Variability Analysis of the Mechanical Parameters in order to Determine the Forming Limit Band

摘要

The variability of the so called noise factors greatly influences the results of any forming process (deep-drawing, stretching, etc.). By taking into account this variability, the number of the rejected parts and the manufacturing costs will decrease. The aim of this work is to evaluate the variability of the mechanical parameters of a DC04 steel sheet (0.85 mm thickness). The experimental data needed for evaluating the variability of the mechanical parameters has been obtained from uniaxial tensile tests. A total number of 113 experiments have been made using samples cut at 0 deg, 45 deg and 90 deg with respect to the rolling direction. In this way, the yield stress and the plastic anisotropy coefficient have been determined for each of the orientations mentioned above. The power hardening law offers the possibility to study the variability of the following parameters: yield stress, strength coefficient and strain-hardening exponent. Based on the dispersion of the stress-strain curves, the mechanical coefficients of the Swift hardening law have been determined using a new method. The input parameters exhibiting the most important influence on the scattering of the forming limit diagram have been also established. Finally, in order to determine the Forming Limit Band (FLB), a Monte-Carlo analysis (MCA) has been performed using values and correlations between the mechanical parameters.