Tuning mechanical properties of 3D printed composites with PLA:TPU programmable filaments

Polylactic acid (PLA) filament is widely used for desktop 3D printing purposes due to its exceptional mechanical properties such as high strength; however, its brittleness restricts its use for producing flexible objects. Thermoplastic polyurethane (TPU) filament which is also widely used for desktop 3D printing, on the other hand, is flexible and commonly used in printing compliant objects with relatively low load-bearing performance. This study investigates the ability to tune the mechanical properties of specimens that are printed using programmable filaments composed of PLA and TPU filaments with different volume ratios of PLA and TPU. Two types of PLA and TPU filament arrangements, i.e., series and parallel, are considered. The PLA:TPU programmable filaments are used to print dogbone specimens for tensile testing. In printing the dogbone specimens, the raster angle is varied, i.e., 0, 45, and 90° with respect to the transverse direction of the specimen. To examine their mechanical behaviors based on different PLA and TPU filament arrangements, compositions, and raster angles, tensile tests are conducted on both programmable filaments and dogbone specimens. This study demonstrates the ability to tune the mechanical properties of printed objects by designing programmable filaments and varying raster angles during printing.