Definition of neutral axis in beam bending\n\nThe line formed by the intersection of the neutral layer with any normal cross-section of a beam is called the neutral axis. State whether this statement is correct.

Introduction / Context:
Understanding the neutral axis helps visualize stress distributions in bending. At the neutral axis, fiber strain and bending stress are zero, transitioning from compression to tension across the section.

Given Data / Assumptions:

• Beam under pure or combined bending (elastic range).
• Plane sections remain plane; material is homogeneous and isotropic.

Concept / Approach:
The neutral layer (or surface) is the locus of points within the beam that experience zero longitudinal strain during bending. Intersecting this surface with a cross-section produces a line: the neutral axis.

Step-by-Step Solution:
Strain distribution in bending is linear: ε = (y / R).At y = 0 (neutral layer), ε = 0 and hence σ = E ε = 0.Intersection with a cross-section gives the neutral axis, lying typically through the centroid for homogeneous beams under pure bending.

Verification / Alternative check:
For symmetric homogeneous sections, the neutral axis passes through the centroidal axis. For non-symmetric sections, it still exists but its position relative to geometric axes depends on stiffness distribution.

Why Other Options Are Wrong:
Limiting the definition to cantilevers, prismatic, or symmetrical sections is unnecessary; the concept applies broadly in elastic bending.

Common Pitfalls:
Confusing neutral axis with zero shear line; assuming neutral axis always aligns with a geometric symmetry axis in composite or nonhomogeneous beams.

Final Answer:
True