PSI - Issue 34

Sanne van den Boom et al. / Procedia Structural Integrity 34 (2021) 87–92 Sanne van den Boom et al. / Structural Integrity Procedia 00 (2021) 000–000

92

6

10 4

6 ·

Weight Max. load Ratio

# [kg] 1 1.532 2 1.560 3 1.523 1 1.370 2 1.389 3 1.372

[kN] 24.1 22.9 26.6 30.2 28.0 24.1 51.8 57.5 59.5

[kN / kg]

Design A - uniform infill

15.7 14.7 17.5 22.1 20.2 17.5 28.7 31.9 34.3

4

Design B - optimized infill

2

Force (N)

Design A Design B Design C

Design C - optimized design 1 1.804

2 1.801 3 1.735

0 2 4 6 8 (mm) 0

(a)

(b)

Fig. 7: Comparison of the performance of di ff erent designs. In (a) the numerical and experimental force-displacement curves of the di ff erent specimens are shown. The solid lines represent the numerical solutions, the dashed lines are the first specimen, the dotted lines are the second specimen, and the dash-dotted lines are the third specimens. The table in (b) summarizes the specimens’ weights, maximum load, and ratio.

at which the iso surface is extracted and an STL is made, as it was shown that this significantly influences the mass. In cases where it is important that the mass does not exceed a certain value, it may be necessary to set a lower volume constraint. Experimental verification of the numerical results shows that the sti ff ness of the di ff erent parts is well predicted. Furthermore, the optimized parts are not only sti ff er than the uniform infill specimens, for which they were optimized, but also stronger. Infill redistribution has the potential to increase the maximum load without increasing the weight or outer appearance of the product. Design optimization may be used to create a sti ff and strong solid part. In this case, design B - optimized infill on average increased the load-to-weight ratio by a factor 1.24 with respect to the uniform infill design, and design C - optimized design on average increased the load-to-weight ratio by a factor 2. Due to a better distribution of the internal forces, the failure mechanism shifted from a single crack in design A - uniform infill to large parts of the structure breaking at once in design B - optimized infill and design C - optimized design . In this work we have taken an integral design and analysis approach, where the material properties specific to 3-D printed parts have been experimentally determined and numerically homogenized, the original design has been analyzed and redesigned using topology optimization, and the parts have been tested experimentally. This approach has the potential to lead to light-weight designs without compromising strength and sti ff ness. To this end, it is rec ommended that the e ff ective material properties of the infill at di ff erent densities is investigated in more detailed and experimentally verified, so that less conservative estimations are needed.

Acknowledgments

The authors would like to thank the Expertise Centrum Additive Manufacturing (ECAM) for providing the original design, Sacha Hermanns and Ron Lautz for making the test set up and performing the experiments, and the Dutch Ministry of Defence for funding this research.

References

Creusen, F., 2019. Micro-scale computational analysis of Fused Filament Fabricated Materials. Master’s thesis. Delft University of Technology. Simulia, 2017. Micromechanics Plugin For Abaqus / CAE. Version 1.15. Somireddy, M., Czekanski, A., Singh, C.V., 2018. Development of constitutive material model of 3d printed structure via fdm. Materials Today Communications 15, 143 – 152. Stolpe, M., Svanberg, K., 2001. An alternative interpolation scheme for minimum compliance topology optimization. Structural and Multidisci plinary Optimization 22, 116–124.