PSI - Issue 42

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Md Niamul Islam et al. / Procedia Structural Integrity 42 (2022) 785–792 Md Niamul Islam et al. / Structural Integrity Procedia 00 (2019) 000–000

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2.2. Mechanical characterisation tests Material properties of 3D printed composites are significantly influenced by the printing parameters and orientation of the matrix and fibres (Chacón et al., 2019; Wang et al., 2019). Hence, mechanical characterisation tests were carried out to understand the quasi-static performance of the fabricated structures and obtain their elastic plastic parameters. Tensile tests were performed following ASTM D638 (ASTM 638-14, 2006) on 2 mm Type IV specimens (Fig. 1a) at 5 mm/min and compression tests were conducted on 10 mm cube specimens (Fig. 1b) at 0.6 mm/min following ASTM D695 (ASTM D695-15, 2010). At least 5 samples were tested for both experiments, with the composites loaded in the fibre direction as shown in Fig. 1.

(a)

(b)

T

C

T

C

y

10 mm

x

Fig. 1. (a) Tensile specimen and orientation of fibres under tensile (T) load. (b) Compression specimen and orientation of fibre under compressive (C) load.

2.3. Ballistic impact and modelling Solid 100 mm × 100 mm × 2 mm composite plates (Fig. 2) were loaded with ballistic impact using an in-house gas gun (Fig. 3) with 9 mm steel spherical projectiles at velocities ranging between 105 – 120 m s -1 .

(e)

(a)

(b)

(-45°) (+45°) (-45°) (+45°) (-45°) (0°) (+45°) (0°) (0°) (-45°) (0°) (+45°) (-45°) (+45°) (-45°) (+45°) x

(c)

(d)

z

y

0.125 mm

x

20 mm

Fig. 2. Plates for ballistic impact (a) with 0° fibre orientation (b), +45° (c) and -45° (d) polymer-matrix filament orientation. (e) Stacking order of plate specimens.