.. _auto_curve_truetoeffectivestress: *CONVERT TRUE TO EFFECTIVE STRESS VS STRAIN CURVE BY REMOVING ALL ELASTIC STRAINS* ================================================================================== Converts a true stress–strain curve into an effective (plastic) stress–strain curve by detecting the yield point and removing all elastic strains. Supports multiple yield-detection strategies, post-necking extrapolation methods (Swift, Hockett-Sherby, etc.), and optional curve smoothing and monotonicity enforcement. Use this worker as a pre-processing step before feeding material curves into LS-DYNA MAT_24 or similar elasto-plastic material cards. When to use ----------- Classification: **process**. Tagged: ``curve_transform``, ``effective_stress``, ``hockett_sherby``, ``mat_24``, ``material_characterization``, ``plastic_strain``, ``post_necking``, ``stress_strain``. Inputs ------ .. list-table:: :header-rows: 1 :widths: 20 20 20 20 20 20 * - Label - ID - Type - Default - Required - Description * - True Stress Strain Curve - truestressstraincurve - vector - — - ✓ - True stress–strain curve (stress in MPa, strain dimensionless) as an XY vector; the input from which elastic strains will be subtracted to yield the effective plastic curve. * - Elastic Modulus - elastic_modulus - scalar - 210.0 - ✓ - Young's modulus of the material in GPa (default 210 GPa for steel); used to compute and remove the elastic strain component from each data point. * - Yield Calculation Type - yield_type - scalar - effective - - Method used to locate the yield point: 'effective' (intersection of the effective curve with the strain axis, default), 'offset' (0.2% offset rule), 'strain' or 'stress' (user-specified threshold), 'linearity' (end of linear region), or 'initial_peak_percentage' (fraction of peak-stress strain). * - Yield Offset Or Strain - yield_offsetor_strain - scalar - 0.002 - - Strain offset or threshold value used when yield_type is 'offset' or 'strain'/'stress'; default 0.002 (0.2%) is standard for steel — increase for polymers. Not used when yield_type is 'linearity'. * - Post Necking Treatment - post_necking_treatment - string - swift - - Extrapolation method applied beyond the necking (diffuse instability) point: 'none' (no extrapolation), 'truncate' (clip at necking), 'offset' (constant offset), 'swift' (Swift power-law fit, default), or other supported hardening laws (e.g., Hockett-Sherby). * - Post-necking Extrapolation Coefficient - slopefor_extrapolation - scalar - 0.0 - - Slope for extrapolation. If 0.0, the necking strain is used for SWIFT based extrapolations. If negative for SWIFT, abs-value becomes the factor. For polymer, this is no-stiffness value. For polymer_segmented, this is no_stiffness:x_sf:y_sf * - Last Strain - last_strain - scalar - 1.0 - - Last strain value for output curve * - Digitize - digitize - scalar - 401 - - Number of points in the output curve. If negative, the effective curve is digitized only when the number of points is less than the abs(digitize) value. * - Saturation Strain - saturation_strain - scalar - 0 - - Stress will be capped beyond this value * - Saturation Percentage - saturation_percentage - scalar - 0 - - Stress will be capped beyond this percentage * - Intersection Point Type - intersection_point_type - scalar - auto - - * - Digitize Option - digitize_option - scalar - yes - - Option to digitize curve to required number of points provided in Digitize input * - Necking Strain - necking_strain - scalar - 0 - - Necking strain * - Poisson's Ratio - poissons_ratio - scalar - 0 - - Poission's ratio * - Loading Type - loading_type - scalar - tension - - Tension-Compression-Shear flag to compute strains * - Enforce Monotonic Y - enforce_y_monotonicity - select - no - - If the input True-stress vs strain has non-monotonic y-values, this option allows to remove them before converting it to effective stress vs strain * - Number Of Extrapolation Segments - num_extra_seg - scalar - 1 - - This is used when the post-necking treatment is extrapolation_regression. The default is 1 which is one-segment resulting in linear extrapolation * - Slope Scale Factor During Extrapolation - slope_sf - scalar - 1.2 - - When post-necking treatment type = extrapolation_regression, each segment slope is multipled by this number * - Smooth Curve - smooth_curve - float - no - - The final hardening curve is smoothed using avaialble options * - How To Treat User-defined Yield Value - user_defined_yield_treatment - scalar - offset - - When user defined yield is provided, this option allows us to either offset or find a smooth fit to satisy the user-defined yield * - Linearly extrapolate when no necking is found - linearly_extrapolate_when_no_necking_is_found - scalar - no - - When necking (localization) is not found, this option allows to linearly extrapolate and overrides the extrapolation type chosen above Outputs ------- .. list-table:: :header-rows: 1 :widths: 20 20 20 20 * - Label - ID - Type - Description * - curve_truetoeffectivestress_output_1 - curve_truetoeffectivestress_output_1 - vector - Effective (plastic) stress–strain curve as an XY vector (stress in MPa, plastic strain dimensionless), with elastic strains removed, post-necking extrapolation applied, and optional smoothing/monotonicity enforcement; ready for direct use in elasto-plastic material cards such as LS-DYNA MAT_24. Disciplines ----------- - data.curve.transform - engineering.material.calibration - engineering.material.characterization Runnable example ---------------- A runnable example is registered for this worker. Open the example workflow on the d3VIEW canvas: `/api/workflow/example?id=curve_truetoeffectivestress `_ .. raw:: html

Auto-generated from transformation schema. Worker id: curve_truetoeffectivestress. Schema hash: 8cfbe81fc72d. Hand-curated docs in workerexamples/ override this page when present.