SWBPIPE · The open manual
Part VI · VerificationVI–B2

Part VI

Verification

B. Elements and loads  ·  Cantilever with a tip force

A straight member ten meters long is fixed at one end and free at the other. A lateral force of 6.0 N acts at the tip. How far does the tip deflect, and what moment does the fixed end carry? This bending case has one element and one load.

This page preserves a recorded benchmark and its expected values. The dated run below is not a new run of the current product.

Independent numerical comparison. The recorded test exercises a benchmark crate. It does not exercise the desktop product route.

A member fixed at one end carries a lateral tip force. The case compares tip deflection and root reaction with hand values. P L
Fig. VI–B2.—Cantilever with a tip force

1.Inputs.

Illustrative values, taken from no standard and chosen so the arithmetic can be followed by hand. Most do not describe a real pipe; read them in any consistent set of units.

QuantitySymbolValue
LengthL10.0 m
Elastic modulusE1200.0 Pa
Second moment of areaIz4.0 m4
Tip forcePy6.0 N

2.Method.

The reference uses elementary cantilever results. Tip deflection is PL3/(3EI). The fixed-end moment magnitude equals force times length. Recovery from the solved displacements gives the moment that the root restraint must supply. This reaction opposes the applied moment: −60.0 N·m, with magnitude 60.0.

δy = PyL3 / (3EIz) = 6.0 × 10.03 / (3 × 1200.0 × 4.0) = 0.4166666666666667 m(1)
Mz = PyL = 60.0 N·m(2)

3.Results.

Tip deflection and fixed-end moment
QuantityExpected
Tip deflection in Y0.4166667 m
Fixed-end moment about Z60.0 N·m

The case record describes these checks:

  • The solver builds one frame element, fixes all six freedoms at the root and solves for the tip.
  • The solved tip deflection in Y matches the hand value.
  • The fixed-end reaction moment recovered from the solution is −60.0 N·m, the hand magnitude with the reaction’s sign.

What it shows. Compared with an independent hand calculation.

Path exercised. The benchmark calls the solver’s components directly: elements, loads, frame solver and stress recovery. It does not go through the program’s own model-to-solve path.

Agreement. Each computed value must match the reference within an absolute difference of 1.0 × 10−9 in the case’s own units. Counts and structural outcomes must match exactly. Long values are shown here to seven significant figures; the tests compare the full values in the record.

4.Recorded command.

This command belongs to the archived source at 462f66975d36cd10d5b8455193ada9517d28d353. Use a checkout of that exact revision. This edition did not run the command. The recorded result does not establish current product support.

git checkout --detach 462f66975d36cd10d5b8455193ada9517d28d353
cd projects/chirality-piping
cargo test --manifest-path validation/benchmarks/mechanics/Cargo.toml cantilever_tip_force_matches_open_mechanics_formula

Hand calculation: validation/hand_calcs/mechanics/cantilever_tip_force.md. Test record, with the recorded run of 2026-07-10, with the strengthened check first run on 2026-09-22: mech-cantilever-tip-force.md.

Contents · Part VI · The program: swbpipe.com · MIT licence