PSI - Issue 31

Mohammad Reza Khosravani et al. / Procedia Structural Integrity 31 (2021) 105–110 Mohammad Reza Khosravani et al. / Procedia Structural Integrity 00 (2020) 000–000

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Experimental observations confirmed that the fracture occurs in the gauge section for intact and defected speci mens. In the defected test coupons, fracture was occurred at the location of defect. In both groups of intact and defected specimens plastic deformation was not observed. Fig. 4 shows the load-defection curves of intact and defected spec imens in two groups of unaged and aged specimens. The displacement controlled loading leads to an almost linear rise until it reaches the peak load. The obtained results indicated that thermal ageing has led to decrease in the fail ure loads of intact and defected specimens. In detail, intact 0 ◦ layer-specimens which are not experienced thermal ageing showed highest fracture load equal to 4591 N. This failure load was decreased to 1225 N in the defected 90 ◦ layer-specimens after thermal ageing.

degree, unaged degree, aged degree, unaged degree, aged

degree, unaged degree, aged degree, unaged degree, aged

Fig. 4. Force-displacement curves of intact (left) and defected specimens (right).

It can be seen from the test results that the thermal ageing has led to changes in the mechanical properties of the examined specimens. This has great implication in the performance of 3D-printed parts which should be considered in their practical applications.

4. Concluding remarks

In 3D printing processes, similar to other automated manufacturing methods, di ff erent defects can occur due to various reasons. In this study, certain gaps were placed into the 3D-printed parts to determine their e ff ects in struc tural performance of the components. Since ageing of materials under normal operating conditions is a long process, accelerated thermal ageing test has been considered to simulate the environmental conditions which are most likely to encounter while in service. The aim of this study was to investigate the influence of defect and accelerated ther mal ageing on mechanical behavior of 3D-printed parts. In this context, PLA material was used to print dog-bone shaped specimens using FDM process. A series of tensile tests was performed on intact and defected specimens in two groups of unaged and aged specimens. Although physical appearance of the specimens are not changed after thermal ageing, their load carrying capabilities are influenced. Experimental results confirmed that thermal ageing changed mechanical behavior of the examined specimens and decreased their failure loads.

Acknowledgements

This work as part of the project “Smart Production Design Center” (SmaP) is funded by the European Regional Development Fund (ERDF) under the program OP EFRE NRW 2014-2020 ( EFRE - 0200545 ).