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Superelastic Adaptive Alloy Could Improve the Success Rate of Childhood Scoliosis Treatment

Dr. Ji Ma with a sample of growing rod developed with the adaptive alloy technology at the Microstructural Engineering of Structural and Active Materials (MESAM) laboratory

Scoliosis is typically defined as the curvature of the spine, which in severe cases can lead to severe physical deformity in addition to pulmonary and cardiac problems. Early-onset scoliosis refers to spine deformity that is present before 10 years of age.

Children with early-onset scoliosis often spend their entire childhood undergoing several surgical procedures to correct the curve in their spine. Surgeons implant metallic growing rods in the spine and expand them in bi-annual surgeries to keep up with the child’s growth. As the body moves, the screws attaching the rods to the bone become loose, increasing the chances of additional complicated surgeries to keep the rod in place.

Dr. Ji Ma, Texas A&M Engineering Experiment Station assistant research scientist, and Dr. Ibrahim Karaman, Chevron Professor I and head of the Department of Materials Science and Engineering at Texas A&M University, have designed a growing rod material that can significantly reduce the complications from corrective surgeries.

The material, a superelastic adaptive alloy, is five times more flexible than any currently available growing rod implants. It allows natural movement of the body and adjusts itself depending on the stress applied by the growing spine. This could potentially improve the success rate of the treatment.

Materials composing the implant are required to be biocompatible, fatigue and corrosion resistant, and they have to be compatible with the biomechanical environment of the patient’s body and the bone.

The bone is a living tissue that responds to the change in forces that arise once an implant is mechanically fixed to the skeleton. Unfortunately, the large mismatch between the mechanical properties of the metallic implants and the bone frequently result in complications, such as implant loosening, bone atrophy from stress shielding, and bone disease near implant extremities. These problems become increasingly important in young patients with osteoporotic or immature bones, where implant-related complication rates are markedly higher, the researchers say.

Using a series of thermo-mechanical processing steps, Ma and Karaman engineered a new titanium shape memory alloy. It possesses stress-dependent elastic properties that gradually decrease as the stress on it is increased.

“By modifying these properties to fit the biomechanical environment of the bone, it is now possible to create a device that satisfies the seemingly conflicting requirements of rigidity and flexibility required in growing rods,” said Ma.

The adaptive alloy allows growing rods to bend at the ends and stay stiff in the middle giving the necessary support to the spine. The patient’s natural movements stay flexible due to reduced friction and stress.

“This is not something you can do with all materials,” said Ma. “We preserve the strength and add flexibility to the implants without compromising the mechanical properties.”

Karaman’s National Science Foundation grant, “Design and In-vitro Characterization of Ni-free Biocompatible Shape Memory Alloys,” led to the present-day technology and its application in early onset scoliosis treatment. The researchers set out to develop a titanium-niobium alloy as an alternative to nickel titanium shape memory alloy since it has better biocompatibility and corrosion resistance similar to the human bone.

They later found evidence that nickel titanium alloy offered the same properties as the titanium niobium alloy. Currently, they are using both the alloys as candidates for the application in growing rods. The adaptive alloy is designed to have bio-inert constituents, less sensitivity to impurities and inclusions, better corrosion resistance, more stable fatigue response and predictable fatigue life.

Ma and Karaman are now working with Dr. Dennis Devito at Children’s Orthopedics of Atlanta to get a surgeon’s perspective on effective application of the technology.

“All children experience at least one complication during their treatment,” said Devito. “Ma and Karaman’s research offers a potential solution to some of the complications.”

The researchers have begun to commercialize the adaptive alloy technology. In 2015, they co-founded Adallo, LLC with Eric Flickinger, CEO at Meditech Spine LLC to develop prototype testing.

This story was originally posted on Texas A&M’s Department of Engineering’s website. Provided is the link:


Students Get First Place in CASMART Student Design Challenge

A group of undergraduate students from the Department of Aerospace Engineering at Texas A&M University won the Consortium for the Advancement of Shape Memory Alloy Research and Technology (CASMART) Student Design Challenge. Cullen Eckhert, Kelli Pickett, Hannah Stroud, Kanika Gakhar and Tyler Fink were under the direction of graduate mentors Robert Wheeler and Robert Saunders, as well as faculty advisors Dr. Dimitris Lagoudas and Dr. James Boyd.

The challenge was intended for undergraduate and graduate students working with CASMART faculty advisors to consider innovative approaches to developing design tools and hardware using shape memory alloy (SMA) technology. Students had the opportunity to showcase their creativity by applying engineering theories and methods they’ve learned, using engineering design principles, and leveraging CASMART members’ experience to address SMA design challenges in the automotive, aeronautics and space industry.

The goals for this group were to design a lightweight and efficient deployment device for a solar array and to fabricate a proof of concept or prototype. Each of the undergraduates worked on solving a specific engineering problem, ranging from a thermal analysis of a satellite in a given orbit to vibrational analysis during launch conditions to the design and operation of a solid state actuator. Each reported on their progress every week during a group meeting.

Every two weeks, the students worked on a different facet of the overall design and developed the necessary tools.

“Overall, the students performed very well and quickly developed their problem solving capabilities by tackling real problems on a weekly basis,” said Wheeler. “As the semester progressed, they also learned how the different requirements or operating conditions can lead to unexpected design implications, as the design of each part affected the system as a whole.”

The design was completed during the spring 2015 semester. During the summer 2015 semester, one of the students, Eckhert — funded through the NSF REU program — worked with Wheeler to build the proof of concept or prototype.

Wheeler presented the completed project at the Smart Materials, Adaptive Structures and Intelligent Systems (SMASIS) conference in September. The group also published a conference paper, “Design of a Reconfigurable SMA-Based Solar Array Deployment Mechanism.” The judges for the competition included senior researchers from Boeing, NASA Glenn, NASA Langley, Sandia National Labs and General Motors.

Wheeler will be taking the work and developing a set of design tools with the CASMART group to allow for future designs of SMA-based actuation systems.

CASMART was established to promote the growth and adoption of SMA actuation technologies by achieving new understanding of the materials, fostering dissemination of technical knowledge and facilitating application of that knowledge. The consortium was initiated in 2007 by Boeing, NASA Glenn, NASA Langley and Texas A&M. More than 16 other organizations have joined to advance the state of the art for SMA technology through a synergy of academic, industry and government expertise.

This story was originally posted on Texas A&M’s Department of Engineering’s website. Provided is the link:


Consortium for the Advancement of Shape Memory Alloy Research and Technology

January 14, 2016
Source: ASM International

SMST recently teamed up with a small international organization of leading players in the SMA actuation field known as CASMART (Consortium for the Advancement of Shape Memory Alloy Research and Technology). CASMART was established in 2006 by government, university, and industry participants to promote the growth and adoption of SMA actuation technologies.

While the group was initially focused on the aerospace sector, it has broadened its scope to SMA-based actuation across industries and includes all aspects of SMA material to application development. CASMART technical work has focused on the intersection of four areas: fundamental technology development, alloy development, material/system modeling, and SMA actuation design and applications.

SMST and CASMART share similar goals, in particular furthering SMA technology and disseminating relevant technical work on materials with shape-memory properties. CASMART seeks to achieve new understanding of the SMA materials, foster dissemination of technical knowledge, facilitate application of that knowledge, and work toward commercialization of the technology.

Specific objectives of CASMART:

—Share applied research supporting Shape Memory Alloy Actuator applications, including material development, tools, processes, and system-level development.

—Provide a forum for exchange of ideas and strengthen collaborations—Promote SMA actuator technology within field and influence professional societies and research

—Propose challenges that push state of the art—Develop SMA actuation test standards

—Promote commercialization of current and future alloys, supporting technologies, and applications

In recent years, CASMART activities have included publishing papers on SMA actuation design and modeling methods, identifying best practices for shape memory effect characterization, and exploring high-temperature SMAs, particularly the NiTiHf material system. In 2015 CASMART initiated a student design challenge focused on exploring SMA actuator design tools to facilitate solutions to three proposed problems. The challenge led to innovative designs for deployable solar cells, automotive vents, and jet engine thermal management. Students presented their designs at a technical conference.

Any questions should be directed to the CASMART Executive Chairman, Dr. Othmane Benafan, NASA.

This story was originally posted on ASM International’s website. Provided is the link:

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