Which statement best describes the typical in-plane shear performance of 0/90 laminates versus ±45 laminates?

Which statement best describes the typical in-plane shear performance of 0/90 laminates versus ±45 laminates?

• A. 0/90 laminates have the best in-plane shear performance.
• B. ±45 laminates are always stiffer in all directions.
• C. 0/90 laminates have strong stiffness along the principal axes but limited shear performance; ±45 laminates optimize in-plane shear response and global stiffness for complex loading.
• D. Both laminate types perform identically under in-plane shear.

Answer: (C)

In-plane shear depends on how the fiber directions in the laminate resist shear deformation in the plane. A laminate with plies at 0° and 90° has very strong stiffness along those principal directions because the fibers align with them, but that setup doesn’t resist shear in the plane as effectively. The fibers aren’t oriented to carry shear directly, so the in-plane shear response stays limited. Plies oriented at ±45°, on the other hand, each contribute to resisting shear in the plane. When you stack these plies, the laminate gains a higher effective shear modulus and a more balanced stiffness in all in-plane directions, which helps under complex loading where shear and normal stresses occur together. That’s why this arrangement is described as optimizing in-plane shear response and providing better global stiffness for mixed loading, compared with 0/90 laminates.

In-plane shear depends on how the fiber directions in the laminate resist shear deformation in the plane. A laminate with plies at 0° and 90° has very strong stiffness along those principal directions because the fibers align with them, but that setup doesn’t resist shear in the plane as effectively. The fibers aren’t oriented to carry shear directly, so the in-plane shear response stays limited.

Plies oriented at ±45°, on the other hand, each contribute to resisting shear in the plane. When you stack these plies, the laminate gains a higher effective shear modulus and a more balanced stiffness in all in-plane directions, which helps under complex loading where shear and normal stresses occur together. That’s why this arrangement is described as optimizing in-plane shear response and providing better global stiffness for mixed loading, compared with 0/90 laminates.