Log
writing
doneI've built the coil spring between a fixed lower seat (dim grey) and a moving upper seat (goldenrod). The wire is a helix of 64 short steel-blue cylinders: 8 per turn over 8 turns (6 active coils plus one closed dead coil at each end). I checked the size, the numbers and a picture at the default inputs, and one test at a higher load.
**How the geometry follows the load:** the dead coils stay closed, with the turns touching, and only the active coils spread out. Their spacing comes from the loaded length, so raising `load-n` lowers the upper seat and squeezes the coils together. If the load would push the spring past solid length, it stops at solid, `coil-bind?` becomes true and the wire turns red. I tested this at 7,000 N: it stopped at 108 mm with coil-bind? true.
**Results at the default inputs (3,500 N):**
| Result | Value |
|---|---|
| Spring rate | 19.83 N/mm |
| Deflection | 176.5 mm |
| Loaded length | 173.5 mm |
| Solid length | 108 mm |
| Spring index | 10 |
| Wahl factor | 1.145 |
| Corrected shear stress | 708.6 N/mm² |
| Utilisation | 0.79 |
| Stored energy | 309 J |
| Spring mass | 2.70 kg |
| Lowest surge frequency | 49.5 Hz |
- **Onset of coil bind:** at these dimensions the spring reaches solid at about 5,035 N.
- **Doc strings:** every result is a computed slot of the model, and each doc string gives its unit and formula.
**Inputs panel (all with sliders):**
- wire diameter: 8–16 mm
- mean coil diameter: 80–160 mm
- active coils: 3–8
- free length: 250–450 mm
- shear modulus
- density
- permissible stress
- **load-n** (the state input): 0–8,000 N
- segments drawn per turn: 6–8
**Assumptions and limits:**
- **Solid length:** I took "closed dead coil" to mean closed but not ground ends, so solid length is (total coils + 1) × wire diameter.
- **At coil bind:** once the spring is solid, the stress, utilisation and energy use the force the coils actually carry, not the extra applied load, which goes into the seats.
- **Surge frequency:** it assumes both ends are fixed and uses only the mass of the active coils.
- **Mass:** it counts all coils, including the dead ones.
- **Drawing:** the wire is drawn as straight segments, so the coils look slightly faceted. The ends are not ground flat.
toolrender
toolevaluate
toolcheck_model
toolwrite_model
toolread_model
toolevaluate
textRemove the stray :pass-down and declare pseudo-inputs.
toolwrite_model
promptA helical compression coil spring for a passenger-car suspension, held between a fixed lower spring seat and an upper seat that moves down with the load. Inputs: wire diameter 12 mm, mean coil diameter 120 mm, active coils 6, one closed dead coil at each end, free length 350 mm, shear modulus 79300 N/mm2, steel density 7850 kg/m3, permissible shear stress 900 N/mm2, and the STATE input load-n (axial force in N, default 3500). Draw the wire as a helix of short cylinders whose pitch follows the loaded length, so the spring visibly shortens as the load rises; if the load would compress it past its solid length, hold it at solid and set coil-bind? true. Compute: spring rate G d^4 / (8 D^3 n) in N/mm, deflection, loaded length, solid length, spring index D/d, the Wahl stress-correction factor, corrected shear stress 8 F D k / (pi d^3), utilisation against the permissible stress, stored energy in J, spring mass, and the lowest surge (natural) frequency of the spring itself in Hz.
(This prompt was written by Claude, Anthropic's AI model, as one entry in a catalog of simulative models of automotive systems.) House brief: key dimensions and operating values are root inputs with input-controls (ranges the model holds at); STATE inputs must really move the parts; each result named above is a computed-slot of MODEL with a doc string giving its unit; simplified but recognisable geometry, about 15 to 80 leaves; colours only from Gendl's own table, hyphenated: :steel-blue, :slate-gray, :dim-gray, :silver, :brass, :copper, :bronze, :firebrick, :goldenrod, :orange, :red, :black, :dark-olive-green.
noteSession 1bb006eb6f2c opened for an external agent.