Mechanical Testing of PMCs under Simulated Rapid Heat-Up Propulsion Environments

11 Pages·2003·4.9 MB·English

by  Stokes, Eric H.

High Tempre Workshop Xxlll
Jacksonville, FL
-10-13 February, 2003
Mechanical Testing of PMCs
under Simulated Rapid Heat-Up Propulsion Environments
(11. In-Plane Compressive Behavior)
Eric H. Stokes
Southern Research Institute
Birmingham, Alabama 352 1 1
E. Eugene Shin and James K. Sutier
NASA Glenn Research Center
Cleveland, OH 44 135
ABSTRACT
Carbon fiber thermoset polymer matrix composites (PMC) with high temperature
polyimide based in-situ polymerized monomer reactant (PMR) resin has been used for
some time in applications which can see temperatures up to 550'F. Currently, graphite
fiber PMR based composites are used in several aircraft engine components including
the outer bypass duct for the GE F-404, exit flaps for the P&W F-100-229, and the
core cowl for the GE/Snecma CF6-80A3. Newer formulations, including PMR-11-50
are being investigated as potential weight reduction replacements of various metallic
components in next generation high performance propulsion rocket engines that can
see temperatures which exceed 550°F. Extensive FEM thermal modeling indicates that
these components are exposed to rapid heat-up rates (up to -200"F/sec) and to a
maximum temperature of around 600°F. Even though the predicted maximum part
temperatures were within the capability of PW-11-50? the rapid heat-up causes
significant through-thickness thermal gradients in the composite part and even more
unstable states when combined with moisture. Designing composite parts for such
extreme service environments will require accurate measurement of intrinsic and
transient mechanical properties and the hygrothermal performance of these materials
under more realistic use conditions.
The mechanical properties of polymers degrade when exposed to elevated
temperatures even in the absence of gaseous oxygen. Accurate mechanical
characterization of the material is necessary in order to reduce system weight while
providing suficient factors of safety. Historically, the testing of PMCs at elevated
temperatures has been plagued by the antagonism between two factors. First, moisture
has been shown to profoundly affect the mechanical response of these materials at
temperatures above their glass transition temperature while concurrently lowering the
material's Tg. Moisture phenomena is due to one or a cumbination of three effects,
i.e., phstization of polymeric material by water, the internal pressure generated by the
volatilization of water at elevated temperatures, and hydrolytic chemical
decomposition. However, moisture is lost fiom the material at increasing rates as
temperature increases. Second, because PMCs are good thermal insulators, when they
are externally heated at even mild rates large thermal gradients can develop within the
material. At temperatures where a material property changes rapidly with temperature
the presence of a large thermal gradient is unacceptable for intrinsic property
characterization purposes. Therefore, long hold times are required to establish
isothermal conditions. However, in the service environments high-heating-rates, high
temperatures, high-loading rates are simultaneous present along with residual
moisture. In order to capture the effects of moisture on the material, holding at-
temperature until isothermal conditions are reached is unacceptable particularly in
materials with small physical dimensions. Thus, the effects due to moisture on the
composite's mechanical characteristics, ie., their so-called analog response, may be
instructive.
One approach employed in this program was rapid heat-up (-20O0F/sec.) and loading
of both dry and wet in-plane compressive specimens to examine the effects of
moisture on this resin dominated mechanical property of the material. Table I shows
the matrix of test performed in this effort.
Table 1 . Matrix of Tests for High Heating Rate Compression Studies
ORIENTATION
COMPRESSION
COMPRESSION
Mechanical Testing of Polymer Matrix Composites
under Simulated Rapid Heat-Up
Propulsion Environments
@I. In-Plane Compression)
Eric H.S hkes, SouthErn Research Institute
Birmingham, Alabama 3521 1
E. Eugene Shin, Ohio Aerospace Institute
Cleveland, OB 44135
James K. Sutter, NASA Glenn Research Center
Cleveland, OH 441 35
High Temple WorkshopX xlll
10-13 February 2003
Jacksonvlik Florida
I j
I
.~ -~
Introduction
Rational for high heating rates
- Air breathing hypersonic propulsion
- Rapid hating rates increases volatilization rates
. . . . .
- Volatiles generate internal pore prcssure . . .
cause damage
- Possible adverse oxidative reactions - . . . . . . .
+
clestr uctive
Plasticiztion affects of moisture at high temperature .
-
loss of stiffness
Introduction
Rational for in-plane compression
- Resin dominated effects
. .
- AP Tension, Xntcrlarninar Shear, and In-plane CM
I I
Resin dominated tests
. .
Across Ply Tension and Tnterlaminar Shear tests . .
- +
require thick materials
- In-plane comprcssion ...........................
Proven test exists
..................................
- Capabilities.
>200°F/sec, 20 mil materials
.... . .- . .
. - . .
j
Introduction
Property vs. Characteristic
- Property .........D ensity, Strength, Permeability
. .
- C.h aracteristic Weight, Length, Load, Mass flow rate
High heating rates and short hold times . . . . . . . . . . . . .
thermal gradients.
.
Mechanical properties . . . . . . . . . . . . . . . . . . . . . .
. change rapidly with temperature.
With longer hold times . . . . . . . . . . . . . . . . . . . . .
. thermal gradient is reduced, moisture is lost.
To capture the effects of moisture . . . . . . . . . . . . . . . .
short hold required.
Characteristic may be instructive.
I
Materials and Methods
woven), lO,SO]SS
OWMENTS
i
Specimen and Anvils
I
Dry Specimens
Mean Weight Loss Of Composite Test Specimens
0.6
80°C/vac./24 hrs followed by 12O"clvac.
0.5
0.2
0.1
0.0
0 5 10 15 20 25
Eiapsed Time (hr"*)
of fkont verses back face
to specimen position within the h a c
44
a
n
I"!
0
33..05 1
::i
f 2.0
a
li
0 5 T3 0
8
0 a
0 0.2 0.4 0.6 0.8 1 1.2
DirffanoefmmcerderofFur~~phf
Data for thermocouples with varying
specimen attachment lengths
--Sample 9F R MSm n (53
=S-a'm-e pl 9F Rurs#9 5mil(.7s)
-Sample9FRu&95mil(l.0~
-Sample 9F Rt1n#9 5mil(l.23
0 5 10 15 20 25 30 35 40
Time (s)
Effect of thermocouple wire diameter
on recorded temperatures
I Tao _.
so0
500
+S ampb 98 RuM5 10 mll(1.D")
+Sample BB liun#25 5m3 (1.0")
200
1 DO
0
0 5 IO 15 20 25 30 35 40 45 50
Tme (s)
~! I
Time-temperatme data for Specimen 9
with the front face covered
800
700
600
- 5DQ
F :::
1
-SampleSF RunM 5m11(0.5")
+Sample 8F RhnM 5m11(.75*)
+SampleSF Kun#4 5mil(l.W)
-SampleSF Run& 5mrI (1.2")
-*SamplsSF Run& 5mil (2.0")
200
-'--S ampie98 RunM lmrl(0 87
'-Sample9B KunN 5rnrl(O 8")
I00
-<-Sample 9B Run84 3mil (0.8")
0
0 5 10 15 20 25 30 35 40
Time (s) o.mner~sI~lbmhRhermPcou~ndals~hsrmocoy~opk3l0as tespBr.l
I
i Time-temperature data for Specimen 9
with the back face covered
800 .. . .
700
i
Brio
- 500
F
5 -SampkSiF Run#B 5mil(0.5")
t 400
i +Sampk 9F Rung6 5mtl(.75")
-SampleSF Run#B 5m11(1.0")
300
+-SampleSF Run# 5m1l( 1.2")
--%mpleSF Run# §mil (2.0")
200
+-SarnpleQB RuWl rnil(0.8")
-*-SampleSB RunM Smit (0.8")
I 100 - ' Samnle 9B Runs 3miltO.8"1
0
i
I
I
-
!
i
Time-temperature data
as a function of location
I
i-I S1 Run#$ Top B
*ISlRun#lktbmA
--
IS1 Run#t kmrnB
-+- IS1 hdl Ceoter A
0 10 za 30 40 50 80 70 80
Time (5) i
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s... .. - ~ .- ... .-- . ~ - . . ~