The Identification Method Research Of TRB’s Material Parameters

At present, the requirements of automobile lightweight increase urgently. New processing technologies and new lightweight structures have appeared. Among those new processing technologies, the flexible rolling technology has a rapid development. The so called flexible rolling technology is a method which can obtain variable thickness blanks at different parts by control the gap between rollers to really realize customization.The TRB(Tailor Rolled Blank,TRB) possess some advantages such as: rational distribution of the material、material performance without mutation、TRB can realize personal customization and so on, but it still have some problems. Among them, the identification method for material parameters of TRB is always a hot research piont for reachers. In order to discuss the identification methods, this paper carried out the following research works:(1) Firstly, taking example by stander tensile test specimens, design tensile test specimens for TRB, then based on this specimen, combining the special geometry of TRB’s transition region, a special specimen which has a same sectional area has completed. After this, using DIC technology, we made a comparison between the two styles specimens, including the full field strain and the fracture location.(2) The uniform thickness area of TRB is larger than the transition region, taking this piont into consideration, the tensile test on uniform thickness area were done to obtain the different stress strain curve then interpolate those curves using lagrange interpolation method, in this way, the three dimension stress strain surface is established. In addition, proposed a harding model for different curves, this model includes a initial strain which have a relationship with blank thickness information. This model is suitable for different curves. Note that, this model contain a parameter, so the optimization of this parameter is also to be done.(3) Specific to TRB’s anisotropy, this paper also proposed a material parameter inverse method, including Micro-indentation test、the finite element model of it and parameter optimization theory. During the Micro-indentation test, three curves from three different planes is to be analyzed. The planes are the plane normal along the thickness direction(Th D), the plane along transverse direction(TD) and the plane normal along the rolling direction(RD). The difference between those curves illustrate the TRB’s anisotropy. The FEM part mainly introduced the influence of boundary conditions and friction. Multi-objective genetic algorithms and surrogate model are studied in parameter optimization theory. In order to validate the accuracy of this method, the pseudo test and tensile test also to be done. Through certification, the result shown that the method mentioned in this paper have a higher precision, can be applied to engineering.