What is the Tsai-Hill failure criterion?

What is the Tsai-Hill failure criterion?

• A. A temperature-based criterion for resin cure.
• B. A stress-based criterion for composite laminates that accounts for interaction among normal and shear stresses to predict ply failure.
• C. A fatigue criterion for matrix cracking only.
• D. A criterion for predicting failure under hydrostatic pressure.

Answer: (B)

Tsai-Hill is a ply-level, stress-based failure rule for laminated composites. It uses the actual in‑plane stresses in a ply (normal and shear) and combines them in a quadratic form with the ply’s strength limits in tension, compression, and shear. The result is a single, dimensionless failure index: when this index reaches 1, the ply is predicted to fail under the given loading. This makes it useful for assessing how different stress components interact under combined loading, rather than judging each stress component in isolation. It’s specifically about predicting ply failure due to the stress state inside the laminate, not about resin cure temperatures, fatigue of matrix cracking alone, or hydrostatic pressure failure.

Tsai-Hill is a ply-level, stress-based failure rule for laminated composites. It uses the actual in‑plane stresses in a ply (normal and shear) and combines them in a quadratic form with the ply’s strength limits in tension, compression, and shear. The result is a single, dimensionless failure index: when this index reaches 1, the ply is predicted to fail under the given loading. This makes it useful for assessing how different stress components interact under combined loading, rather than judging each stress component in isolation. It’s specifically about predicting ply failure due to the stress state inside the laminate, not about resin cure temperatures, fatigue of matrix cracking alone, or hydrostatic pressure failure.