RPI Masters Engineering Project:Preliminary Design and Optimization of Composite Tension-Torsion Strap

for Rotor Systems4/21/2010

Ryan T. Casey

Tension-Torsion Strap

MD500 Rotor System

1. CF Load2. Torsional Twist due to Pitch Input3. Small Flatwise Bending due to Pitch Housing Deflection

Methodology

• Utilize Classic Laminate Theory to Determine Equivalent Material Properties

• Create ANSYS models (static)– Determine Kts– Determine Stresses & Strains in Pitch

Section, Lug-to-Pitch Section Transition• Lug Failure Modes• Optimize Geometry • Recommendations for Future Work

ANSYS Models

Preliminary Design Constraints• Lug Sizing - e/d = 2• Use IM7/8552 (Carbon/Epoxy) Unidirectional Tape

– Case1 (02/+-452/902/+-452/02)– Case2 (0/+-45/0)– Case3 (03/+-45/03)

• Length Varies between 12-18 in• CFmax = 30000lb, Max Pitch Angle = +/- 10deg

Equivalent Properties via Classic Laminate Theory Case Ex: psi Ey: psi Ez Gxy: psi Gyz Gzx n12 n23 n31

1 9.38E+06 6.68E+06 6.68E+06 3.70E+06 2.48E+06 3.70E+06 0.45 0.35 0.45

2 1.30E+07 3.61E+06 3.61E+06 3.32E+06 1.34E+06 3.32E+06 0.74 0.35 0.74

3 1.83E+07 2.68E+06 2.68E+06 1.97E+06 9.91E+05 1.97E+06 0.63 0.35 0.63

Stress Concentration (Kt)

Lug Analysis

ntnt FKt

tdWP )(

lbpsiinininPnt 38118)000,120(4.348).75.3(

MSnt = 0.27 for max CF load 30,000lb

Net Tension Failure Load (Pnt)

Bearing Failure

FEA Results

0.4% Elongation

FEA Results• Effect of Flatwise Bending Load on Shear Stresses

– 0.5 deg flatwise displacement

Shear XY Radius Shear XY Shear ZX

CF & 10 deg Twist 14900 psi 9024 psi 7300 psi

CF, 10 deg Twist, & Bending 15247 psi 8975 psi 7305 psi

Percent Variation (%) 2.33 -0.54 0.08

Final Configuration

Recommendations

Questions?