Additive manufacturing is a rapidly growing cutting edge technology. Number of experimental studies have shown that strength of product manufactured by additive Fused Deposition Method (FDM) is influenced by different processing parameters involved during manufacturing. This research paper presents experimental and theoretical investigation of fracture toughness of ABS material fabricated with variation in some of process parameters such as Axis Orientations, Raster Orientation, Infill Percentage, Layer Height and Number of Shells. Experiment was designed to manufacture number of cracked specimens with variation in process parameters, measure their tensile strengths for fracture toughness and compare stress intensity factor (SIF) for all of the specimens. This study helps to understand, how different raster orientations affect the fracture toughness of 3D printed structures and also tells us under which process parameters additive manufactured cracked structures provide better strength.