Strain rate dependent mechanical properties of 3D printed polymer materials using the DLP technique

Abstract Three-dimensional (3D) printing technology shows great potential for applications in aerospace engineering, biomedical engineering, and conceptual model preparation. Digital light processing (DLP) 3D printing technology is often used to produce fine components for these applications due to its high precision and efficiency. In this paper, the mechanical properties of DLP printed polyurethane acrylate resin were investigated. Different strain rates were accomplished by using a universal testing machine for quasi-static loading and a Hopkinson bar for dynamic loading. The experimental results show the obvious stain rate effect, anisotropy, and ductile-to-brittle transition for the 3D printed polymers. In addition, the results reveal that anisotropy decreases with the increase in strain rate. The fracture patterns for specimens subjected to different loadings were observed using an optical microscope. The results show that the tensile fracture in the vertical (interlayer) direction is flatter than that in the parallel (in-plane) direction. The specimens subjected to parallel compression show symmetric convex deformation and cracking, while those subjected to vertical compression exhibit asymmetric single-ended cracking. A one-dimensional (1D) phenomenological constitutive model was used to fit the experimental data, and this constitutive model was shown to describe well the mechanical behaviors of the 3D printed materials under uniaxial tension and compression using different strain rates.