**Acknowledgements**

*Truss and Frames - Recent Advances and New Perspectives*

melted metal is added on each side of the truss clot by clot. Thus, each clot does not create perfect solid shape and it is not precisely connected with each truss. These are shown in **Figure 9**. Therefore, due to these reasons, material properties for 4D cube models made by the 3D printing DMLS skill show lower than solid material properties. Based on broken section in the sample (1) or (2) shown in **Figure 11**, there shows two issues. One is that melted metals are not connected with each other like a solid precisely. Due to this reason, connected sections in each model as Type 1 or Type 2 are easily broken after outer loading. These are shown as arrows in **Figure 11(1)** and **(2)**. The other one is there shows a space in additive layer when additive manufacturing makes a shape of specimen. Because of the space in the additive layer, each truss created by melted metals does not have enough to support

*Crushed samples shown as arrows: (1) core-filled model. (2) core-spaced model.*

This chapter focused on finding material properties for two models defined as core-filled model, Type 1, and core-spaced model, Type 2, created by the 3D printing direct metal laser sintering (DMLS) technique. The models use aluminum alloy AlSi10Mg powder with a skill of direct laser sintering. After the uniaxial compressive test, it is proved that core-filled model has an elastic modulus of 19.7%, compressive yield strength of 12.2%, ultimate strength of 294.8%, and percentage of elongation of 11% higher than core-spaced model. It also shows core-filled model have a higher strength but core-spaced model shows a lower strength after compression. There shows two issues that melted metals by DMLS skill are not connected with each other like a solid precisely and there shows a space in additive layer when additive manufacturing makes a shape of specimen. These issues are the main reasons for weaker strength or lower elastic modulus in the models. It is hoped that the two models be made sandwich core structure and then the structure be investigated more deeply. In nearby future, it is hope that 3D printing techniques such as FDM [8, 10], SLS [9], DLP [7, 8], SLA [11, 13], LOM [11, 14], SL [14], MPSL [14], 3DP [14], FFF [15, 16], or DMLS [17, 18] are applied into making hypercube models and then it is to do the testing to check what is the differences of mechanical properties are. In addition, it is expected that hypercube models are applied into make a sandwich panel and then they are to be obtained to find mechanical properties. Finally, it is hope that the sandwich panels will be

approved to be selected as one of aerospace materials.

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outer loadings.

**Figure 11.**

**10. Conclusion**

This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (grant number NRF-2018R1D1A1B07041383).
