FILAMENT WOUND VESSEL Field of Invention
This invention relates to a filament wound vessel. The vessel may comprise a storage tank or transportation vehicle such as an overland truck or railway car. Background of the Invention
In application Serial No. 113,240 filed January 18, 198 a railway hopper car is disclosed in which "E" type glass, low alkali, lime-alumina, borosilicate glass filaments are passed through a liquid polyester (Isophthalic acid and pro lene glycol) resin containing styrene monomer for unsatura- tion to form flat bands of about one foot in width which ar wound about a mandrel in a helical winding pattern at an an of not more than +30 to the longitudinal axis of the car b
This winding technique results in the following properties:
+20 Fiber Orientation Properties at Room Temperature Along the Axial Direction
Property Test Method Specified Value Tensile Strength #STM D638-72 at least 80,000 psi (Modified)
Compressive Strength ASTM D695-69 at least 80,000 psi
(Modified)
Longitudinal Shear Fed. Specifi¬ at least 5,000 psi Strength cation LP 406 Method 1401 (rec¬ tangular punch) Flexural Strength ASTM D790-71 at least 80,000 psi Method II (Modified)
Flexural Modulus ASTM D790-71 at least 4.3 x 10" Method II psi (Modified)
Bearing Strength ASTM D953-54 at least 25,000 psi (Modified)
Glass Content by ASTM D2584 at least 60, and pref Weight ably from 60 to 70 percent
Density ASTM D742-66 at least .06 and pref ably from .06 to .07 lb/in.3
Flam ability Rating Fed. Test "Self Extinguishing by Method STD. this Test." No. 406 Method 2021
SUBSTITUTE SHEET
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However, this results in a structure in which the properties in the winding direction are significantly different from the properties along the axis ofthe car body. * Furthermore, the properties in the y direction or 90 to the longitudinal axis of the vessel, are not substantiall equal to those in the x direction, or along the longitudinal axis of the vessel (0°). Moreover, it is not clear and has not been demonstrated that the properties resulting from this winding technique are sufficient to withstand the rail environment and the impact loads encountered in switch¬ ing yards.
U.S. Patent 3,486,655 discloses the formation of a filament wound vessel comprising forming a plurality of layers of alternate longitudinal and transverse windings, each winding having at least one point of intersection and two points of return. Adjacent layers are formed so that the points of intersection of adjacent layers are out of register.
However, the longitudinal windings do not appear to be substantially parallel with the longitudinal axis of the vessel and the transverse windings do not appear to be sub¬ stantially perpendicular to the longitudinal axis of the vessel. Furthermore, the resulting properties of the vessel are not stated and thus this patent does not teach hat properties may be expected from this winding technique. Summary of the Invention
One object of the present invention is to provide a wound vessel (or structure) having quasi-isotropic propertie or properties in which the mechanical properties in the x direction along the longitudinal axis of the vessel are approximately equal to the mechanical properties in the y direction perpendicular to the longitudinal axis of the vessel, and in which the mechanical properties in a directio +45° to the longitudinal axis of the vessel are substantiall equal to the mechanical properties in a direction -45 to the longitudinal axis of the vessel.
Another object of the present invention is to provide a filament wound vessel which can withstand the lading and environmental loads normally applied to the vehicle in servi
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Another object of the present invention is to provide a filament wound railway car which can withstand the lading loads and the impact loads the car is normally subjected to in switching yards, and corrosive atmospheres encountered in service.
In accordance with the present invention, a filament wound vessel includes at least one layer of resin impregnat glass fiber rovings formed into bands, and hoop wound upon a rotating mandrel in a direction approximately 90° to the longitudinal axis (x direction) of the mandrel. The strand are thus orientated at approximately 90 to the vessel (y direction) . Preferably the bands are about six (6) to twelve (12) inches in width and do not overlap but lay adjacent to each other. Preferably more than one such hoop layer is applied.
Next, at least one layer of weft unidirectional fabric comprising rovings of glass fibers woven together with a suitable thread such as cotton fiber in the warp direction into a relatively wide band about twenty (20) to about thirty (30) inches in width is then hoop wound upon the first hoop wound roving layer(s) with a resin binder. This results in the glass fibers being orientated parallel with the longitudinal axis of the vessel (x direction) at approx imately 0 . The resin binder is simultaneously applied by coating the band, or spraying the binder upon the previous layer. Preferably for speed in fabrication, the wide bands are wound in an overlapping manner as in roof shingles wherein one and preferably two applied layers overlap the first applied layer. Next, at least one band of resin coated or impregnated rovings is helically wound at an angle of from about +40 to about +60°, or -40° to about -60° to the longitudinal axis of the vessel (counterclockwise rotation positive) . Preferably, at least one additional band of resin coated or impregnated rovings is helically wound in a direction opposite to the first helically wound band. Preferably, several bands are helically wound alternatively at +45 , -45 until appropriate thickness to withstand shear and multiaxial loads is obtained.
SUBSTITUTE SHEET
Preferably, at least one layer of weft unidirectional woven fabric, woven with a suitable thread in the warp direction, is hoop wound along the longitudinal axis of the vessel upon the helically wound bands of rovings. A resin binder is simultaneously applied by spraying or dipping the fabric. This results in glass fibers being orientated at approximately 0 (x direction) . A relatively wide band of about twenty (20) to about thirty (30) inches wide is applied. Preferably the wide band is wound in an overlapping shingles arrangement, including at least one and preferably two layers of overlap of the first applied layer. Preferably, at least one additional band of resin impregnated rovings are hoop wound in a direction approx¬ imately 90 to the longitudinal axis of the vessel (y direc tion) . Preferably the bands are approximately six (6) to twelve (12) inches in width and are wound in a non-overlap relationship.
Through appropriate design, a vessel wall may thus be fabricated as described above which has many layers havi different filament orientations which result in a laminate which approximates a "balanced" laminate, i.e., a laminate which is symmetrical about its midpoint.
The winding technique of the present invention can also be utilized to produce filament wound vessels from other materials such as fiber rovings and fiber strands. If othe fiber rovings and other fiber strands are utilized, quasi- isotropic properties still may result from the winding technique of the present invention. Description of Preferred Embodiments In the drawings, a mandrel 10 having a contour similar to the internal shape of at least a portion of the resultin vessel body is supported for rotation by means of a pair of adapters 12 each having flange portions 14 through which fasteners 16 extend into the mandrel body. The adapter 12 includes a shaft 18 which is driven by an electric motor 20 in a known manner. At the opposite end a suitable bearing 22 is provided. Vertical supports 24 support the motor and the bearing 22 above a floor 26.
SUBSTITUTE SHEET
Fiberglass rovings, for example, of commercially available "E" type glass threads wound into rovings, are passed through a container 30 containing a suitable resin 32 (Figure 2). The type "E" glass is, for example, Owens Corning Fiberglass Corporation 431DA-450 yield. Type 30, Certain-Teed 625-A8, 450 yield, or PPG Industries Hybond 2077, 675 yield material. It should be noted that other reinforcements such as Dupont's Kevlar or graphite filamen can be used to provide required strength and stiffness, bu generally at a much higher cost. Preferably the resin is the polyester type comprising a condensation product of isophthalic acid and propylene glycol in a first condensati reaction. A second step in the polymerization process in¬ cludes a condensation product of fumaric acid, adipic acid, and tetrachlorophalic anahydride with the reaction product of the first stage. The result of this step is thinned with styrene monomer as is described in greater detail in said application serial number 113,240. Other resin system such as epoxy or vinyl ester materials can also be used but with a penalty in cost and/or manufacturing problems.
The glass rovings 28 are coated with the resin in the container 30 and are formed into bands 34 approximately six (6) inches thick. These bands 34 are then wound about the mandrel 10 in abutting relationship as indicated in Figure 1 at 34a, 34b, 34c, 34d, 34e, 34f, etc. until all of the mandrel is covered. It is apparent that when the band 34 is rotated about the mandrel 12, which is rotating, for example, at a speed of three revolutions per minute, that the strands 28 are wound in a direction 90 with respect to the longitudinal axis A of the mandrel and the resulting vessel. This is considered the x direction in this appli¬ cation. Preferably, a second layer 36 of resin coated band is hoop wound upon the first band 34 in the same manner to form abutting layers 36a, 36b, 36c, 36d, etc. Preferably still a third layer of bands 38 is hoop wound about second layer 36, including layers 38a, 38b, 38c, so that a three layer hoop wound structure is obtained.
Next, as illustrated in Figure 3, a unidirectional glass fabric indicated generally at 40 comprising glass
SUBSTITUTE SHEET
strands 42 of "E" type glass as specified previously, is woven with a suitable thread such as cotton fiber in a direction 90° with respect to the glass strands 42 at an arial density of about 260 ounces per square yard. The type fabric is, for example, Profor Kyntex D156. The fabr preferred is approximately twelve (12) strands per inch. While cotton is a suitable thread, it will be apparent to those skilled in the art that other threads for weaving of the strands may be utilized. The fabric is provided in relatively wide segments of approximately 24 inches in width. The fabric 40 is hoop wound upon the layers 34, 36, 38 as indicated at 46. It is to be noted that hoop winding the fabric 40 results in the glass strands 42 being located in the x direction parallel to the longitudinal axis of the vessel A (0 ) . Preferably, the fabric is wound in an overlapping relationship as shown in Figure 4 wherein a second layer 48 is overlapped upon the first applied layer 47. Furthermore, preferably, still a third layer 50 is applied which overlaps layer 48, and also to some extent may overlap layer 47.
It is apparent that if the width of the fabric is 24 inches and layer 48 is started eight (8) inches inboard of layer 47, and layer 50 is wound on the mandrel eight (8) inches inboard of layer 48, that two (2) overlapping layers each of eight (8) inches are achieved. Obviously, a construction of one (1) overlap, for example, of twelve (12 inches, or three (3) layers overlap of six (6) inches, could be utilized within the scope of the invention. It will be apparent, however, that hoop winding the fabric in this manner with the overlap technique, reduces the number of passes necessary to achieve a multi-layer construction.
Next, as illustrated in Figure 5, at least one band of resin coated rovings, indicated generally at 54, is helically wound at an angle of about +40° to +60° with respect to the longitudinal axis of the vessel, and at -40° to -60 with respect to the longitudinal axis of the vessel In this regard, counterclockwise rotation with respect to the longitudinal axis of the vessel, is considered positive Thus, a layer 54 of rovings is applied in a direction of
SUBSTITUTE SHEET
-45 in Figure 5. The band of rovings are conveniently six (6) inches wide, and are applied in abutting relation. As was the case in Figure 1, the rovings which produce lay 56 are first impregnated in the resin 32. Figure 5 illus- trates three (3) layers wound at the -45° angle of winding 56, 56a, 56b, etc. After the layer 56 is thus applied, another layer 58 is preferably applied at a direction of +45 . Thus the layer 58 is applied in a series of abuttin strips 60, 60a, 60b, etc. The layers are wound in a helic mode, and in so doing, the windings extend over the end portion of the mandrel. It is preferred to provide a plurality of alternate layers helically wound at -45 , +45 as indicated in Figure 6 at 56, 58, 60, 62, 64 and 66. Figure 6 also illustrates the first layer 33 of abutting hoop wound bands 34, 36 and 38, and the hoop wound fabric layer 46 including overlaps 47, 48 and 50.
Wound portion 54 includes bands of rovings 56. For many applications, the number of helically wound layers can be reduced. The number of layers will depend upon the load carrying capability and safety factor required for the particular application.
After application of the helically wound layer(s) 54, another portion 70 of weft unidirectional fabric is pre¬ ferably applied in the manner described above and illustrat in Figures 3 and 4. Preferably the fabric is wound in an overlapping relationship. Thus as illustrated in Figure 6, hoop winding of the layers 71, 72 and 74 in each case align the strand of glass in the woven fabric in a direction parallel to the longitudinal axis A of the vessel (x direct Two (2) overlapped layers are illustrated, but it is appare that one (1) or more than two (2) overlapped layers may be applied. For some..applications, only one (1) layer may be required.
Preferably, at least one additional portion 80 of hoop wound band of rovings is applied over the portion.70. This - hoop wound portion 80 is applied in the same manner as illustrated in Figures 1 and 2, including coating or impreg nating individual strands 82, 84, 86 with the resin 32. Preferably, a plurality of layers 82, 84 and 86 are thus
SUBSTITUTE SHEET / U
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applied in abutting relationship similar to layers 34, 36 and 38 in Figure 1. The number of layers will thus vary with the strength required and safety factor required for an individual application. In the embodiment illustrated in Figure 6, eighteen (18 plies or layers of glass are applied. However, this may , vary depending upon the specific properties desired, environment of the vessel, and safety factor desired. After application of the layers^, the vessel is re- moved from the mandrel 10, cutting as needed helically wound portions 54 at the ends 92 and 94, and a wound vessel 90 is obtained in a generally cylindrical shape as shown in Figure 7.
The resulting vessel has quasi-isotrppic properties. Thus the tensile strength in the x direction along the longitudinal axis of the vessel is substantially equal to the tensile strength in the y direction, 90 to the longi¬ tudinal axis of the vessel. For purposes of this applicati a positive direction is defined as counterclockwise rotatio from the longitudinal axis of the vessel. Furthermore, the elongation under similar loads in the x and y directions is substantially equal.
Also, the tensile compressive strength and shear strength in a direction +45 to the longitudinal axis of the vessel is substantially equal to the tensile compressiv strength, and shear strength in the direction -45 to the longitudinal axis of the vessel. Similarly, the elongation in a direction +45 to the longitudinal axis of the vessel is substantially equal to the elongation in a direction -45 to the longitudinal axis of the vessel.
Separately formed end portions 96 and 98 may then be adhesively bonded and/or mechanically fastened to the cylinder 91. End portions 96 and 98 may be formed of a composite sandwich panel of balsa wood care having fiber- glass facings on either side indicated at 95, 97 and 99 in Figure 8. An alternative approach is to use a single wall laminate as end portions which are also adhesively bonded and/or mechanically fastened to the cylinder and which act as membranes during loadings. A lading input opening 102
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ay then be formed in a top of the vessel, and a lading output opening 104 provided in the bottom. As shown in Figure 7, supports 106 and 108 may then be used to mount the vessel on the ground floor, thus a storage tank 110 results.
The vessel 90 may be mounted upon an overland truck as illustrated in Figure 9. Overland truck 120 includes a cab 122 having tires 124. Bulkheads 126 and 128 maintain the vessel in place upon the bed 130. Rear wheels 132 support the end portion of the overland truck.
In Figure 10, the railway car 140 includes trucks at either end 142 having wheels 144. A stub sill 146 includes coupler 148 to connect the car to adjacent cars in the train. A transverse bolster 150 is provided on the truck having a center plate 152 which engages a depending portion 154 of a metallic car body bolster 155 to which is connected car body 90 with heavy duty fasteners 156. Saddles 158 support the outer transverse portion of the vessel body 90. Lading may be loaded into the vessel through the inlet or hatch opening 102, and the lading removed through an outlet 104, for example, containing a ball valve of known construction.
The resulting properties in the x direction, in the y direction and in the +45° and -45 directions, must be such as to enable the filament wound structure to withstand the lading forces which it encounters in service and also withstand the loads and the environment which the particular service may apply to the vessel. For example, for a static storage tank such as illustrated in Figure 7, the primary problem may be the corrosive attack of the atmospheric and/o lading in the tank. The filament wound fiberglass structure is resistant to many corrosive atmospheres and ladings. This material is particularly resistant to the following environments, salts e.g., sodium chloride, phosphates, sul- phates and detergents. A transportation vehicle such as an overland truck is subjected to loads of the lading within th vessel, corrosion of the lading and the environment, and to fatigue loads which an overland truck encounters as it travels along highways. iUBSTlTUT-. SH-.-.T
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A railway freight car is subjected to corrosive atmos pheres of the lading and surrounds, and to lading loads due to the large weight of lading being transported and also to longitudinal train action, and impact loads in switching yards which are all substantially large. Impact loads in switching yards occasionally occur from impacts at speeds up to ten miles an hour.
The vessel walls are formed of a fiber-reinforced organopolymeric resin composite comprising from about 60 to about 75 weight percent of glass reinforcing filaments and from about 25 to about 40 weight percent of a structura polyester organopolymeric matrix resin, said matrix having a heat distortion temperature of at least about 90°C, a flexural strength of at least about 20,000 psi, a flexural modulus of at least about 5.0 x 10 psi, and a tensile elongation of at least about 3.0 percent, said glass rein¬ forcing filaments of said resin composite of said car body being oriented in said car body at an angle such that said glass filaments and said matrix resin are capable of pro- viding a composite comprising from about 70 to about 80 percent by weight of glass fibers and from about 20 to abou 30 percent by weight of said matrix resin and in the direct of winding having a tensile strength of at least about 100,000 psi, a flexural modulus of at least about 5 x 10 psi, an interlaminar shear strength of at least about
5,000 psi, an interlaminar shear strength after 24 hour water boil of at least about 5,000 psi, a flexural strength at room temperature of at least about 100,000 psi, a flexural fatigue strength for 1 x 10 completely reversed cycles of at least about 30,000 psi, and a density of from about .06 to about .08 pounds per cubic inch, a bearing strength of at least about 25,000 psi and a self-extinguish ing flam ability rating.
The following properties are important to the vessel of the present invention, particularly, when a rugged environment such as rail car use is contemplated. The present invention is capable of providing the following in the x and y directions (0 and 90 to the longitudinal axis of the vessel) and at an angle of +45 and -45 with respec
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to the longitudinal axis of the vessel.
COMPOSITE PROPERTIES PROPERTY TEST METHOD SPECIFIED VAL
Tensile Strength ASTM D638-77 at least 25,000
Compressive Strength ASTM D695-77 at least 25,000
Interlaminar Shear ASTM D2344-76 at least 5,000 p Strength
Flexural Strength ASTM D790-71 at least 25,000 Method II
Flexural Modulus ASTM D790-71 at least 2.5 x 10 Method II psi
Longitudinal Shear Fed. Test Methods at least 5,000 Strength STD. No. 406 Method 1041
Density ASTM D792-66 at least .06, pre ferably from .07 to .08 lb./in.3
Glass Content ASTM D2584-68 at least 60, and By Weight preferably from 7 to 80 percent
Flammability Rating Fed. Test Methods "Self Extinguish STD. No. 406 ing by this test Method 2021
Because the reinforced composite should exhibit structural properties over a wide range of environmental conditions, such a uniaxial composite should also best meet or exceed certain performance parameters when tested at 165 F or after being subjected to boiling water, as follows
PROPERTY TEST METHOD SPECIFIED VALUE
Tensile Strength ASTM D-2290-76 at least 100,000 at 165°F and D-2291-76 psi
Tensile Modulus ASTM D-2290-76 at least 5 x 10 at 165°F and D-2291-76 psi
Interlaminar Shear ASTM D-2344-76 at least 5,000 Strength After 24 psi Hour Water Boil
Flexural Strength ASTM D-790-71 at least 100,000 at Room Temperature Method II psi
Flexural Modulus at ASTM D-790-71 at least 5 x 10 6 Room Temperature psi
As indicated, the resin-glass filament system should be capable of providing at least these values in the fila¬ ment direction when used in a composite test specimen at 0 , 90 , +45 , or -45 or any other desired orientation relative to the longitudinal axis of the vessel.
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In The Drawings
Figure 1 is a schematic side elevation view of an apparatus for forming the wound vessel of the present invention. Figure 2 is a schematic plan view illustrated forming bands to be wound upon the mandrel shown in Figure 1.
Figure 3 is a schematic side elevation view illus¬ trating the application of weft unidirectional fabric.
Figure 4 is a schematic illustration of the overlap of weft unidirectional fabric.
Figure 5 is a schematic perspective view illustrating helically winding rovings at -45 and +45°.
Figure 6 is a schematic side elevation view illus¬ trating the wound layers in accordance with the present invention.
Figure 7 is a schematic side elevation view illus¬ trating the wound vessel of the present invention used as a storage tank.
Figure 8 is a schematic view of the end portion of the vessel illustrated in Figure 7.
Figure 9 is a schematic view illustrating the wound vessel of the present invention as a tank overland truck. Figure 10 is a schematic side elevation view illus¬ trating the wound vessel of the present invention used as a tank in a railway tank car.
Figure 11 is an end elevation view of Figure 10.
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