The integration of untethered, multi-stimuli responsive actuation into soft microrobotic devices is a goal in the development of “smart” materials. This manuscript reports on a dual-stimuli responsive bilayer actuator consisting of a light responsive liquid crystal network (LCN) and a magnetic responsive polydimethylsiloxane (PDMS) composite. This design is of facile fabrication with ample design freedom, using no additional adhesion layers. Untethered control of the bilayer permits motions including bending and rotation, steered individually or in synchronization. Through a systematic study the direct impact of the PDMS layer was elucidated on the light triggered rate of actuation and maximum deformation amplitude of the LCN film. The alignment (homeotropic or planar) of the LCN has a profound effect on the resulting bilayer actuation. It is demonstrated, both experimentally and theoretically, that the rates of sample heating and actuation are directly correlated and highlight the critical role of the PDMS as a heat sink. The maximum amplitude of displacement of the bilayer is tied to the stiffness, being inversely correlated to the PDMS thickness to the third power. These results give insights and provide straightforward design rules to fabricate bilayer actuators with programmed multi-responsive properties.

An innovative deicing system for aircraft leading edges has been developed which integrates heater elements into fibre metal laminates. Such an electrical system can lead to weight reductions and more efficient performances compared to conventional bleed air systems. However, the combination of thermal and mechanical loadings also raises new questions on the durability of such a structure, in particular due to the repeated heating to elevated temperature. The linear viscoelastic creep behaviour, including the effects of temperature and ageing, is therefore investigated for manufactured FM906 glass-fibre epoxy composite as used in heated GLARE. A master curve is derived based on the time–temperature and time–age superposition. The effect of physical ageing during loading is included in a long-term creep prediction.

Heated GLARE, a Fibre Metal Laminate with an integrated heater element, has a promising potential as de- or anti-icing system in aircraft structures. To investigate the long-term durability of heated GLARE previously reported thermal cycling tests up to 12,000 cycles are extended up to 144,000 cycles and moisture conditioning is included. Similar testing up to 72,000 cycles is performed on FM906 glass-fibre epoxy laminates with an integrated heater element to study the influence of the aluminium layers in GLARE. In all test results the initial decrease in interlaminar shear values from 0 to about 10,000 thermal cycles is followed by a recovery phase and a resumed decline after roughly 60,000 cycles. The decrease in ILSS is expected to be caused by internal stress relief which is counteracted by the positive effect of physical ageing due to elevated temperature exposure. Thermal cycling of conditioned samples generally resulted in slightly larger decreases in interlaminar shear strength for both heated GLARE and heated FM906 glass-fibre epoxy laminates.

By integrating heater elements in Fiber Metal Laminates, such as GLARE, the material has a promising potential as de- or anti-icing system in aircraft structures. Application of this so called "heated GLARE" material will however result in increase and (up to ten fold) more frequent temperature loading compares to the regular flight conditions. To investigate the long-term effects thermal cycling tests are performed up to 36000 cycles in three different temperature ranges. Both heated GLARE and FM906 glass-fiber epoxy samples have been thermal cycled using an in-house developed thermal cycling setup. Heating is performed in two different ways, from the outside using Peltier elements and from the inside using integrated heater elements. In addition, continuous heating tests are performed to further examine the effect of aging and internal stress relaxation. FM906 glass-fiber epoxy samples cycled by external heating show an increase in interlaminar shear strength (ILSS) as a result of physical aging, whereas internal heating shows a decrease. Most GLARE samples cycled by internal heating shows an increase in ILSS. The continuous heating tests on heated GLARE confirm that aging and internal stress relief have counteracting effect on the ILSS. The temperature level determines, which effect is most dominant.