High-force cofired multilayer actuators

摘要

Abstract: Various structural control applications (e.g., high-precision machining) require high-force actuation. Actuators made by stacking and gluing plates are not suitable for many of these applications because, unless the plates are very thin ($LS 1 mm), the glued stack requires high voltages ($GRT 1 kV) and stacks of very thin plates require extreme care in fabrication to avoid compliance due to the joints. This paper describes an effort to fabricate high-force, co- fired multilayer actuators. The actuator modules were designed to be approximately 50 mm $MUL 50 mm $MUL 20 mm (height), with 20 1-mm thick layers and a 12.7-mm diameter hole in the center for a prestress bolt. The modules were to be stacked together to form an actuator capable of delivering $GRT 50 $mu@m stroke at 5$DGR@C under a load of approximately 10,000 lb. The major challenge in this task is fabricating the co-fired modules because of their size. It is exceptionally difficult to burnout and sinter such a large multilayer device without introducing flaws such as delaminations and, to the best of our knowledge, this had never been done successfully before. Three co-fired, high force actuator modules were fabricated and electrically and mechanically characterized. The capacitance of the actuator modules ranged from 1.5 to 9.4 $mu@F. Co-fired actuators gave modulus values of 12.2 $MUL 10$+6$/ psi (at E $EQ 1 MV/m) which was close to the modulus of the material. The peak-peak strain of an actuator module at 0 prestress was 600 ppm (at a field of E $EQ 1 MV/m). At 2000 psi prestress, the strain measured was about 450 ppm (p-p).!2