A pressure vessel includes a ported fitting having an annular flange formed on an end thereof and a tank that envelopes the annular flange. A crack arresting barrier is bonded to and forming a lining of the tank within the outer surface thereof. The crack arresting barrier includes a cured resin having a post-curing ductility rating of at least approximately 60% through the cured resin, and further includes randomly-oriented fibers positioned in and throughout the cured resin

DeLay, Thomas K.

NASA Technical Reports Server

1111111111111111111inmuuu ~ 
(12) United States Patent 
DeLay 
(54) COMPOSITE PRESSURE VESSEL 
INCLUDING CRACK ARRESTING BARRIER 
(75) Inventor: Thomas K. DeLay, Huntsville, AL (US) 
(73) Assignee: The United States of America as 
Represented by the Administrator of 
the National Aeronautics and Space 
Administration, Washington, DC (US) 
(*) Notice: 	 Subject to any disclaimer, the term of this 
patent is extended or adjusted under 35 
U.S.C. 154(b) by 0 days. 
(21) Appl. No.: 13/544,066 
(22) Filed: 	 Jul. 9, 2012 
Related U.S. Application Data 
(63) Continuation of application No. 12/604,954, filed on 
Oct. 23, 2009, now abandoned. 
(51) Int. Cl. 
F17C1106 	 (2006.01) 
F17C1116 	 (2006.01) 
(52) U.S. Cl. 
CPC .... F17C1116 (2013.01); F17C1106 (2013.01) 
USPC 	 .......................................................... 220/588 
(58) Field of Classification Search 
USPC ................... 220/588, 586, 581, 62.19, 62.11, 
220/560.12, 560.04, FOR. 127; 206/0.6 
IPC .................. B65D 1/40,3/22, 90/02; F 17 1/16, 
F17C 1/06, 1/04 
See application file for complete search history. 
(56) 	 References Cited 
U.S. PATENT DOCUMENTS 
1,364,786 A * 	 1/1921 Samuel ........................... 442/64 
1,651,521 A * 12/1927 Lucas-Girardville ......... 220/589 
2,253,093 A * 	 8/1941 Ludwig et at ................. 138/150 
2,744,043 A * 	 5/1956 Ramberg ...................... 156/155  
(1o) Patent No.: 	 US 8,561,829 B1 
(45) Date of Patent : 	 Oct. 22 9  2013 
3,150,792 A * 9/1964 Bright 	 ........................ 220/62.19 
3,198,687 A * 8/1965 Royer 	 ........................... 428/138 
3,207,352 A * 9/1965 Reinhart, Jr ................... 220/589 
3,390,703 A * 7/1968 Marlow 	 ......................... 138/114 
4,004,706 A * 1/1977 Guldenfels et al............ 220/586 
4,674,674 A 6/1987 Patterson et al. 
4,842,909 A 6/1989 Brassell 
5,202,165 A 4/1993 Lusignea et al. 
5,429,845 A * 7/1995 Newhouse et al. 	 .......... 428/34.1 
5,632,151 A 5/1997 Baker et al. 
5,840,802 A * 11/1998 DeRudder et al ............... 525/63 
2002/0179603 Al* 12/2002 Darras et al ................ 220/62.11 
2004/0020932 Al 2/2004 Brunnhofer 
2004/0040969 Al* 3/2004 DeLay et al . 	 ................. 220/586 
2004/0089440 Al 5/2004 Sanders 
2004/0256395 Al 12/2004 Lak et al. 
2006/0054628 Al 3/2006 Matsuoka et al. 
2006/0169704 Al 8/2006 Brunnhofer 
FOREIGN PATENT DOCUMENTS 
EP 0379822 B1 8/1990 
JP 58121399 A 7/1983 
JP 2006062320 A 3/2006 
WO 91/02645 Al 3/1991 
WO 00/18225 Al 4/2000 
WO 2004/044477 A2 5/2004 
* cited by examiner 
Primary Examiner Jacob K Ackun 
Assistant Examiner Robert J Hicks 
(74) Attorney, Agent, or Firm Peter J. Van Bergen; James 
J. McGroary 
(57) 	 ABSTRACT 
A pressure vessel includes a ported fitting having an annular 
flange formed on an end thereof and a tank that envelopes the 
annular flange. A crack arresting barrier is bonded to and 
forming a lining of the tank within the outer surface thereof. 
The crack arresting barrier includes a cured resin having a 
post-curing ductility rating of at least approximately 60% 
through the cured resin, and further includes randomly-ori-
ented fibers positioned in and throughout the cured resin. 
14 Claims, 1 Drawing Sheet 
12 
	
14C 
	
10 
14 	 12A 
16 
1 4B 
14C 	 14A 
	
14B 14C 
	 16 
12A 
16 	 16B 
16A 
a. 
t' 
,. P 
16C 
https://ntrs.nasa.gov/search.jsp?R=20150003130 2019-08-31T11:25:14+00:00Z
U.S. Patent 	 Oct. 22 9  2013 	 US 8,561,829 BI 
12 
14C 
	
10 
14 	 12A 
~p 	 16 
B 
4C 	 14A 
4B 
14C 
	 16 
12A 
FIG. 1 
16 	
16B 
16A 
	 16 	
16B 	
16A 
.e 	 • 	 .: da 
	
FIG. 2A 	 FIG. 2B 16C 
30 
	
32
-- 
	 32A 32B 
14 
1 
1 
34 
FIG. 3 
US 8,561,829 B1 
1 	 2 
COMPOSITE PRESSURE VESSEL 	 approximately 60% throughout the cured resin, and further 
INCLUDING CRACK ARRESTING BARRIER 	 includes randomly-oriented fibers positioned in and through- 
out the cured resin. 
CROSS-REFERENCES TO RELATED 
APPLICATIONS 
	 5 	 BRIEF DESCRIPTION OF THE DRAWING(S) 
This application is a continuation application of U.S. 
patent application Ser. No. 12/604,954, filed on Oct. 23, 2009 
now abandoned. 
ORIGIN OF THE INVENTION 
The invention described herein was made by an employee 
of the United States Government and may be manufactured 
and used by or for the Government of the United States of 
America for governmental purposes without the payment of 
any royalties thereon or therefor. 
BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to pressure vessels. More specifi-
cally, the invention is a composite pressure vessel that 
includes a crack arresting barrier as part thereof. 
2. Description of the Related Art 
The aerospace industry relies heavily on the structural 
integrity of composite-based, cryogenic-fluid (e.g., liquid 
hydrogen) storage tanks for its space vehicles. Accordingly, 
the aerospace industry is very concerned about the formation 
and propagation of micro-cracks in composite tanks as such 
cracks can affect a tank's structural performance and provide 
paths for gas permeation through the tank's wall. While stud-
ies quantifying the micro-cracking phenomena are ongoing, 
methods/system for stopping such crack propagation do not 
exist. Most current efforts involve process enhancement of 
"off the shelf" composite tank material and structures, i.e., an 
orderly wound fiber tank structure permeated with a matrix 
resin. Current micro-crack studies have demonstrated that 
crack growth in such composite structures occurs in the 
matrix resin and travels along the ordered fiber windings. The 
cracking of the matrix resin affects structural integrity and 
also provides a leak path for gasses that are to be contained by 
the structure. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to 
provide a pressure vessel that resists cracking. 
Another object of the present invention is to provide a 
pressure vessel that arrests crack propagation. 
Still another object of the present invention is to provide a 
pressure vessel suitable for use in the storage of cryogenic 
fluids. 
Other objects and advantages of the present invention will 
become more obvious hereinafter in the specification and 
drawings. 
In accordance with the present invention, a pressure vessel 
includes a rigid ported fitting having an annular flange formed 
on an end thereof and a rigid tank enveloping the annular 
flange. The ported fitting fauns an opening of the tank that has 
an inner surface and an outer surface. A crack arresting barrier 
is bonded to the tank and forms a lining of the tank within the 
outer surface thereof. The crack arresting bather also enve-
lopes the annular flange. The crack arresting barrier includes 
a cured resin having a post-curing ductility rating of at least 
Other objects, features and advantages of the present 
invention will become apparent upon reference to the follow-
ing description of the preferred embodiments and to the draw- 
10 ings, wherein corresponding reference characters indicate 
corresponding parts throughout the several views of the draw-
ings and wherein: 
FIG. 1 is a cross-sectional view of a composite pressure 
vessel incorporating a crack arresting barrier in accordance 
15 with an embodiment of the present invention; 
FIG. 2A is an isolated cross-sectional view of a crack 
arresting barrier in accordance with an embodiment of the 
present invention; 
FIG. 2B is an isolated cross-sectional view of a crack 
20 arresting barrier in accordance with another embodiment of 
the present invention; and 
FIG. 3 is a cross-sectional view of a composite pressure 
vessel incorporating a crack arresting barrier in accordance 
with another embodiment of the present invention. 
25 
DESCRIPTION OF THE PREFERRED 
EMBODIMENT(S) 
Referring now to the drawings and more particularly to 
3o FIG. 1, a pressure vessel that includes a crack arresting barrier 
in accordance with the present invention is illustrated in 
cross-section and is referenced generally by numeral 10. The 
size and shape of pressure vessel 10 are not limitations of the 
present invention as size/shape are typically dictated by the 
35 particular application. In general, pressure vessel 10 can be 
used to contain a fluid material (e.g., gas or liquid) under 
pressure. 
In the illustrated embodiment, pressure vessel 10 includes 
an outer rigid tank 12 that can be constructed in accordance 
40 with a variety of known processes/materials. For example, if 
pressure vessel 10 is to contain cryogenic fluids, tank 12 
could be a composite wrapped structure, i.e., an orderly 
arrangement of fiber (e.g., carbon fiber) wraps held together 
in a rigid fashion by a resin matrix that permeates the fiber 
45 wraps. Tank 12 has an open-end 12A for receiving a fitting 14 
that defines the fluid entry/exit port of pressure vessel 10. 
Generally speaking, fitting 14 is an open-ended sleeve ofrigid 
material (e.g., metal) having a flared end 14A that is captured 
within tank 12 adjacent open-end 12A. That is, flared end 14A 
50 is essentially an annular flange of fitting 14 that extends 
radially outward beyond the confines of open-end 12A. A 
portion 14B of fitting 14 that extends from open-end 12A can 
be threaded internally and/or externally as indicated at 14C. 
Pressure vessel 10 also includes a continuous crack arrest- 
55 ing bather 16 that lines the inside surface area of tank 12 and 
is disposed between flared end 14A and tank 12. In general, 
barrier 16 bonds to the inside surface of tank 12 as well as 
flared end 14A of fitting 14. The construction and placement 
of bather 16 resists cracking and also serves to arrest the 
60 propagation of any cracks that do form. Possible construc-
tions for barrier 16 will be explained with reference to FIGS. 
2A and 2B where isolated cross-sectional views of a portion 
of barrier 16 are presented. 
FIG. 2A illustrates an embodiment of barrier 16 that is 
65 defined by a resin 16A (i.e., indicated by cross-hatching) that 
incorporates randomly oriented fibers 16B therein. Resin 
16A is any resin matrix material that remains ductile after 
US 8,561,829 B1 
3 
	
4 
curing. For many cryogenic applications the ductility rating 	 Although the invention has been described relative to a 
of resin 16A is at least approximately 60%, i.e., cured resin 	 specific embodiment thereof, there are numerous variations 
16A can be elongated by 60% prior to failure at room tem- 	 and modifications that will be readily apparent to those 
perature. Fibers 16B can originate as individual fibers that are 	 skilled in the art in light of the above teachings. It is therefore 
mixed/dispersed within resin 16A prior to the curing thereof. 5 to be understood that, within the scope of the appended 
Fibers 16B can also be in the form. of a felt material in which 	 claims, the invention may be practiced other than as specifi- 
case resin 16A permeates the felt material composed of fibers 	 cally described. 
16B. Accordingly, it is to be understood that the means and 
	
The invention claimed is: 
methods for constructing barrier 16 are not limitations of the 	 1. A pressure vessel, comprising: 
present invention as barrier 16 could be laid up, sprayed on, 10 	 a rigid ported fitting having an annular flange formed on an 
etc., the inner surface of tank 12. 	 end thereof, 
FIG. 2B illustrates another embodiment of barrier 16 that 	 a rigid tank enveloping said annular flange wherein said 
includes resin 16A and fibers 16B as described above, and 	 ported fitting forms an opening of said tank, said tank 
further includes nano-sized particles 16C mixed in resin 16A. 	 having an inner surface and an outer surface; and 
Particles 16C can be any of a variety of organic or inorganic 15 	 a crack arresting barrier bonded to and forming a lining of 
filler particles. When included in barrier 16, particles 16C aid 	 said tank within said outer surface thereof, said crack 
in the prevention of gas permeation through barrier 16 if a 	 arresting barrier enveloping said annular flange, said 
micro-crack should develop. 	 crack arresting barrier including a cured resin having a 
Regardless of its particular construction details, crack 	 post-curing ductility rating of at least approximately 
arresting barrier 16 functions as follows. In terms of crack 20 	 60% throughout said cured resin, said crack arresting 
resistance, the ductility of resin 16A allows barrier 16 to yield 
	
barrier further including (i) randomly-oriented fibers 
or flex without cracking. Thus is important as pressure vessel 	 positioned in and throughout said cured resin, and (ii) 
10 experiences pressure cycles. Since pressure vessel 10 does 	 nano-sized particles mixed in said cured resin. 
not rely on barrier 16 for strength, such yielding of barrier 16 
	
2. A pressure vessel as in claim 1, wherein said tank is a 
does not impact the structural integrity of pressure vessel 10. 25 composite wrapped tank. 
Furthermore, this yielding feature of barrier 16 allows it to 	 3. A pressure vessel as in claim 1, wherein said crack 
also function as a shear ply between tank 12 and fitting 14. 	 arresting barrier comprises a continuous layer disposed 
More specifically, barrier 16 bonds to both tank 12 (near open 	 between the entirety of said outer surface of said tank and the 
end 12A) and flared end 14A, and yields to shear forces that 	 entirety of said inner surface of said tank. 
can develop between tank 12 and flared end 14A during 30 	 4. A pressure vessel as in claim 1, wherein said crack 
pressure cycling. Accordingly, even though barrier 16 does 	 arresting barrier comprises a continuous layer bonded to the 
not possess the strength of the materials used for tank 12 and 	 entirety of said inner surface of said tank and bonded to said 
fitting 14, barrier 16 contributes to the overall structural integ- 	 annular flange. 
rity of pressure vessel 10 by forming a shear ply between tank 
	
5. A pressure vessel as in claim 1, wherein said fibers are 
12 and flared end 14A. Still further, in the event that a micro- 35 incorporated in a felt material. 
crack develops in bather 16, propagation of such a crack is 	 6. A pressure vessel as in claim 1, wherein said fibers are 
limited by the random orientations of fibers 16B. That is, the 	 individual fibers dispersed in said cured resin. 
random orientations of fibers 16B interrupt cracks in barrier 	 7. A pressure vessel, comprising: 
16. 	 a cryogenic tank having an open end; 
It is to be understood that the present invention is not 40 	 an open-ended sleeve having a threaded end and a flared 
limited to the pressure vessel construction described above. 	 end with said flared end disposed in said open end of said 
For example, FIG. 3 illustrates a pressure vessel 30 that 	 cryogenic tank; and 
includes a rigid tank 32 made from multiple layers such as 	 a crack arresting barrier lining and bonded to the inside 
three rigid layers 32A, 32B and 32C. The particular construc- 	 surface area of said cryogenic tank, said crack arresting 
tion of layers 32A-32C is not a limitation of the present 45 	 barrier bonded to said flared end of said sleeve, said 
invention. A rigid fitting 34 is disposed in tank 32 with a flared 	 crack arresting barrier including a cured resin having a 
end 34A thereof being disposed adjacent inner most layer 	 post-curing ductility rating of at least approximately 
32C. Pressure vessel 30 also includes a crack arresting barrier 	 60% throughout said cured resin, said crack arresting 
36 disposed continuously between layers 32B and 32C. Note 	 barrier further including (i) randomly-oriented fibers 
that barrier 36 additionally or alternatively be placed between 50 	 positioned in and throughout said cured resin, and (ii) 
layers 32A and 32B without departing from the scope of the 	 nano-sized particles mixed in said cured resin. 
present invention. Barrier 36 is a ductile composite config- 	 8. A pressure vessel as in claim 7, wherein said cryogenic 
ured as one of the above-described embodiments of barrier 	 tank is a composite wrapped tank. 
16. In addition, pressure vessel 30 includes a flexible collar 38 
	
9. A pressure vessel as in claim 7, wherein said fibers are 
disposed between and coupled to tank layer 32C and flared 55 incorporated in a felt material. 
end 34A. Collar 38 is also a ductile composite configured as 	 10. A pressure vessel as in claim 7, wherein said fibers are 
one of the above-described embodiments of barrier 16. 	 individual fibers dispersed in said cured resin. 
Accordingly, collar 38 forms a shear ply between tank 32 and 
	
11. A pressure vessel as in claim 7, wherein said sleeve is a 
fitting 34. 	 metal sleeve. 
The advantages of the present invention are numerous. A 60 	 12. A pressure vessel, comprising: 
simple crack arresting barrier of a ductile resin incorporating 	 a tank having an open end; 
randomly oriented fibers improves the overall structural 	 an open-ended sleeve having a threaded end and a flared 
integrity of a pressure vessel by inhibiting crack formation/ 	 end with said flared end disposed in said open end of said 
propagation and gas permeation. The barrier can also form a 	 tank; and 
shear ply between the vessel's rigid tank and rigid ported 65 	 a crack arresting barrier lining and bonded to the inside 
fitting. The design is suitable for use in cryogenic and non- 	 surface area of said tank, said crack arresting barrier 
cryogenic applications. 	 bonded to said flared end of said sleeve, said crack 
US 8,561,829 B1 
5 	 6 
arresting barrier including a felt permeated with a cured 
resin having nano-sized particles mixed in and through-
out said cured resin, said cured resin having a post-
curing ductility rating of at least approximately 60% 
throughout said cured resin. s 
13. A pressure vessel as in claim 12, wherein said tank is a 
composite wrapped tank. 
14. A pressure vessel as in claim 12, wherein said sleeve is 
a metal sleeve. 
* * * * * 	
10 


Composite Pressure Vessel Including Crack Arresting Barrier

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server