【作者】 潘成亮；

【导师】 冯志华；

【作者基本信息】 中国科学技术大学 ， 测试计量技术及仪器， 2010， 博士

【摘要】 本论文就新型的基于螺旋电极结构的压电纤维、压电圆柱和压电圆片扭转驱动器结构进行了深入的理论分析和实验研究,并探索了其在压电旋转马达、光学扫描镜等方面的应用。首次提出一种表面缠绕螺旋电极结构的压电纤维扭转驱动器,是已知目前国际上最小的压电扭转驱动器。根据不同坐标系下应变和应力转换关系解释了该驱动器的变形原理,建立了压电纤维驱动器扭转和纵向静态变形和动态振动的理论模型,得到了压电纤维耦合振动的等效电路,对其主要材料参数和结构参数对驱动器扭转角、谐振频率等性能指标的影响作了详细的分析和评估,为结构优化提供了全面的理论依据。通过ANSYS有限元仿真研究压电纤维表面螺旋电极结构的电场分布情况,指出实际电场分布存在的缺陷,分析电场集中和弯曲等电场分布不均匀性对压电纤维驱动器性能的影响。总结薄壁、厚壁和实心压电纤维在不同螺旋电极结构参数下的电场分布的变化趋势,进而分析压电纤维内部应变和应力的分布规律,添加系数k以修正扭转位移表达式,分析估算修正系数k随压电纤维厚径比和电极螺旋角的变化规律,从而完善了静态变形理论模型。以直径1mm、壁厚0.2mm的压电纤维管为基体加工出螺旋电极式扭转驱动器样品,并测试样品的静动态特性,实验结果体现出该驱动器优良的扭转性能。长度50mm、电极螺旋角43°的样品在1000V电压驱动下,静态扭转角达到1.7°;在10kHz的扭转谐振频率点,500Vp-p正弦电压可激励产生2.5°的扭转振动。通过测试比较不同驱动器样品,验证了相同电场强度下静态扭转变形随电极螺旋角的变化曲线,得出45°左右的螺旋电极可提供最大扭转位移的结论;验证了扭转和纵向谐振频率随电极螺旋角和纤维长度的变化趋势。发展了另外两种基于螺旋电极结构的压电扭转驱动器:基于刻槽螺旋电极结构的压电柱型扭转驱动器和基于平面螺旋电极结构的压电圆片扭转驱动器。阐述了两种驱动器的电极结构设计思路和扭转变形原理,分别加工出两种驱动器样品并进行实验测试分析。直径8mm、长度10mm、电极螺距12mm的压电柱型扭转驱动器样品,2200V电压驱动下静态扭转角达到0.035°,一阶扭转谐振频率达到31kHz,一阶纵向谐振频率达到55kHz,5Vp-p正弦压电驱动下扭转谐振振幅达到0.00087°,纵向谐振振幅达到43nm;直径27mm、厚度0.2mm的压电圆片扭转驱动器,1000V电压驱动下静态扭转位移达到0.0052o,变形虽小,但扭转谐振频率高达226.5kHz,且具有很高的机械品质因子。探索螺旋电极式压电扭转驱动器在压电冲击旋转马达和光学扫描镜等方面的应用,设计制作了基于压电纤维扭转驱动器和压电柱型扭转驱动器的两种压电冲击旋转马达。压电纤维马达600Vp-p驱动电压下的步进角达到0.063o,1000Vp-p、3kHz电压驱动下的堵转力矩可达到0.08mNm;压电柱马达2200Vp-p电压驱动下的步进角达到0.022°,1400Vp-p电压驱动和1.6mNm负载时仍可保持7.4rpm的转速。微型化压电纤维马达和大力矩压电柱马达可满足多种场合高精度角度定位和驱动的需求。设计加工了基于压电纤维扭转驱动器的微型光学扫描器,阐述了扫描器的驱动原理和扫描特性,加工样品在400Vp-p驱动电压下水平扫描角度达到17.9°,频率6780Hz,竖直扫描角度达到2.6°,频率10330Hz,可实现高频率、大角度的二维光学扫描,在激光扫描显微镜、医学内窥镜探头、条形码阅读器等方面具有一定的应用价值。更多还原

【Abstract】 In the dissertation, we performed deep analyses and experimental researches to investigate new types of piezoelectric fiber, bulk, and discal torsional actuators based on helical electrode structures and explored their applications in piezoelectric rotary motor and optical scanner.A torsional piezoelectric fiber structure with external helical electrodes was first proposed, which was the smallest piezoelectric torsional actuator in the world. Working principle was explained with strain and stress transforming principles in different coordinate systems. Theoretical models of static deformation and dynamic vibration were built and equivalent circuit of coupled vibrations was also obtained. Influences of primary material and structure parameters on the evaluation criteria of the actuator, such as torsional displacement and resonant frequencies, were analyzed and estimated for the optimization of the structure.With help of finite element analysis software ANSYS, we simulated distribution of electric field in piezoelectric fiber driven by external helical electrodes and pointed out that the actual distribution of electric field was deficient. Influences of these non-uniformities, such as concentration and distortion of the electric field, on the performance of piezoelectric fiber actuator were analyzed. We concluded the changing trends of electric field distributions with different structure parameters of piezoelectric fiber and helical electrodes, and deduced the distribution of strain and stress among the fiber material. A compensation factor k was defined to regulate the expression of torsional displacemet and the trends of the compensation factor k as functions of piezoelectric fiber thickness and electrode helcal angle were investigated.Prototype actuators were manufactured using piezoelectric hollow fibers with an outer diameter of 1 mm and a wall thichness of 0.2 mm and their static and dynamic characteristics were also tested. Experimental results indicated that these actuators have outstanding actuation abilities. Sample with a length of 50 mm and an electrode helical angle of 43°could produce a static torsional angle of 1.7°under a driving voltage of 1000 V. The amplitude of torsional vibration reached up to 2.5°at resonant frequency of 10 kHz under a driving voltage of 500 Vp-p. Through some deliberate comparing experiments, the modified theoretical curve of torsional displacement as a function of electrode helical angle was verified, which indicated that the torsional deformation was maximized with an electrode helical angle around 45°. The trends of the resonant frequencies of torsional and longitudinal vibrations as functions of electrode helical angle and fiber length were also validated in experiment.We developed another two types of piezoelectric torsional actuator, which were piezoelectric bulk actuator with grooved helical electrodes and piezoelectric discal actuator with planar spiral electrodes. Designs of electrode structures and principles of torsional derformations in these two actuators were described respectively. Prototype samples of the two actuators were fabricated and tested. Piezoelectric bulk actuator with a diameter of 8 mm, a length of 10 mm, and electrode pitch of 12 mm could produce a static torsional angle of 0.035°under a driving voltage of 2200 Vp-p. Its first-order torsional and longitudinal resonant frequencies reached up to 31 kHz and 55 kHz, respectively. The amplitudes of these two vibrations were 0.00087°and 43 nm, respectively, under a driving voltage of 5 Vp-p. Piezoelectric discal actuator with an outer diameter of 27 mm and a thichness of 0.2 mm produced a static torsional angle of 0.0052°under a 1000 V voltage. In despite of small torsional deformation, it had a high resonant frequency of 226.5 kHz with a large mechanical Q-factor.The applications of developed piezoelectric actuators in aspects of piezoelectric impact rotary motor and optical scanner were explored. Two types of piezoelectric impact rotary motors based on piezoelectric fiber actuator and bulk actuator were designed, fabricated and tested. Piezoelectric fiber motor could produce a step angle of 0.063°under a saw driving voltage of 600 Vp-p and had a stall torque of 0.08 mNm under a driving voltage of 1000 Vp-p at 3 kHz. Piezoelectric bulk motor could produce a step angle of 0.022°under a driving voltage of 2200 Vp-p and remained a speed of 7.4 rpm with a braking torque of 1.6 mNm under a driving voltage of 1400 Vp-p at 8 kHz. The miniature piezoelectric fiber motor and large-torque bulk motor could satisfy several requirements in the applications of precision angular positioning and actuation. We also designed and fabricated a novel optical scanner based on torsional piezoelectric fiber actuator. Working principle and scanning characteristics of such miniature scanner were described. Sample with a mirror of 1 mm×1 mm could produce a horizontal scanning angle of 17.9°at 6780 Hz and a vertical scanning angle of 2.6°at 10300 Hz under an applied voltage of 400 Vp-p. The two-dimensional optical scanning with large amplitudes and high frequencies indicated its application potentials in laser scanning microscopes, barcode readers, and medical endoscopic imaging systems.更多还原