Georgia Tech School of Aerospace Engineering January 10, 2000 Improved Methods for Measurement of Extension-Twist Coupling in Composite Laminates Michael D. Schliesman 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 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 Georgia Tech School of Aerospace Engineering January 10, 2000 Existing Testing Methods l Thrust-Bearing Apparatus l Rotating-Frame Apparatus l Air-Bearing Apparatus 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 Georgia Tech School of Aerospace Engineering January 10, 2000 Restoring Moment l Cylindrical End Mass Deflected Not Deflected POR Georgia Tech School of Aerospace Engineering January 10, 2000 Data Acquisition l Laser Twist Measurement Base Window Laser End Mass Paper h Georgia Tech School of Aerospace Engineering January 10, 2000 Improved Rotating-Frame Apparatus 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 ++ Georgia Tech School of Aerospace Engineering January 10, 2000 Symmetric Testing Method l Testing Setup 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 Georgia Tech School of Aerospace Engineering January 10, 2000 Predictions l Analytical and Finite Element Predictions Axial Load (N) End Twist (deg) Georgia Tech School of Aerospace Engineering January 10, 2000 Testing Results l Rectangular vs. Cylindrical End Mass Axial Load (N) End Twist (deg) 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 Georgia Tech School of Aerospace Engineering January 10, 2000 Testing Results l Scatter in Symmetric Testing Method End Twist (deg) Axial Load (N) 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 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