PSI - Issue 69

Stefano Rodinò et al. / Procedia Structural Integrity 69 (2025) 20–25

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Fig. 1. Diagram illustrating the constructed active composite of SMA-polymer, with (a) depicting its key dimensions and (b) providing an exploded view to highlight its various elements.

Table 2. Key geometric parameters of the active composite specimen. Parameters

Value (mm)

Total length, L Total width, W Total thickness, h

162.5

53

5.2 1.5

Thickness of the PC/ABS layer, h p

SMA wire pitch, p

11.8

SMA wire diameter, d SMA wire distance, h SMA

0.3

3

2.2. Experimental Setup and Instrumentation The experimental characterization was conducted utilizing a specialized low-speed, open-type wind tunnel facility with a closed test section configuration. The facility architecture comprises four primary functional segments (Fig. 1): (i) A convergent inlet section (A) facilitating initial flow acceleration and conditioning (ii) Dual test sections (B) with distinct cross-sectional geometries (iii) A diffuser section (C) for pressure recovery (iv) A fan section (D) providing controlled flow generation. The facility incorporates two distinct test sections with cross-sectional dimensions of 800×800 mm and 400×400 mm respectively. For this investigation, the narrower test section was selected to achieve the requisite flow velocities while maintaining appropriate specimen-to-tunnel dimensional ratios. This configuration enables flow velocities ranging from 0-54 m/s in the selected test section, compared to 0-15 m/s in the larger section.

Fig. 2. Wind tunnel test facility. The experimental apparatus incorporates a specialized mounting system developed specifically for this investigation. A precision-machined steel shaft provides secure specimen mounting while minimizing flow interference. The mounting assembly integrates electrical terminals enabling controlled Joule heating activation of the shape memory elements. Specimen deformation measurements were facilitated through a calibrated reference grid system implemented for precise optical displacement tracking, the full mounting setup is reported in Fig. 3. In addition, the