New Tools for Structural Testing: Piezoelectric Impact Hammers and Acceleration Rate Sensors

Small-size ultra-high-precision mechanical systems demand special testing methodologies, such as a better high-frequency response, a precise impact position, an extremely high repeatability, etc. Utilizing the fact that signals obtained from piezoelectric sensing elements are strongly influenced by the interfacing circuitry, piezoelectric sensors that can be used to measure acceleration rate were developed. Both analytical and experimental results indicate that acceleration rate sensors can detect the arrival of realistic shock earlier than conventional accelerometers can. An ultra-high-precision high-speed piezoelectric impact system with an on-line load cell was also modeled, designed, and built. The sensitivity of this on-line load cell was calibrated by using a standard quartz load cell. This innovative high-speed impact hammer system was found to have a timing accuracy in the range of microseconds and a positioning accuracy in the range of micrometers.