Elastic behavior: Poisson’s ratio (ν) is the ratio of lateral strain to axial strain within the elastic limit. For structural and pressure-vessel steels, what value is commonly assumed?

Introduction / Context:
Poisson’s ratio relates lateral contraction to axial elongation in elastic deformation. It is required in stress analysis, finite element modeling, and code calculations involving elastic moduli and volumetric strain. For common steels, a standard nominal value simplifies preliminary design.

Given Data / Assumptions:

• Carbon or low-alloy steel within elastic limits at room temperature.
• Small strains; isotropic, homogeneous material behavior assumed.
• No significant temperature-dependent variation considered.

Concept / Approach:
For most metals, Poisson’s ratio lies between about 0.25 and 0.35. Structural steels typically exhibit ν close to 0.3 in the elastic range, which is consistent with companion elastic constants (Young’s modulus E ≈ 200 GPa and shear modulus G ≈ 77 GPa via E = 2 G (1 + ν)).

Step-by-Step Solution:

Verification / Alternative check:
Back-calculating G from E and ν = 0.3 yields G ≈ 77 GPa, matching handbooks for mild steel.

Why Other Options Are Wrong:

• 0.01: Unrealistically low; would imply almost no lateral contraction.
• 0.75 or 0.95: Physically unrealistic for stable isotropic solids in linear elasticity (upper bound near 0.5 for incompressible behavior).

Common Pitfalls:
Using ν values outside realistic ranges in FEA; assuming ν is independent of temperature or metallurgy at high precision without data.

Final Answer:
0.3