Shape Memory Alloy Deployment of Membrane Mirrors for Spaceborne Telescopes

摘要

The objectives of this research were to develop and refine a shape memory alloy (SMA) modeling approach, the martensite twin reorientation (MTR) subroutine to predict the transient response of a spaceborne membrane optic SMA deployment actuator spine system. In concert with a commercial finite element solver this application supports multi- dimensional temperature-displacement transient predictions of the shape memory effect (SME) exhibited by SMAs through implementation of a phenomenological constitutive law. The scope of this study was to model the relation of input power magnitude and waveform to stress fields reaction forces and thermal fields for the figure acquisition of a gossamer reflector. Of particular interest is the stress and thermal field history of the polymeric membrane concentrator through the deployment to prevent mechanical and thermal failure as limited experimental or modeling analysis results exists for SMA deployment schemes. Thermal authority over the concentrator was found locally limited to the spine interface. Upon aperture engagement, the integrated model's first excursion cycle frequency excited by all three loading regimes was non-unique, regardless of the preceding temporal character of the spine's response. This tendency suggests a coupling between the structural dynamic designs for deployment and in-service, deployed architectures. Aspects of the deployment sequence warranting further study and issues for tackle to further develop the MTR subroutine are identified. Technology addressed through this thesis research is intended to foster and mature successive large, launch-packaged space vehicle programs.