Abstract: Described herein are self-supporting structural elements formed of an integral sheet characterized by alternating elevations and depressions which sinusoidally vary about a flat or curved surface of neutrality, the element being suitable for use as a core in composite shell structures. The sinusoidal core element is curvilinearly continuous in passing from the peaks of the characteristic elevations through the surface of neutrality to the floors of adjoining depressions so that stress-raising discontinuities characteristic of prior art core elements are avoided. The core elements, which may be formed of any rigid metal material, e.g., steel, are preferably sinusoidally configured by explosive forming against a suitably configured die. The core elements can be employed singly or in plural, stacked relationship between both parallel and tapered or other irregular boundary layers.

Abstract: Described herein are self-supporting structural elements formed of an integral sheet characterized by alternating elevations and depressions which sinusoidally vary about a flat or curved surface of neutrality, the element being suitable for use as a core in composite shell structures. The sinusoidal core element is curvilinearly continuous in passing from the peaks of the characteristic elevations through the surface of neutrality to the floors of adjoining depressions so that stress-raising discontinuities characteristic of prior art core elements are avoided. The core elements, which may be formed of any rigid metal material, e.g., steel, are preferably sinusoidally configured by explosive forming against a suitably configured die. The core elements can be employed singly or in plural, stacked relationship between both parallel and tapered or other irregular boundary layers.