NUMERICAL PREDICTIONS FOR AN ANISOTROPIC MATERIAL CONTAINING ELLIPSOIDAL VOIDS AND EXHIBITING TENSION-COMPRESSION ASYMMETRY. Sarvenaz Hashem-Sharifi*, Guadalupe Vadillo Department of Continuum Mechanics and Structural Analysis. University Carlos III of Madrid. Avda. de la Universidad, 30. 28911 Leganés, Madrid, Spain (shashem@pa.uc3m.es , gvadillo@ing.uc3m.es) Key Words: Void growth, Tension-compression asymmetry, Triaxiality, Lode parameter, void orientation, void shape ABSTRACT Ductile fracture at the high triaxiality regime is well known to be controlled by void nucleation, growth, and coalescence. However, under medium and low stress triaxiality values where void growth is limited and shear deformations appear, damage is still not well predicted. Metals and metallic alloys with hcp crystal structure exhibit tension–compression asymmetry in yielding. Despite recent progress in modeling their yield behavior in the absence of voids [1], the description of the coupling between plasticity and damage by void evolution in these materials still remains a challenge. In the present work, we have studied the effect of anisotropy on void evolution for materials that exhibit tension–compression asymmetry. For that purpose, we have performed finite element simulations using a cubic cell with different types of voids inside, ranging from spherical to general ellipsoidal shapes and subjected to periodic boundary conditions. An effective method for controlling triaxiality and the Lode parameter throughout the loading history is provided [2]. The behavior of the matrix material is described by the CPB06 anisotropic criterion developed by Cazacu et al. [1]. The effects of void shape, void orientation, and the strength differential parameter are systematically analyzed and discussed for low and medium triaxiality values. [1] Cazacu, O., Plunkett, B., Barlat, F., 2006. Orthotropic yield criterion for hexagonal closed packed metals. International Journal of Plasticity 22, 1171-1194. [2] Vadillo, G., Reboul, J., Fernández-Sáez, J., 2016. A modified Gurson model to account for the influence of the Lode parameter at high triaxialities. European Journal of Mechanics-A/Solids 56, 31–44.