SYMPOSIA PAPER Published: 01 January 1995

Fracture of Glass-Epoxy Laminates Under Torsion and Combined Tension-Torsion Loads


An experimental program and a finite element stress analysis were conducted to study delamination failures in glass-epoxy laminates subjected to torsion and combined tension-torsion loads. Nine laminate configurations with three ply orientations and three stacking sequences were evaluated. The failures consisted of through-the-thickness shear cracks in off-axis plies, which promoted delaminations at adjacent 0° interfaces. The predominant stress in all cases is the interlaminar shear stress, σxz. Dispersing off-axis plies away from the laminate midplane increased the torsion load-carrying capability but did not significantly increase twist capability. The failure torque and twist angles were higher under combined tension-torsion loads than under torsion load alone due to the increased torsional rigidity and the compressive interlaminar normal stress induced by the tension load.

Author Information

Sen, JK
McDonnell Douglas Helicopter System, Mesa, AZ
Fish, JC
Lockheed Martin Skunk Works, Palmdale, CA
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Developed by Committee: D30
Pages: 440–466
DOI: 10.1520/STP14029S
ISBN-EB: 978-0-8031-5297-7
ISBN-13: 978-0-8031-2012-9