1. Introduction
Polycrystalline materials dominate industrial and technological applications due to their ubiquitous existence, low-cost and ease of manufacturing. During the sheet metal operations, e.g. bending, stamping, drawing and stretching, among the various possible modes of failure, such as wrinkling, scoring, the tearing of a polycrystalline sheet metal is the most common, resulting from an uneven or exorbitant amount of plastic deformation forming a localized neck and therefore limiting the formability of the polycrystalline sheet metal. In the sheet-metal forming industry, it is therefore, of high importance that the failure of metal sheets due to localized necking must be analyzed. In 1963, a breakthrough in formability assessment …show more content…
Hence, the theoretical methods are preferred and a significant amount of research has been already done to characterize the formability of a sheet metal using various computational models. In the available theoretical methods for obtaining FLD of a sheet metal, the response of a material deforming plastically is obtained either using the continuum theory (macro scale) of plasticity or using the theory of crystal plasticity (meso scale) and a separate plastic instability criterion is employed to predict the limiting strains. The formability and mechanical properties can be improved by regulating the texture during thermo-mechanical processing of a sheet metal and this can be achieved by having an efficient theoretical model that can illustrate the evolution of texture for multiaxial deformation paths. It is widely recognized that the deformation-induced texture and anisotropy strongly affects the localization of plastic flow (Barlat, 1987; Zhou and Neale, 1995; Tóth et al., 1996; Wu et al., 1997;Boudeau et al., 1998; Boudeau and Gelin, 2000; Tang and Tai, 2000). Since, the continuum theory of plasticity does not account for texture evolution during deformation of a polycrystalline sheet metal, crystal plasticity (CP) based models are needed for a more objective …show more content…
This rate tangent based ACP-FFT methodology, has been verified, validated and is presented in detail, is published elsewhere [reference]. The proposed model accounts for the grain to grain interactions, intragranular texture evolution, grain morphology and provides full field solutions to micromechanical fields within reasonable computational times. In this implementation, effect of grain morphology on predictions of FLD for a FCC polycrystalline material is studied in detail. To our knowledge, this effect is studied for the first time using a full-field, FFT-based CP model and since this proposed methodology is able to capture the vital microstructural effects, a significant improvement in predictions of FLD for aluminum alloys has been achieved over the Taylor based M-K model. The plan of this paper is as follows: In section 2, the details of the accelerated CP-FFT model and the M-K method are presented. In section 3, we present the FLD predictions for AA5754 at room temperature (25 0C) and FLD of AA3003 at 25 0C, 200 0C and 250 0C respectively, for linear strain paths using the proposed methodology and compare these results with those obtained from CP-Taylor based M-K model as well as with the corresponding measured FLDs. In section 4, we
Polycrystalline materials dominate industrial and technological applications due to their ubiquitous existence, low-cost and ease of manufacturing. During the sheet metal operations, e.g. bending, stamping, drawing and stretching, among the various possible modes of failure, such as wrinkling, scoring, the tearing of a polycrystalline sheet metal is the most common, resulting from an uneven or exorbitant amount of plastic deformation forming a localized neck and therefore limiting the formability of the polycrystalline sheet metal. In the sheet-metal forming industry, it is therefore, of high importance that the failure of metal sheets due to localized necking must be analyzed. In 1963, a breakthrough in formability assessment …show more content…
Hence, the theoretical methods are preferred and a significant amount of research has been already done to characterize the formability of a sheet metal using various computational models. In the available theoretical methods for obtaining FLD of a sheet metal, the response of a material deforming plastically is obtained either using the continuum theory (macro scale) of plasticity or using the theory of crystal plasticity (meso scale) and a separate plastic instability criterion is employed to predict the limiting strains. The formability and mechanical properties can be improved by regulating the texture during thermo-mechanical processing of a sheet metal and this can be achieved by having an efficient theoretical model that can illustrate the evolution of texture for multiaxial deformation paths. It is widely recognized that the deformation-induced texture and anisotropy strongly affects the localization of plastic flow (Barlat, 1987; Zhou and Neale, 1995; Tóth et al., 1996; Wu et al., 1997;Boudeau et al., 1998; Boudeau and Gelin, 2000; Tang and Tai, 2000). Since, the continuum theory of plasticity does not account for texture evolution during deformation of a polycrystalline sheet metal, crystal plasticity (CP) based models are needed for a more objective …show more content…
This rate tangent based ACP-FFT methodology, has been verified, validated and is presented in detail, is published elsewhere [reference]. The proposed model accounts for the grain to grain interactions, intragranular texture evolution, grain morphology and provides full field solutions to micromechanical fields within reasonable computational times. In this implementation, effect of grain morphology on predictions of FLD for a FCC polycrystalline material is studied in detail. To our knowledge, this effect is studied for the first time using a full-field, FFT-based CP model and since this proposed methodology is able to capture the vital microstructural effects, a significant improvement in predictions of FLD for aluminum alloys has been achieved over the Taylor based M-K model. The plan of this paper is as follows: In section 2, the details of the accelerated CP-FFT model and the M-K method are presented. In section 3, we present the FLD predictions for AA5754 at room temperature (25 0C) and FLD of AA3003 at 25 0C, 200 0C and 250 0C respectively, for linear strain paths using the proposed methodology and compare these results with those obtained from CP-Taylor based M-K model as well as with the corresponding measured FLDs. In section 4, we