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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Bidirectional shape memory device

A resistively heated shape memory polymer device is operated using resistive heating to heat the shape memory polymer device. The resistively heated shape memory polymer device is made by providing a wire that includes a resistive medium. The wire is coated with a first shape memory polymer. The wire is exposed and electrical leads are attached to the wire. In one embodiment the shape memory polymer device is in the form of a clot destruction device. In another embodiment the shape memory polymer device is in the form of a microvalve. In another embodiment the shape memory polymer device is in the form of a micropump. In yet another embodiment the shape memory polymer device is in the form of a thermostat or relay switch.

Marion, III, John E.↗
DOE OSTI2026

Design, characterization and shape recovery behavior of 3D/4D printed shape memory polymers (SMPs)

Shape memory polymers (SMPs) represent a paradigm shift in material science, uniquely capable of undergoing reversible shape transformations triggered by external stimuli, positioning them as pivotal in developing next-generation biomedical devices, aerospace components, and adaptive structures. Extensive research has been done on SMPs with a major focus on high-temperature programming methods, which can limit energy efficiency and applicability with temperature-sensitive materials. Additionally, while various SMP blends have demonstrated great potential, limited work has been done on the suitability for 3D printing these materials, particularly under high-strain and ambient temperature programming conditions. In this study, a three-component optimized SMP composition was evaluated by 3D printing via the Material Extrusion (MEX) technique and investigating its ambient temperature-programming behavior at high strains. The SMP formulation studied was a tailored blend of thermoplastic polyurethane (TPU), polycaprolactone (PCL), and an octadecane diol-based copolymer (OBC) that exhibits robust shape memory behavior, high strain tolerance, and efficient force generation. Rigorous thermal, mechanical, and shape recovery analyses, along with optimized printing parameters and consistent shape recovery rates of up to 90%, were achieved under dynamic mechanical analysis (DMA), even under ambient programming conditions. This work demonstrates the SMP composition’s potential for adaptive, self-deployable systems with 4D printing characteristics ideal for bio-inspired structures and artificial muscle fibers.

Sudan, Kavish [University of Louisville, KY]↗
DOE OSTI2017

In-situ studies on martensitic transformation and high-temperature shape memory in small volume zirconia

Recently, the shape memory effect with significant recoverable shape deformation has been discovered in small volume single-crystal zirconia. The application potential for such shape memory ceramics has spurred in-depth exploration of the martensitic transformation crystallography and high temperature shape memory effect. In this paper, the martensitic transformation of micron-sized zirconia has been studied in both a pristine as-produced condition and after micromechanical compression, using synchrotron scanning micro X-ray diffraction (μXRD). The pristine zirconia was found to transform into the monoclinic phase via a different crystallographic path than the compressed zirconia, resulting in distinct monoclinic variant preferences. The characteristic martensitic transformation temperatures were also found to be higher after uniaxial compression than in the pristine condition. Such observations provide insight on the differences between stress-induced and thermally-induced martensitic transformation. Moreover, we have observed a full cycle of the shape memory effect with large recoverable strain (7%) in micron-sized zirconia at a temperature of 400 °C. Finally, our findings provide an important guideline to tailor the high-temperature shape memory properties of zirconia for further scientific research and engineering applications.

36 MATERIALS SCIENCE↗
DOE OSTI2022

High-temperature superelasticity in NiTiPt and NiTiPd shape memory alloys

Alloying NiTi shape memory alloys with sufficient Pt and Pd at the expense of Ni has been shown to increase transformation temperatures well above those possible with the binary composition, enabling consideration of a new class of high-temperature mechanical sensors and actuators. To achieve shape memory behavior at temperatures greater than 200 °C, previous studies of NiTiPt and NiTiPd compositions have focused primarily on alloys with greater than 16 at.% Pt and 25 at.% Pd. While generally not the focus, none of these previous studies demonstrated superelastic behavior at high temperatures. In an effort to identify alloys that transform to austenite at approximately 200 °C and exhibit superelastic behavior with recoverable strains greater than 2%, a series of Ti-rich NiTiPt ternary alloys with 15.5–16.5 at.% Pt, and Ti-rich NiTiPd ternary alloys with 25–26 at.% Pd have been targeted. The polycrystalline alloys were processed via arc melting followed by homogenization heat treatment. Thermomechanical properties were measured using electro-discharge machined tension test coupons and a miniature load frame equipped with a clamshell furnace. Ultimately, superelasticity in uniaxial tension with clear plateau regions was demonstrated and characterized in these alloys at temperatures between 219 °C and 270 °C.

Massad, Jordan E.↗
DOE OSTI2016

Phase-Change Thermoplastic Elastomer Blends for Tunable Shape Memory by Physical Design

Shape-memory polymers (SMPs) change shape upon exposure to an environmental stimulus.1-3 They are of considerable importance in the ongoing development of stimuli-responsive biomedical4,5 and deployable6 devices, and their function depends on the presence of two components.7 The first provides mechanical rigidity to ensure retention of one or more temporary strain states and also serves as a switch capable of releasing a temporary strain state. The second, a network-forming component, is required to restore the polymer to a prior strain state upon stimulation. In thermally-activated SMPs, the switching element typically relies on a melting or glass transition temperature,1-3,7 and broad or multiple switches permit several temporary strain states.8-10 Chemical integration of network-forming and switching species endows SMPs with specific properties.8,10,11 Here, we demonstrate that phase-change materials incorporated into network-forming macromolecules yield shape-memory polymer blends (SMPBs) with physically tunable switching temperatures and recovery kinetics for use in multi-responsive laminates and shape-change electronics.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Superelasticity and cryogenic linear shape memory effects of CaFe 2 As 2

Shape memory materials have the ability to recover their original shape after a significant amount of deformation when they are subjected to certain stimuli, for instance, heat or magnetic fields. But, their performance is often limited by the energetics and geometry of the martensitic-austenitic phase transformation. We report a unique shape memory behavior in CaFe 2 As 2 , which exhibits superelasticity with over 13% recoverable strain, over 3 GPa yield strength, repeatable stress–strain response even at the micrometer scale, and cryogenic linear shape memory effects near 50 K. These properties are acheived through a reversible uni-axial phase transformation mechanism, the tetragonal/orthorhombic-to-collapsed-tetragonal phase transformation. These results offer the possibility of developing cryogenic linear actuation technologies with a high precision and high actuation power per unit volume for deep space exploration, and more broadly, suggest a mechanistic path to a class of shape memory materials, ThCr 2 Si 2 -structured intermetallic compounds.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Functional Performances of CuZnAl Shape Memory Alloy Open-Cell Foams

Shape memory alloys (SMAs) with cellular structure offer a unique mixture of thermo-physical–mechanical properties. These characteristics can be tuned by changing the pore size and make the shape memory metallic foams very attractive for developing new devices for structural and functional applications. In this work, CuZnAl SMA foams were produced through the liquid infiltration of space holder method. In comparison, a conventional CuZn brass alloy was foamed trough the same method. Functional performances were studied on both bulk and foamed SMA specimens. Calorimetric response shows similar martensitic transformation (MT) below 0 °C. Compressive response of CuZnAl revealed that mechanical behavior is strongly affected by sample morphology and that damping capacity of metallic foam is increased above the MT temperatures. The shape memory effect was detected in the CuZnAl foams. The conventional brass shows a compressive response similar to that of the martensitic CuZnAl, in which plastic deformation accumulation occurs up to the cellular structure densification after few thermal cycles.

36 MATERIALS SCIENCE↗