How Fiber Direction Influences Tube and Plate Properties

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The Fiber Orientation’s Effect on Properties The way fibers are oriented in a carbon fiber or fiberglass layup influences its properties for making everything from tubes to space-ships. Builders must consider those properties during their design process. Below we will explain how each of the common fiber orientations affect the properties. 1. 0° Orientation If a part will only be loaded in one direction it’s ideal to have all the fibers oriented in that direction. Pultruded rod and tubing are examples of a part that contains only 0° fibers. Since most parts aren’t loaded in only one direction we need to add other angles to maximize strength. A tube that sees only bending and no twisting would still likely benefit from some additional fiber angles. Adding 90° layers helps the tube maintain its shape better so that it doesn’t buckle prematurely. 2. 90° Orientation As previously mentioned, 90° layers are often added to tubes to make them more resistant to buckling and crushing. High concentrations of 90° or “hoop” layers can also be found in pressure vessels. Since the force is trying to enlarge the tube in a pressure vessel, 90° layers resist the force best. When 90° layers are used in conjunction with 0° layers in a plate, its referred to as bidirectional. Using woven cloth can be an easy way to quickly build parts with fiber in both 0° and 90° directions.
3. ±45° Orientation 45° layers serve different purposes depending on the application. You’ll almost always see a +45° paired adjacent to a -45° layer. This is to keep the laminate “balanced” and from forcefully twisting when loaded. When 45° layers are used in a plate that already contains an equal mix of 0° and 90° layers the plate becomes quasi-isotropic. Whereas a bidirectional plate has equal properties in two directions, a quasi-isotropic plate has quasi-equal properties in any direction. In a tube, 45° layers perform the job of adding torsional strength and stiffness. That’s because when a tube is twisted, the force acting on the laminate is actually at forty-fivedegrees. Some laminates will use angles other than 45° as a compromise between bending, crushing and torsion performance. Since 0° layers aren’t possible on filament wound tubes it’s common to see 10° or 15° layers use instead. Choosing the Right Fiber Orientation Now that you know how each fiber orientation affects the properties, you can choose the right layup. If you need a tube that performs in a wide variety of conditions, a bidirectional layup is ideal. If you need a tube that performs well in twisting, pick a product with more 45° layers. If you need to increase thickness quickly, a woven material might be a good choice. Rock West Composites offers plates and tubes with layups to meet almost any demand. If you need a custom or engineered layup for your project give us a call or shoot us an email. If you have more questions about how fiber orientation affects the performance of a part, our customer service representatives would be happy to help.
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How Fiber Direction Influences Tube and Plate Properties

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