Abstract: A rigid porous, deformation resisting, nonresilient inflexible thermoset resin foam having macroscopic open cells and the method of making the same. The method comprises foaming and partially curing a polyepoxide or polyurethane resin in which the cells are closed. The partially cured resin is softened by heating and then crushed to compress the cells to produce an open-celled product. The crushed foam is reexpanded and finally cured. The foam may be filled for strengthening with a filler such as carbon black before or after the final cure.

Abstract: A sound attenuating panel for installation in the high velocity air flow region of an engine nacelle and/or other applications requiring sound absorbing material. The panel utilizing a single layer of either a metallic or nonmetallic cellular honeycomb core with a solid or perforated septum disposed internally therein. The septum may have a planar or non-planar configuration within the individual cells of the core thereby providing means for reducing the noise level of various sound frequencies created by a jet engine or any other sound producing devices for that matter. The invention of the planar or non-planar septum provides structural stabilization and/or vibration dampening to a bonded sandwich assembly.

Abstract: A method of making a panel for installation in the high velocity air flow region of an engine nacelle and other applications requiring sound absorbing material and increased air frame strength. The panel utilizes a single layer of either a metallic or nonmetallic cellular core with a solid or perforated septum disposed internally therein. The septum may have a planar or nonplanar configuration within the individual cells of the core thereby providing means for reducing the noise level of various sound frequencies created by a jet engine or any other sound producing devices for that matter. The planar or nonplanar septum provides structural stabilization and/or vibration dampening to a bonded sandwich assembly. The panel may also be used in strengthening air frame construction and other applications besides sound attenuating panels.

Abstract: In a matrix print head, a plurality of elongated printing elements, mounted in a frame, are driven axially by electromagnetic means to effect printing on record media positioned adjacent to the printing ends of the printing elements. Freely riding tubular elements are placed on the printing elements between support members forming part of the frame, in order to dampen the bending and vibration of the printing elements, and thus reduce or eliminate consequent fatigue failure.