Uniaxial calibration from engineering stress–strain (tension + compression)
Optimizing...
Overview
This web tool performs parameter identification for incompressible or weakly compressible
hyperelastic material models using uniaxial experimental data provided as
engineering strain and engineering stress.
Supported constitutive models include Neo‑Hookean, Mooney–Rivlin (2‑term and 3‑term),
Ogden models (N = 2 and N = 3), Arruda–Boyce, an Extended Tube formulation, and a
rate‑dependent Bergstrom–Boyce variant.
Model parameters are calibrated by minimizing the discrepancy between experimental
and predicted uniaxial responses using a range of optimization strategies,
including random‑walk pattern search, Nelder–Mead local optimization, and
global or hybrid global‑to‑local approaches.
The tool supports combined fitting of tension and compression data, optional
weighting between datasets, and diagnostic metrics such as separate
goodness‑of‑fit indicators for tension and compression.
Uniaxial Test Data (Tension + Compression)
Option B enabled: sample data loads on start. First real import auto-clears sample once. Later imports append without wiping the other dataset.
Enable datasets for fitting (applies to preprocessing + fit)
Tip: for mixed T+C, keep Auto-zero OFF in preprocessing.
Used in fit & plots
Used in fit & plots
Uniaxial Tension
Engineering strain ε ≥ 0
Engineering Strain
Stress
Uniaxial Compression
Engineering strain ε ≤ 0 (must be > −1)
Engineering Strain
Stress
Excel/CSV import
Import and clears sample data.
Columns: importer auto-detects headers containing “strain” and “stress”; otherwise uses the first two columns.
Data Processing
Binning is disabled when Mullins is enabled or a path-dependent model is selected (history must be preserved).
Raw vs Cleaned Data
Blue = tension, Red = compression (cleaned). Grey tones = raw.
Solver Settings
Weight
Weight
Total point-weight = (error weighting) × (tension/compression weight). Set weight=0 to ignore a dataset.
Everyiters/gen
Idle.
Mullins affects unloading/reloading only. For monotonic data it often stays inactive.
Optimized Parameters
R² (All) — diagnosticN/A
R² (Tension) — diagnosticN/A
R² (Compression) — diagnosticN/A
Same fitted parameter set; R² is computed on subsets only for reporting.
Blue = Best-so-far, Green dashed = Current candidate. Experiment points are split: orange (tension) and purple (compression).