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naca-tn-3825

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National Advisory Committee for Aeronautics, Technical Notes - Comparison of Mechanical Properties of Flat Sheets, Molded Shapes, and Postformed Shapes of Cotton-Fabric Phenolic Laminates

The first known literature reference to the fact that cured phenolic
laminates can be formed when heated is contained in a footnote to a table
in a paper published in 1922 by Dellinger and Preston (ref. 1). They
stated that thin sheets could be pressed to simple shapes when warm. How-
ever, the art and commercial application of postforming phenolic laminates
was developed within the last 15 years. Postforming was developed and
used extensively, especially in the construction of aircraft components,
during World War II. One of the foremost early workers with this tech-
nique, Beach (refs. 2 to 7 and ref. 8 by Nash and Beach), refers to the
process as thermoelastic forming of laminates. Types of laminates partic—
ularly suited for postforming, methods of postforming, and applications of
postforming have been described by various investigators (refs. 9 to 17).

The fact that phenolic laminates can be postformed points out
forcefully that thermosetting plastics are to some extent thermoplastic.
Fully cured standard grades of phenolic laminates in thin sheets become
soft and pliable at elevated temperatures and can be formed into simple
shapes. However, forming is easier, more complicated shapes can be made,
and improved results are obtained if appropriate modifications are made
in the resin and fabric used. The resin may be modified to obtain a wide
range of flexibility at the temperature of forming (ref. 8); the use of
undercured stocks is not recommended by Beach (see ref. 8). Fabrics that
stretch more, without rupturing, than the ducks commonly used in plastic
laminates may be used (ref. 18). With a suitably formulated resin the
limitigg factor in forming is the amount the fabric can be stretched.

This report presents data on the properties of (a) several commer-
cial postforming cotton-fabric phenolic laminates, (b) industrially post-
formed shapes made from one of these materials, (c) industrially molded
shapes made from a similar base fabric and resin, and (d) laboratory
postforming stock, molded shapes, and postformed shapes made from the
same lot of resin—coated fabric used by one of the manufacturers to
make one of their commercial postforming stocks.

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naca-tn-3825

  • Version
  • 120 Downloads
  • 1.88 MB File Size
  • 1 File Count
  • January 31, 2017 Create Date
  • January 31, 2017 Last Updated
Scroll for Details

National Advisory Committee for Aeronautics, Technical Notes - Comparison of Mechanical Properties of Flat Sheets, Molded Shapes, and Postformed Shapes of Cotton-Fabric Phenolic Laminates

The first known literature reference to the fact that cured phenolic
laminates can be formed when heated is contained in a footnote to a table
in a paper published in 1922 by Dellinger and Preston (ref. 1). They
stated that thin sheets could be pressed to simple shapes when warm. How-
ever, the art and commercial application of postforming phenolic laminates
was developed within the last 15 years. Postforming was developed and
used extensively, especially in the construction of aircraft components,
during World War II. One of the foremost early workers with this tech-
nique, Beach (refs. 2 to 7 and ref. 8 by Nash and Beach), refers to the
process as thermoelastic forming of laminates. Types of laminates partic—
ularly suited for postforming, methods of postforming, and applications of
postforming have been described by various investigators (refs. 9 to 17).

The fact that phenolic laminates can be postformed points out
forcefully that thermosetting plastics are to some extent thermoplastic.
Fully cured standard grades of phenolic laminates in thin sheets become
soft and pliable at elevated temperatures and can be formed into simple
shapes. However, forming is easier, more complicated shapes can be made,
and improved results are obtained if appropriate modifications are made
in the resin and fabric used. The resin may be modified to obtain a wide
range of flexibility at the temperature of forming (ref. 8); the use of
undercured stocks is not recommended by Beach (see ref. 8). Fabrics that
stretch more, without rupturing, than the ducks commonly used in plastic
laminates may be used (ref. 18). With a suitably formulated resin the
limitigg factor in forming is the amount the fabric can be stretched.

This report presents data on the properties of (a) several commer-
cial postforming cotton-fabric phenolic laminates, (b) industrially post-
formed shapes made from one of these materials, (c) industrially molded
shapes made from a similar base fabric and resin, and (d) laboratory
postforming stock, molded shapes, and postformed shapes made from the
same lot of resin—coated fabric used by one of the manufacturers to
make one of their commercial postforming stocks.

FileAction
naca-tn-3825 Comparison of Mechanical Properties of Flat Sheets, Molded Shapes, and Postformed Shapes of Cotton-Fabric Phenolic Laminates.pdfDownload 
17,005 Documents in our Technical Library
2449533 Total Downloads

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Newest Additions

NASA-RP-1060 Subsonic Aircraft: Evolution and the Matching of Size to Performance
NASA-RP-1060 Subsonic Aircraft: Evolution and the Matching of Size to Performance
AA-CP-20212-001
AA-CP-20212-001
ADPO10769 Occurrence of Corrosion in Airframes
The purpose of this lecture is to provide an overview ...
MIL-STD-1759 Rivets and Rivet Type Fasteners Preferred for Design
The purpose of this book form standard is to provide ...
MIL-STD-810G Environmental Engineering Considerations and Laboratory Tests
This standard contains materiel acquisition program planning and engineering direction ...