Conventionally, plastic anisotropy is calibrated by using standard uniaxial tensile and biaxial test results. Alternatively, heterogeneous strain field specimens in combination with full-field measurements can be used for this purpose. As reported by the literature, such an approach reduces the number of required tests enormously, but it is challenging to obtain reliable results. This paper presents an alternative methodology, which represents a compromise between the conventional and heterogeneous strain field calibration technique. The idea of the method is to use simple tests, which can be conducted on the uniaxial testing machine, and to avoid the use of advanced measuring equipment. The procedure is accomplished by conducting standard tensile tests, which are simple and reliable, and by a novel heterogeneous strain field tensile test, to calibrate the biaxial stress state. Moreover, only two of the parameters required for full characterisation need to be inversely identified from the test response; the other parameters are directly determined from the uniaxial tensile test results. This way, a dimension of optimization space is reduced substantially, which increases the robustness and effectiveness of the optimization algorithm.

In designing high-performance, lightweight components, cellular structures are one of the approaches to be considered. The present study aimed to analyze the effect of the infill line distance of 3D printed circular samples on their compressive elastic behavior. Lightweight cellular poly-lactic acid (PLA) samples with a triangular infill pattern were exposed to cyclic compressive loading and their stiffness was investigated. PLA is one of the most commonly used thermoplastic materials in additive manufacturing using the fused filament fabrication (FFF) process. Cylindrical samples with a diameter of 11.42 mm and a height of 10 mm were printed using FFF technology with two different infill line distances (1.6 mm and 2.4 mm). Comparing the nominal compressive stress-nominal strain curves under cyclic loading showed that the first cycle response was significantly different with respect to the subsequent ones. Furthermore, an analysis of the dependence of the modulus of elasticity on the effects of cyclic loading was performed. It was found that through elastic deformation, and combined elastic and plastic deformation, the samples’ properties such as stiffness could be altered.

This paper presents a numerical method for simultaneous optimization of blank shape and forming tool geometry in three-dimensional sheet metal forming operations. The proposed iterative procedure enables the manufacturing of sheet metal products with geometry fitting within specific tolerances (surface and edge deviations less than 0.5 or 1.0 mm, respectively) that prescribe the maximum allowable deviation between the simulated and desired geometry. Moreover, the edge geometry of the product is affected by the shape of the blank and by an additional trimming phase after the forming process. The influences of sheet metal thinning, edge geometry, and springback after forming and trimming are considered throughout the blank and tool optimization process. It is demonstrated that the procedure effectively optimizes the tool and blank shape within seven iterations without unexpected convergence oscillations. Finally, the procedure thus developed is experimentally validated on an automobile product with elaborated design and geometry which prone to large springback amounts owning to complex-phase advanced high strength steel material selection.