For flexibility in forming a curved surface, a honeycomb configuration using multiple pleats has proved superior to the usual core structures. The partial pleats formed in individual cell walls permit movements to and from the central axis without tearing

Carmody, R. J.

English

NASA Technical Reports Server

PANEL OF FLEXIBLE HONEYCOMB
	
HONEYCOMB CORE 
April 1964
NASA TECH BRIEF
Brief 63-10385 
This NASA Tech Brief is issued by the Technology Utilization Division to acquaint industry 
with the technical content of an innovation derived from the NASA space program. 
Flexible Honeycomb Structure Can Bend to Fit Compound Curves 
Single Cell of Comb 
	
The problem: Honeycomb structure is often speci- 	 are involved in allowing the expansion or compression 
	
fied for lightweight panels requiring high strength; but 	 of upper or lower cross sections. Since each pleat 
	
for curved panels the standard honeycomb materials 	 consists of four angles, each individual angle is 
	
have limited flexibility. If, in forming a curved panel, 	 required to flex only to a limited extent, thereby avoid- 
	
the bonds between the foils are destroyed, the struc- 	 ing the development of large localized stresses and 
	
tural strength of the panel is reduced. A lightweight 	 resultant buckling even when the cell is subjected to 
	
honeycomb structure is needed that will bend to fit 	 extreme flexing. 
compound curves.	 The honeycomb structure may be fabricated from 
	
The solution: A new configuration of honeycomb 	 aluminum, stainless steel, plastic, paper, or fiberglass, 
	
utilizing multiple pleats that has superior flexibility to 	 depending upon requirements for the finished panel. 
other honeycomb cores currently available. 	 Practical fabrication may be accomplished by cutting 
	
How it's done: The configuration of the cellular 	 strips of material in the desired width (1/4 inch to 
	
structure resembles a Maltese cross, as shown in the	 several inches) and forming them to a pattern repre- 
	
illustration. The four partial pleats formed in the indi-	 senting the upper half of a series of side-by-side 
	
vidual cell walls permit these walls to move toward or 	 Maltese crosses. Two such formed strips then assem- 
	
away from the central axis without causing tearing or 	 bled in mirror-image fashion constitute a single series 
	
cell wall collapse. As each cell is deformed in the	 (or line) of cells. Assembled strips may then be secured 
	
process of fitting the honeycomb structure to a curved	 with appropriate soldering, welding, blazing, or ad- 
	
surface, a multiplicity of important functional angles 	 hesive techniques. 
-	 (continued overleaf) 
	
This document was prepared under the sponsorship of the National 	 this document, or that the use of any information, apparatus, method, 
	
Aeronautics and S pace Administration. Neither the United States Govern ,	 or process disclosed in this document may not infringe privately-owned 
	
ment. nor NASA. nor any person acting on behalf of NASA: A. Makes	 rights; or B. Assumes any liabilities with respect to the use of, or for 
	
any warranty or representation, express or implied, with respect to the	 damages resultin g from the use of, any information, apparatus, method, 
	
accuracy, completeness, or usefulness of the information contained in 	 or process disclosed in this document.
https://ntrs.nasa.gov/search.jsp?R=19630000068 2020-03-11T16:47:48+00:00Z
A completed honeycomb core can be fitted to a 
compound surface by placing the core over the curved 
surface and applying a downward force. Flexibility 
results from the partial pleats in each wall of the cell. 
These pleats may be opened or closed along either 
their X- or their Y-axis. Tests have shown that cores 
with 3/16-inch cells could be bent successfully over a 
compound curve having a 2-inch radius. 
Notes: 
I. Flexible honeyàomb panels would find use in com-
pound-curve structures such as aircraft parts where 
strength with minimum weight are essential.
2. Potential large uses of flexible honeycomb panels 
are seen in the roof and body section of automo-
biles, building construction, and particularly tank 
trucks or railroad cars which must have insulation 
with low weight. 
Patent status: NASA encourages the immediate 
commercial use of this invention. It is owned by 
NASA, and a patent application has been filed. When 
patented, royalty-free nonexclusive licenses for its 
commercial use will be available. Inquiries concerning 
license rights should be made to NASA Headquarters, 
Washington, D.C. 20546.
Source: R. J. Carmody 
Marshall Space Flight Center (M-FS-13) 
Brief 63-10385


Flexible honeycomb structure can bend to fit compound curves

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