1. Georgia Tech School of Aerospace Engineering January 10, 2000 Improved Methods for Measurement of Extension-Twist Coupling in Composite Laminates Michael D. Schliesman

2. Georgia Tech School of Aerospace Engineering January 10, 2000 Introduction l Coupling in Off-Axis Laminates   In-Plane Extension-Shear Coupling F   F Extension-Twist Coupling

3. Georgia Tech School of Aerospace Engineering January 10, 2000 Introduction l Want to Use Extension-Twist Coupling in Design l Experimental Validation of Analytical Method l Requires Precise Experimental Data

4. Georgia Tech School of Aerospace Engineering January 10, 2000 Existing Testing Methods l Thrust-Bearing Apparatus l Rotating-Frame Apparatus l Air-Bearing Apparatus

5. Georgia Tech School of Aerospace Engineering January 10, 2000 Improving the Rotating-Frame Apparatus l Benefits  High Fidelity to Rotor Blade Environment  Investigation of Aeroelastic Characteristics l Problems to Overcome  Restoring Moment  Poor Method of Data Acquisition

6. Georgia Tech School of Aerospace Engineering January 10, 2000 Restoring Moment l Cylindrical End Mass Deflected Not Deflected POR

7. Georgia Tech School of Aerospace Engineering January 10, 2000 Data Acquisition l Laser Twist Measurement Base Window Laser End Mass Paper h   

8. Georgia Tech School of Aerospace Engineering January 10, 2000 Improved Rotating-Frame Apparatus

9. Georgia Tech School of Aerospace Engineering January 10, 2000 Symmetric Testing Method [+  /-  ] [-  /+  ] Symmetric Test Specimen Net Twist of Specimen ++ F 0° F -- Twist of Specimen Components F ++

10. Georgia Tech School of Aerospace Engineering January 10, 2000 Symmetric Testing Method l Testing Setup

11. Georgia Tech School of Aerospace Engineering January 10, 2000 Predictions l Analytical Method  Finite Displacement Analysis  Closed Form Solution  Geometric Nonlinear Effects l Numerical Method  Finite Element Analysis (ABAQUS)  2200 S4R Elements  Geometric Nonlinear Effects

12. Georgia Tech School of Aerospace Engineering January 10, 2000 Predictions l Analytical and Finite Element Predictions Axial Load (N) End Twist (deg)

13. Georgia Tech School of Aerospace Engineering January 10, 2000 Testing Results l Rectangular vs. Cylindrical End Mass Axial Load (N) End Twist (deg)

14. Georgia Tech School of Aerospace Engineering January 10, 2000 Testing Results l Aeroelastic Effect End Twist (deg) Angular Speed (rps) Chamber Evacuated Chamber Not Evacuated

15. Georgia Tech School of Aerospace Engineering January 10, 2000 Testing Results l Scatter in Symmetric Testing Method End Twist (deg) Axial Load (N)

16. Georgia Tech School of Aerospace Engineering January 10, 2000 Conclusions l Isolation of Extension-Twist Relationship  Cylindrical End Mass Eliminated Restoring Moment  Symmetric Method Provided Inconclusive Results l Dependent on Accuracy of Specimen Manufacturing l Simple Method Shows Promise l Vibration Visualization  1P Sampling of Twist Provides Dynamic Measurement  Investigation of Aeroelastic Characteristics

17. Georgia Tech School of Aerospace Engineering January 10, 2000 Future Work l Refine Symmetric Testing Method  Accurate Specimen Manufacturing  Accurate Twist Measurement l Submit Method to ASTM