PSI - Issue 64

Saim Raza et al. / Procedia Structural Integrity 64 (2024) 1200–1207 Raza / Structural Integrity Procedia 00 (2024) 000 – 000

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5. Design implications of corrugated surface of 3DPC compared to traditional concrete flat surface As the robot's extruder deposits the concrete mortar, a pile of layers, extended from the overlapping base (trough) to a peak (crest) with gently curved sides, stacks on top of each other. This construction technique inherently produces a corrugated surface on the printed structure. Naively attributing these corrugations to structural appendages, one might mistakenly take the trough-to-crest depth, , as the ineffective depth of the structure (as shown in Fig. 5 this depth is half the thickness of the layer, in the real prism). However, we have seen that this oversimplification can lead to unrealistic overestimation of cracking moments, particularly for structures under bending. Despite seeming inconsequential, the corrugated ridges can introduce local stress concentration as shown in Prihar et al. (2024), potentially leading to premature failure at cracking loads lower than predicted.

I) simple prism

II) real prism with a sharp tip, =8 mm

III) real prism with a narrow fillet, =8 mm and = 0.55 mm , =2.05 mm, and = 1 mm Fig. 5. A schematic view illustrating the three-point bending configuration as applied to a prism with four distinct architectural variations. The dashed yellow line stands for the corrugated tip. 5.1. Illustrating Stress Concentration in 3DPC Members: Requirements & Case Study Conditions To capture the effect of corrugation on stress concentration, we model a prism undergoing three-point bending, where the prism architecture can be represented by four different candidates as follows: I) simple prism with no corrugation, II) real prism with a sharp tip, III) real prism with a narrow fillet (radius of fillet: = 0.55 mm), IV) real prism with a wide fillet (radius of fillet: = 1 mm). As shown in Fig. 5, the prism has a nominal depth of = 38 mm (trough-to-trough distance in corrugated architectures), with the span length = 148 mm and width = 38 IV) real prism with a wide fillet, =8 mm