Determination of effective elastic properties of ferritic ductile cast iron by computational homogenization, micrographs and microindentation tests

A micro-mechanical analysis of thermo-elastic properties and local residual stresses in ductile iron based on a new anisotropic model for the graphite nodules

“…The main problem in this case is the choice of suitable values for the elastic constants, especially Young's modulus, which is usually taken in the range 4-25 GPa [6]. These values are macroscopically consistent in the sense that they allow recovering the global elastic properties of ductile iron according to common micromechanical homogenization procedures [14]. Furthermore, they are also in fairly 3 good agreement with nano-indentation tests [15] [16] performed according to the OliverPharr method [17].…”

Genetic Algorithm-Based Optimization Methodology of Bézier Curves to Generate a DCI Microscale-Model

“…This effect can be explained as the system represented in Equation (2) becomes indeterminate as the curve degree used is greater than the number of points that the contour has, generating spurious Table 1 shows the generated models, where geometric evolution it can be seen as the Bézier curve degree increases. In relation to the models obtained using a fixed Bézier curve degree for all of the nodules, it can be seen that the curves that are obtained with Bézier degrees of 4 are curves with high CSF est values and high E r values, therefore do not approximate adequately to the geometry of the digital contours; on the other hand, as the curve degree increases (degree 10), the curves approximate to the contours obtained digitally preserving the smoothness that characterizes them, unlike the models that are obtained with commercial img2CAD software and the models that are obtained by another methodologies [11,14,16], where no smooth algorithms has been applied.…”

“…Table 1 shows the models obtained from four nodules (A, B, C and D) using the three different methods mentioned, besides the CSF est and E r values for each graphite nodule are shown, where the maximum errors are highlighted in bold. Regarding the models that are generated using a fixed Bézier degree for all the nodules, three different models were created with the following degrees: 4, 10, and 18. high CSFest values and high Er values, therefore do not approximate adequately to the geometry of the digital contours; on the other hand, as the curve degree increases (degree 10), the curves approximate to the contours obtained digitally preserving the smoothness that characterizes them, unlike the models that are obtained with commercial img2CAD software and the models that are obtained by another methodologies [11,14,16], where no smooth algorithms has been applied. Table 1.…”

“…The behavior of both these phases, the ferritic matrix and the graphite, was considered as isotropic. The values of the Young's modulus of the graphite and the ferritic matrix used were 15 GPa and 235 GPa, respectively, and the Poisson ratio of 0.28 for both of the phases [16]. The geometric models were discretized by means of solid tetrahedral elements, which are the basic three-dimensional elements that are used by the abovementioned software, producing a total number of 88658 elements.…”

“…In this context, there is the work of Kasvayee et al [14], which studied the distribution of strains that were produced in a tensile test of a DCI, when comparing finite element simulation and measurements by digital image correlation, in their work they used real micrographs to produce their models. Another work is that of Fernandino et al [16], in which it was developed a methodology for predicting the elastic behavior of a DCI using multi-scale analysis. The procedure combines computational techniques for FEA, micrographic analysis to generate FEA models, and micro-indentation tests to identify the elastic behavior of the different phases of the microstructure.…”