JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 41

thermoplastics

Thermoplastic composites
for aerospace applications

By
Uday Vaidya, PhD
Professor & Chair,
Materials Science & Engineering
Director, Materials Processing & Applications Development (MPAD) Center
University of Alabama at Birmingham (UAB)

A

The benefits of thermoplastics include
light weight, excellent cost effectiveness,
high specific strength and stiffness,
enhanced vibration damping and acoustic attenuation, impact damage tolerance
(kinetic energy absorption), ability to
tailor material forms (design flexibility),
ability to mould complex geometries and

contours, superior shear and fracture
strength, tailored thermal conductivity,
recyclability, ability to incorporate EMI
shielding, robustness/durability in
harsh environments and environmental
harmlessness. Thermoplastic composites
offer an extremely flexible, robust yet
cost-effective fabrication process for
both limited and volume production of
aerospace structural components such as
trajectory kits, brackets, electronic base
boards, floor member, grid fins, wings,
shrouds, antenna, engine inlets and
stowage doors.

Promising opportunities
Currently, aerospace designers and
integrators do not have sufficiently comprehensive materials/processing/performance know-how to replace traditional
isotropic metals such as aluminium and
titanium. Historically, thermoplastics
were seen to be difficult to process when
they included fibre reinforcements.

However, in recent years, a wide range
of thermoplastic material options have
emerged; yet their use is very limited.
There are now promising opportunities
to use high-end engineered thermoplastic polymers with high-performance
fibre reinforcements in robust processing
technologies.
Carbon fibre thermoplastics are increasingly preferred over traditional metal
alloys such as aluminium and titanium.
This is also the case for carbon fibre
thermoset epoxy composites, due to
their superior specific modulus, specific
strength and impact damage tolerance at
reduced weight. Thermoplastic material
forms applicable for aerospace use are
generally classified into three categories:
discontinuous fibres, continuous fibres
and hybrids (combining discontinuous
and continuous fibres). This broad range
of material options provides a wide
design space to produce cost-efficient,

No96 April 2015 / jec

Feature Aeronautics

thermoplastic composite is comprised of a discontinuous and/or
continuous fibre reinforcement
- such as carbon, glass or Kevlar - in a
structural thermoplastic polymer - such
as polyamide (PA), polyphenylene
sulphide (PPS) or polyetherether ketone
(PEEK). A thermoplastic polymer is
reversible in its thermal history: it softens
upon heating past its glass transition
temperature and solidifies upon cooling
[1-3].

Thermoplastic composites are emerging rapidly in aerospace, aviation and missile/defence applications. Thermoplastic composites offer lightweight advantages, high
specific modulus and strength, design flexibility, ease of
processing, and recyclability. This paper presents some
recent work by the University of Alabama at Birmingham
(UAB) team in aerospace components featuring discontinuous and continuous carbon fibre thermoplastic materials, including complex-shaped baseplates for electronic
housings, stowage doors, shrouds, fins and structural loadbearing members. The processes used include extrusioncompression, fibre injection, tailored blanking and vacuum
forming, which enable rapid cycle times.

composites magazine 41
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015

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