An inverse method applied to the determination of deformation energy distributions in the presence of pre-hardening stresses

Abstract

This paper presents an experimental procedure to estimate the deformation energy distribution within plane samples submitted to mechanical loading. This procedure combined a digital image correlation (DIC) technique giving in-plane displacement fields with an identification method that separately provided fields of material properties and stress distributions developed during the loading. The method was first applied to simulated data to characterize the capabilities of the image processing. Finite element computations were first performed on a complex structure using a standard linear kinematical hardening model to generate multistage loadings leading to heterogeneous displacements and distributions of deformation energy. Loads and displacements were then used as inputs to check the robustness of the image processing by comparing the identified deformation energy fields with the computed ones. The procedure was then applied to experimental data. Tests were conducted under conditions similar to the numerical tests. The identification of a linear kinematical hardening model gave deformation energy patterns showing a good agreement with the simulated results, even in the presence of residual stresses induced by a prehardening.

Deformation studies from in situ SEM experiments of a reactor pressure vessel steel at room and low temperatures

“…The DIC analysis was conducted using KelKins software [27] following the procedures described in [28]. On the acquired images of 2048 by 1768 pixels, the chosen correlation subset size was 60 pixels, the grid spacing was 10 pixels.…”

Correlating bonded joint deformation with failure using a free surface strain field mining methodology

“…an interface crack or porosity), local materials properties (e.g. interfacial fracture toughness, elastic moduli) and failure criteria to predict more realistic stress distributions and joint performance …”

“…interfacial fracture toughness, elastic moduli) and failure criteria to predict more realistic stress distributions and joint performance. [7][8][9][10][11][12][13][14][15][16] From one perspective, bottom-up methodologies have been successful: When models are based on locally measured properties and specific defect configurations, they provide a better match to the experimentally measured behaviour. However, the burden of exhaustive material, specimen and structure characterization effectively limits the applicability of these bottom-up strategies to basic research.…”