CHECK CURVE Y-MONOTONICITY (MAT_024 VS MAT_187 GATE)

Detect strictly-descending y-axis segments in a curve. For material calibration this is the MAT_024-vs-MAT_187 model-selection gate: a descending sigma_y(eps_p) hardening curve means MAT_024 radial-return is the wrong model (it needs a non-negative tangent modulus); use *MAT_187 (SAMP-1) for softening polymers.

When to use

Classification: data.

Tagged: curve, monotonicity, reversal, mat24, mat187, hardening, material_calibration.

Inputs

Label	ID	Type	Default	Required	Description
Curve	curve	vector	—	✓	Input curve (X/Y vector pair). For the MAT_024 gate pass the RAW (un-enforced) effective-plastic hardening curve eps_p vs sigma_y.
Tolerance	tolerance	scalar	0		Reversal threshold: a segment counts as a reversal when y[i] < y[i-1] - tolerance. Default 0 (strict), so flat perfect-plasticity segments are NOT flagged.

Outputs

Label	ID	Type	Description
curve_check_monotonicity_output_1	curve_check_monotonicity_output_1	keyvalue	Reversal report: n_points, reversal_count, is_monotonic, reversals [{index,y_prev,y}], first_reversal_index, and a message. A reversal means MAT_024 radial-return is invalid (descending sigma_y(eps_p)) – use *MAT_187 (SAMP-1).

Disciplines

• engineering.material.calibration
• data.curve.transform

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