, were verified with the mode shapes and natural frequencies found by experimental measurements. In self-heating, considered as operating on resonant frequencies of piezoelectric material, the resonant frequency and corresponding mode shape calculated by the material constants from resonance method in FEM are more accurate than the material property provided by the manufacturer and literature. When the wide-bandwidth frequency is needed to design the application of piezoelectric ceramics, this study completely provided the measurement method and dynamic verification for the anisotropic electromechanically material property.

Structural Dynamics and Response of Roof Tiles Under Wind Loading

2006 ◽  
Author(s):  
Satoru Okamoto
Keyword(s):  
Wind Tunnel ◽  
High Speed ◽  
Natural Frequencies ◽  
Basic Mechanism ◽  
Video Camera ◽  
Flow Speed ◽  
Test Method ◽  
Wind Loading ◽  
Natural Mode ◽  
Set Up

A series of wind tunnel tests was conducted on the vibration and scattering behavior of full-sized model of roof tiles, which were used widely for roofings of Japanese wooden dwellings. This study has investigated the nature and source of the vibrating and scattering behavior of roof tiles with the aim of providing a better insight to the mechanism. The roof tiles were set up on the pitched roof in the downstream of the flow from the wind tunnel. The vibrations for the roof tiles were measured by the Laser Doppler Vibrometry and the accelerometer, and the practical natural frequencies of the roof tiles were analyzed by the impulse force hammer test method. The motions of the vibration and scattering were observed by the high-speed video camera. Based on the consideration on the results of the measurements, there is a basic mechanism which can lead to flow-induced vibrations of the roof tiles. This mechanism is similar to that of the so-called fluttering instability, which appears as the self-excited oscillation in the natural mode of the structure at the certain critical flow speed. The values of the frequencies for the oscillating relate to the values of natural frequencies of the vibration.

Mechanical and Rotordynamic Design, Fabrication and Testing of a High-Speed Miniature Cryocooler Motor

2007 ◽  
Author(s):  
Dipjyoti Acharya ◽  
Lei Zhou ◽  
Liping Zheng ◽  
Thomas X. Wu ◽  
Jay Kapat ◽  
...  
Keyword(s):  
Permanent Magnet ◽  
High Speed ◽  
Room Temperature ◽  
Permanent Magnet Synchronous Motor ◽  
Synchronous Motor ◽  
Experimental Results ◽  
Test Set ◽  
And Performance ◽  
Set Up ◽  
Made In

An attempt has been made in this work to design, fabricate and performance evaluate a 2 kW permanent magnet synchronous motor operating at 200,000 rpm and at the temperature of both room temperature and 77 K. Structural, thermal and rotordynamic aspects were considered and models were developed on an iterative basis. Prototypes were fabricated and models were validated through experimental results. The PMSM motor/generator prototype was fabricated. At this stage, experimental results were obtained for the test set-up operating at 200,000 rpm and air at room temperature. Models developed were validated comparing to experimental results.

scholarly journals Vibration identification of the roadheader cutting head using high-speed cameras

2019 ◽  
Vol 252 ◽  
pp. 03018 ◽  
Author(s):  
Piotr Cheluszka ◽  
Rajmund Mann
Keyword(s):  
Comparative Analysis ◽  
High Speed ◽  
Movement Analysis ◽  
Test Set ◽  
Movement Trajectories ◽  
Cutting Head ◽  
University Of Technology ◽  
Photogrammetric Method ◽  
Set Up ◽  
3D Software

Vibrations of the roadheader cutting head were measured by means of two methods during the cutting performed on the test set-up created at the Faculty of Mining and Geology at the Silesian University of Technology. The first of them included installing accelerometers on the roadheader boom near the cutting heads. In the second one, a photogrammetric kit was used, major components of which were high-speed cameras connected with TEMA Motion 3D software used for movement analysis. Based on the motion recorded in videos, the cutting head movement trajectories were delineated, with their velocity and acceleration determined. This article presents a photogrammetric method, as well as selected results of the comparative analysis of cutting head vibrations using both methods when cutting simultaneously with two cutting heads, with the boom inclination perpendicular to the floor.

scholarly journals Implementation of an In-Situ Infrared Calibration Method for Precise Heat Transfer Measurements on a Linear Cascade

2019 ◽  
Vol 141 (2) ◽  
Author(s):  
Svenja Aberle ◽  
Martin Bitter ◽  
Florian Hoefler ◽  
Jorge Carretero Benignos ◽  
Reinhard Niehuis
Keyword(s):  
Heat Transfer ◽  
High Speed ◽  
Calibration Method ◽  
Linear Cascade ◽  
Speed Test ◽  
Global Calibration ◽  
Geometric Conditions ◽  
Angular Dependency ◽  
Set Up

For heat transfer measurements on the center blade of a linear cascade, the infrared measurement technique was set up. As a highly challenging condition, the angular dependency of the infrared signal was identified. Beside a shallow angle of view, limited by geometric conditions, the curved blade surface necessitated the consideration of this dependency. Therefore, a powerful in-situ calibration method was set up, which accounts for the angular dependency implicitly. In contrast to usual procedures, the correlation of the measured infrared intensity and the temperature was calibrated by a separate calibration function for each position on the blade. In all, three different calibration approaches were proceeded and assessed. Initial measurements in low-speed test conditions delivered physically more reasonable results, using a local calibration compared to a usual global calibration. By means of these data, an evaluation of the aerodynamic characteristic of the cascade was enabled. With few modifications, the procedure is capable to deliver high-precision heat transfer measurements in the high-speed cascade wind-tunnel at the Institute of Jet Propulsion.

scholarly journals Dynamic Measurements for Determining Poisson’s Ratio of Young Concrete

2018 ◽  
Vol 58 (1) ◽  
pp. 95-106 ◽  
Author(s):  
Lamis Ahmed
Keyword(s):  
Poisson’S Ratio ◽  
Resonance Method ◽  
Poisson's Ratio ◽  
Early Age ◽  
A Value ◽  
Young Concrete ◽  
Impact Resonance ◽  
Set Up ◽  
The Impact ◽  
Non Destructive

Abstract Knowledge of the elastic properties of concrete at early age is often a pre-requisite for numerical calculations. This paper discusses the use of a laboratory technique for determining Poisson’s ratio at early concrete age. A non-destructive test set-up using the impact resonance method has been tested and evaluated. With the method, it has been possible to obtain results already at 7 hours of concrete age. Poisson’s ratio is found to decrease sharply during the first 24 hours to reach a value of 0.08 and then increase to approximately 0.15 after seven days.

Effect of Microfillers on Selected Destructive and Nondestructive Mechanical Properties of Cement Mortars: Different Types of Recycled Materials

2016 ◽  
Vol 722 ◽  
pp. 195-200
Author(s):  
Tomáš Plachý ◽  
Pavel Tesárek ◽  
Lukáš Hlubocký ◽  
Jaromír Hrůza ◽  
Jozef Fládr ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Speed ◽  
Resonance Method ◽  
Recycled Concrete ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Measuring Device ◽  
Cement Mortars ◽  
Marble Powder ◽  
Non Destructive

The paper presents the use of non-destructive testing to determine the evolution of mechanical properties. For testing, we used the resonance method. The measuring device of company Brüel&Kjær was used. Specifically, evolution of dynamic modulus of elasticity (determined from the longitudinal and transverse vibration) and the shear modulus was determined for the first 28 days after production of the samples. The results of non-destructive method were also used for verifying the relevance of the results of destructive testing, specifically the results of the compressive strength and a three-point flexural strength. Testing of mechanical properties was performed on samples of cement mortars, where the micronized recycled concrete and micronized marble powder were used as microfillers, both materials were prepared on a high-speed mill of the Lavaris company (Czech Republic).

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