PSI - Issue 28

Najat Zekriti et al. / Procedia Structural Integrity 28 (2020) 1745–1754 Najat Zekriti and al/ Structural Integrity Procedia 00 (2019) 000–000

1747

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2. Methods and Materials 2.1. Experimental setup

The material used is ABS, a rigid, heat-resistant, tough, engineering plastic that commonly used in computer keyboard keys, LEGO bricks, automotive field... It is an amorphous polymer composed of three monomers, acrylonitrile, butadiene and styrene. Olivera and Muralidhara (2016). To do this work, two types of ABS were used ABS extruded and the other one printed. The printed samples were built, in our laboratory, layer by layer by 3D printer machine using FDM. The setting up of the 3D printer machine as shown in the following table:

Table 1. Extrusion parameters. Infill density (%)

100

Feed rate (mm/s)

20 mm/s

Layer thickness (mm) Extruder temperature (°C)

0.2

250

Bed temperature (°C)

80

Raster angles

1.2

Filament orientation -45°/+45° The samples for tensile testing were produced in accordance with BS EN ISO 527-2:2012. The dimensions of the samples are shown in the fig.1.

Fig. 1. Sample geometry (a) SENT; (b) Prepared specimen for DIC method.

We led Experimental tests over standard specimen and SENT specimen for both extruded and printed samples for tensile tests with four crosshead speeds of 1mm/mn, 10 mm/mn, 50 mm/mn and 100 mm/mn. A notch of initial length artificially damages these specimens with a surface textured with a spray paint spot creating random black artificial speckle of the order of a millimetre. The more random this texture is, the more efficient the DIC method is. In order to estimate the displacements and strain fields at the crack-tip, the experimental device consists of a universal testing machine, a digital camera with a spatial resolution of 4608x2592 pixels, aligned with the test specimens such that the crack faces coincide with horizontal axis of the image co-ordinate system, with artificial lighting adjusted to ensure adequate image contrast. The presented images below show the test bench and the specimens for a tensile test in order to characterize study and compare the behavior of printed and extruded specimens.