Implementation and Evaluation of the Virtual Fields Method: Determining Constitutive Model Parameters From Full-Field Deformation Data.

Abstract

The Virtual Fields Method (VFM) is an inverse method for constitutive model parameter identification that relies on full-field experimental measurements of displacements. VFM is an alternative to standard approaches that require several experiments of simple geometries to calibrate a constitutive model. VFM is one of several techniques that use full-field experimental data, including Finite Element Method Updating (FEMU) techniques, but VFM is computationally fast, not requiring iterative FEM analyses. This report describes the implementation and evaluation of VFM primarily for finite-deformation plasticity constitutive models. VFM was successfully implemented in MATLAB and evaluated using simulated FEM data that included representative experimental noise found in the Digital Image Correlation (DIC) optical technique that provides full-field displacement measurements. VFM was able to identify constitutive model parameters for the BCJ plasticity model even in the presence of simulated DIC noise, demonstrating VFM as a viable alternative inverse method. Further research is required before VFM can be adopted as a standard method for constitutive model parameter identification, but this study is a foundation for ongoing research at Sandia for improving constitutive model calibration.

Extracting Constitutive Mechanical Parameters in Linear Elasticity Using the Virtual Fields Method Within the Ordinary State-Based Peridynamic Framework

“…This could be different with other virtual fields. Also, it should Influence of missing data: the black line shows the linear regression between the residual Φ with respect to the missing distance around the specimen be noted that the bulk modulus K is more sensitive to Gaussian noise than the shear modulus G. The conclusion from this noise analysis is similar that presented in [34], in which the VFM is applied within CCM.…”

Experimental and numerical fatigue assessment of duplex welded transversal stiffeners

“…This technique was at first exclusively used in material sciences, but lately is also becoming popular in structural engineering [65,66]. Presently, the processing of the measured data is performed using the virtual fields method (VFM) [67,68]. DIC proved robust for cases where strain concentrations due to change in geometry of weld beads exist.…”

Calibration of elastoplastic constitutive model parameters from full‐field data with automatic differentiation‐based sensitivities

“…We will not discuss VFM further, save to say it has been used to calibrate parameters in finite deformation elastoplastic constitutive models. [19][20][21][22][23][24][25] In FEMU, an objective function that quantifies the weighted mismatch between model predictions and corresponding experimentally measured quantities of interest is minimized by iteratively updating the parameters of a FE model using an optimization algorithm. A basic objective function contains data from load-displacement curves, but more sophisticated objective functions employ full-field displacements or strains obtained from DIC.…”