INCREMENTALLY ADJUSTABLE ROTOR-BLADE TRACKING TAB USING SMA COMPOSITES

Advanced helicopter rotor systems are designed with non-metallic composite materials for fatigue strength and low radar signature for reduced observability. They incorporate non-metallic composite blades and non-metallic tracking tabs. Adjustment of the existing non-metallic tracking tabs is complex and inefficient since it requires heating and cooling a thermoplastic tab material for each track adjustment. Several track-tab adjustments are required until optimum tracking is achieved. In this paper, a method for achieving direct in- flight incremental adjustment of the tracking tab is presented. The method utilizes a special tab material that can be remotely activated by the pilot from the cabin while in forward flight. This material is a composite consisting of shape memory alloy (SMA) wires embedded into a polymeric matrix. The activation of the SMA composite tab is done through electric current controlled from the pilot cabin and sent through conductors along the blade to the tracking tab. The proposed method will achieve in-flight tracking tab adjustment, will minimize the adjustment cycles and will reduce by at least a factor of ten the total tracking time. The implementation of the proposed incrementally adjustable in-flight tracking tab will rapidly minimize the once-per-rev helicopter vibration forward flight. This will lead to reduced crew fatigue, increased component life, and reduced maintenance for the helicopter. Additionally, the proposed method will also be serve as emergency system to reduce unbalanced vibrations due to ballistic damage of the rotor blade .

[1]  Craig A. Rogers,et al.  One-Dimensional Thermomechanical Constitutive Relations for Shape Memory Materials , 1990 .

[2]  Victor Giurgiutiu,et al.  Design of displacement-amplified induced-strain actuators for maximum energy output , 1997 .

[3]  Craig A. Rogers,et al.  Adaptive Composite Materials with Shape Memory Alloy Actuators for Cylinders and Pressure Vessels , 1995 .

[4]  Victor Giurgiutiu,et al.  Design and preliminary tests of an SMA active composite tab , 1997, Smart Structures.

[5]  Victor Giurgiutiu,et al.  Efficient use of induced strain actuators in aeroelastic active control , 1994, Other Conferences.

[6]  Craig A. Rogers,et al.  Active vibration and structural acoustic control of shape memory alloy hybrid composites: Experimental results , 1990 .

[7]  J. Jia,et al.  Formulation of a Mechanical Model for Composites With Embedded SMA Actuators , 1992 .

[8]  David John Barrett,et al.  A One-Dimensional Constitutive Model for Shape Memory Alloys , 1995 .

[9]  Chen Liang,et al.  Modelling of the Two-Way Shape Memory Effect , 1992 .

[10]  C. R. Fuller,et al.  Active control of sound radiation from panels using embedded shape memory alloy fibers , 1990 .

[11]  C. Liang,et al.  Structural modification of simply-supported laminated plates using embedded shape memory alloy fibers , 1991 .

[12]  Craig A. Rogers,et al.  Bending and Shape Control of Beams Using SMA Actuators , 1991 .

[13]  K. Wu,et al.  The Effect of Strain Rate on Detwinning and Superelastic Behavior of Ni Ti Shape Memory Alloys , 1996 .

[14]  K. Wu,et al.  The effect of strain rate on detwinning and superelastic behavior of NiTi shape memory alloys , 1996 .

[15]  C. A. Rogers,et al.  The Effect of Thermoplastic Composite Processing on the Performance of Embedded Nitinol Actuators , 1991 .

[16]  Victor Giurgiutiu,et al.  Energy-Based Comparison of Solid-State Induced-Strain Actuators , 1996 .

[17]  Friedrich K. Straub,et al.  Applications of torsional shape memory alloy actuators for active rotor blade control: opportunities and limitations , 1996, Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring.

[18]  C. Rogers,et al.  Modeling of two-way shape memory effect , 1991 .