Session: 03-11-01: Multifunctional Materials

Paper Number: 151987

151987 - Complex Actuation Response of Functionally Graded High Temperature Shape Memory Alloys 

Shape Memory Alloys (SMAs) are multifunctional materials with various properties useful for aerospace application. Developments of Additive Manufacturing (AM) approaches for SMAs has allowed for greater customizability in regards to the geometry of components. In addition to complex shapes, Functionally Graded (FG) SMAs are another possibility enabled by AM. In this work, NiTiHf FGMs produced via Laser Powder Bed Fusion (LPBF) are studied. The functional grading is achieved through tuning the laser scanning parameters to selectively evaporate nickel, altering the alloy composition and thus the phase transformation response. Thermomechanical modeling is performed to better understand the behavior of the NiTiHf FGMs and inform aspects of the FGM design. First, an SMA constitutive model is calibrated for various constituent NiTiHf compositions which form the FGM. The calibrated material models are then used to predict the component-scale response, the results of which provide key insights towards the experimentally observed phenomena. The NiTiHf properties are extremely sensitive to processing history, which can be highly inconsistent in LPBF due to the large number of impactful factors. Thus, approximation techniques to account for material property variability in the constitutive models are explored. Furthermore, by the very nature of an FGM, there may exist too many compositions to feasibly characterize each individually. To address this, a “generalized parameters” calibration and modeling approach is proposed to account for many alloy compositions while avoiding a large experimental burden. The predictive capabilities of the various models are assessed and the efficacy of the corresponding techniques are examined. Beyond use as a prediction tool, the potential to use modeling as an inverse design tool is also discussed. Furthermore, reduced order modeling is explored as a means to capture the composition-dependent material response, which may be applicable to actuation control.

Presenting Author: Haoyi Tian Texas A&M University

Presenting Author Biography: Haoyi is an aerospace engineering PhD student at Texas A&M University. He is advised by Dr. Dimitris Lagoudas and works on the modeling of shape memory alloys.