Strain rate sensitivity of five 3D printed polymer materials

The strain rate sensitivity on the uniaxial compressive response of five 3D printed polymer-based materials was investigated. Five commonly used polymers – acrylonitrile butadiene styrene (ABS), nylon, polylactic acid (PLA), toughened polylactic acid (TPLA), and thermoplastic polyurethane (TPU) – were studied. Cylindrical specimens (Ø8 mm × 8 mm) were printed using an Ultimaker S5 3D printer, with a print layer height of 0.1 mm and identical print paths. The manufacturing quality of the 3D-printed specimens was assessed using X-ray computed tomography (CT) at a resolution of 27 μm. Among the materials tested, TPU and nylon exhibited the highest levels of porosity. Low-strain rate tests ranging from 10 -3 /s to 1/s were carried out using a universal testing machine, while tests at strain rates above 1/s were conducted with a split-Hopkinson pressure bar. All five polymers exhibited positive strain rate sensitivity. The strain rate coefficients in the Johnson-Cook (J-C) material model were 0.049, 0.072, 0.071, 0.073, and 0.625 for ABS, nylon, PLA, TPLA, and TPU, respectively. The J-C model successfully captured the strain rate effects for ABS, PLA, TPLA, and nylon but failed to capture the low strain rate behaviour for TPU. • 3D-printed polymers exhibit high strain-rate sensitivity. • ABS, PLA, TPLA, and nylon show reasonable agreement with the Johnson-Cook model. • TPU exhibited different mechanical behaviour at quasi-static and dynamic loading rates. • Porosity distribution in 3D-printed samples were material-dependent.