Automated Tow/Tape Placement System

manufacturing
Automated Tow/Tape Placement System (LAR-TOPS-342)
High-precision, tool-less composite manufacturing
Overview
In recent years, industry adoption of thermoplastic composites (TPCs) in lieu of thermosets and metallic structures has increased for the fabrication of air and launch vehicle components. Manufacturing of TPCs, performed via automated tape laying (ATL) and automated fiber placement (AFP), uses machines that place prepreg tow or tapes on molds in a unidirectional manner, which then undergo cure cycles, autoclaving, and other steps that require special tooling. The process is time, material, and energy intensive, requires large facilities to house equipment, and limits the size, mechanical properties and shapes of the parts manufactured. To address these limitations, NASAs Langley Research Center has developed a simplified, tool-less automated tow/tape placement (ATP) system. The invention uses two opposed ATP cars working in tandem to achieve tool-less operation, bidirectional lay-up, and expansion of the design space and size of TPC components that can be manufactured using ATP systems.

The Technology
This NASA invention enables several benefits that mitigate limitations associated with conventional ATP systems, including the following: (1) avoids obtuse head rotation or cross-tool translation when laying adjunct tape plies, (2) simultaneously places tape on both sides of a part via two robots, (3) eliminates external anchoring frame requirements, and (4) translates parts during build while also translating the applicator head. The ability to perform simultaneous layup on opposite sides of the component, as well as reduction of head rotation reversal during bidirectional tape layup, offers increased layup speed. The invention offers increased placement accuracy as a result of reduced movement between tape layup operations and the eliminated need for an anchoring frame (facilitated by simultaneous pressure extrusion of prepreg by the two robots). NASAs automated tow/tape placement system has two key unique features: the use of two opposed ATP cars to enable a tool-less process, and an on-the-fly reversal tape/tow laydown tooling head. The system uses two opposing (i.e., underside-to-underside) ATP cars, and can build parts vertically, horizontally, or at any other angle, depending on the workspace available. The ATP die wheels can be reversed or turned to draw the composite back and forth at different angles to create a layer-by-layer composite structure. Both cars can dispense TPC tape thus, either car can function as an opposing tool surface while the other performs prepreg lay-up. For structures that do not vary in thickness, both cars can lay tape at the same time doubling layup speed. Current ATP robots must rotate the large tooling head, or traverse panels without layering tape to achieve bidirectional layup, where each additional movement introduces alignment error. To increase layup rate while simultaneously minimizing misalignment, NASAs system incorporates an on-the-fly reversal tape/tow laydown tooling head to enable efficient bidirectional layup.
A conventional, multi-axis AFP system operating at NASA's Langley Research Center.
Benefits
  • Tool-less: NASAs automated tow/tape placement system eliminates the need for post-layup composite or metallic processing infrastructure (e.g., pre-assembled tooling, autoclaves, molds, ovens), as well as the need for a starting frame for initial prepreg anchoring.
  • Increased layup speed: By reducing head rotation reversal during bidirectional tape layup and performing simultaneous tape placement on opposite sides of a part, NASAs invention offers increased layup speed.
  • Enhanced placement accuracy: NASAs ATP system reduces movement between tape layup (e.g., for bidirectional layup), resulting in decreased tape misalignment.
  • Real-time quality inspection: The invention includes a closed-loop, real-time, in-situ process for inspection and verification of bond quality.
  • Enables large composite structures in remote applications: Because NASAs system enables tool-less builds, it can be used to build unique structures with minimal infrastructure as such, it is ideal for fabrication in remote locations, such as space.

Applications
  • Composite manufacturing: NASAs automated tow/tape placement system can be used to fabricate aerospace quality composite structures spanning broad sizes and geometries.
  • In-space composite manufacturing: Because it does not require tools for operation, NASAs system is ideal for composite fabrication in remote locations, including in-space use.
Technology Details

manufacturing
LAR-TOPS-342
LAR-19705-1 LAR-19705-1-CIP
11/628,636
Similar Results
Image credit: NASA
Calibration System for Automated Fiber Placement
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.
helicopter
Method and Means to Analyze Thermographic Data Acquired During Automated Fiber Placement
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).
Fabrication of Fiber-Metal Laminates with Non-Autoclave Processes
Fabrication of Fiber-Metal Laminates with Non-Autoclave Processes
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.
Selective laser melting at NASA
3D-Printed Composites for High Temperature Uses
NASA's technology is the first successful 3D-printing of high temperature carbon fiber filled thermoset polyimide composites. Selective Laser Sintering (SLS) of carbon-filled RTM370 is followed by post-curing to achieve higher temperature capability, resulting in a composite part with a glass transition temperature of 370 °C. SLS typically uses thermoplastic polymeric powders and the resultant parts have a useful temperature range of 150-185 °C, while often being weaker compared to traditionally processed materials. Recently, higher temperature thermoplastics have been manufactured into 3D parts by high temperature SLS that requires a melting temperature of 380 °C, but the usable temperature range for these parts is still under 200 °C. NASA's thermoset polyimide composites are melt-processable between 150-240 °C, allowing the use of regular SLS machines. The resultant parts are subsequently post-cured using multi-step cycles that slowly heat the material to slightly below its glass transition temperature, while avoiding dimensional change during the process. This invention will greatly benefit aerospace companies in the production of parts with complex geometry for engine components requiring over 300 °C applications, while having a wealth of other potential applications including, but not limited to, printing legacy parts for military aircraft and producing components for high performance electric cars.
Helicopter Xray
Continuous Fiber Composite for Use in Gears
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.
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