PSI - Issue 47

5

Stefano Rodinò et al. / Procedia Structural Integrity 47 (2023) 579–588 Carmine Maletta / Structural Integrity Procedia 00 (2018) 000–000

583

1 � 6 � ℎ � �ℎ � �ℎ � � � � �ℎ �� � � ℎ ��

(18)

The tip deflection of the active composite beam v can be obtained from the curvature by the following equation: �� � 1 � �  �� (19) the corresponding axial displacement u can be calculated as follows: �� � sin �  � (20) 3. Experiments 3.1. SMA-composite prototype A case study was implemented to validate the analytical model and a prototype was made by Fused Deposition Modeling (FDM) 3D printing. The design task was carried out considering both geometric and thermo-mechanical constraints. In fact, composite stiffness and strength must be compatible with actuation thermo-mechanical loads generated by the SMA wire activation. To this aim different possible polymer samples obtained by 3D printing were preliminary analyzed by three-point bending tests. The test specimens (127x12.7x3.2 mm 3 ) were made according to D790 standard [39]. The Young’s modulus was calculated from the load displacement curves for all investigated materials and results are summarized in Table 1.

Table 1. Summary of the 3D printed materials used to choose the polymeric material.

Material

Description

Young's modulus / GPa

CFR Nylon

3DXTech PA6 Nylon with excellent strength and stiffness. It is also resistant to high temperatures (>150°C) 3.9

PLA + Graphite

ILOALFA Grafylon 3D is a PLA (Polylactic Acid) integrated with graphite powders, offering superior mechanical performance compared to classic PLA 4.4

PLA

FILOALFA PLA

3.7

PETG

Zortrax Z-PETG is an industrial-grade 3D printing material made with the popular thermoplastic PET and enriched with the addition of glycol to eliminate brittleness 1.2

PP

Polypropylene (PP) is one of the most commonly used polymers in industry 0.2

PVDF

3DXTech Polyvinylidene Fluoride is an excellent choice for applications that require chemical resistance, high-heat resistance, and superior abrasion resistance. 1.8