The influence of thermal and resonance considerations on the design of brazed cylindrical grids

The mechanical properties of a cylindrical grid are determined by such parameters as grid length, diameter, wire size, TPI, and siderod configuration. Because the grid resonates in several different modes, each of these parameters affects each resonant mode in a different way or to a different degree. Small cylindrical brazed grids have been found to have a torsional vibration mode, a cantilever vibration mode, and a vibration mode in which the normal circular-cylindrical shape of the grid assumes the shape of an elliptic cylinder. There are, in addition, resonances due to the vibration of the individual lateral wires. This paper analyzes the effects on mechanical resonance of various design parameters, such as truss wires, multiple siderods, low-pitch end hands, and variations of length and diameter. Data are presented to show the improved resonant-frequency performance obtained with grid designs based on this analysis. The effects of each design on thermal characteristics are also discussed.