Can Anisotropy Contribute to Tuning Thermal Expansion of Titanium Alloy Structures?

Titanium alloys are widely adopted in aerospace applications owing to their exceptional strength-to-weight ratio. Consequently, their operation in extreme thermal environments, ranging from cryogenic to high temperatures, makes controlling thermal expansion critical for maintaining structural integrity. This study introduces a multiscale computational framework to predict and tailor the thermal expansion behavior of Ti–7Al alloy for thermally stable aerospace components. First, single-crystal thermal expansion coefficients are evaluated through molecular dynamics simulations. To capture the macroscopic response of this hexagonal close-packed (HCP) alloy, a numerical homogenization approach is developed by integrating these single-crystal characteristics with an orientation-dependent microstructure formulation. The orientation dependence induces anisotropy, represented through a thermal stiffness matrix that quantifies the direction-dependent behavior. Using this framework, a formulation is proposed to obtain the closure, showing all possible values of thermal expansion coefficients of the alloy. Subsequently, the approach is applied to two representative aerospace components, a combustion chamber cross-section and a turbine blade segment, under property constraints derived from the closure framework, to maintain uniform strain and retain the original shape over a wide temperature range. Comparative analyses between the baseline and optimized structures highlight the role of anisotropy in tailoring properties and demonstrate the preservation of original shapes.