Shape memory polymers structure with different printing direction: Effect of fracture toughness

Abstract

The direction in which three-dimensional (3D) printing is carried out strongly affects the mechanical properties of the resultant printed part due to differences in interface bonding strengths between layers. In this work, we study the effect of printing direction (e.g., 0°, 30°, 45°, 60° and 90°) on the fracture toughness of the UV-curable specimen fabricated by digital light process (DLP) 3D printing. A compact tension specimen was used to measure the fracture toughness for different print directions. The digital image correlation(DIC) technique was used to characterize the full strain fields of the specimens. The crack pattern and crack surface were investigated using optical and scanning electron microscopy. The obtained results indicate that samples prepared at 0° and 90° exhibited higher crack resistance compared with that of other directions. DIC analysis indicated that the tendency of the crack path was consistent with the actual crack path. The reported fracture test results for computerized tomography of a specimen prepared with different directions provide a means to reveal the fracture mechanism of a DLP 3D printed structure.