Parameter Estimation of a Nonlinear Burgers Model using Nanoindentation and Finite Element-based Inverse Analysis

TL;DR

This paper develops a finite element-based inverse analysis method using surrogate models to accurately estimate nonlinear viscoelastic properties of soft materials from nanoindentation data.

Contribution

It introduces a novel nanoindentation-based characterization technique for nonlinear viscoelastic materials using finite element modeling and surrogate model optimization.

Findings

Successful calibration of nonlinear viscoelastic parameters

Optimization of surrogate model for computational efficiency

Enhanced accuracy in material property estimation

Abstract

Nanoindentation involves probing a hard diamond tip into a material, where the load and the displacement experienced by the tip is recorded continuously. This load-displacement data is a direct function of material's innate stress-strain behavior. Thus, theoretically it is possible to extract mechanical properties of a material through nanoindentation. However, due to various nonlinearities associated with nanoindentation the process of interpreting load-displacement data into material properties is difficult. Although, simple elastic behavior can be characterized easily, a method to characterize complicated material behavior such as nonlinear viscoelasticity is still lacking. In this study, a nanoindentation-based material characterization technique is developed to characterize soft materials exhibiting nonlinear viscoelasticity. Nanoindentation experiment was modeled in finite element analysis software (ABAQUS), where a nonlinear viscoelastic behavior was incorporated using user-defined subroutine (UMAT). The model parameters were calibrated using a process called inverse analysis. In this study, a surrogate model-based approach was used for the inverse analysis. The different factors affecting the surrogate model performance are analyzed in order to optimize the performance with respect to the computational cost.