In situ laminography investigating damage evolution and strain heterogeneity during plane strain tension loading and non-proportional loadin

The aim of this study is to identify the deformation and damage interactions of aluminium alloy sheets under plane strain tension conditions for different microstructures. Plane strain tension conditions are identified as critical in forming processes as early localization and the lowest deformation at fracture are found under these conditions. Using flat samples with local thickness reductions, the plane strain state can be achieved. In contrast to tomography, in situ laminography allows the evolution of the microstructure and damage as well as strain (via image correlation techniques) to be studied in the plane strain tension zone. In addition, the role of pre-strain on failure in plane strain tension will be investigated by performing a load path change on a newly designed sample. The role of crystallographic texture, obtained by complementary EBSD, on strain heterogeneity and localization followed by damage and failure will be further investigated by simulations.

本研究旨在明确不同微观结构下铝合金板材在平面应变拉伸条件（plane strain tension conditions）下的变形与损伤相互作用。平面应变拉伸条件在成形过程中被认为至关重要，因为在此条件下会出现早期局部化现象以及断裂时的最小变形量。通过使用局部厚度减薄的扁平试样，可实现平面应变状态（plane strain state）。与断层扫描（tomography）相比，原位层扫技术（in situ laminography）能够在平面应变拉伸区域研究微观结构、损伤及应变（通过图像相关技术（image correlation techniques）测量）的演化过程。此外，通过对新设计的试样进行加载路径改变，将研究预应变（pre-strain）在平面应变拉伸失效中的作用。通过互补的电子背散射衍射（EBSD）获得的晶体学织构（crystallographic texture）对应变异质性（strain heterogeneity）、应变局部化（localization）及其后续损伤与失效的作用，将通过模拟进一步研究。