# Safe and Sustainable Design of Composite Smart Poles for Wireless Technologies
## 3 Results  
### Impact Dynamics of the Selected GFRP Shift  
During the design process, prior to manufacture of full-scale products, experimental validation and qualification was started in phases. For a composite 5 GP, even for no-traffic sites, the critical damage is impact-type loads at the shaft root. In this study, an experimental campaign was realized by a step-by-step approach starting from QS indentations on GFRP panel sections and, further, to full-scale impact tests on the tubular shaft (more details in Section 2.2). The QS testing serves as a limit case (reference and control) for impact-concerned design since dynamic effects are omitted. In general, the deformations of the curved specimens clearly localized close to the contact areas. The localization for the GFRP panel can be seen in Figure 8, where the deformations of the lower surface in the indentation case (at the maximum loading moment) are evident. The localization challenges the sizing process of the pole since the ultimate (fracture) behaviour starts playing a big role in the GFRP's deformation response.  
\begin{table}
\begin{tabular}{l l} \hline
**Fluid Domain** & **Solid Domain** \\ \hline Turbulence model used: \(k\)-\(\omega\) SST & \\
**Inlet:** & **Heated surface:** \\ Velocity 0.4 m/s & Fixed temperature gradient \\ Turbulent intensity 4.00\% & Zero pressure gradient \\ \(k\) = 0.00038 m\({}^{2}\)/s\({}^{2}\), \(\omega\) = 51.57 1/s & **Fluid-solid walls:** \\ Temperature 300 K & Temperature calculated \\ Pressure with zero gradient & Zero pressure gradient \\
**Walls:** & **Outer surfaces:** \\ Velocity—no slip & Zero temperature gradient (adiabatic) \\ Turbulent variables—wall functions & Zero pressure gradient \\ Zero pressure gradient & \\ Temperature calculated & \\
**Outlet:** & \\ Zero velocity gradient & \\ Zero gradient of turbulent variables & \\ Fixed pressure (atm pressure) & \\ Zero temperature gradient & \\ \hline \end{tabular}
\end{table}
Table 2: Input selections used for the CFD analysis of heat management with 3D printed heat exchangers.  
Figure 8: The mechanical testing of a panel specimen: the DIC-resolved displacement field during the indentation loading of the half-circular specimen at the moment of maximum load.  
The contact force versus displacement of the loading head was defined for different loading configurations during the testing campaign (see Figure 9). The results show clearly the effects of specimen size and support on the load response. For the similar size half-circular specimen, the trend of the loading in the QS indentation and drop-weigh impact is essentially similar regardless of the difference in the support (semi-rigid or open boundary). However, when comparing the impact response of the tubular specimen to the half-circular panel, the indentation and impact cases showed clear differences in terms of maximum load and ultimate deflection. Figure 9 also includes local FEA of the GFRP panel (failure criteria applied) [27]. It was confirmed, as is typical for composites, that the load-carrying capability after the damage onset remains. The first failure mode due to the impact was internal delamination and often visible crack in the axial direction of the shaft.