How to use this calculator
Number the segments from the wall outward and give each one’s length, area and modulus. Each load acts at the right-hand end of its segment and is positive when it pulls away from the wall. Leave unused segments and loads at 0.
Formulas
Internal forceNi = sum of the loads to the right of a cut in segment i
Deformationδ = Σ NiLiAiEi
Worked example
Steel bar: 0.5 m of 600 mm², then 0.4 m of 300 mm²; 50 kN pushing at the step and 30 kN pulling at the end (the default)
- N2 = 30 kN (tension); N1 = 30 − 50 = −20 kN (compression).
- σ1 = −20 000/600 = −33.3 MPa; σ2 = 30 000/300 = 100 MPa.
- δ = −20 000 × 500/(600 × 200 000) + 30 000 × 400/(300 × 200 000) = −0.083 + 0.200 = 0.117 mm longer.
Frequently asked questions
Why cut from the free end?
The part to the right of the cut has only known loads on it, so the wall reaction never has to be found first.
What if both ends are fixed?
Then the bar is statically indeterminate: the end reactions also depend on the deformation (total δ = 0). Solve for one reaction with that extra condition.