Physics-based strain pre-extrapolation technique for inverse Finite Element Method

Abstract

The inverse Finite Element Method (iFEM) is a model-based technique for the structure’s displacement field computation, based on an optimized strain sensor network. In real applications, sensors cannot be applied to the whole structure due to practical constraints and limitations. In this context, strain pre-extrapolation techniques can predict the strain value where physical sensors are not available, but the sensor network must well describe the strain pattern on the whole structure. However, if sensors are located far from local discontinuities, the strain field will be no more correctly pre-extrapolated, resulting in a wrong displacement field reconstruction. The present work presents a physics-based strain pre-extrapolation, where the physical knowledge of the discontinuity, together with its analytical stress formulation, supports the pre-extrapolation technique and thus the iFEM field reconstruction. The particular cases of a hole in a plate and a hole in a strip are considered in four numerical case studies with increasing complexity, always providing significative result’s improvement with respect to the previous state-of-the-art pre-extrapolation technique.