Induced-shear piezoelectric actuators for rotor blade trailing edge flaps

Much of the current rotorcraft research is focused on improving performance by reducing unwanted helicopter noise and vibration. One of the most promising active rotorcraft vibration control systems is an active trailing edge flap. In this paper, an induced-shear piezoelectric tube actuator is used in conjunction with a simple lever–cusp hinge amplification device to generate a useful combination of trailing edge flap deflections and hinge moments. A finite-element model of the actuator tube and trailing edge flap (including aerodynamic and inertial loading) was used to guide the design of the actuator–flap system. A full-scale induced shear tube actuator flap system was fabricated and bench top testing was conducted to validate the analysis. Hinge moments corresponding to various rotor speeds were applied to the actuator using mechanical springs. The testing demonstrated that for an applied electric field of 3 kV cm−1, the tube actuator deflected a representative full-scale 12 inch flap ±2.8° at 0 rpm and ±1.4° for a hinge moment simulating a 400 rpm condition. The per cent error between the predicted and experimental full-scale flap deflections ranged from 4% (low rpm) to 12.5% (large rpm). Increasing the electric field to 4 kV cm−1 results in ±2.5° flap deflection at a rotation speed of 400 rpm, according to the design analysis. A trade study was conducted to compare the performance of the piezoelectric tube actuator to the state of the art in trailing edge flap actuators and indicated that the induced-shear tube actuator shows promise as a trailing edge flap actuator.

[1]  J. G. Leishman,et al.  Unsteady aerodynamics of a flapped airfoil in subsonic flow by indicial concepts , 1995 .

[2]  Inderjit Chopra,et al.  Design and testing of a helicopter rotor model with smart trailing edge flaps , 1994 .

[3]  Chulho Kim,et al.  New torsional actuator based on shear piezoelectric response , 1998, Smart Structures.

[4]  Ron Barrett,et al.  WIND TUNNEL TESTING OF A HIGH AUTHORITY AIRSPEED INSENSITIVE ROTOR BLADE FLAP , 1999 .

[5]  Dhananjay K. Samak,et al.  Feasibility study to build a smart rotor: trailing edge flap actuation , 1993, Smart Structures.

[6]  Inderjit Chopra,et al.  Analysis of a bending-torsion coupled actuator for a smart rotor with active blade tips , 2001 .

[7]  S. Hall,et al.  Development of a piezoelectric servoflap for helicopter rotor control , 1996 .

[8]  Ron Barrett,et al.  BENCH-TOP CHARACTERIZATION OF AN ACTIVE ROTOR BLADE FLAP SYSTEM INCORPORATING C-BLOCK ACTUATORS , 1998 .

[9]  Inderjit Chopra,et al.  Design and testing of a helicopter trailing edge flap with piezoelectric stack actuators , 1996, Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring.

[10]  David B. Domzalski,et al.  Development of a piezoelectric actuator for trailing edge flap control of full scale rotor blades , 2001 .

[11]  Robert A. Ormiston,et al.  Hover Testing of a Small-Scale Rotor with On-Blade Elevons , 2001 .

[12]  Chulho Kim,et al.  High authority piezoelectric torsional actuators , 1998, ISAF 1998. Proceedings of the Eleventh IEEE International Symposium on Applications of Ferroelectrics (Cat. No.98CH36245).

[13]  Qiming Zhang,et al.  Piezoelectric actuator generating torsional displacement from piezoelectric d15 shear response , 1998 .

[14]  Inderjit Chopra,et al.  Analysis and Testing of a Froude Scaled Helicopter Rotor with Piezoelectric Bender Actuated Trailing Edge Flaps , 1997 .

[15]  Inderjit Chopra,et al.  Wind tunnel testing of a Mach-scaled rotor model with trailing-edge flaps , 2000 .

[16]  Inderjit Chopra,et al.  Hover Test of a Mach-Scale Rotor Model with Active Blade Tips , 2000 .

[17]  Taeoh Lee,et al.  DESIGN -AND SPIN TESTING OF~~AN ACTIVE TRAILING EDGE FLAP ACTUATED WITH PIEZOSTACKS , 1999 .

[18]  Inderjit Chopra,et al.  Advances in the development of an intelligent helicopter rotor employing smart trailing-edge flaps , 1996 .

[19]  Inderjit Chopra,et al.  Trailing Edge Flap Activated by a Piezo-Induced Bending-Torsion Coupled Beam , 1999 .

[20]  Inderjit Chopra,et al.  Wind Tunnel Test of Blade Sections with Piezoelectric Trailing-Edge Flap Mechanism , 2001 .

[21]  Inderjit Chopra,et al.  Design, Fabrication and Testing of a Mach Scaled Rotor Model with Trailing-Edge Flaps , 1999 .

[22]  Robert A. Ormiston,et al.  SMALL-SCALE ROTOR EXPERIMENTS WITH ON-BLADE ELEVONS TO REDUCE BLADE VIBRATORY LOADS IN FORWARD FLIGHT , 1998 .

[23]  Inderjit Chopra,et al.  Wind Tunnel Testing Of A Mach-Scaled Active Rotor With Trailing-Edge Flaps , 2001 .

[24]  Inderjit Chopra,et al.  Design and static testing of a trailing-edge flap actuator with piezostacks for a rotor blade , 1998, Smart Structures.