Design and testing of piezoelectric flight control actuators for hard-launch munitions

A new technique is presented for designing actuators for guided hard-launch adaptive munitions by using actuator and substrate strain limits, static analysis methods and matching the local actuator strains along its length by varying the width. This Load-Matched design technique leads to an exponential area distribution as a function of length which is contrasted against the conventional rectangular actuator shapes that have been used in all adaptive hard-launch munitions up till now. To demonstrate the viability of this new Load-Matched actuator design, ten 600mg, 100mm long rectangular and ten identical mass and length, exponentially shaped, Load-Matched actuator specimens were designed and built to withstand the maximum possible accelerations. Predicted design static strain distributions are presented along with limits, showing that rectangular actuators exhibit a strong strain peak at the root while Load-Matched actuators have a much more even distribution and a gentle maximum near the middle. Shock table testing showed that the rectangular specimens were predicted to fail at 3,500g's, but survived acceleration levels 9.5- 12% higher than expected (3,833 to 3,931g's). The exponentially shaped Load-Matched actuators proved that they could withstand shocks from 17 to 21% over the predicted failure acceleration level of 8,000g's (9,377 to 9,670g's).