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Linear elastic member

Axial response

FFL

Inputs

Positive = tension; negative = compression.
Uniform area, away from local load effects.
Unloaded gauge length of the member.
Linear-elastic material modulus.

Results

Average normal stressσ

10

Elastic strainε

50

Ideal length changeΔL

0.05

σ = F / A; ε = σ / E; ΔL = FL / AE

A first-pass number, not a code check, certification, or approval. Read the method and its limits below. What this is and is not.

Nearby: Beam deflection & reactions · Elastic stability · Solid-shaft torsion · Baseline L10 life

Method

Formula, when it applies, and when it does not

Inspect average stress, elastic strain, and ideal length change for a prismatic member under axial load.

σ = F / A; ε = σ / E; ΔL = FL / AE

When

  • Uniform cross-section
  • Axial loading
  • Linear-elastic response

Don’t

  • Average stress is a simplified measure; do not apply it at a local load introduction, notch, or connection without a suitable model.
Boston University mechanics notes