Fused filament fabricarion of continous fiber-reinforced thermoplastics for compliant mechanisms

In the last decade composite materials, previously almost exclusively used in aerospace and automotive industries, are becoming widespread thanks to the introduction of the fused filament fabrication (FFF) process in the additive manufacturing technology. With respect to the standard and more widely used material subtractive technologies, the FFF layer-by-layer construction process is capable of manufacturing parts featuring very complex geometry. Moreover, the deposition of reinforcing filaments provides components with highperformance mechanical characteristics. Since FFF is a relatively new technology, studies are still needed to fully understand the mechanical behavior of composite materials realized with FFF and how all the process parameters (e.g., layer thickness, filament deposition direction, type of matrix and reinforcement, the interaction between matrix and reinforcement) affect the final result. This paper deals with the preliminary experimental analysis of straight beams realized in carbon-fiber-reinforced Nylon White composite material with the MarkForged MarkTwo threedimensional printer. Envisaged application of the considered straight beams is as flexible elements in compliant mechanisms. In particular, tensile and bending tests are performed on nine different straight beam specimens in order to provide a first understanding on how the filament disposition within the sample affects its mechanical response. From the results it is found that the proper position of the reinforcement filaments provides a very effective means to tune the selective compliance of beam flexures.