Buried element deicer

DETAILED DESCRIPTION The invention is directed to the insulative placement of electrically continuous thin strips of heating element material as one layer in a multi-layer acoustic laminate material that produces a composite system which performs its normal acoustic functions and that in, addition prevents ice buildup.
A general description of the acoustic material taught by the above referenced patents is a laminate buildup comprising a honeycomb core constructed of aluminum or the like sandwiched between a perforate sheet and an imperforate sheet.
The perforate sheet includes an overlay of porous material which is exposed to air flow.
Such acoustic material is used in areas of excessive noise such as is produced at the front of a fan-jet engine or the like.
The present invention is directed to the sandwiching of a thin layer of flat ribbon electrical heating element between the perforate sheet and porous material.
In order to maintain the through fluid resistance between the outer surface of the porous material and the cells of the honeycomb material, the layer of heating element must also include perforations which align with the normal perforation pattern of the perforate sheet.
The heating element can be perforated prior to its intended use or can be adhered to an imperforate sheet and the heating element and imperforate sheet can then be simultaneously perforated.
The latter method is preferable as preperforated material may present a perforation alignment problem when later joined.
The joined materials can be perforated by any convenient method.
The preferred method is by grit blasting as set forth in patent application Ser.
No.
752,088 filed July 5, 1985.
As set out in that patent application, any shape of material can be perforated, including planar, curvilinear, compound curved, etc.
An object of this invention is to provide a combined laminate material that provides sound suppression and prevents ice buildup in and around aircraft engines.
Another object of this invention is a method of providing ease of manufacturing of the combined acoustic material and heating element