New Materials for Next-Generation Commercial Transports (1996) / Chapter Skim
Currently Skimming:
4 Polymetric Composite Materials and Processes
4 Polymetric Composite Materials and Processes
Pages 36-44
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 36... ...
and highperformance and toughened matrix polymers has led to application on the Boeing 777 empennage to expand the primary structural applications. The factors currently driving new materials applications on commercial aircraft will place added emphasis on design simplification, low-cost processing, and durability and maintainability.
|
From page 37... ...
Toughened thermoses and thermoplastic polymers, described in the following sections, with improved values of delamination fracture toughness and resulting improvements in the structural parameter of compression strength after impact resulted from this work. The committee believes that future work will focus on the development of systems compatible with innovative processes described later in this chapter and the optimization of composite properties to provide resistance not only to delamination, but also to other forms of damage such as fiber damage and matrix cracking.
|
From page 38... ...
The increased notch sensitivity for toughened matrix systems is attributable to increased fiber damage and matrix cracking, that occurs in systems with high delamination resistance The committee believes that, in the future, materials optimization efforts will take a balanced approach that considers both small-scale (including most impact threats) and lar=,e-scale (including penetrations and severed elements)
|
From page 39... ...
parts that include features such as molded-in metal inserts, lightweight core materials, and thickness variations can be produced Two-part resin systems that do not need refrigeration (e.g., epoxy and vinyl ester) are generally used Capital equipment and tooling can be relatively inexpensive compared with other closed-mold processes Time-consuming debulking steps are elirrunated Limitations Lower production rates than other molding processes High-performance aircraft resin systems require further advances in process development, materials charactenzanon, and physical property opumizanon.
|
From page 40... ...
Modeling techniques to predict exact cure profile sequences for the RFI process and verification techniques are currently under development. Textile Preforms Fiber preforms represent a major component of the cost of RTM and RFI structural composites.
|
From page 41... ...
Efforts continue to develop high-temperature, high-elongation polymeric diaphragm materials which have the potential to reduce fabrication costs by easing part removal. Diaphragm foxing of thermoplastic composite laminates requires pressures up to 200 psi to assure consolidation and complete foxing.
|
From page 42... ...
Manufacturing costs can be as low as 15-20 percent of finished product cost, thereby providing high material value. The advantages of Pultrusion include low tooling costs, low labor costs, and the possibility of producing parts with no inherent limit on length.
|
From page 43... ...
Advanced Tow Placement for Thermosets Automated tow placement using thermosetting materials was pioneered by Hercules in the early 1980s. The process features strict control of ply orientation and thickness with complex geometries required for wing skins.
|
From page 44... ...
Thus, a primary criterion in the development of manufacturing processes for the next generation of commercial transports has been the potential for low-cost production of components. The committee believes that the trend to develop low-cost production processes such as resin transfer molding, resin film infusion, diaphragm forming, pultrusion, advanced tow placement, and nonautoclave processing will be continued for the foreseeable future.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.