What are typical failure modes of piezoelectric transducers?
The 5 typical failure modes for piezoelectric crystals are: 1) Cracking of the wafer from being over-driven, signal is too strong. 2) By being driven by a signal with too much DC content, which distorts the shape of the wafer, making it easier to crack even with normal AC drive signals. 3) Being driven by too low of a frequency, such that it is out of the crystals natural resonate frequency range, making it prone to cracking. 4) Being driven by too hi of a frequency, such that it is out of the crystals natural resonate frequency range, making it overheat until it cracks or the metal coating melts. 5) Corrosion. These wafers have a thin tin or platinum plating that corrodes quickly if it is not in a sealed container, such that only the ultra-sound can enter or exit the container. Some designs include resistive heaters behind the crystal to prevent moisture from forming on its surface.