@inproceedings{tolliver_jiang_xu_2014, title={Piezoelectric actuators with active and passive frames}, DOI={10.1115/smasis2013-3064}, abstractNote={Electromechanical actuators that generate large displacements, have large load capabilities, and demonstrate strong resonance characteristics are in great demand in the areas of precision positioning, active vibration control, and energy harvesting. Piezoelectric materials have been widely investigated for these applications because of their high energy density, quick response time, and relatively low driving voltages, but they demonstrate very small strain, typically about 0.1%. We present experimental and finite element results for two designs that use active and passive frames, respectively, to enhance the small strain in piezoelectric multilayer stacks. The first design, stacked-HYBATS, employs the synergetic contribution of d33 and d31 mode piezoelectric material. Finite element results show that this structure can generate over 50 microns of displacement and nearly 40 N of blocking force in a 36 mm × 22 mm × 10 mm footprint. The second design employs frames made from passive materials to form two stages of strain amplification in a 42 mm × 30 mm × 20 mm footprint. This two-stage design can produce over 600 microns of displacement and has a blocking force of 27 N. The active and passive materials of both designs can be varied to maximize displacement and/or blocking force. The stacked-HYBATS and the two-stage amplification system display favorable force-displacement capabilities and are promising for a variety of manufacturing and space technology applications.}, booktitle={Proceedings of the ASME Conference on Smart Materials, Adaptive Structures and Intelligent Systems - 2013, vol 1}, author={Tolliver, L. and Jiang, X. N. and Xu, T. B.}, year={2014} }
 @article{xu_tolliver_jiang_su_2013, title={A single crystal lead magnesium niobate-lead titanate multilayer-stacked cryogenic flextensional actuator}, volume={102}, ISSN={["0003-6951"]}, DOI={10.1063/1.4790142}, abstractNote={A “33” mode single crystal lead magnesium niobate-lead titanate flextensional actuator with large displacement, high load capability, and broad bandwidth was designed, prototyped, and evaluated at temperatures ranging from room temperature to cryogenic temperatures. Measuring 27.4 × 10 × 13.6 mm (height) overall and weighing 9.2 g, the actuator generates a 96.5 μm displacement in the Z-direction at 170 Vrms. The level of displacement remained constant under compressive loads up to 5 kg force. The actuator maintains 66% of its room temperature displacement at −196 °C. The measured displacements matched well with those modeled using ANSYS finite element analysis.}, number={4}, journal={APPLIED PHYSICS LETTERS}, author={Xu, Tian-Bing and Tolliver, Laura and Jiang, Xiaoning and Su, Ji}, year={2013}, month={Jan} }
 @article{tolliver_xu_jiang_2013, title={Finite element analysis of the piezoelectric stacked-HYBATS transducer}, volume={22}, ISSN={["1361-665X"]}, DOI={10.1088/0964-1726/22/3/035015}, abstractNote={Finite element modeling (FEM) of a piezoelectric multilayer-stacked hybrid actuation/transduction system (stacked-HYBATS) is investigated in this paper using ANSYS software. This transducer consists of two positive strain components operating in d33 mode and one negative strain component operating in d31 mode to generate large displacements. FEM results are compared with experimental and analytical results to provide insight into the actuation mechanisms, verify the device’s three displacement components, and estimate its blocking force. FEM calculations found the effective piezoelectric coefficient to be exceptional, about 3.11 × 106 pm V−1 at resonance. Stacked-HYBATS was quantitatively compared to commercially available flextensional actuators using finite element analysis. It was found that under the same electric field the yielded displacement of a stacked-HYBATS is about 200% and 15% larger than that of a same-sized d31 and d33 flextensional actuator, respectively. These findings suggest that stacked-HYBATS is promising for precision positioning, vibration control, and acoustic applications.}, number={3}, journal={SMART MATERIALS AND STRUCTURES}, author={Tolliver, Laura and Xu, Tian-Bing and Jiang, Xiaoning}, year={2013}, month={Mar} }