8/25/2025 Taylor Parks
Written by Taylor Parks
MechSE Professor Huseyin Sehitoglu has won a four-year grant from the National Science Foundation’s Division of Materials Research to analyze shear-related failure of shape memory materials—i.e., nickel titanium alloys that can experience reversible transformations.
Under load or through the removal of load, shape memory materials experience shifts between two lattice structures—austenite (original shape) and martensite (shape when stretched). Under cyclic loading over time, these materials can sustain irreversible deformations that lead to compromised performance and durability.
Given that reversible transformation is an important characteristic for applications such as cardiovascular stents, which can expand and contract with changes in body temperature, as well as structural dissipation under impact, and actuators for motion control including those used in space, there is a need to continually improve the performance and long-term endurance of these materials.
“Their performance matters under repeated actuation because fatigue can occur with repeated temperature changes and stress cycling,” Sehitoglu said. “The improvement in performance can occur by minimization of high internal stresses to minimize cracking while developing large displacements to fulfill their function.”
Sehitoglu’s research lab has continually contributed to the field’s understanding of phase transformations in metals including shape memory alloys. For this grant, he will work with in-situ loading stages at the Materials Research Laboratory with the goal of learning how to mitigate irreversible deformations via compositional modifications, the introduction of precipitates, and modified crystal lattices.
“In the first year of the grant, our aim is to understand how internal arrangements of interfaces within the shape memory material intersect and form potential defects that shed light into the performance of these materials,” he said. “We will analyze diffraction patterns obtained from simulations with experimental patterns to confirm the validity of our models.”
This semester, Sehitoglu will also advise a Senior Capstone Design (ME 470) team focused on using a new desktop fatigue machine to test nickel titanium wires under cyclic loading conditions.
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Huseyin Sehitoglu holds the John, Alice, and Sarah Nyquist Endowed Chair. He serves as Director of the Fracture Control Program and Chief Editor of the journal Shape Memory and Superelasticity.
His NSF-funded study is “Scientific Understanding of Interfaces in Transforming Materials.”