Automated Tow/Tape Placement System

NASA's new calibration system is a proprietary method to quickly design and make predictable and repeatable gap-and-overlap defects when employing AFP. The system creates defects within the course of layup with known sizes, geometries, and locations. Using this defect-creation technique, one can now accurately quantify the ability to detect defects on inspection systems, perform accurate risk assessments, and calibrate in-situ inspection equipment to specific materials. The equipment that makes the defects can be efficiently and inexpensively 3D printed. This technique is currently being used to successfully calibrate NASA's in situ inspection system for their AFP equipment. AFP is experiencing increasing adoption in aerospace, automotive, and other industries that leverage large-scale advanced composite components. NASA's new AFP calibration system could be very useful to companies that develop and manufacture AFP machines or AFP machine inspection equipment to improve the quality of their products in a provable manner. Furthermore, users of AFP machines may find value in the tool for creating their own calibration standards.

The latent heat of the item under fabrication is used to create a thermal image of a just completed tape bond. The image is then analyzed to detect anomalies in real-time. The defect data can be used in a feedback process to guide the bonding operation and tag the defect location for subsequent inspection. Image processing is a key element of the successfully implementing the process. The image process technique used not only reduces processing resources (such as CPU usage, memory, etc.), but also allows for a number of standard time-based analysis algorithms, typical of flash thermography, to be applied to the data (the reconstructed sequence).

The FMLs resulting from the NASA process have similar properties to traditionally produced metal/composite hybrid laminates including, as compared to either the composite or metal only structures, improved load carrying capability, lighter weight, improved stiffness, improved impact resistance and damage tolerance, and improved permeation resistance. The NASA process can be applied to various FML types, including GLARE (glass, aluminum, epoxy), and TIGR (titanium, graphite). Typical manufacturing processes are costly and complex shapes are hard to produce, whereby the NASA process enables use of these kinds of laminates without an autoclave or press, thus increasing the size that can be produced and decreasing the cost. The resin pathways in the foils enable connection between the plies that can improve the interlaminar strength of the final part. Functionally the NASA process creates resin columns in the transverse direction of the plies. NASA is working to optimize the final properties by varying the size and distribution of the pathways.

Designers are constantly seeking to improve the power-to-weight ratio of components in rotorcraft and other flight vehicles. One approach has involved using lightweight carbon fiber composite materials to replace gear web portions and other components that are typically made from steel. The problem with using fiber composite materials comes when more complex shapes are required. To create thickness variation and other accommodations for complex shapes, manufacturers can stack cut continuous fiber plies and/or form short, fiber-reinforced composite material to the desired shape. Unfortunately, these methods leave cut fiber ends within the structure, which often become initial sites for high cycle fatigue damage in high speed, high power density applications. Glenn's new method tackles this problem with one of three approaches. The first approach is applicable to gears that are planar in shape and have a single hub and a single rim. The hub and web sections of the gear are made as an integrated structure with decreased thickness from the hub inner diameter to the web outer diameter. The thickness variation is accomplished using multiple layers of continuous fiber composite material formed to specific shapes and separated by filler materials. The second approach is applicable to gears that have an extended gear body in the axial direction rather than a simple planar structure. In this approach, the gear body is made using multiple layers of continuous fiber composite material in the shape of a solid of revolution. The third approach is a power transfer assembly made by combining approaches one and two. With any of these three approaches, the material can be tailored to the structure by the properties of fibers used, the number of fiber layers used, and the location of the fibers relative to the neutral axis of the structure. Glenn's innovation opens the door for carbon fiber composite materials to be used for many applications for which they were previously unsuited.

NASA's plasma-deposition process provides the ability to tailor various properties while designing functional parts by selecting specific materials and processing parameters to meet the end goal. Specifically, the plasma process deposits metal particles that are heated as they travel axially at low velocity through an inert gas plasma. The accelerated powder particles become molten, strike the substrate fabric (uniaxial, biaxial, and multiaxial) and rapidly solidify, imparting very little heat to the substrate while forming a metal-to-fiber bond, as well as a metal-to-metal bond. The resulting metal-coated fabric is porous, so the polymer matrix can pass through the product precursor during the infusion process. The amount of metal deposited can be controlled, as can the number of plies of fabric that are ultimately stacked to produce the preform for the polymer matrix infusion process. A variety of infusion processes can be utilized to prepare the FML, including resin transfer molding (RTM), resin film infusion (RFI), and vacuum-assisted resin transfer molding (VARTM). The tailorable aspect of the process allows for specific product design. By varying the combination of metal particle, fiber, fabric type, metal layer thickness, fabric direction, number of layers, polymer matrix resin, infusion process, and cure conditions, the characteristics of the final part can meet the needs of various applications.