https://www.rockwestcomposites.com/round-tubing/fiberglass-tubing - Take a close look at a section of carbon fiber or fiber glass tubing or plate and you will see that the fibers go in different, specific directions. Comparing different styles of tubing you might notice that fiber direction, also known as orientation, is not always uniform. Composite tubing and plate manufacturers use different orientations depending on what they want to accomplish with the finished product.
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.