Development of an electromagnetic compatible composite-insert embedded in a double-curved sandwich panel

Composite sandwich structures, which are widely employed in engineering structures, require a multitude of inserts. In certain instances, the necessity for a specialized insert arises from the unique characteristics of a particular application. In applications such as weather radar radomes, double-curved sandwich panels should be designed with electromagnetic (EM) transparency as a primary objective. The use of metal inserts should be restricted to the absolute minimum. Given the limitations of using metal materials to protect against EM radiation and the need to enhance the load-bearing capacity of the joint against pull-out loads, a composite insert has developed as an innovative solution. In this study, a composite insert of a double-curved sandwich dome has been developed using silica nanoparticles, and its mechanical strength against pull-out load has been evaluated through both experimental and numerical analysis. The strength results obtained have been compared with analytical estimates. Additionally, the buckling of the double-curved sandwich dome against a wind speed of 220 km/h has been investigated numerically. The critical buckling load for wind loading for the full-scale sandwich radome was estimated to be 16,303 N. According to the numerical results obtained with the Abaqus finite element (FE) software, the maximum pull-out force applied to the connection area is approximately 10.7 kN. A parametric study of geometric variables and experimental results showed that it is possible to achieve a stronger composite insert (by 1 wt % nano silica particles) by 20.7% lighter and 102.65% more bearing capacity.