Prediction of Yield Surface and Hysteresis Loop for Cyclic Mechanical Loading for Laser Powder Bed Manufactured Ti6Al4V R. Venkateshwaran∗, L. Ladani School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, 85281, USA ∗ vravinar@asu.edu Keywords: Hill Anisotropy, Cyclic Hardening, Titanium Alloy. Ti-6Al-4V is one of the most common alloys used in jet engines and other aerospace applications. In many of these applications, material is subject to cyclic mechanical loading. However, manufacturing parts made from this alloy using conventional methods such as forging or cutting is a difficult task. Recent work in additive manufacturing offers a convenient way for such parts to be manufactured with relative ease as well as less wastage [1]. Selective Laser melting, powder bed fusion process is one such robust technique. This study intends to define a mathematical model which can be used for predicting the cyclic plastic deformation and subsequent cyclic hardening behavior of a Ti6Al4V material made using laser powder bed process subjected to cyclic loading. The model will consider anisotropic behavior of additively manufactured titanium alloy as well as both isotropic and kinematic hardening behavior. The anisotropy in the material properties is incorporated with the help of Hill Yield Criteria [2]. Combined isotropic and kinematic hardening behaviors are modeled using Voce’s Non-Linear isotropic hardening model as well as Chaboche’s Kinematic hardening model [3],[4]. Equations from the two models are combined with the Hill 48 criteria to develop an equation which predicts the yield surface of the complex anisotropic behavior combined with isotropic and kinematic hardening. This yield surface is then plotted for a few different loading conditions. This combined model is then used for prediction of the hysteresis loops for the same loading conditions which can then be utilized for predicting the life of the sample. References [1] Agius, Dylan, et al. “Efficient Modelling of the Elastoplastic Anisotropy of Additively Manufactured Ti-6Al-4V.” Additive Manufacturing, vol. 38, 2021, p. 101826–. [2] Hill, R. (1983). The Mathematical Theory of Plasticity. New York: Oxford University Press [3] Chaboche, J. L. (1989) Constitutive equations for cyclic plasticity and cyclic viscoplasticity. International Journal of Plasticity. 5(3), 247-302. [4] Chaboche, J. L. (1991). On some modifications of kinematic hardening to improve the description of ratchetting effects. International Journal of Plasticity. 7(7), 661-678. 53
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