FAQ: : I have a problem with a measurement for ceramic ring alone. We received new ceramics, along with the manufacturer testing and I'm checking data with the TRZ® Analyzer and PiezoHolder and I found much more 'damped' resonance with lower Q than that presented by the manufacturer. Please check the following: Q should be 1200, whilst I measured less than 400; resonance impedance should be 11 ohms, but I got 39 Ohms there is some strange additional damping / load. Can you tell me why? Mr. L.S.
PiezoHolder and ring geometry are not the best one for measuring Qm. To test an ultrasonic device or piezo element for Qm, you need to support it in a nodal point, like the center of a disc for the radial mode, or in a nodal line, like a booster outer diameter. Otherwise, the mechanical contact dampens the vibration and reduces the Qm as you reported. In the PiezoHolder testing a ring, the contact point and support are out of the nodal point/line, which reduces the Qm result (it decreases because the contact points dampen the vibration). Still, you can perform evaluations, but keep in mind you may have a considerably systematic error.
Learn more about internal cracks the detection in piezoelectric ceramics.