A numerical methodology to design heterogeneous mechanical tests

• Design of a mechanical test able to characterize the material behavior under several stress and strain paths and amplitudes.
• Optimization methodology for specimen initial shape as well as loading path conditions.
• Finite element analysis with a virtual material derived from experimental data.
• A one-step optimization procedure by using rigid tools.
• A sequential incremental optimization technique considering local displacements.

Today, the constitutive behavior of a material is analyzed by means of mechanical tests and, consequently, reproduced using numerical models adjusted to each material through parameters. With the development of full-field measurement methods, recent material parameters identification strategies take advantage of the use of heterogeneous tests. Generally, the development of such mechanical tests is made by trial-and error approaches. In the present work, an innovative numerical optimization process for the design of heterogeneous tests is presented. The main goal is the design of a mechanical test able to characterize the material behavior of thin metallic sheets under several strain paths and strain amplitudes. Two different optimization approaches were proposed, namely (i) a one-step procedure designing both specimen shape and loading path by using rigid tools and (ii) a sequential incremental technique designing the specimen shape and the loading path of the specimen considering local displacements. The obtained results revealed that the numerical methodology proposed is capable for designing a single experiment able to fully characterize the several stress states encountered in sheet metal forming processes.