Development of Methods for Spreading Fiber Materials and Application of Additive

Sammanfattning

Composite is a word that is often used to describe certain materials. It was originally defined as a material that contained at least two distinctively different constituents. In modern times the word composite is commonly used to refer to either fiberglass or carbon fiber laminates. Those types of composites are used in a wide variety of products in many different industries. Carbon fibers are used in anything from core material in ping pong rackets to wing skins in fighter jets. Many of the applications where those composites are used require two distinct properties of the material. Specific strength, which refers to how much load the material can hold without breaking per unit of material mass. Specific stiffness, which refers to how stiff the material is, per unit mass of material. Composites are often used for their excellence in these properties, but at a cost of more expensive material, compared to historically used materials such as steel or aluminum. Composites often incorporate small-diameter fibers, either lengthy or short, but also plastics, either thermo-sets or thermo-plastic. The plastic constituent is referred to as the matrix in the material. Its primary functions are to facilitate load transfer between the fibers and to maintain the structural integrity and geometry of the component. Owing to the intrinsic properties of the fiber-matrix interaction, additional constituents can be incorporated into the composite without significantly compromising its structural integrity. This project explored how additives in powder state could be added to a composite so that the [hidden words] could be validated. The project was conducted at Oxeon, via a preliminary mission statement compiled by the customer Saab. The project was executed exclusively within the boundaries of Oxeon’s and Saab’sresources, although with help from third parties in certain areas. The main scope of the project was to, but not limited to, choosing materials for stated applications. It also involved development of methods for spreading said materials into spread-tow-tapes. Tapes had to be manufactured into woven or discontinuous fiber composites. In addition to this, methods for incorporating additive within the composite manufacturing process had to be developed. Manufacturing laminates is common knowledge within the composite manufacturing industry. Adding additives is a process that is not nearly as established. This meant that background research and innovative thinking had to be used to find suitable manufacturing processes. Two low TRL manufacturing processes were developed during the project. One separate process for spread-tow fabric, STF, composites and one for discontinuous fiber composites, DFC. A process for incorporating additive into a resin film was developed. The film was manufactured by dispersing additive powder into low-viscosity epoxy. The epoxy was then cast into a thin resin film. Multiple layers of STF and resin film were combined into laminates. The DFC composite was manufactured using a significantly different method. Spread tow tapes were fed into a DFC matt machine. The machine placed flakes of tapes onto a form. [Hidden words]. The stack of fibers andadditive was thereafter transformed into a composite by infusing it with epoxy using vacuum infusion. A total of nine 30 cm x 30 cm square laminates were manufactured throughout the project, except for all smaller experimental laminates. Six laminates were manufactured as the first batch. Two laminates per fiber structure with two different concentrations of additive each. Two reference laminates were manufactured, one for STF and one for DFC. Due to complications in the manufacturing process, an excessive amount of [Hidden words] was inadvertently added to the [Hidden words] laminates. To ensure that the properties of the laminates could properly be analyzed, one extra referencelaminate for the DFC structure was manufactured for batch two. In batch two, the best performing volume fraction of additivefrom batch one was used while manufacturing two [Hidden words] laminates, one from each fiber type. It was concluded that the precision and accuracy of the amounts of which the additive was incorporated into the composite was low. Both the accuracy and precision were very high in certain parts of the process, but worse in other stages. It was also concluded that the manufacturing techniques that were used in this project might not be suitable for larger-scale production. However, there are established industrial manufacturing methods that could be slightly revised to work with the materials from this project.