Characterization of mutli-material interfaces in polyjet additive manufacturing

Relatively few engineering devices and structures are monolithic, as combinations of materials are often needed to obtain the necessary functionality, performance, weight, and cost requirements. Progress in additive manufacturing now allows multiple materials and even blends of materials to be produced in a single manufacturing process, opening new opportunities for expeditiously achieving functional and performance targets. Just as interactions at interfaces have long been of interest in the area of adhesive bonding, similar issues need to be addressed for printed composite materials. In this study, a Stratasys PolyJet system was used to produce configurations consisting of a soft acrylic layers (TangoBlackPlus) sandwiched by two stiffer acrylic strips (VeroWhitePlus). Several test methods based on the double cantilever beam specimen, a common experimental approach to characterize adhesive performance, were evaluated to characterize the fracture resistance of the assembled layers. Failures nominally occurred at the interface between the two types of materials. Further testing is providing insights into the effects of print direction, postcuring, and interface architecture on the resulting fracture energies. These studies suggest the opportunities for designing printed interfaces with improved performance and durability for multi-material additive manufacturing products.