where expertise comes together - since 1996 -

The Largest Open Access Portal of Nondestructive Testing (NDT)

Conference Proceedings, Articles, News, Exhibition, Forum, Network and more

where expertise comes together
- since 1996 -
879 views
Technical Discussions
Ed Ginzel
R & D, -
Materials Research Institute, Canada, Joined Nov 1998, 1300

Ed Ginzel

R & D, -
Materials Research Institute,
Canada,
Joined Nov 1998
1300
02:35 Sep-06-1996
Pulser de-polarization

Lately PC style Pulser-receivers have provided a
selection of pulse shaping features such as positive,
negative or bipolar (as well as energy level, duration,
etc). Traditionaly a negative spike or squarewave
pulse has been used on transducers. Is it possible
to deteriorate polarization of poled piezoceramics
using positive squarewave pulsing?





 
 Reply 
 
Bill Grandia
Bill Grandia
02:24 Sep-07-1996
Re: Pulser de-polarization
: Lately PC style Pulser-receivers have provided a
: selection of pulse shaping features such as positive,
: negative or bipolar (as well as energy level, duration,
: etc). Traditionaly a negative spike or squarewave
: pulse has been used on transducers. Is it possible
: to deteriorate polarization of poled piezoceramics
: using positive squarewave pulsing?

It is known that a piezo-electric element always ages with time, especially in the first few weeks after manufacturing, even without operating the element.
When operating the element with a driver voltage opposed to the polarization direction, the deterioration speed in enhanced. For this reason, it is expected that the positive portion of the bipolar square wave driver acts destructively. From experience, driving a PZT5A element with a toneburst (400 kHz, 16 cycles at 500 Hz PRF) over a period of several years, no noticeable deterioration has been noticed.





 
 Reply 
 
Gerhard Splitt
R & D,
Private, Germany, Joined Nov 1998, 38

Gerhard Splitt

R & D,
Private,
Germany,
Joined Nov 1998
38
03:22 Sep-08-1996
Re: Pulser de-polarization
: : Lately PC style Pulser-receivers have provided a
: : selection of pulse shaping features such as positive,
: : negative or bipolar (as well as energy level, duration,
: : etc). Traditionaly a negative spike or squarewave
: : pulse has been used on transducers. Is it possible
: : to deteriorate polarization of poled piezoceramics
: : using positive squarewave pulsing?

: It is known that a piezo-electric element always ages with time, especially in the first few weeks after manufacturing, even without operating the element.
: When operating the element with a driver voltage opposed to the polarization direction, the deterioration speed in enhanced. For this reason, it is expected that the positive portion of the bipolar square wave driver acts destructively. From experience, driving a PZT5A element with a toneburst (400 kHz, 16 cycles at 500 Hz PRF) over a period of several years, no noticeable deterioration has been noticed.

The depolarization with a "wrong" pulser polarization only occurs at high values of the electric field strength which then will act as a depolarization field
This is true only for high frequncy piezoceramic (above 10 MHz) and for high pulser voltages (over 500 Volts).
Therefore it is clear that at 400 kHz with a tonburst pulser no deterioration effect was observed.
Of course, at elevated temperatures the depolarization will occur at lower critical values.

Gerhard Splitt



 
 Reply 
 

Product Spotlight

Robotic laser shearography enables 100% inspection of complex, flight-critical composite structures

An article in “Composites World Magazine” showcases Non Destructive Testing of aero-structures
...
with Laser Shearography. Over the years Dantec Dynamics has supplied many solutions for the aerospace industry. Referring to specific customer projects several of these cases are examined to outline the advantages of using Laser Shearography for automated defect detection.
>

PAUT Probes

Typical Phased Array probes have frequencies between 1MHz and 20MHz and the number of wafers is 10
...
to 128. M2 Electronics offers customers conventionally ultrasound probes and the ability to provide high-precision Phased Array Ultrasound Probes of up to 256 wafers. We can also customize the probe for our customers to meet the specific application requirements of the user.
>

Ultrasonic Testing Immersion Tanks with Unmatched Scanning Features

TecScan’s non-destructive testing Ultrasonic Immersion Tanks & scanners are designed for high pe
...
rformance and demanding NDT testing applications. Our Scan3D™ line of High Precision Immersion Tanks are specifically designed for automated ultrasonic testing of complex composites parts used in aerospace and industrial applications.
>

Cygnus 6+ PRO Multi-Mode Ultrasonic Thickness Gauge

The Cygnus 6+ PRO thickness gauge is the most advance gauge within the Cygnus range with key featu
...
res including: comprehensive data logging; A-scan and B-scan display; manual gain control; Bluetooth connectivity; and much more. With its unique dual display and three measuring modes (Multiple-Echo, Echo-Echo and Single-Echo), this surface thickness gauge offers maximum versatility for inspections.
>

Share...
We use technical and analytics cookies to ensure that we will give you the best experience of our website - More Info
Accept
top
this is debug window