Suppressing shock-induced oscillations of a compliant panel with viscoelastic materials

The influence of structural viscosity on the fluid–structure interaction between a normal shock-wave and a compliant panel is investigated. Two compliant panels are designed to allow significant static deformation while exhibiting different dynamic behaviors. For this purpose, two distinct elastomeric materials are used based on their dynamic responses within the shock oscillation frequency range: polyurethane 40A for the elastic panel and Tango Polyjet 61A for the viscoelastic panel. Dynamic mechanical analyses characterize the materials’ dynamic properties, enabling the evaluation of natural vibration modes and frequencies of both structures. The elastic panel exhibits natural vibration frequencies that align with the ones of the natural oscillations of the shock-wave. Wind-tunnel experiments reveal strong dynamic coupling between the elastic panel and the shock-wave, leading to large-amplitude, synchronized oscillations when the shock is centered on the panel. In contrast, the viscoelastic panel is designed to avoid the fluid–structure coupling observed in the elastic panel. The marked viscoelastic properties of the material shift the natural vibration modes to higher frequencies, outside the shock-wave’s natural oscillation range. As a result, in its interaction with the shock-wave, the viscoelastic panel exhibits only a large static deformation – greater than that of the elastic panel – without any dynamic fluid–structure coupling, regardless of the shock position. These findings demonstrate that viscoelastic materials hold significant potential for flow control applications, providing structural damping and frequency-dependent stiffening, which effectively decouple static deformation from dynamic interaction. Our results suggest that viscoelastic panels could be optimized as adaptive bumps for shock control, responding to fluid dynamics without inducing unwanted dynamic coupling.