Axial Deformation Calculator
Elongation δ = PL/AE, stress and strain of an axially loaded bar.
INPUTS
kN
m
mm²
GPa
RESULTS
Elongation δ = PL/AE
1.25 mm
Axial stress σ = P/A
83.33 MPa
Strain ε = σ/E
416.7 με
Axial stiffness k = AE/L
80 kN/mm
How it works
δ = PL/AE is Hooke's law applied to a whole member: force times length over area times stiffness. It is how truss deflections, anchor-bolt stretch, and column shortening are computed. The grouping AE/L is the member's axial stiffness — the truss equivalent of a spring constant.
Worked example
P = 100 kN tension on a 3 m steel bar with A = 1200 mm²: σ = 83.3 MPa, ε = 417 με, δ = PL/AE = 100e3·3000/(1200·200e3) = 1.25 mm.
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