Plastic Ideal Yield Stress

Compute an ideal perfectly plastic flat-bed thickness profile H²=2·tau_y·x/(rho·g); not a Glen steady-state dome or yield-strength determination.

Description

Perfectly plastic ice at a fixed yield stress produces an ideal thickness profile above a flat bed.

Perfectly plastic ice at a fixed yield stress produces an ideal thickness profile above a flat bed. Its shape differs from a viscous steady-state ice dome.^[1]

Compute an ideal perfectly plastic flat-bed thickness profile H²=2·tau_y·x/(rho·g); not a Glen steady-state dome or yield-strength determination.

When to use Plastic Ideal Yield Stress

Use this for the following task: Compute an ideal perfectly plastic flat-bed thickness profile H²=2·tau_y·x/(rho·g); not a Glen steady-state dome or yield-strength determination.

Prepare the measurements and calibration parameters in the declared units. Keep vector entries aligned and choose a consistent spatial frame and time basis.

How to use Plastic Ideal Yield Stress and understand its results

Prepare the measurements and calibration parameters in the declared units. Keep vector entries aligned and choose a consistent spatial frame and time basis.
Enter distancesFromTerminusM, yieldStressPa, iceDensityKgPerM3, gravityMPerSecondSquared using the field table, then run the tool.
Read plasticThicknessProfileM. Interpret flags, units, ordering and placeholder values using the rules below.
Review any reported issue or failed check, correct the supplied values when appropriate, and verify the result in its intended context.

Input field	Meaning	Value type and bounds	Requirement
distancesFromTerminusM	Distances from terminus m	list of number; each entry: number	Required
yieldStressPa	Yield stress pa	number	Required
iceDensityKgPerM3	Ice density kg per m3	number	Required
gravityMPerSecondSquared	Gravity m per second squared	number	Required

Use nonempty nonnegative distances measured from the terminus. Require positive yield stress, density and gravity, then evaluate the square-root thickness.^[2]

H(x) = sqrt(2 τy x/(ρg))

This summarizes the declared operation. Units, indexing, inclusivity and exceptional cases are explained in the surrounding text.

Output field	Meaning	Value type
plasticThicknessProfileM	Plastic thickness profile m	list of number

json

{
  "input": {
    "distancesFromTerminusM": [
      0,
      1,
      4
    ],
    "yieldStressPa": 2,
    "iceDensityKgPerM3": 1,
    "gravityMPerSecondSquared": 1
  },
  "output": {
    "plasticThicknessProfileM": [
      0,
      2,
      4
    ]
  }
}

Limitations and assumptions

The yield stress is an input, not an inferred strength. No accumulation, Glen rheology, sliding or bed relief is included.

Constants and empirical coefficients are supplied rather than calibrated. Check units and observational applicability before interpreting the model. Malformed requests produce input errors. A successfully evaluated request can still contain false flags, empty result lists or a result outside the supplied threshold; those outcomes have the meanings stated above.

Alternative or Complementary methods

Choose Steady State Thickness Profile Vialov for this operation: Evaluate ideal Vialov flat-bed, no-sliding, isothermal Glen-flow half-dome with uniform ice-equivalent accumulation and zero terminus thickness; no bed geometry or transient dynamics. For a complementary task, use Basal Shear Stress for this operation: Calculate local slab driving and shape-corrected basal shear; longitudinal stress gradients and spatial force balance are excluded.

Further background: Ice rheology.

References

Ice rheology — PISM
Plastic Ideal Yield Stress — tool.io

Similar or alternative tools

Steady State Thickness Profile Vialov
Evaluate ideal Vialov flat-bed, no-sliding, isothermal Glen-flow half-dome with uniform ice-equivalent accumulation and zero terminus thickness; no bed geometry or transient dynamics.
Basal Shear Stress
Calculate local slab driving and shape-corrected basal shear; longitudinal stress gradients and spatial force balance are excluded.