Assessing model form uncertainty in fracture models using digital image correlation

Today, in aerospace and automotive industries, structural components are more and more designed up to their functional limits, pursuing weight minimization without compromising the mechanical integrity. Especially in the aforementioned domains, the fracture behavior is of utmost importance in this respect. Yet, due to the complexity of the underlying physical phenomena and corresponding models, taking fracture into account in a virtual design process still proves to be highly challenging. Nevertheless, in recent years, there has been a strong development in various numerical simulation techniques that can simulate crack initiation and growth, i.e. techniques such as the Extended Finite Element Method (XFEM), Meshless Methods as the Element Free Galerkin Method (EFG) or the Phase Field Fracture (PFF) modeling approach. In this paper, the objective is to examine to what extend these approaches are applicable in a design context by assessing their relative value regarding validity and uncertainty. Also, some numerical aspects regarding efficiency and stability are discussed. The work is based on the study of a specific case. First, standard compact tension experiments are performed. These results are used to identify the necessary material properties and associated parametric uncertainty levels for each of the considered fracture modelling approaches. Next, a validation study is performed in which stereo Digital Image Correlation (DIC) is applied during the actual crack propagation phase in the same compact tension test. The model form uncertainty is assessed by comparing the set of DIC full field displacement and strain measurements with the range of the numerical predictions including uncertainty of the different modelling strategies.

ISBN:978-3-030-48778-2

Jaar van publicatie:2020