Modelling of Smart Composites for Morphing Structures

Integrated morphing structures could significantly impact many industries, from aerospace to automotive racing. By combining multiple materials, it is possible to develop load-bearing primary structures whose shape can be directly controlled, eschewing the use of complex mechanical, hydraulic, or electrical actuator assemblies. The approach to morphing composites developed in this thesis combines shape memory alloys (SMAs) co-cured into carbon fibre reinforced epoxy laminates. SMAs provide the actuation and control capability while the composite laminate enables the structure to bear load. The goal of this thesis is to take a coupled approach to developing the characterization, modelling, and manufacturing of morphing SMA hybrid composites (SMAHCs). The first issue tackled in this thesis is the characterization of the thermomechanical behaviour of SMAs. A new characterization process is developed as an extension of existing standard tests to includes the effects of functional stabilization and thermal behaviours required for actuation applications. This process is used to characterize a NiTiCu SMA using differential scanning calorimetry (DSC) and tensile testing. Functional stabilization is shown to effect mechanical properties by as much as 70 [%], demonstrating the importance of characterizing this phenomenon. A novel device which enables the coupled thermo-electro-mechanical fatigue characterization of shape memory alloys is developed. The device is demonstrated to be able to capture the change in resistivity associated with SMA phase transformations as well as the plasticity effects of functional stabilization. A finite element model for SMAHCs is developed using ABAQUS and the experimentally measured SMA material properties. The SMAHC finite element model is used to execute a parametric study to investigate the