SHAPE MEMORY ALLOYS (SMAS) EXHIBIT A PHASE TRANSFORMATION THAT IS DRIVEN BY TEMPERATURE AND STRESS. CHANGES…

Public award description

SHAPE MEMORY ALLOYS (SMAS) EXHIBIT A PHASE TRANSFORMATION THAT IS DRIVEN BY TEMPERATURE AND STRESS. CHANGES IN THESE FIELDS CAN BE USED TO EXPLOIT BEHAVIORS SUCH AS THE SHAPE MEMORY EFFECT (SME) AND PSEUDOELASTICITY. THE MICROSTRUCTURE AND BEHAVIOR OF SMA MATERIALS ARE QUITE COMPLEX. VARIOUS CONSTITUTIVE MODELS HAVE BEEN DEVELOPED OVER THE LAST TWENTY YEARS TO SIMULATE THEIR COMPLEX BEHAVIOR FOR DESIGN OF SYSTEMS INCORPORATING SMA COMPONENTS. SMAS HAVE BEEN SUCCESSFULLY IMPLEMENTED IN MEDICAL APPLICATIONS FOR MANY YEARS, PARTLY BECAUSE THE PSEUDOELASTIC EFFECT IS USUALLY EMPLOYED EXCLUSIVELY THEREBY SIMPLIFYING THE SYSTEM CONSIDERABLY. MODELS FOR PSEUDOELASTIC BEHAVIOR LACK MUCH OF THE COMPLEXITY OF COMPREHENSIVE SMA CONSTITUTIVE MODELS. CONSEQUENTLY, IMPLEMENTATIONS OF PSEUDOELASTIC MODELS CAN BE FOUND IN COMMERCIAL STRUCTURAL ANALYSIS CODES, WHICH HAVE AIDED SIGNIFICANTLY IN THE IMPLEMENTATION OF SMA MATERIALS FOR MEDICAL APPLICATIONS. SUCCESSFUL IMPLEMENTATION OF SMAS IN OTHER TECHNOLOGY AREAS LIKE AEROSPACE, WHERE EMPLOYMENT OF THE SME IS OFTEN DESIRABLE, HAS BEEN MORE AD HOC AND RECENT. THE SCARCITY AND DELAY IN IMPLEMENTATION IS DUE TO THE COMPLEXITY OF SMA BEHAVIOR AS AN ACTUATOR. A COMPREHENSIVE SMA CONSTITUTIVE MODEL IS REQUIRED FOR HIGH-FIDELITY ANALYSIS AND DESIGN INCORPORATING SUCH COMPLEX BEHAVIOR. MODELS OF THIS TYPE HAVE NOT BEEN AVAILABLE IN COMMERCIAL STRUCTURAL ANALYSIS CODES, THEREBY EXACERBATING THE SLOW APPLICATION OF SMA ACTUATION TECHNOLOGY. RECENT ADVANCES IN SMA MATERIALS SYNTHESIS AND PROCESSING ARE ENABLING NEW APPLICATIONS FOR SMA MATERIALS, E.G., AT HIGHER TEMPERATURES, WHICH IS OFTEN ACCOMPANIED BY ADDITIONAL MICROSTRUCTURAL COMPLEXITY.