Extperimental Characterization of 3D Printed Thermoplastic Plates Subjected To Low Velocity Impact
thesisposted on 23.05.2021, 13:39 by Hari Prasad Prudhvi Desu
Poly Lactic Acid (PLA) is a biodegradable material which is being extensively used in industrial applications. Due to its low glass transition temperature and cost, PLA is ideal as a feed stock in 3D printing applications. However, it has a brittle nature which makes it vulnerable to impact loads. In this paper, PLA is used to make 3D printed plates that are impact tested using an in-house low velocity impact test apparatus. A high-speed camera and an infrared thermography system are used to investigate the impact damage properties of the material. The plates manufactured with 0° orientation are used to conduct two different experiments; one with varying energies and the other with varying thickness at two different impact locations, namely at plate’s centre and close to a clamped edge. At 1 J impact energy, the plates showed a tensile crack behaviour (cracks between extrudates) and for 3 J energy it showed a mixed crack behaviour of tensile and shear (cracks along and across extrudates) with more energy dissipations than the 1 J impact. For the 1 J impact, more energy is dissipated at the centre of the plate (42.3%) than the impact close to a clamped edge (32.8%), whereas for the 3 J impact more energy is dissipated near clamped edges (97.1%) compared to the centre of the plate (54.9%). Subsequently, the 3 J impact is used for the second experiment due to the higher energy dissipation. Finally, an experimental study is conducted on plates with varied layer thickness from 0.10 mm to 0.18 mm. Results show that the increase in layer thickness (decrease in number of layers) increases the impact absorption for plates impacted at their centre. For plates impacted near their clamped edge, a zig-zag impact damage pattern of increasing and decreasing magnitudes is observed, but the energy dissipation values are higher than the centre impacted plates.