《纺织复合材料》课程参考文献（Principles of the Manufacturing of Composite Materials）CHAPTER 5 Filament Winding and Fiber Placement

Copyrighted Materials Copyright @ 2009 DEStech Publications Retrieved from www.knovel.con CHAPTER 5 Filament Winding and Fiber Placement 1. FILAMENT WINDING 1.1.Introduction Filament winding is a process used to make composite structures such as pressure vessels, storage tanks or pipes. Composite pressure vessels offer light weight and high strength. Applications include oxygen tanks used in aircraft and by mountain climbers, compressed natural gas cylin- ders for vehicles, drive shafts for automobiles, and pipes for conducting corrosive liquids. Filament winding is a comparatively simple operation in which con- tinuous reinforcements in the form of rovings or monofilaments are wound over a rotating mandrel. Specially designed machines, traversing at speeds synchronized with the mandrel rotation, control the winding angles and the placement of the reinforcements. Structures may be plain cylinders or pipes or tubing, varying from a few centimeters to one or two meters in diameter. Spherical, conical, and geodesic shapes are within winding capability. End closures can be incorporated into the winding to produce pressure vessels and storage tanks. A schematic of a simple filament winding setup is shown in Figure 1.2(b)and repeated here as Figure 5.1. Figure 5.2 shows a photo of a fila- ment winding machine [repeat of Figure 1.2(c)]. The basic mechanism consists of pulling a roving (number of strands) of fibers from the creels. These are spread out using a bank of combs. The fibers then go through a bath of resin (for the case of wet winding). On exit from the bath of resin, the fibers are collimated into a band. The band 205

CHAPTER 5 1. FILAMENT WINDING 1.1. Introduction Filament winding is a process used to make composite structures such as pressure vessels, storage tanks or pipes. Composite pressure vessels offer light weight and high strength. Applications include oxygen tanks used in aircraft and by mountain climbers, compressed natural gas cylin￾ders for vehicles, drive shafts for automobiles, and pipes for conducting corrosive liquids. Filament winding is a comparatively simple operation in which con￾tinuous reinforcements in the form of rovings or monofilaments are wound over a rotating mandrel. Specially designed machines, traversing at speeds synchronized with the mandrel rotation, control the winding angles and the placement of the reinforcements. Structures may be plain cylinders or pipes or tubing, varying from a few centimeters to one or two meters in diameter. Spherical, conical, and geodesic shapes are within winding capability. End closures can be incorporated into the winding to produce pressure vessels and storage tanks. A schematic of a simple filament winding setup is shown in Figure 1.2(b) and repeated here as Figure 5.1. Figure 5.2 shows a photo of a fila￾ment winding machine [repeat of Figure 1.2(c)]. The basic mechanism consists of pulling a roving (number of strands) of fibers from the creels. These are spread out using a bank of combs. The fibers then go through a bath of resin (for the case of wet winding). On exit from the bath of resin, the fibers are collimated into a band. The band 205

用 FIGURE 5.I Schematic of the filament winding process (courtesy of Wiley Interscience). FIGURE 5.2 The placement of fiber band on the mandrel.(www.gilgwang.com/english/ frp/grp01.html). 206

FIGURE 5.1 Schematic of the filament winding process (courtesy of Wiley Interscience). FIGURE 5.2 The placement of fiber band on the mandrel. (www.gilgwang.com/english/ frp/grp01.html). 206

Filament Winding 207 goes through a fiber feed and is then placed on the surface of a mandrel. The fiber feed traverses back and forth along the length of the mandrel. The mandrel is attached to a motor,which gives it rotational motion.The combined motion of the fiber feed and the rotation of the mandrel make the fiber bands spread over the surface of the mandrel.By covering the surface of the mandrel with many layers,one can build up the thickness of the part.The fiber orientation can be controlled by varying the speed of traverse of the fiber feed and the rotational speed of the mandrel.Fila- ment winding is usually used to make a composite structure in the form of surfaces of revolution,such as cylinders or spheres.The surfaces of these structures are usually convex due to the need to apply tension on the tows while these tows are placed on the surface of the mandrel.If the sur- face is concave,bridging of the fibers over the concave surface may oc- cur.As can be seen from these figures,the basic components of a filament winding system consist of a mandrel and devices to place the fiber tows on the surface of the mandrel to build up the thickness for the part. 1.2.The Winding Process The operation of filament winding is the reverse of the conventional machining process of milling on a lathe.In milling,one starts with a cy- lindrical surface and one removes the material from the surface one strip at a time.In filament winding,one deposits the material on the surface of the mandrel one strip at a time.The most basic form of filament winding is a two-degrees-of-freedom operation.This consists of the rotation of the mandrel and the linear movement of the feed along the axis of the mandrel.Two-axis filament winding machines can be used to wind pipes.Filament winding machines with more degrees of freedom exist. The availability of the additional degrees of freedom can be useful in winding at the end of the part,such as heads of pressure vessels,or the winding of shapes more complex than straight cylinders such as those with variation in cross section (i.e.cones)or spheres.For example,for the case of a four-axis winding machine,the basic movements are man- drel rotation and feed traverse.To these are added a cross-slide perpen- dicular to the mandrel axis and a fourth axis of motion,rotation of the feed eye.These latter permit more accurate fiber placement at the ends. Winding machines with more degrees of freedom up to the level of multi-degrees-of-freedom robots are available.To illustrate the concept of filament winding,only the simple operation of machines with two de- grees of freedom will be described in this chapter.Depending on the co- ordination between the rotational motion and the axial motion,different

goes through a fiber feed and is then placed on the surface of a mandrel. The fiber feed traverses back and forth along the length of the mandrel. The mandrel is attached to a motor, which gives it rotational motion. The combined motion of the fiber feed and the rotation of the mandrel make the fiber bands spread over the surface of the mandrel. By covering the surface of the mandrel with many layers, one can build up the thickness of the part. The fiber orientation can be controlled by varying the speed of traverse of the fiber feed and the rotational speed of the mandrel. Fila￾ment winding is usually used to make a composite structure in the form of surfaces of revolution, such as cylinders or spheres. The surfaces of these structures are usually convex due to the need to apply tension on the tows while these tows are placed on the surface of the mandrel. If the sur￾face is concave, bridging of the fibers over the concave surface may oc￾cur. As can be seen from these figures, the basic components of a filament winding system consist of a mandrel and devices to place the fiber tows on the surface of the mandrel to build up the thickness for the part. 1.2. The Winding Process The operation of filament winding is the reverse of the conventional machining process of milling on a lathe. In milling, one starts with a cy￾lindrical surface and one removes the material from the surface one strip at a time. In filament winding, one deposits the material on the surface of the mandrel one strip at a time. The most basic form of filament winding is a two-degrees-of-freedom operation. This consists of the rotation of the mandrel and the linear movement of the feed along the axis of the mandrel. Two-axis filament winding machines can be used to wind pipes. Filament winding machines with more degrees of freedom exist. The availability of the additional degrees of freedom can be useful in winding at the end of the part, such as heads of pressure vessels, or the winding of shapes more complex than straight cylinders such as those with variation in cross section (i.e. cones) or spheres. For example, for the case of a four-axis winding machine, the basic movements are man￾drel rotation and feed traverse. To these are added a cross-slide perpen￾dicular to the mandrel axis and a fourth axis of motion, rotation of the feed eye. These latter permit more accurate fiber placement at the ends. Winding machines with more degrees of freedom up to the level of multi-degrees-of-freedom robots are available. To illustrate the concept of filament winding, only the simple operation of machines with two de￾grees of freedom will be described in this chapter. Depending on the co￾ordination between the rotational motion and the axial motion, different Filament Winding 207

208 FILAMENT WINDING AND FIBER PLACEMENT types of winding can be obtained.These are:polar,helical,circuit and pattern,layer,hoop,longitudinal,and combination. 1.2.1.Polar Winding This is also called planar winding.In this process,the mandrel remains stationary while a fiber feed arm rotates about the longitudinal axis,in- clined at the prescribed angle of the wind.The mandrel is indexed to ad- vance one fiber bandwidth for each rotation of the feed arm.This pattern is described as a single circuit polar wrap(Figure 5.3).The fiber bands lie adjacent to each other;a completed layer consists of two plies oriented at plus and minus the winding angle 1.2.2.Helical Winding In this process,the mandrel rotates continuously while the fiber feed carriage traverses back and forth.The carriage speed and mandrel rota- tion are regulated to generate the desired winding angle.The normal pat- tern is multi-circuit helical.After the first traverse,the fiber bands are not adjacent.Several circuits are required before the pattern repeats.A typi- cal 10-circuit pattern is shown in Figure 5.4. In the above configuration one needs to distinguish between the straight cylindrical part and the head (or dome).In the straight cylindri- cal part,the relation between the rotational displacement and axial dis- placement can be established.Refer to Figure 5.5.This figure shows the developed surface of the straight part of the cylinder.The dimension of the base is nD where D is the diameter of the mandrel.Let o be the wind- ing angle (angle between fiber path and the axis of the cylinder),b be the band width of the fiber band,and L be the axial distance traveled by the FIGURE 5.3 Planar winding

types of winding can be obtained. These are: polar, helical, circuit and pattern, layer, hoop, longitudinal, and combination. 1.2.1. Polar Winding This is also called planar winding. In this process, the mandrel remains stationary while a fiber feed arm rotates about the longitudinal axis, in￾clined at the prescribed angle of the wind. The mandrel is indexed to ad￾vance one fiber bandwidth for each rotation of the feed arm. This pattern is described as a single circuit polar wrap (Figure 5.3) .The fiber bands lie adjacent to each other; a completed layer consists of two plies oriented at plus and minus the winding angle. 1.2.2. Helical Winding In this process, the mandrel rotates continuously while the fiber feed carriage traverses back and forth. The carriage speed and mandrel rota￾tion are regulated to generate the desired winding angle. The normal pat￾tern is multi-circuit helical. After the first traverse, the fiber bands are not adjacent. Several circuits are required before the pattern repeats. A typi￾cal 10-circuit pattern is shown in Figure 5.4. In the above configuration one needs to distinguish between the straight cylindrical part and the head (or dome). In the straight cylindri￾cal part, the relation between the rotational displacement and axial dis￾placement can be established. Refer to Figure 5.5. This figure shows the developed surface of the straight part of the cylinder. The dimension of the base is πD where D is the diameter of the mandrel. Let α be the wind￾ing angle (angle between fiber path and the axis of the cylinder), b be the band width of the fiber band, and L be the axial distance traveled by the 208 FILAMENT WINDING AND FIBER PLACEMENT FIGURE 5.3 Planar winding

DOME 11 DOME 12 10 AXIS POLAR PORRTA POLAR PORRT B 1510139 FIGURE 5.4 An example of a helical winding pattern. TTD FIGURE 5.5 Developed envelope with fiber path. 209

209 FIGURE 5.4 An example of a helical winding pattern. FIGURE 5.5 Developed envelope with fiber path