EFFECT OF ELEVATED TEMPERATURES ON
THE STRENGTHS OF SMALL SPECIMENS
OF SANDWICH CONSTRUCTION
Cr THE AIRCRAFT TYPE
Tests Conducted after Exposure to. Elevated
Temperatures for 192 Hours
September 1952
INFORMATION REVIEWED
AND REAFFIRMED
1958
LOAN COPY
Please return to:
Wood Engineering Research
Forest Products Laboratory
Madison, Wisconsin 53705
This Report is One of a Series Issued in Cooperation with the
AIR FORCE-NAVY-CIVIL SUI3COMMITTEE
on
AIRCRAFT DESIGN CRITERIA
Under the Supervision of the
AIRCRAFT COMMITTEE
of the
MUNITIONS BOARD
No. 1804-114
UNITED STATES DEPARTMENT OF AGRICULTURE
FOREST SERVICE
FOREST PRODUCTS LABORATORY
Madison 5, Wisconsin
In Cooperation with the University of Wisconsin
EFFECT OF M gVATED TEMPERATURES ON THE STRENGTHS OF SMALL
SPECIMENS OF SANDWICH CONSTRUCTION OF THE AIRCRAFT TYPETests Conducted after Exposure to Elevated
Temperatures for 192 Hours
By
EDWARD W. KUENZI, Engineer
Forest Products LeboratorykE, Forest Service
U. S. Department of Agriculture
•••••••••n••n
Introduction
The purpose of this study was to determine the mechanical properties of five
sandwich constructions at room temperature, at various elevated temperatures
(160° to 600° F.) after exposure to those temperatures for 192 hours, and at
room temperature after exposure to the same elevated temperatures for 192
hours. The materials tested were selected several years ago and the test
results are not representative of currently available high-temperature-resistant materials which will give higher-strength constructions at elevated
temperatures.
The experimental work of this study parallels the work reported in Forest
Products Laboratory Report No. 18041 except in regard to procedure changes
that were necessary because of the long-time exposures.
-This progress report is one of a series prepared and distributed by the
Forest Products Laboratory under U. S. Navy, Bureau of Aeronautics Order
No. NAer 01319 and U. S. Air Force No. USAF-18(600)-70. Results here
reported are preliminary and may be revised as additional data become
available.
2
-Maintained at Madison, Wis., in cooperation with the University of
Wisconsin.
3-Nuensi, E. W. Effect of Elevated Temperatures on the Strengths of Small
Specimens of Sandwich Construction of the Aircraft Type. Tests Conducted
Immediately after the Test Temperature was Reached. Forest Products
Laboratory Report No, 1804. 1949.
Rept. No. 1804-B
-1-
Agriculture-Madisqn
Materials
Five sandwich constructions that previously had been tested after short-time
exposure to elevated temperaturea• were tested in this study after 192 hours'
exposure to various elevated temperatures.
The specific sandwich constructions tested were as follows:
Core
Facings
0.020-inch 24S-T3 clad aluminum
Adhesive
1/4-inch end-grain balsa 25 and 30A
.020-inch 24S-T3 clad aluminum 1/2-inch aluminum honey- comb
35
.020-inch 24S-T3 clad aluminum 1/2-inch cotton-cloth
honeycomb
35
1/2-inch glass-cloth
honeycomb
1
1/2-inch glass-cloth honeycomb
1
5 plies of glass cloth
112-114 •
5 plies of glass cloth
181-114
The balsa wood had a density of 5 to 8 pounds per cubic foot and was cut so
that the grain direction was normal to the facings of the finished sandwich.
The facings were bonded to this core with adhesive 25 (a high-temperaturesetting formulation of thermosetting resin and synthetic rubber) and adhesive
30A (an intermediate-temperature-setting, acid-catalyzed phenol resin).
The aluminum-honeycomb core was made of 0.003-inch, nonperforated 2SH-18
aluminum foil formed to a honeycomb of 3/8-inch cells. Adhesive 35 (a hightemperature-setting formulation of thermoplastic and thermosetting resins)
was used to bond together adjacent ribbons of the corrugated foil. The
facings were bonded to this core with adhesive 35.
The cotton-cloth honeycomb of 3/8- to 7/16-inch hexagonal cells was made of flounce cotton sheeting impregnated with a phenol resin.
The cores of glass-cloth honeycomb were made of glass-cloth 112-114 impregnated with resin 1, a laminating resin of the polyester (diallyl phthalatealkyd) type, and formed to 3/16-inch hexagonal cells. Glass-cloth facings
were wet-laminated to the cores with resin 1.
4
-Adhesive 1 corresponds to adhesive A in Report No. 1804. Likewise, adhesive
35 corresponds to adhesive J, 25 to M, and 30A to N.
Rept. No. 1804-B -2-
The manufacturing techniques used to prepare the sandwich constructions, as
well as more detailed descriptions of the materials, are given in Forest
Products Laboratory Report No. 1574, "Fabrication of Lightweight Panels of the
Aircraft Type."
Testing Apparatus and Procedures
Except for an additional exposure to elevated temperatures for 192 hours, the
testing apparatus, testing procedures, temperatures, and specimen sizes were
identical to those described in Forest Products Laboratory Report No. 1804.2
Tests were made in compression on short and long specimens. Tests were also
conducted in shear and in tension.
Specimens mere'exposed for 192 hours at elevated temperatures of 160°, 250°,
350°, 450°, and 600° F., in the same type of oven in which they were to be
tested. After exposure for 192 hours at these temperatures, specimens to be
tested at the elevated temperature were immediately transferred to the test
oven and tested. They were not allowed to cool. Specimens to be tested at
room temperature were allowed to cool at room temperature before being tested.
Results of Tests
The mechanical properties of the five sandwich constructions, as determined
by the tests, are presented in tables 1 to 5 and in graphical form in figures
1 to 10.
The general trend toward lower strength at the elevated temperatures of the
tests was more pronounced after exposure for 192 hours than was previously
observed after short-time exposure.• After short-time exposure, most constructions had some strength at 600° F., but, after 192 hours' exposure,
many had little or no strength at 350° and 450° F.
Aluminum-balsa sandwich construction having 0.020-inch 24ST clad aluminum
facings on a core of 1/2-inch end-grain balsa showed slight improvement in
column strength after being exposed to 160° and 250° F. for 192 hours as
compared to a steady decline of about 10 percent at 250° F. after a short3 At 350°, 450°, and 600° F. the column
time exposure at these temperatures.strength was zero after 192 hours' exposure as compared to approximately
15, 19, and 97 percent drops in strength at those temperatures, respectively,
after a short-time exposure. The edgewise compressive strength followed a
similar decline. The shear strength dropped 12 percent at 160° F., 19 percent at 250° F., and to zero at 350°, 450°, and 600° F. after 192 hours'
exposure as compared to a steady decline to practically no strength at 600°
F. after a short-time exposure. The shear modulus was little affected at
160° and 250° F. but dropped to zero at higher temperatures after 192 hours'
Rept. No. 1804-B
3_
exposure as compared to a sudden drop of 40 percent at 160° F. followed by
a gradual decline to zero at 600° F. after a short-time exposure. The
tensile strength showed a steady decline to zero at 350° F. and above after
192 hours' exposure as compared to more gradual decrease to practically no
strength at 600° F. after short-time exposure.
All-aluminum sandwich construction having 0.020-inch 24ST clad aluminum
facings on a core of 1/2-inch aluminum honeycomb of 0.003-inch, nonperforated
2SH-18 aluminum foil formed to 3/8-inch hexagonal cells showed im provement of
a few percent in strength up to 350° F. and then a steady decline to zero at
600° F. after 192 hours' exposure. After short-time exposure, the column
strength showed a steady decline to a pproximately 65 percent of its roomtemperature strength at 600° F. Edgewise compression strength showed similar
declines, although improvement was not observed at 350° F. after 192 hours'
exposure and decrease in strength was more marked at 250° F. after short-time
exposure. The shear strength showed approximately steady decline to zero at
600° F. for both long-time and short-time exposure. This was observed also
for shear modulus after 192 hours' exposure. The ,short-time exposure showed
some improvement in modulus at 160° F., followed by a sharp drop to approximately 20 percent of its room-temperature value at 250° F. and above. Tensile
strength gradually declined to zero at 450° F. after 192 hours' exposure and
to practically zero after short-time exposure at 600° F.
Aluminum-cotton cloth sandwich constructions having 0.020-inch, 24ST clad
aluminum facings on a 1/2-inch core of cotton-cloth honeycomb of 4-ounce
impregnated cotton sheeting formed to 3/8-inch hexagonal cells showed strength
declines similar to the all•aluminum sandwich construction except that columncompression strength values were zero after 192 hours' exposure at 350° F.
and shear modulus values showed no improvement at 160° F. after short-time exposure. The strength level of this construction was, of course, considerably
lower than that of the all-aluminum construction.
Glass-cloth sandwich constructions showed increasing decline in all strength
properties with increasing temperature to zero or nearly zero at 450' F.
after 192 hours' exposure. The strength properties after short-time exposure
showed steady decline to practically zero at 600° F.
After exposure to the various elevated temperatures for 192 hours, the specimens that were cooled at room temperature before being tested had approximately
the same strength properties as those tested at the elevated temperatures
(figs. 2, 4, 6, 8, 10). The shear and tensile strength values were more nearly
like the strength values at room tem perature (75° F.) after long-time exposure
to temperatures up to 250° F. than after short-time exposurel Exposures at
higher temperatures than 250° F. had increasingly deleterious effects, as the
temperatures were increaaed, on the room-temperature strength.
Rept. No. 1804-B
Conclusions
Exposure of five types of sandwich construction to moderately elevated temperatures (250° F.) for 192 hours improved the mechanical properties at those
temperatures, as compared with the properties after short-time exposure to
the same temperatures in previous tests.— The strength of constructions having
aluminum facings on balsa, aluminum honeycomb, or cotton-cloth honeycomb cores
was not affected until they were exposed to 350° F. for 192 hours. Above this
temperature the strength decreased rapidly. The glass-cloth constructions
showed increasingly declining strength at higher temperatures. The allaluminum sandwich had some strength at 450° F. as compared to little or no
strength for the other constructions. At 600° F. all constructions were so
weakened that they had essentially no strength. The long-time exposure had
similar effect on the properties at room temperature.
Exposure to higher temperatures (350° to 600° F.) for 192 hours had a more
deleterious effect on strength than did short time exposure to the same temperatures.
Rept. No. 1804-B
-5-
Table 1.--Effect of exposure for 192 hours at elevated temperatures on the column strength
of sandwich constructions
Maximum facing stresses
Conditioning temperature
: 160° F.
: .
75° F.
Testing temperature
75° F.:160° F.: 75° F.: 250° F.: 75° F. : 350° F.: 75° F. : 450° F.: 75° F. :600°
75° F.
•
•
P.s.i.
600° F.
:
450° F.
350° F.
250° F.
: P.s.i. :P.s.i. :P.s.i. :
F.:75° F.
•
•
P.s.i. : P.s.i. : P.s.i. : P.s.i. : P.s.i. : P.s.i. : P.s.i.:P.s.i.
Facings, 0.020-inch clad 24S-3 aluminum; core, 1/2-inch end-grain balsa
:
:
;
:
:
0 :
0
0 : 15,900
0
0 :
0
0 :
0 : 5,200
:
:
:
:
:
30,800 : 31,000 : 31,400: 30,800: 31,300 • 33,400 : 0 :• 4,200
:▪ 30,600
29,300
33,100
30,000
31,200
Av.
:
:
:
:
:
32,000
31,700
31,300
31,300
28,600
: 32,600:
:.32,500:
: 32,700:
: 30,000:
: 29,400:
30,600:
30,700:
30,600:
30,100:
32,100:
31,700
31,100
32,000
31,000
30,700
:
:
t
:
:
34,500
33,400
32,300
34,200
32,400
0
0
0
0
0
:
:
:
:
:
0
0
0
0
0
:
:
:
:
:
0 :
0
: 0
0
0
0
0
0
:
:
:
:
:
0
0
0
0
0
:
:
:
:
:
0 :
0
0
0
0
0
Facings, 0.020-inch clad 24S- 115 aluminum; core, 1/2-inch aluminum honeycomb
30,800
24,200
31,900
32,300
32,000
Av.
:
:
:
:
:
31,600
31,000
31,400
31,400
31,400
:
:
:
:
:
31,800: 32,000: 32,800 : 34,000 : 31,900 : 34,000 : 13,200
32,200: 33,200: 32,200 : 34,000 : 31,000 : 32,300 : 9,100
33,600: 33,500: 33,100 : 32,700 : 30,800 e 37,400 : 12,100
31,900: 32,000: 33,100 : 33,500 : 32,500 : 36,100 : 12,100
33,200: 32,200: 33,800 • 32,700 : 30,100 : 37,000 : 13,200
:
:
:
:
:
14,500
18,500
18,900
17,700
16,900
:
:
:
:
:
30,200 : 31,400 : 32,500: 32,600: 33,000 • 33,400 • 31,300 • 35,400 : 11,900 : 17,300 • 0
0
0
0
0
0 • 0
0.020-inch clad 24B-T aluminum . core 1 2-inch cotton-cloth hone comb
Av.
0:
29,000 : 29,200 : 27,800: 30,300: 26,600 : 30,300 : 1,400 : 28,100 : 28,600 : 28,800: 31,000: 30,000 : 31,600 : 1,300 : 17,600 :
300 : 12,900 :
29,700 : 28,800 : 30,100: 30,500: 30,200 : 31,200 :
26,400 : 28,500 : 28,200: 30,000: 26,500: 30,900 : 2,800 : 21,000 :
0 : 6,700 :
27,800 : 29,600 : 28,400: 31,000: 28,100 : 32,500 : O :
:
O :
:
:
0 :
0:
0 :
0:
0:
0
0
0
00
:
:
:
:
:
0
0
0
0
0
28,200 : 28,900 : 28,700: 30,600: 28,300 : 31,300 : 1,200 :▪ 11,600 :
.
0.
0
:
0
:
:
:
:
:
0
0
0
0
0
:
:
:
:
:
0
0
0
0
0
700 :
0
: 0
Facings, five plies of glass cloth 112-114; core, 1/2-inch glass-cloth honeycomb
16,000 : 19,300 :
16,800 :
15,800 :
17,700 •
17,300 :
Av.
15,300: 18,700: 12,300 : 17,400: 8,000 : 8,800 : 18,800 : 15,400: 19,500: 11,700 : 18,900 : 7,800 : 8,800 : 18,000 : 14,400: 20,100: 12,300 : 17,700 : 8,200 : 9,600 : 0 : 11,300 :
• 15,100: 18,400: 11,000 : 18,900 :
17,000 : 15,500: 19,400: 12,600 : 18,200 : 6,700 : 10,800 : 16,700 : 18,300 : 15,100: 19,200: 12,000 : 18,200. 6,100 : 9,900 : 0
0
0
0
0
:
:
:
:
:
0 :
600
800
800
700
700
Facings, five plies of glass cloth 181-114; core, 1/2-inch glass-cloth honeycomb
23,700 : 22,400 : 19,600: 24,200: 15,400 : 23,700 : 10,400 : 15,100 : 22,200 : 21,200 : 20,200: 24,000: 14,900 : 24,000 : 11,600 : 13,900 : 21,800 : 22,800 : 19,000: 24,200: 14,600 : 23,200 : 10,400 : 15,700 : 21,800 : 23,000 : 19,200: 22,800: 14,700 : 23,800 : 11,700 : 15,900 : 21,000 : 22,600 : 18,800: 22,800: 14,000 : 21,600 : 10,600 : 13,900 : :
22,100 : 22,400 : 19,400: 23,600: 14,700 : 23,300 : 10,900 : 14,900 : Av.
Report No. 1804-B
Z
m 90446
F
200
200
200
400
100
:
:
:
:
:
200 :
1,100
900
900
900
800
:
:
:
:
:
900 :
0 :
0 :
0 :
0 :
0 :
0
0
0
0
0
0 : 0
Table 2.--Effect of exposure for 192 hours at elevated temperatures on the com pressive strength
of sandwich constructions
Maximum facing stresses
. Conditioning temperature
75°F.
160° F.
350° F.
250° F.
450° F.
:
600° F.
Testing tempe▪ rature
75° F.
: 75° F.:160° F.: 75° F.: 250° F.: 75° F. : 350° F.: 75° F. : 450° F.: 75° F. :600° F.:75° F.
P.s.i.
: P.s.i. :P.s.i. :P.s.i. : P.s.i. : P.s.i. :• P.s.i. : P.s.i. :
P.s.i. :
P.s.i. : P.s.1.:P.s.i.
Facings, 0.020-inch clad 24S-T3 aluminum; Core, 1/2-inch end-grain balsa
47,800
44,600
47,900
49,600
Av.
:
:
:
:
47,000
46,600
48,000
50,500
:
:
:
:
49,000:
47,300:
50,500:
51,600:
48,400:
47,500:
48,200:
48,900:
49,300
50,500
50,500
51,900
:
:
:
:
49,500
52,300
51,400
43,800
:
:
:
:
47,500 : 49,100 : 49,300: 48,400: 42,400 : 49,800 : 0
0
0
0
0
: 2,100 :
:
0 :
: 4,900 :
:
0 :
:
0 :
47,500 • 48,200 • 49,500: 48,300: 48,900 : 49,400 :0
: 1,400 :
0
0
0
0
0
:
:
:
:
:
:
:
:
:
:
0
0
0
0
0
:
:
:
:
:
0 :
0
: 0
39,200 : 42,900 : 43,200: 42,100: 40,600 : 46,600 : 26,200 : 33,800 : 14,200 : 19,600 : 0
36,200 : 42,600 : 43,800: 43,000: 42,900 : 45,400 : 31,200 : 35,600 : 15,900 : 18,200 : 0
0
: 0
: 0
: 0
: 0
: 0
36,800 : 42,500 : 41,800: 42,300:▪ 41,200 : 45,400 : 30,500 : 35,800 : 14,600 : 18,700 :0
:. 0
0 :
0
0
0
0
0
0
0
0
0
0
Facings, 0.020-inch clad 24S-T3 aluminum; core, 1/2-inch aluminum honeycomb
33,000 : 44,100 : 40,100: 43,400: 40,600 : 46,000 : 30,700 :. 36,400 : 13,900 : 20,100 : 0
38,500 : 42,300 : 40,700: 41,600: 39,000 : 42,400 : 34,400 : 37,100 : 14,600 : 17,400 : 0
37,000 : 40,600 : 41,200: 41,500: 43,000 : 46,500 : 30,200 : 36,200 : 14,600 : 18,000 : Av.
Facings, 0.020-inch clad 24S-T3 aluminum; core, 1/2-inch cotton-cloth honeycomb
34,400
32,400
32,400
32,300
35,700
Av.
:
:
:
:
:
37,000 : 31,600: 35,600: 37,000 • 37,800 : 14,500 : 16,700 : 36,700 : 33,800: 38,600: 34,400 : 36,900 : 141 000 : 18,300 :
36,500 : 30,700: 35,800: 34,300 : 37,500 • 7,200 : 15,400 :
37,200 : 31,300: 38,200: 35,800 : 40,500 : 7,200 : 18,000 :
36,400 : 32,600: 33,200: 32,300 : 36,100 : 9,500 : 21,100 :
0 :
0 :
0
0
0
0
0
0
0
0
33,400 • 36,800 : 32,000: 36,300: 34,800 : 37,800 : 10,500 : 17,900 : 0 :
:
:
:
:
:
:
:
:
0 :
0
0
: 0
: 0
0
0
0
: 0
: 0
: 0
0
: 0
0
0
0
0
:
:
:
:
Facings, five plies of glass cloth 112-114; core, 1/2-inch glass-cloth honeycomb
17,600
18,500
21,100
18,000
24,700
Av.
:
:
:
:
:
22;000
23,200
21,100
21,000
22,300
:
:
:
:
:
18,800:
20,000:
20,200:
18,800:
17,500:
20,100: 16,400 : 28,200 : 8,500 : 10,800 : 25,200: 14,800 : 22,100 : 8,800 : 12,300 :
20,200: 13,500 : 24,400 : 9,100 : 12,100 : 22,100: 15,900 : 24,400 : 8,800 : 12,000 :
24,400: 14,800 : 25,800 : 9,000 : 11,000 : 0 :
0 :
300 : 2,800 :
200 : 3,500 :
200 : 4,000 :
0 :
0
: 0
20,000'. 21,900 : 19,100: 22,400: 15,100 :▪ 25,000 : 8,800 : 11,600 :
100. 2,100 :
0
: 0
300 : 1,200 :
200 :
900 :
200 :
800 :
800 :
200 :
300 :
500 :
0
0
0
0
0
:
:
:
:
:
800 :
0
:0
0 :
0
0
0
0
Facings, five plies of glass cloth 181-114; core, 1/2-inch glass-cloth honeycomb
24,400
29,800
21,600
25,300
30,000
Av.
:
:
:
:
:
32,600
30,200
28,600
35,400
31,900
:
:
:
:
:
31,400:
34,000:
28,300:
28,200:
26,U00:
32,600: 19,500 : 35,200 : 10,300
29,700: 15,700 : 32,800 : 9,000
27,200: 18,000 : 34,500 : 10,200
32,500: 17,800 : 35,600 : 12,700
27,800: 17,000 : 38,100 : 9,000
:
:
:
:
:
18,700
17,200
15,000
13,700
16,900
:
:
:
:
:
26,200 : 31,700 :. 29,700: 30,000: 17,600 • 35,200 : 10,200 : 16,300 : Report No. 1804-B
Z M 90447 F
200 :
0
0
0
0
0
Table 3.--Effect of exposure for 192 hours at elevated temperature on the modulus
of rigidity of sandwich constructions
Shear modulus
Conditioning temperature
75°F.
:
160° F.
250° F.
350° F.
450°
;
F.
600° F.
Testing temperature
:600° F.:75 0 F.
75° F.
:
75° F.
P.s.i.
:
P.s.i. : P.s.i.: P.s.i.: P.s.i. : P.s.i. : P.s.i. :• P.s.i. : P.s.i. : P.s.i. : P.s.i.:P.s.i.
:160° F.:
75°
F.: 250° F.: 75° F. : 35
▪ 0'
F.: 75° F. :
450° F.: 75° F.
Facings, 0.020-inch clad 24S-13 aluminum; core, 1/2-inch end-grain balsa
25,400 : 24,200 : 22,600: 20,700: 25,500 : 19,750 :
19,400 : 26,500 : 24,000: 21,200: 26,100 : 18,800 : 21,900 : 23,000 : 18,500: 21,400: 28,700 : 25,600 : 21,200 : 19,000 : 22,200: 23,600: 24,200 : 24,600 :
21,800 : 22,600 : 25,300: 19,700: 31,800 : 23,500 : Av.
21,900 : 23,100 : 22,500: 21,300: 27,300 :▪ 22,400 :▪
0 :
0 :
0 :
0 :
0 :
0 :
0 :
0 :
0 :
0 :
0
0
0
0
0
0 :
0 :
0
•.
•.
•.
••
•.
0
0
0
0
0
:
:
:
:
:
0
0
0
0
0
:
:
:
:
:
0
0
0
0
0
0
:
0
:0
Faci s 0.020-inch clad 24S-T aluminum • core 1 2-inch aluminum hone amb
35,500
48,900
47,000
38,800
34,400
Av.
:
:
:
:
:
0 :
0 :
0 :
0 :
0 :
0
:0
38,500 : 42,100: 51,400: 31,600 : 37,800 : 23,900 : 36,600 34,600 : 35,400: 42,700: 27,400 : 46,800 : 20,600 : 38,200 • 41,200 : 35,300: 44,900: 35,400 : 46,600: 30,900 : 42,600 34,500 : 37,400: 45,900: 31,900 : 39,300 : 21,100 : 44,500. 44,600 : 46,300: 49,400: 36,800 : 34,500 : 20,700 : 34,400 40,900 : 38,700 • 39,300: 46,9oo: 32,600 :▪ 41,000 :▪ 23,400 :▪ 39,300 0
0
0
0
0
Facings, 0.020-inch clad 24S-T3 aluminum; core, 1/2-inch cotton-cloth honeycomb
6,310 : 6,85o : 6,440: 6,700: 6,500 : 7,33o
7,210 : 7,390 • 7,090: 7,500: 6,250: 6,890
6,570 : 6,76o : 6,900: 7,690: 6,050 : 6,670
7,090: 6,410. 8,020: 7,200: 5,940: 8,400
7,890: 6,190: 8,080: 7,420: 7,100: 7,030
411r.
:
:
:
:
:
7,010. 6,720. 7,310: 7,300: 6,370. 7,260 :
0
0
0
0
0
:
:
:
:
:
o :
0
0
0
0
0
:
:
:
:
:
0
0
0
0
0
o :
0
:
:
:
:
:
0
0
0
0
0
:
:
:
:
:
0
0
0
0
0
: 0
: 0
: 0
0
: 0
0
:
0
:0
Facings, five plies of glass cloth 112-114; core, 1/2-inch glass-cloth honeycomb
19,600
19,600
21,600
21,900
19,300
Av.
:
:
:
:
:
19,300
16,100
17,400
15,100
18,800
:
:
:
:
:
11,200: 20,400: 6,730 : 24,000 •
11,90o: 22,300: 7,480 : 26,600 11,800: 21,000: 6,430 : 29,800 •
11,200: 24,200: 7,120 : 27,900 •
10,600: 20,800: 6,370 : 24,600 •
20,400 : 17,300 : 11,300: 21,700: 6,830 : 26,600 •
:
:
:
:
:
0
0
0
0
0
• 17,600 :
0
• 20,000
18,800
• 15,50o
• 16,900
• 16,800
:
0
0
0
0
0
:
:
:
:
:
0
0
0
0
0
:
:
:
:
:
0
0
0
0
0
0
:
0
:0
0
0
0
0
0
:
:
:
:
:
Facings, five plies of glass cloth 181-114; core, 1/2-inch glass-cloth honeycomb
Av.
• 24,500 • 15,400: 24,000- 6,500 • 24,800 •
19,700 : 20,000 : 14,200: 22,700: 6,990 : 25,900 •
24,800 : 21,200 : 13,400: 22,000: 6,250 : 23,100 •
18,900 : 21,200 : 13,900: 22,800: 5,360 : 24,500 •
19,700 : 18,200 : 11,400: 21,400: 5,070 : 24,300 :
:
•
:
t
:
20,800 : 21,000 : 13,700: 22,60o: 6,030 : 24,500 Report No. 1804-B
z M 90448 F
0
0
0
0
0
:
:
:
:
:
0
0
: 0 : 0
:
0
0
0
0
0
:
o•.
0
•.
•.
0
0
:
Table 4.--Effect of exposure for 192 hours at elevated temperature on the shear strength
of sandwich constructions
Shear strength
Conditioning temperature
160° F.
75° F. 350° F.
250° 7.
600° F.
450° F.
Testing temperature
75°
F.
.
_
: 75° F. :160° F.: 75° F.: 250° F.: 75° F. : 350° - F:: 75° F. : 450° F.: 75° F. :600° F.:75° F.
P.s.i.
: P.s.i. : P.s.i.: P.s.i.: F.s.i. : P.s.i. : P.s.i. : P.s.i. : P.s.i. : P.s.i. : P.s.i.:P.s.i.
Facings, 0.020-inch clad 24S-T3 aluminum; core, 1/2-inch end-grain balsa
260
270
: 230
: 280
: 280
: 230
: 270
:
:
:
:
:
260
: 260
: 230 : 250 :
240
270
26o
Av.
210 : 260 : 1 210 :
220 : 240 -220
:
220 : 260 : 1330 :
230 : 240 :
200 :
250 : 270 :
210 :
210 :
200
230
240
230
220
:
:
:
:
:
220 :
0
0
0
0
0
:
:
:
:
:
0 :
:
:
:
:
:
0
0
0
0
0
0
0
0
0
0
:
:
:
:
:
0
0
0
0
0
:
:
:
:
:
0 :
0
0
:
0
: 0
:
:
10
10
: 10
: -10
: 10
0
: 0
0
0
0
0
0
0
0
0
0
0
Facings, 0.020-inch clad 24S-T3 aluminum; core, 1/2-inch aluminum honeycomb
190
180
210
190
180
Av.
190
: 210
: 190
: 190
: 190
: 180
:
:
:
:
: 190
: 180 : 200 :
200 : 190
170 : 190
180 : 200
180 : 200
: 170 : 210
:
:
:
:
160
140
140
150
150
:
:
:
:
:
150 :
190
190
190
190
180
:
:
:
:
:
190 :
115 :
110 :
100 :
120
125 : -115
130 : 124
140 : 117
135 : 125
: 13,m
: 132
: 150
28
:
:
53
100 :
140 : 120
:
95 :
95 :
155
40
:
10
: 10 : 10
. : 10 : 10
:
Facings, 0.020-inch clad 248-T3 aluminum; core, 1/2-inch cotton-cloth honeycomb
Av.
160
170
170
170
190
:
:
:
:
:
170
: 160 160
180
170
150
150
: 130 : 150
: 14o : 160
140 : 170
: 150 : 160
: 150 : 160
:
:
:
:
:
: 140 : 160 :
Facings, five plies of
100
100
100
100
100
:
:
:
:
:
100 :
glass
140
130
130
150
140
:
:
:
:
:
10 :
5 :
10 :
10 :
0 :
140 : • 7 :
:
:
:
:
:
0
0
0
0
0
O
O
O
O
O
:
:
:
:
:
0
0
0
0
0
:
:
:
:
:
o :
0
O
:
0
: 0
0
0
0
0
0
cloth 112-114; core, 1/2-inch glass-cloth honeycomb
1 1 90
11 70 : 1220 : 1140
1160
1180 : _180
124o T1 0
:
1180 : 1210 : 1200 : 1220 : -1
1 90 : 1230 : t. 0
1 20 : 1230
4- 0
i90 : 1230 : 1-180 : ii(-u-
:
—1.
1—50 : 1200 : 1 90 : 1180 : T
:
00
: 1170 : 1170 : 1220 : 1140 : 1230 : 1120 : 2140 : 4-
1200
: 1150 : 1180 : 1180 : liao : 1.230 : 1100 : 1230 : T. (o) :
Av.
190
: 190
: 180 : 200 :
0
0
0
0
0
130 :
210 :
100 :
200 :
0
1 0 : 20 : 20
1 o : lo : lo
1 0
: 10 : 10
1 0 : 110
: 10
1 0 : 10 : 10
0
:
0
: 0
Facings, five plies of glass cloth 118-114; core, 1/2-inch glass-cloth honeycomb
1240 : 1260 : 1220 : 1220 : 1150 : 1240 : 1110 : 1160 : 1 0: 1 0: 10 : 40
1
: 1190 : 1210 : 1230 : 112 : 111,0g : 1110 : 1160 : 1 o : 1 o : o : 4o
-220 : 1260 : 1220 : 1240
: 0
: 0
: 1 0
2:100 : 1120 : 1 0
: 10
: 1 0
: lo
1 70 : I 0
1200 : 2250 : 1200 : 1240 : _170 : 1240 : 1120 : _1
2220 : 2250 : 1210 : 1230 : 2150 : 1220 : 1100 : 1180 : 1 0 : 1 0 : 10 : 10
Av.
220
: 240
: 210 : 230 :
160 :
230 :
110 :
160 :
0
0
:
0
: 0
1Bond failure occurred in these specimens. The values for them are not included in the averages unless
bond failure occurred in most specimens in the same group.
Report No. 1804-B
Z149044.93.
Table 5.--Effect of exposure for 192 hours at
of sandwich constructions
elevated temperature on the tensile
strength
Tensile strength normal to facings
Conditioning temperature
75° F.
250° F.
160° F.
!
600° F.
450° F.
350° F.
Testing temperature
75° F.
: 75° F. :160° F.: 75° F.: 250° F.: 75° F. : 350° F.: 75° F. : 450° F.: 75° F. :600° F.:75° F.
P.s.i.
: P.s.i. : P.s.i.: P.s.i.: P.s.i. : P.s.i. :▪ P.s.i. :• P.s.i. :• P.s.i. : P.s.i. : P.s.i.:P.s.i.
Facings, 0.020-inch clad 248-T3 aluminum; core, 1/2-inch end-grain balsa
1,520 : 1,630 : 11,570: 11,590: 755
1,220 : 1,655 • 11,535: 11,880: , 455
1,865 : 1,585 :
930: 1,910: .*80
1,895 : 1,435 1,200: ,1,940: 625
1,735 : 1,540 :
990: =1,810: 945
:
Au.
:
: •
:
: 1,400 :
: 1,070 :
0 :
0 :
0 :
0
0
0
0
:
0 :
.
0 :
:
: 1,260 :
0 :
0 :
: 1,370 :
: 1,290 :
: 1,180 :
:
1,645: 1,570. 1,040: 1,910: 695
0 :
:
:
:
:
0
0
0
0
:
:
:
:
0
0
0
0
0
:
:
0
0
:
0
:
:
:
10
:
10
:
0
:
0
:
:
:
:
0
0
0
0
0 :
:
0 :
0
:
:
:
:
:
0
:
:
0
0
0
0
Facings, 0.020-inch clad 24S-T3 aluminum; core, 1/2-inch aluminum honeycomb
1 465 : 1 460 : 1 425:
1 455 : 1 515: 1 475: 1
1 415 : 1 495 :
445: 1
1 515 .1 445 :
395: 1
1 485 : 455 : 1 415:1
465 :
Av.
475 :
430:
505: 1350 : 1 485 : .1 95 : 1100 : 110 : 125
455: 2325 : 1 440 • 1 30 : 1160 : 110 : 215
395: 1380 : 1 460 : 1 65 : 1 65 : 115 : 110
445: 1305 : 1 485 : 1100 : T. 90 : 1 5 : 115
525: 2380 : 1 500 : 1 95 • 1165 : I 0 : 1 5
465: 350
475 :
:
75 :
115 :
10 :
15
40
10
: 20
: 10
: 10
: 10
: 10
: 10
Facings, 0.020-inch clad 24S-T3 aluminum; core, 1/2-inch cotton-cloth honeycomb
210 :
200 :
1 190 : 1 210 :
225 : I 200 :
220 :
225 : 1
250 :
195 :
.1
220 :
Av.
210: 1 165: 1
180:
175:
:
:
:
:
:
0
0
0
0
0
:
:
:
:
:
0
0
0
0
0
:
:
:
:
:
0
0
0
0
0
0 :
10 :
0 :
0
:
0
:
0
:
175 :
:
:
:
170 :
0 :
0 :
155 :
0 :
5 :
115 :
0 :
185: 1 160: 145
:
160 :
175: 145
:
155 :
180:
210 :
0 :
10 :
10 :
0
0
0
0
0
195: 135
145: 160
170: 125
210: 150
10 :
10 :
Facings, five plies of glass cloth 112-114; core, 1/2-inch glass-cloth honeycomb .
1 400 : 1 395 : 1 435: 1 510: 1245 : + 455 : 1145 : 1175 : 1 0 : 1 0 : 10
1 335 : 1 465 : 1 435: 1 530: 2290
: too
T- 0 : ..
T- o
: 1I 515: 1130 : 1190 :
0 : ...i 0
: 10
__I o
: o
395: .1._- 500: 1190
: _
1-
: 4- 440: 1150 : 11 90 :
1 470 : 1 440 : 1 390: 1 520: 1 260 : I 560 : 1145 : 1190 : 1- 0 : 1 0
: lo
: 10
1
1
Av.
T
450
325
365::
11.70:
T-
53o:
1 255
:
T
46 5 : 1.140 : 1175 :
:: .1- 405
395 :
415 :
425:
520: 250
:
485 :
140 :▪
185 :
0
0 :
:
0
Facings five plies of ass cloth 118-114; core 1 2-inch :lass-cloth hone comb
520: 1285
: 1 375 : 1165 : 1170 : 10:10 : 10
1 340 : 1 285 : -3- 448:
lo
: T- 415: _1
1 405 : 1 430 :1 330: 4- 415: 2250
1 45 : 1170 : TO:TO
10:10 : 10
: 1 400: 1130 : 1145 :
290 : 4.- 375 : 1 255: 4 470: 1275
lo
10:10
: 1 400: 1140 : 1175 :
1 360 : 1 355 : 4.- 345:
385: 1215
1 20 : 1 95 :
: lo
10:10
: I 385 : _1
1 375: 1 440 :.1 280: 1 370: 2290
355 :
Av.
375 •
330:
430:
265
:
395 :
140
:
150
:
0 :
0
0
: 10
10
!
: 10
: 10
: 10
: 10
:
:
=Bond failure occurred in these specimens. The values for them are not included in the averages unless
bond failure occurred in most specimens in the same group.
Report No. 1804-B
Z M 90450 F
0
0