JEC COMPOSITES MAGAZINE - Issue #106 - July 2016 - 34

aero-engines

Fig. 2: Building block

was conducted on a curved panel and
also on a half ring that were cut out of a
full-size ring. For the component test,
an FBO test was conducted such that
a rotating fan blade was cut off causing
it to fly outward and strike against the
inner wall of a full-scale fan case.
The coupon test was also conducted on
the fan blade and SGV to select a material and a moulding method, and the
sub-component and component tests
were conducted to verify the parts and
the material.

Fan case development
Coupon test (flat plate impact test)
In order to select a high energy absorbing material suitable for the fan case,
high-speed impact tests were conducted
on relatively small flat test plates as test
pieces. Three types of material systems
were chosen as candidate materials by
reinforcement system and moulding
method. The three types of material
systems included 1) combinations of a
3D preform and RTM (Resin Transfer
Moulding) (3D-RTM), 2) autoclave
moulding of tough matrix prepreg materials, and 3) combinations of a modified
epoxy matrix and filament winding
(FW). The epoxy matrix used in FW

Fig. 3: Coupon impact test

Fig. 4: Coupon impact test, screening result

was modified in the course of this development. The high-speed impact test
involved shooting a projectile (steel cylinder) from an air gun toward the centre
of each of the test pieces with the outer
circumference of the test piece fixed in
place. An evaluation was conducted on
the basis of the absorbed energy calculated from the speed before and after
the projectile penetrated through the
test piece. Figure 3 illustrates the test
piece impact test.
Figure 4 illustrates the test results for
the energy absorbed by the three types
of materials. The dashed line represents
the result obtained from a titanium
alloy test piece of equivalent weight. As
shown in Figure 4, the energy absorbed
by the 3D-RTMs and the tough matrix
prepreg materials is less than or equal
to that of the titanium alloy. However,
among the three types of FW modified
epoxy matrices, the absorbed energy
of D2 and D3 is higher than that of the
titanium alloy, especially D2 which
is at least 1.5 times that of the titanium alloy. Whereas all the other test
pieces are only deformed in a small area
around the impact spot, D2 is deformed
with a larger area bulging out, and the
difference is considered to explain the
difference in absorbed energy.
From the results of the series of coupon
tests, FW using the D2 modified epoxy
matrix was selected as the fan case
material including a moulding method,
and this material system was used to
conduct the sub-component and component tests at the upper stages of the
building block.

34 jec composites magazine / No106 July 2016

Fig. 5: Schematic of the curved panel impact test

Fig. 6: Damage mode correlation between test and
analysis

Sub-component test
Curved panel impact test
The first-stage sub-component test is a
curved panel impact test. In this test, a
1/8 ring was cut out of a full-size ring
as a test piece, and a titanium alloy flat
plate was shot with an air gun into the
test piece.
In FBO, the behaviour exhibited by a
broken fan blade colliding with a fan
case is very complicated, unlike a headon collision as in the flat plate test. It
collides with the inner surface of the
fan case with a certain orientation, and
the inclination determines the collision
Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #106 - July 2016
