FAQ: What should I do if I do not know the d33 value of PZT-4 or PZT-8 correctly? Is there a way to measure the d33 to use it in the prestress procedure with PiezoClamping®?
d33 typical charge constant for the PZT-8 and PZT-4 piezoelectric materials.
We suggest using the following typical values:
- PZT-8 (Navy type III) and similar: 245 pC/N
- PZT-4 (Navy type I) and similar: 290 pC/N
- PZT-5A (Navy type II) and similar: 390 pC/N
The uncertainty for the typical values is ±14 %. For exact values, you can measure the d33 using a d33 meter or an instrumented press. At ATCP we use an instrumented press to measure it, the procedure consists in applying a controlled force and measuring the charge. This approach has the advantage of measuring the d33 meter at high stress. The typical d33 meters on the market applies only at low stress.
PS: When we developed PiezoClamping®, the d33 average value and standard deviation was a major concern. We did not know how this parameter would change from one manufacturer to another, from lot to lot and among units in the same lot. Then we decided to perform a study to understand that important topic properly and gathered piezo samples from close customers from all around the world. If the d33 deviation was too high, it would be necessary to measure it before using the PiezoClamping®. We found the average d33 for PZT-8 is equal to 245 pN/C and the standard deviation of ±35 pC/N (±14 %). We also found the data reported by the manufacturers are not reliable, their results are precise but not accurate (that happens when you use a test equipment that is not calibrated). Therefore, by using the PiezoClamping and the typical values, you will have precise results (±1 %,) but an uncertainty of ±14 % because of the d33 typical values deviation. For instance, when you set the PiezoClamping® for 45 MPa, the real prestress will be within the 38.7-51.4 MPa range. This sounds bad at first, but the variation when using torque control is around ±45 %. Besides, since the PiezoClamping® precision is 1 %, you will have all your transducers with nearly the same prestress whatever it is within the 38.7-51.4 MPa range.
Learn more about prestress technology.