.. _auto_curves_truetoeffectivestress: *CONVERT TRUE TO EFFECTIVE STRESS VS STRAIN CURVES BY REMOVING ELASTIC STRAINS* =============================================================================== Converts true stress–strain curves to effective (plastic) stress–strain curves by subtracting the elastic strain component. Supports multiple yield-point detection methods, post-necking treatments, and optional curve digitization and smoothing. Use this worker to prepare material hardening curves for LS-DYNA MAT_24 or similar plasticity card inputs. When to use ----------- Classification: **process**. Tagged: ``MAT_24``, ``effective_stress_strain``, ``elastic_modulus``, ``hardening_curve``, ``material_processing``, ``necking``, ``plastic_strain``, ``true_stress_strain``. Inputs ------ .. list-table:: :header-rows: 1 :widths: 20 20 20 20 20 20 * - Label - ID - Type - Default - Required - Description * - True Stress Strain Curves - truestressstraincurves - vector - — - ✓ - One or more true stress vs. true strain curves (unitless strain, stress in GPa or MPa consistent with elastic_modulus); each curve is supplied as an XY vector pair. * - Elastic Modulus - elastic_modulus - scalar - 210 - ✓ - Young's modulus of the material in GPa (default 210 GPa for steel); used to compute and subtract the elastic strain component from each curve. * - Yield Type - yield_type - scalar - offset - - Method used to locate the yield point: 'offset' (default, 0.2% offset rule), 'effective' (stress at zero plastic strain), 'strain' (fixed strain threshold), 'stress' (fixed stress threshold), 'linearity' (end-of-linear-range), or 'initial_peak_percentage' (fraction of peak-initial-stress strain). * - Yield Strain Or Offset or R2 Limit - yield_strainor_offset - scalar - 0.002 - - Numerical parameter paired with yield_type — for 'offset' this is the offset strain (default 0.002 for steel; use higher values such as 0.02 for polymers); for 'strain'/'stress' modes it is the fixed threshold value; for 'linearity' mode it is the R² limit. * - Post Necking Treatment - necking_treatment - string - none - - Strategy for handling post-necking data: 'none' keeps the curve as-is, 'truncate' removes data beyond the necking point, or an extrapolation/extension method; leave as 'none' when diffuse-necking strain is not a concern. * - Slope For Extrapolation - slopefor_extrapolation - scalar - 0 - - Slope for extrapolation * - Last Strain - last_strain - scalar - 1 - - Last strain value for output curve * - Digitize - digitize - scalar - 100 - - 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 - - * - Saturation Percentage - saturation_percentage - scalar - 0 - - * - 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 Y Monotonicity - 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 * - Remove Intersections - remove_intersections - scalar - no - - Remove intersections before and after converting to effective stress * - Number Of Extrapolation Segments - num_extra_seg - scalar - 1 - - 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 * - Extrapolation Slope - extra_slope_type - scalar - respective - - When extrapolating curves using linear extrapolation, this slope type can determine which slope to use * - Smooth Curve After Conversion - smooth_curve - float - no - - The final hardening curve is smoothed using the selected method to achieve smooth derivative * - How To Treat User-defined Yield - 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 * - curves_truetoeffectivestress_output_1 - curves_truetoeffectivestress_output_1 - vector - Effective (plastic) stress vs. effective plastic strain curves corresponding to each input true stress–strain curve, with elastic strains removed, yield-point correction applied, and post-necking treatment enforced; suitable for direct use as LS-DYNA MAT_24 hardening input. 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=curves_truetoeffectivestress `_ .. raw:: html

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