Senior R&E technical leader, McDonnell Douglas Helicopter System, Mesa, AZ
Senior design specialist, Lockheed Martin Skunk Works, Palmdale, CA
Pages: 27 Published: Jan 1995
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.
composite laminates, delamination, glass-epoxy, interlaminar fracture, three-dimensional finite element analysis, torsional loading, combined loading
Paper ID: STP14029S