An indentation-based technique to determine in-depth residual stress profiles induced by surface treatment of metal components

Abstract

A B S T R A C T A novel identification methodology is introduced in this paper for determining the residual stress profile induced into metal components by hardening surface treatments. The procedure is based on the indentation test, performed at different maximum penetration depths, supplemented by the numerical simulation of the experiment and by inverse analysis. Several provisions increase the effectiveness and diminish computing times and costs of the proposed identification tool, in view of its intended practical and repetitive use in industrial environments. In particular, a parametric analytical description of the expected residual stress profile reduces the number of unknowns, while an interpolation technique based on radial basis functions replaces most numerical analyses, to be otherwise performed by finite elements. The robustness of the proposed methodology is improved by the consideration of a proper orthogonal decomposition technique. The reliability of the results provided by the present approach is verified against the simulation of the test based on some available experimental data.

An effective computational tool for parametric studies and identification problems in materials mechanics

“…During the test, the force exerted on the tip is monitored versus the corresponding penetration depth. The deformed configuration of the specimen surface can be mapped after the removal of the indentation apparatus and this information can be exploited to parameter identification purposes as shown, e.g., in [23,24,[38][39][40][41][42]. The simulation of the test can be carried out by the FE method, taking into account the non-linear effects associated with large plastic deformations and frictional contact, besides the non-linear material response.…”

“…This is done with specific reference to loadingunloading cycles of simple components, having in mind common experimental setting for material calibration purposes [20,21,[38][39][40][41][42]. However, the outcome of the present study can be easily generalised to many other meaningful engineering situations requiring to perform repetitive non-linear analyses of solids and structures.…”

“…For some application, in fact, the snapshot matrix may even consist of only experimental data, if these are available in a sufficient number, as in [26]. POD is profitably combined with radial basis function (RBF) interpolation [36][37][38], which returns an effective and accurate analytical representation of the system response for varying input parameters. RBFs allow the knot points of the interpolation to be randomly distributed in the region of interest, thus permitting to overcome the limitation of a box-shaped search domain and to include a large number of variables.…”

An inverse analysis approach based on a POD direct model for the mechanical characterization of metallic materials

“…In the present paper, the identification of the material parameters is carried out by combining, through inverse analysis, experimental data obtained from the indentation curve and pile-up of the imprint geometry, with a computationally economical, 'a priori' calibrated, finite element model reduction procedure, based on the Proper Orthogonal Decomposition (POD), as described in [17]. The latter is required to avoid the computational demand and possible convergence problems of running standard finite element simulations for the direct analyses.…”

Material model calibration through indentation test and stochastic inverse analysis

“…Recently the use of computational methods through 'inverse analysis' has been gaining popularity and is a subject of vast literature (see e.g. [2,3,4]). In this concept, the test is simulated, traditionally by the use of Finite Element Modeling (FEM), while the results of simulation are compared to those measured in the experiment in the form of a 'discrepancy function'.…”