Electrostrictive PVDF-TrFE Thin Film Actuators for the Control of Adaptive Thin Shell Reflectors

This paper presents the technology to control the shape of thin polymer doubly curved shell structures with a unimorph layer of strain actuators to achieve high quality, light-weight, foldable space reflectors. The selected active material is PVDF-TrFE deposited by spin coating; it is electrostrictive, isotropic and enjoys an excellent piezoelectric coefficient d 31 ≃ 15 pC/N when properly annealed, but has a nonlinear, quadratic behavior. The strain actuation is controlled by an array of segmented electrodes. The purpose of this study is to evaluate the material properties achieved in the manufacturing process. A simple, unidirectional model of electrostrictive material is considered and the material constants (electrostrictive constant Q 33 , piezoelectric constant d 31 , spontaneous polarization P s and poling strain S P ) are estimated from various static and dynamic experiments. The final part of the paper illustrates the control authority on a small demonstrator with seven independent electrodes and compares the experimental results with numerical finite element simulations.

Download Full-text

Adaptive Shell Spherical Reflector Actuated with PVDF-TrFE Thin Film Strain Actuators

Actuators ◽

10.3390/act10010007 ◽

2020 ◽

Vol 10 (1) ◽

pp. 7

Author(s):

Kainan Wang ◽

Thomas Godfroid ◽

Damien Robert ◽

André Preumont

Keyword(s):

Thin Film ◽

Active Material ◽

Quadratic Model ◽

Influence Functions ◽

Regularization Technique ◽

Thin Polymer ◽

Optical Modes ◽

Electrostrictive Material ◽

Ill Conditioning ◽

Good Agreement

This paper discusses the design and manufacturing of a thin polymer spherical adaptive reflector of diameter D=200 mm, controlled by an array of 25 independent electrodes arranged in a keystone configuration actuating a thin film of PVDF-TrFE in d31-mode. The 5 μm layer of electrostrictive material is spray-coated. The results of the present study confirm that the active material can be modelled by a unidirectional quadratic model and that excellent properties can be achieved if the material is properly annealed. The experimental influence functions of the control electrodes are determined by a quasi-static harmonic technique; they are in good agreement with the numerical simulations and their better circular symmetry indicates a clear improvement in the manufacturing process, as compared to a previous study. The low order optical modes can be reconstructed by combining the 25 influence functions; a regularization technique is used to alleviate the ill-conditioning of the Jacobian and allow to approximate the optical modes with reasonable voltages.

Download Full-text

Anisotropic Doubly-Curved Shells. Higher-Order Strong and Weak Formulations for Arbitrarily Shaped Shell Structures

10.15651/978-88-938-5080-3 ◽

2018 ◽

Cited By ~ 3

Author(s):

Francesco Tornabene ◽

Michele Bacciocchi

Keyword(s):

Higher Order ◽

Shell Structures ◽

Doubly Curved Shells ◽

Doubly Curved

Download Full-text

Fabrication of Doubly-Curved CFRP Shell Structures With Control Over Fiber Directions

Computer-Aided Design ◽

10.1016/j.cad.2021.103028 ◽

2021 ◽

pp. 103028

Author(s):

Masahito Takezawa ◽

Yuto Otoguro ◽

Kohei Matsuo ◽

Tadahiro Shibutani ◽

Akio Sakurai ◽

...

Keyword(s):

Shell Structures ◽

Doubly Curved

Download Full-text

Vibration analysis of the coupled doubly-curved revolution shell structures by using Jacobi-Ritz method

International Journal of Mechanical Sciences ◽

10.1016/j.ijmecsci.2017.12.002 ◽

2018 ◽

Vol 135 ◽

pp. 517-531 ◽

Cited By ~ 48

Author(s):

Qingshan Wang ◽

Kwangnam Choe ◽

Dongyan Shi ◽

Kinam Sin

Keyword(s):

Vibration Analysis ◽

Ritz Method ◽

Shell Structures ◽

Revolution Shell ◽

Doubly Curved

Download Full-text

Design and Testing of a PMN-PT Based Compact Hybrid Actuator

Smart Materials, Adaptive Structures and Intelligent Systems, Volume 1 ◽

10.1115/smasis2008-495 ◽

2008 ◽

Cited By ~ 5

Author(s):

A. Chaudhuri ◽

N. M. Wereley

Keyword(s):

Flow Rate ◽

Smart Materials ◽

Active Material ◽

Maximum Flow ◽

Length Change ◽

Basic Operation ◽

Test Results ◽

Electrostrictive Material ◽

Hybrid Actuation ◽

Design And Testing

Substantial research has been conducted in the development of hybrid hydraulic actuators driven by various smart materials. The basic operation of these actuators involves high frequency bidirectional length change of an active material stack (rod) which is converted to unidirectional motion of a hydraulic fluid by a set of active or passive valves. In this paper, we present the design and experimental test results of a compact hybrid actuation driven by the electrostrictive material PMN. The active material was actuated at different frequencies, with variations in the applied voltage and fluid bias pressure to study their effects on performance. The tests were carried out under no-load conditions and also with external weights to find the maximum flow rate and blocked force respectively. The maximum actuator velocity was calculated to be 330 mm/s and the corresponding flow rate was 42.5 cc/s. The blocked force of the actuator was found to be 63 N and the maximum power output was 8 W. Dynamic tests were also conducted to find the PMN stack response without any fluid loads. Results of the experiments are presented and compared with simulation data.

Download Full-text