Response of Microvascular Composites to In-Plane Shear Loading

Microvascular composites were manufactured with precise channel spacing aligned to and transverse to the fiber direction using a custom tool. Stainless-steel tubes and sacrificial polylactic acid were used to produce microchannels following the standard curing schedule with modification to the post-cure step. Optical and radiographic evaluation showed that the microchannels were well-aligned. Transverse microchannels yielded large resin “eyes” and voids near the channels, as well as deformed the sacrificial PLA filament, while microchannels aligned to the fibers yielded undisturbed microstructures with circular cross-section channels. In-plane shear testing revealed that transverse microchannels cause a disturbance in the stress state of the composites when subjected to shear loading. Channels aligned to the fibers failed at the microchannels, though their penalty to the shear properties was small. This study shows that the shear properties of microvascular composites are comparable to those of neat composites, allowing for the addition of multifunctionality with little penalty.