| Soft active materials (SAMs) are capable of large, environmentally stimulated deformations. A SAM activates when an applied force, temperature, humidity, voltage, magnetic fields, pH or light induces a change in shape, color or modulus. Examples include elastomers, liquid crystals and colloidal dispersions. Recently, SAMs have seen burgeoning research efforts to employ their unique capabilities in a variety of fields from MEMS sensors, aerospace deployable structures, automotive sensors, self-regulating microfluidics, adaptive optics, tissue engineering, drug delivery and minimally-invasive surgery devices. Given the complexity of these applications, their realization requires computational and theoretical tools to simulate SAM behavior. Therefore, finite deformation constitutive models are needed for the development of predictive analysis and design tools.;The objective of this thesis is to characterize and model the mechanical responses of three thermally responsive polymeric SAMs. These materials are: (1) a thermally responsive hydrogel exhibiting temperature-dependent volume changes during swelling or shrinking via the uptake or loss of water, respectively, (2) a thermally activated amorphous shape memory polymer (SMP) capable of one-way shape memory effects, and (3) a thermally activated semicrystalline SMP capable of both one-way and two-way shape memory effects. For these materials, separate constitutive models were developed and the individual SAMs were subjected to specific thermomechanical characterization experiments to provide insight into the material behavior for guidance in modeling efforts. Coupled thermomechanical constitutive models were implemented into a computational code and the thermomechanical experiments were used to calibrate and test the model's effectiveness in predicting the deformation of the associated SAM. To explore the application of the individual models as design tools, various material applications are simulated and some are realized through manufacturing of SAM-based actuators. Results of the experimental characterizations, model predictions and application simulated behaviors, as well as methods for manufacturing and characterizing the SAM-based actuators are presented. |
