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Defence Research and
Development Canada
Recherche et de´veloppement
pour la de´fense Canada
Accelerated ageing of composites
Equipment and experimental protocol design and development
Royale S. Underhill
Neil Chambers
DRDC – Atlantic Research Centre
Defence Research and Development Canada
Scientific Report
DRDC-RDDC-2016-R109
August 2016
Accelerated ageing of composites
Equipment and experimental protocol design and development
Royale S. Underhill
Neil Chambers
DRDC – Atlantic Research Centre
Defence Research and Development Canada
Scientific Report
DRDC-RDDC-2016-R109
August 2016
c
⃝Her Majesty the Queen in Right of Canada, as represented by the Minister of National
Defence, 2016
c
⃝Sa Majesté la Reine (en droit du Canada), telle que réprésentée par le ministre de la
Défense nationale, 2016
Abstract
Composites have the potential to be lightweight, durable, corrosion- and cavitation-
free materials. The technology has been incorporated successfully into aircraft and
commercial sea vessels. The Cooperative Research Ships (CRS), Composite Propeller
Working Group (COMPROP) is investigating the feasibility of using composites for
marine propellers. One aspect of the work is to develop an understanding of how com-
posites age when immersed in seawater for extended periods of time. Ageing can be
examined with immersion in real-time, but this is not practical for material screening
and selection purposes. One can accelerate ageing by elevating the temperature of
the samples, using the principle of time-temperature superposition.
This work documents the design and manufacture of an environmental immersion
chamber (EIC) for use in accelerated ageing experiments. The second part of this
document reports the design and manufacture of extensions for a four-point bend
jig that would allow testing of samples up to 455 mm long. The EIC was shown to
maintain seawater at 60◦C for 24 hours at a tolerance of ±1◦C. The four-point bend
jig had sufficient capability for deflection for the longest composite samples that will
be aged.
Significance for defence and security
Composite materials use in shipbuilding has increased in recent years due to benefits
in terms of weight and durability. Some estimates predict that composite propellers
may reduce weight up to 70%, increase overall fuel efficiency up to 5% and reduce
noise up to 5 dB. In order to select appropriate composite materials, they must be
characterized with respect to how they degrade when immersed in seawater. This
report outlines the design of equipment and methodology for studying such a degra-
dation.
DRDC-RDDC-2016-R109 i
Résumé
Parmi les composites, il existe des matériaux légers, durables, exempts de corrosion
et de cavitation. Cette technologie est déjà utilisée avec succès sur les aéronefs et les
navires commerciaux. Le groupe de travail sur les hélices en composite (COMPROP)
de l’organisme Cooperative Research Ships (CRS) étudie la faisabilité d’utiliser des
composites dans la fabrication d’hélices de navire. Une partie du travail consiste à
comprendre l’effet de l’eau de mer sur le vieillissement des composites immergés pen-
dant de longues périodes. On peut étudier le vieillissement grâce à l’immersion en
temps réel, mais cette méthode n’est pas pratique pour la présélection et la sélection
des matériaux. Il est possible d’accélérer le vieillissement en augmentant la tempéra-
ture des échantillons, en vertu du principe d’équivalence temps-température.
Ce travail documente la conception et la fabrication d’une chambre climatique d’im-
mersion (CCI) utilisée pour mener des expériences de vieillissement accéléré. La
deuxième partie de ce document rend compte de la conception et de la fabrication
d’extensions de gabarits de flexion quatre points, ce qui permettrait de mettre à
l’épreuve des échantillons d’une longueur maximale de 455 mm. La CCI peut main-
tenir la température de l’eau de mer à 60◦C pendant 24 heures avec une tolérance de
±1◦C. La capacité du gabarit de flexion quatre points est suffisante pour dévier les
plus longs échantillons de composite qui seront vieillis.
Importance pour la défense et la sécurité
Le recours aux matériaux composites dans la construction navale a augmenté au
cours des dernières années en raison de leurs avantages sur le plan du poids et de la
durabilité. Selon certaines estimations, les hélices en composite pourraient permettre
jusqu’à 70% de réduction du poids, jusqu’à 5% d’augmentation du rendement énergé-
tique global et jusqu’à 5 dB de réduction du bruit. Pour pouvoir choisir les matériaux
composites appropriés, il faut savoir comment ils se dégradent lorsqu’on les immerge
dans l’eau de mer. Le présent rapport porte sur la conception de l’équipement et la
méthodologie utilisée pour étudier cette dégradation.
ii DRDC-RDDC-2016-R109
Table of contents
Abstract ....................................... i
Significance for defence and security ....................... i
Résumé ....................................... ii
Importance pour la défense et la sécurité ..................... ii
Table of contents .................................. iii
List of figures .................................... v
Acknowledgements ................................. vii
1 Introduction ................................... 1
2 Background ................................... 1
2.1 Fibre reinforced polymers ........................ 1
2.2 Marine context .............................. 2
2.3 Accelerated ageing ............................ 2
2.4 Flexural properties ............................ 2
2.5 Intended accelerated ageing experiment ................ 4
2.5.1 Samples ............................. 4
2.5.2 General ageing procedure ................... 5
2.6 Intended four-point bend experiment .................. 6
3 Design of the environmental immersion chambers .............. 6
3.1 Design requirements ........................... 6
3.2 Final design ............................... 7
4 Four-point bend jig ............................... 12
4.1 Design requirements ........................... 12
4.2 Final design ............................... 12
DRDC-RDDC-2016-R109 iii
5 Experimental verification ............................ 17
6 Conclusion .................................... 20
References ...................................... 21
Annex A: EIC draft sheets ............................ 23
Annex B: Four-point bend system draft sheets ................. 31
iv DRDC-RDDC-2016-R109
List of figures
Figure 1: Three-point bend method, reproduced from Wikipedia under the
Creative Commons ShareAlike 3.0 license. ............. 3
Figure 2: Four-point bend method, reproduced from Wikipedia under the
Creative Commons ShareAlike 3.0 license. ............. 3
Figure 3: Composite samples, woven reinforcements, nominal thickness:
12 mm. Uni-directional carbon fibre samples have the same
macroscopic appearance as the woven ones. ............. 4
Figure 4: A cross-section of the final EIC design without samples. ...... 8
Figure 5: Top view of the EIC without the cover. ............... 8
Figure 6: A preview of the different types of sample holders. ......... 9
Figure 7: Differential Scanning Calorimetry results showing glass transition
temperatures (Tg). .......................... 10
Figure 8: Partially assembled EIC. ....................... 10
Figure 9: EIC completely assembled and fully functional. ........... 11
Figure 10: Original four-point bend mounts with roller supports. ....... 13
Figure 11: Roller support fitted into the T-slot of the original mount. . . . . 14
Figure 12: Bottom of the roller support showing bump and bolt hole, bump
is needed for good fit into the T-slot. ................ 15
Figure 13: Four-point bend system top extension. ............... 15
Figure 14: Four-point bend system bottom extension. ............. 15
Figure 15: Four-point bend extensions installed. The original fixture is black,
the new extensions are silver aluminum. ............... 16
Figure 16: Four-point bend system with a long FRP sample. Note that the
bottom extension was not needed. .................. 18
Figure 17: Four-point bend system with a short FRP sample. The top roller
supports are installed in reverse, compared to the previous figure. 19
DRDC-RDDC-2016-R109 v
Figure A.1: Small sample holder. ......................... 23
Figure A.2: Medium 1 sample holder. ....................... 24
Figure A.3: Medium 1 compressed sample holder. ................ 25
Figure A.4: Medium 3 sample holder. ....................... 26
Figure A.5: Large sample holder. ......................... 27
Figure A.6: Medium 2 and large sample holder. ................. 28
Figure A.7: Sample holder layout. ......................... 29
Figure A.8: Full assembly. ............................. 30
Figure B.1: Top extension. ............................. 31
Figure B.2: Bottom extension. ........................... 32
vi DRDC-RDDC-2016-R109
Acknowledgements
Thanks are given to Mr. Tomasz Lemczyk for his technical help in the heating and
design of the environmental immersion chamber (EIC), the minor adaptations needed
for the actual use of the four-point bend apparatus, and some of the photography
used in this report.
Thanks are given to Ms. Nancy Hervé for her help in design of both the EIC and the
four-point bend test system, and some of the photography used in this report.
Thanks are given to Mr. Irv Keough for performing the DSC analysis.
Thanks are given to Dr. Allison Nolting for her guidance in designing the four-point
bend test system.
Further acknowledgment is given to the machinists from Fleet Maintenance Facility
Cape Scott, who manufactured the various EIC parts.
DRDC-RDDC-2016-R109 vii
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viii DRDC-RDDC-2016-R109
1 Introduction
Due to an increasing interest in using fibre reinforced polymers (FRP) for the con-
struction of marine parts, DRDC Atlantic Research Centre, Dockyard Laboratory
(Atlantic) has undertaken experiments to evaluate FRP ageing in seawater. This re-
search is part of the COMPosite PROPeller Work Group (COMPROP WG) of the
Cooperative Research Ships (CRS).
FRPs are a subset of composite materials, in which a polymer matrix is reinforced
with fibres. By reinforcing the matrix, the material receives important benefits, such
as being nonconductive and having high strength, while leaving it lighter than metallic
materials such as steel and bronze. This makes FRPs excellent candidates for potential
improvements to naval vessel parts.
One disadvantage of polymers is that they can absorb water. This often leads to
degradation, and lowering the strength and stiffness of the composite. The purpose of
the study at DRDC Atlantic Research Centre is to explore the degradation of FRP
when immersed in seawater for extended periods of time. Ageing an immersed sample
under normal operational conditions (temperature, pressure), can take a long period
of time; the ageing process can be accelerated by using elevated temperatures and
the theory of time/temperature superposition. One of the main goals of the DRDC
Atlantic Research Centre study is to determine whether accelerated ageing can be
used to predict the degradation that occurs under normal conditions. The variables
to be examined in the accelerated aging of FRPs are the water temperature that
the samples are immersed in, the sample thicknesses, and the type of fibre. Two
different temperatures will be investigated. Two different thicknesses of samples will
be immersed (nominally 6 mm and 12 mm), and three different reinforcing fiber
layouts will be used (carbon unidirectional, carbon woven, and glass woven). Two
environmental immersion chambers (EIC) were built to facilitate these experiments.
This report will discuss the design and manufacture of the EICs and their operating
procedure, as well as the assembly of the four-point bend jig machined for use with the
DRDC Atlantic Research Centre, Dockyard Laboratory (Atlantic) MTS load frame.
2 Background
2.1 Fibre reinforced polymers
Fibre-reinforced polymer (FRP) (sometimes referred to as fibre-reinforced plastic) is
a composite with a polymer matrix and fibre filler. In industrial applications, the
fibres are usually glass or carbon, but can also be aramid (an aromatic polyamide).
For this ageing study, the FRPs were manufactured by Airborne International (the
Netherlands) and consist of an epoxy matrix with carbon or glass fibre reinforcements.
DRDC-RDDC-2016-R109 1
2.2 Marine context
FRPs offer additional anticipated advantages over metallic propeller materials. FRPs
make a strong yet light and more adaptive blade. Using FRPs is expected to reduce
noise and improve cavitation performance and low frequency electric signatures [1].
Furthermore, being non-metallic materials, the FRP propellers are non-corroding.
These advantages make FRPs a good material for marine applications.
2.3 Accelerated ageing
The primary goal of this design project was to create an Environmental Immersion
Chamber (EIC) to accelerate ageing of FRP samples. Accelerated ageing can be
achieved by manipulating: temperature, stress levels or sample thickness [2]. For this
study, elevated temperature, and different sample thicknesses were chosen. No stress
will be applied to the sample during the immersion since the flexural properties were
desired once the material is aged.
Our EIC utilizes elevated temperatures. By examining FRP response at more than
one temperature, one can employ time-temperature superposition, which will help
determine the validity of the accelerated testing on the FRP degradation (if any).
The two EICs will be filled with Halifax harbour water, maintained at two different
temperatures, with samples immersed for four different periods of time, removed from
the water, dried, weighed and the flexural modulus determined via four-point bending.
The results will be compared to immersion in a natural environment (experiments
performed at Airborne in the Netherlands) to determine if the EIC was accurate in
simulating accelerated ageing.
2.4 Flexural properties
The flexural properties of the FRP will be measured, and compared between “dry”
and immersed samples. The “dry” samples are controls that will not be immersed, and
testing will occur on the as-received specimens. Flexural properties can be determined
using either three-point or four-point bending. While three-point bend tests (see
Figure 1) are easier to set up and measure, they also selectively cause the sample to
break at the center load because it has the largest bending moment [3]. A four-point
bend test (see Figure 2) will have a uniform bending moment between the two most
central loads, allowing the sample to break along the inherent flaws present in this
area [3]. Four-point bend tests are more representative of the true mode of failure.
The disadvantage to four-point bend testing is that the deflection is more difficult to
measure as it does not occur under one of the load points, but at the center.
The four-point bend test was chosen for this experiment. The flexural properties ob-
2 DRDC-RDDC-2016-R109
Figure 1: Three-point bend method, reproduced from Wikipedia under the Creative
Commons ShareAlike 3.0 license.
Figure 2: Four-point bend method, reproduced from Wikipedia under the Creative
Commons ShareAlike 3.0 license.
DRDC-RDDC-2016-R109 3
served will be yield stress and strain, ultimate bending stress and strain, and rupture
stress and strain. These properties will be measured by bending the samples in a servo
hydraulic load frame fitted with a four-point bend jig, the development of which is
discussed later in this report.
2.5 Intended accelerated ageing experiment
2.5.1 Samples
The samples used for this experiment were manufactured by Airborne International.
The matrix was an epoxy of Epikote 862 resin with Lonzacure Dedta 80 hardener.
Three different fibre layouts were examined: uni-directional carbon fibre (CF UD),
woven roving carbon fibre (CF WR) (see Figure 3(a)), and woven roving glass fibre
(GF WR) (see Figure 3(b)). The uni-directional carbon layups were either 0◦or 90◦,
while the woven roving layups were either 0◦or 45◦.
Five different dimension sets were supplied by Airborne International. Those dimen-
sion sets are:
•6 mm thick by 13 mm wide by 120 mm long,
•6 mm thick by 18 mm wide by 227.5 mm long,
•6 mm thick by 18 mm wide by 310 mm long,
•12 mm thick by 18 mm wide by 240 mm long, and
•12 mm thick by 36 mm wide by 455 mm long.
The samples were given the names of small, medium 1, medium 3, medium 2 and
large respectively. Samples medium 1 and medium 3 are the same with the exception
(a) carbon fibre (b) glass fibre
Figure 3: Composite samples, woven reinforcements, nominal thickness: 12 mm.
Uni-directional carbon fibre samples have the same macroscopic appearance as the
woven ones.
4 DRDC-RDDC-2016-R109
of length and medium 3 only came in CF UD, while medium 1 only came in CF WR
and GF WR.
The thicknesses were varied to observe the effect on ageing since a lot of literature
focuses on thin composites, but less on thick composites. The varying lengths allow
the samples to have a span to depth (or thickness) ratio (16:1) for four-point bend
testing as required by ASTM standard D6272 [4].
Samples were divided in three groups: a control (no immersion (i.e. room tempera-
ture (RT) and t=0)), those to be immersed in water at 40◦C, and those to be immersed
in water at 60◦C. These samples will be immersed for either 4, 8, 16 or 32 weeks, to
simulate ageing. For an overview of the sample layout see Table 1.
A total of 1080 samples will be tested (including the control group), 960 of which will
be conditioned at elevated temperatures in an immersion chamber before weighing
and four-point bend testing.
Table 1: A sample overview. Note that this only represents one of the three FRP
systems, and that 10 replicates of each sample are made in order to have statistical
relevance.
Ageing
Durations
(weeks)
Sample Thickness (mm)
S M1&M3 M2 L
t= 0 RT RT RT RT
t= 4 45◦C or 60◦C 45◦C or 60◦C 45◦C or 60◦C 45◦C or 60◦C
t= 8 45◦C or 60◦C 45◦C or 60◦C 45◦C or 60◦C 45◦C or 60◦C
t= 16 45◦C or 60◦C 45◦C or 60◦C 45◦C or 60◦C 45◦C or 60◦C
t= 32 45◦C or 60◦C 45◦C or 60◦C 45◦C or 60◦C 45◦C or 60◦C
2.5.2 General ageing procedure
The samples are to be weighed to determine their initial, dry weight. The sample
holders shall be loaded with the samples and arranged in the two EICs. The EICs are
then filled with Halifax harbour water and heated to the desired temperature (either
40◦C or 60◦C). The temperature of the EICs will be monitored using a data logger
placed between the outside of the barrel and the insulation. The intermediate lid and
final top are sealed to the barrel with silicone grease to minimize evaporation. Tap
water will be used to maintain the water level to account for loss due to evaporation.
Once a month, the water in the barrel will be completely drained and exchanged for
fresh seawater.
On weeks 4, 8, 16 and 32 samples will be removed from the EIC, gently dried using
paper towel and weighed to determine the amount of water absorbed. Once weighed,
DRDC-RDDC-2016-R109 5
the samples will be stored in plastic bags to maintain a constant humidity until
they can be mechanically tested. Testing will be on a custom four-point bend test
jig mounted on a MTS servo hydraulic load frame, with a load capacity of 25kN.
The load and deflection data will be recorded and the sample’s yield stress & strain,
ultimate bending stress & strain, and rupture stress & strain will be calculated.
2.6 Intended four-point bend experiment
The intended four-point bend experiment will follow the ASTM International stan-
dard test method for flexural properties of unreinforced and reinforced plastics and
electrical insulting materials [4]. The distance between the loading noses (i.e. the load
span) will be one half of the support span. A 16:1 support span-to-depth ratio shall
be used. The specimens will be deflected until either: (1) rupture occurs in the outer
fibres, (2) a maximum fibre strain of 5% is reached, or (3) the machine force reaches
max 24 kN, whichever comes first.
3 Design of the environmental immersion chambers
3.1 Design requirements
During the design of the EIC, there were several requirements and restrictions. These
involved temperature, size/form, water quality, strength and cost.
With respect to temperature, the samples needed to be immersed at two different
designated temperatures. These temperatures needed to be chosen such that the FRP
matrix remains below the glass transition temperature (Tg). It is generally accepted
that if the specimens are kept below the Tg, then the accelerated ageing will have
similar degradation mechanisms to real-time ageing [2]. The water temperature had
to be held constant with a tolerance of ±1◦C, spanning months.
It was necessary to immerse a total of 960 samples in an EIC, not necessarily all
at once. Fewer sequential runs of the ageing are desirable to minimize the length of
time for the experiment. Therefore, the ideal design size would fit 480 samples, all
together. Alternatively, two EICs, each holding 240 samples was also considered. The
sample holders also needed to be large enought to allow water to flow freely past the
samples’ midsection.
For water quality, the liquid medium to be used in the EIC needed to be as similar to
sea water as possible. Simultaneously, water circulation, algae growth and material
selection (possible electrolytic reaction) had to be considered.
The structural integrity of the EIC also needed to be considered. The EIC needed to
support the weight of sample holders and samples, even without the supporting force
6 DRDC-RDDC-2016-R109
of buoyancy.
Finally, the design needed to be cost effective. Whenever possible, the EIC should be
designed from readily available, inexpensive materials.
3.2 Final design
The final design can be seen in Figure 4; the EIC pictured was cross sectioned in or-
der to see two rows of sample holders. The blue barrel is commercial-off-the-shelf and
made of polyethylene and is insulated with green polyurethane foam. The intermedi-
ate lid is made of polyoxymethylene (POM) and the top is made of black neoprene
foam. Finally, the supporting rods, as seen in Figure 5, which hold the sample holders,
are made of stainless steel.
The sample holders, as seen in Figure 6, are made of POM and threaded onto stainless
steel 1
4
′′-20 threaded rods, using 1
4
′′-20 stainless steel nuts and stainless steel pins to
divide the sample levels. For drafting sheets on sub-assemblies and the full assembly
of the EIC, see Annex A.
The EIC was filled with Halifax harbour water heated to either 40◦C or 60◦C, tem-
peratures below the Tg of the specimens to be aged. The Tg of the epoxy used in the
composite specimens was determined by differental scanning calorimetry (TA instru-
ments DSC Q100), performed on all three variations of filler; GF WR, CF WR and
CF UD. The Tg of the epoxy was determined to be 124–132◦C (Figure 7). To heat
the water, constant temperature immersion heaters were suspended in the tops of the
EICs (VWR circulator model 1110 or VWR MX open bath).
Figures 8and 9show the EIC in operation.
DRDC-RDDC-2016-R109 7
Figure 4: A cross-section of the final EIC design without samples.
Figure 5: Top view of the EIC without the cover.
8 DRDC-RDDC-2016-R109
Figure 6: A preview of the different types of sample holders.
DRDC-RDDC-2016-R109 9
Figure 7: Differential Scanning Calorimetry results showing glass transition temper-
atures (Tg).
Figure 8: Partially assembled EIC.
10 DRDC-RDDC-2016-R109
Figure 9: EIC completely assembled and fully functional.
DRDC-RDDC-2016-R109 11
4 Four-point bend jig
With a smaller scale four-point bend testing mount already available, only two ex-
tensions (one to add to the top, and another for the bottom) were needed to test the
largest samples. Therefore two simple aluminum extensions were designed.
4.1 Design requirements
During the design of the extensions, requirements included strength, fitting into the
original mounts and alterations to accomodate additional flexion.
For strength, the extensions had to be made much stiffer then the samples being
tested, in order to test the flexural properties of the FRP samples and not the prop-
erties of the extension. Aluminum was chosen.
For fitting into the original mounts (as seen in Figure 10), the extensions needed to
have a T-slot design made in the top (to fit the stand-offs as seen in Figure 11), a
bump on the bottom (to fit in the original T-slot as seen on Figure 12) and holes for
the bolts which will hold the extension to the original base through its T-slot.
The system had to allow for extra room for deflection, as it was anticipated that com-
posite samples would deflect more than allowed by the original setup which was de-
signed for metallic specimens. To accomodate the deflection, space must be provided
in the centre of the bottom extension. The jig also needed to facilitate the continu-
ous measurement of the deflection at the center of the sample. A laser displacement
system was chosen to measure the deflection at the center top of the sample. The top
extension must have an opening to mount the laser with double-sided tape.
4.2 Final design
The final design for the two extensions can be seen in Figures 13 and 14. These fit
into the original mount using bolts threaded into the T-slots. For drafting sheets of
the two extensions, see Annex B. The entire setup with original mount and extensions
installed can be seen in Figure 15.
12 DRDC-RDDC-2016-R109
Figure 10: Original four-point bend mounts with roller supports.
DRDC-RDDC-2016-R109 13
Figure 11: Roller support fitted into the T-slot of the original mount.
14 DRDC-RDDC-2016-R109
Figure 12: Bottom of the roller support showing bump and bolt hole, bump is
needed for good fit into the T-slot.
Figure 13: Four-point bend system top extension.
Figure 14: Four-point bend system bottom extension.
DRDC-RDDC-2016-R109 15
Figure 15: Four-point bend extensions installed. The original fixture is black, the
new extensions are silver aluminum.
16 DRDC-RDDC-2016-R109
5 Experimental verification
In order to verify that the EIC were able to complete their primary task, the chamber
was assembled, filled with Halifax harbour water and heated up 40◦C. The EIC were
left for 24 hours to allow the temperature to equilibrate, and then the temperatures
were measured using NIST calibrated thermometers. They were found to be 40.1◦C
and 40.2◦C. The EIC were then heated to 60◦C, and were shown to maintain their
temperatures to within ±1◦C for 24h.
The four-point bend test system was evaluated by bending one of the longest unaged
unidirectional carbon fibre samples (12 mm by 36 mm by 625 mm) and ensuring it had
sufficient room to bend (see Figure 16). It was found that the original bottom support
was sufficient for all the samples sizes to be tested, even the longest at 625 mm. As
such the bottom extension was not used.
The large travel distance laser purchased to measure deflection was found to have
insufficient resolution, and so a shorter travel distance laser was substituted. This
required some additional machining of the top extension to accomodate the cable
plug. The original large travel distance laser would have been fully seated in the
top extension allowing the upper roller supports to be installed fully together for
the short load spans. Unfortunately, the short travel distance laser protruded from
the top extension, blocking the top roller supports. To compensate, the top roller
supports were installed in reverse for the short small load spans, allowing the rollers
to be brought closer together (see Figure 17). This still resulted in a deviation from
the originally planned 40 mm load span to 44 mm as this was the closest the top
roller supports could be placed. The top rollers were installed in reverse for only the
short, 44 mm, setup. They were installed correctly for all other setups.
The test showed that samples may not bend to rupture, and so it is anticipated that
the condition of deflection until a maximum fibre strain of 5% is reached will be most
relevant.
DRDC-RDDC-2016-R109 17
Figure 16: Four-point bend system with a long FRP sample. Note that the bottom
extension was not needed.
18 DRDC-RDDC-2016-R109
Figure 17: Four-point bend system with a short FRP sample. The top roller supports
are installed in reverse, compared to the previous figure.
DRDC-RDDC-2016-R109 19
6 Conclusion
This report documents the design and manufacture of an environmental immersion
chamber (EIC) to hold FRPs in heated water for periods up to 32 weeks. This report
also documents the design and manufacture of two four-point bend extensions used
to facilitate the use of an already available setup with the FRP samples.
Experimental verification showed that the EIC was able to hold its temperature for
24 hours without deviating from its set temperature more that ±1◦C.
It was found that the bottom extension for the four-point bend jig wasn’t needed.
The large travel distance laser was found to have insufficient resolution, and was
substituted for a shorter travel distance laser. Changing the laser resulted in a 10%
deviation in the testing methodology for the shortest samples. They will be tested
with a load span of 44 mm instead of 40 mm because the new laser prevents the top
roller supports from being placed any closer together. With these modifications, the
four-point bend test functions properly according to ASTM method D6272.
20 DRDC-RDDC-2016-R109
References
[1] Black, S. (2011), Composite propeller for Royal Navy minehunter,
High-Performance Composites.
[2] Davies, P. and Rajapakse, Y., (Eds.) (2014), Accelerated Aging Tests for Marine
Energy Applications, Vol. 208 of Durability of Composites in a Marine
Environment, p. 170, Waterloo: Springer.
[3] XFEM Skier (2013), Shear Moment Diagram [Illustration] (online),
Wikipedia.org, https://en.wikipedia.org/wiki/Shear_and_moment_diagram
(Access Date: 2016-05-04). Permission to copy and modify by Wikipedia.org
under the Creative Commons ShareAlike 3.0 license.
[4] ASTM Standard D6272-10, 201 (2008), Standard Test Method for Flexural
Properties of Unreinforced and Reinforced Plastics and Electrical Insulating
Materials by Four-Point Bending.
DRDC-RDDC-2016-R109 21
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22 DRDC-RDDC-2016-R109
Annex A: EIC draft sheets
8
8
8
8
8
8
8
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3
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3
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3
3
3
5
5
5
5
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29/07/2015
1
DRDC DL(A)
Small Sample Holder
Neil Chambers
1:10
ITEM NO.
PartNo
DESCRIPTION
Material
QTY.
1
HS
Standard Sample Holder Handle
Delrin
1
2
TS
Small Sample Holder Top
Delrin
1
3
D5
0.5in Divider
Stainless Steel
20
4
MS
Small Sample Holder Midsection
Delrin
5
5
D8
0.8in Divider
Stainless Steel
30
6
RS
Small Sample Holder Rod (1/4"-20
Threaded)
Stainless Steel
1
7
BS
Small Sample Holder Bottom
Delrin
1
8
Nut
1/4"-20 Nut
Stainless Steel
7
Draftsperson:
Subassembly Name:
Date:
Initials:
Tolerance:
Company Name:
# needed:
Scale:
Figure A.1: Small sample holder.
DRDC-RDDC-2016-R109 23
1
2
3
4
5
6
7
4
4
4
4
8
8
8
8
5
5
5
5
5
5
29/07/2015
1
DRDC DL(A)
Medium 1 Sample Holder
Neil Chambers
1:8
ITEM NO.
PartNo
DESCRIPTION
Material
QTY.
1
HS
Standard Sample Holder Handle
Delrin
1
2
TM1
Medium 1 Samplhe Holder Top
Delrin
1
3
MM1
Medium 1 Sample Holder Midsection
Delrin
2
4
D5
0.5in Divider
Stainless Steel
8
5
D10
1.0in Divider
Stainless Steel
12
6
RM1
Medium 1 Sample Holder Rod (1/4"-20 Threaded)
Delrin
1
7
BM1
Medium 1 Sample Holder Bottom
Delrin
1
8
Nut
1/4"-20 Nut
Stainless Steel
4
Draftsperson:
Subassembly Name:
Date:
Initials:
Tolerance:
Company Name:
# needed:
Scale:
Figure A.2: Medium 1 sample holder.
24 DRDC-RDDC-2016-R109
8
8
8
5
5
3
3
3
1
2
3
4
5
6
7
29/07/2015
1
DRDC DL(A)
Medium 1 Compressed Sample Holder
Neil Chambers
1:6
ITEM NO.
PartNo
DESCRIPTION
Material
QTY.
1
HS
Standard Sample Holder Handle
Delrin
1
2
TM1
Medium 1 Samplhe Holder Top
Delrin
1
3
D10
1.0in Divider
Stainless Steel
6
4
MM1
Medium 1 Sample Holder
Midsection
Delrin
1
5
D5
0.5in Divider
Stainless Steel
4
6
RM1C
Medium 1 Compressed Sample
Holder Rod (1/4"-20 Threaded)
Stainless Steel
1
7
BM1
Medium 1 Sample Holder Bottom
Delrin
1
8
Nut
1/4"-20 Nut
Stainless Steel
3
Draftsperson:
Subassembly Name:
Date:
Initials:
Tolerance:
Company Name:
# needed:
Scale:
Figure A.3: Medium 1 compressed sample holder.
DRDC-RDDC-2016-R109 25
8
8
8
4
4
3
3
3
1
2
3
5
4
6
7
29/07/2015
1
DRDC DL(A)
Medium 3 Sample Holder
Neil Chambers
1:8
ITEM NO.
PartNo
DESCRIPTION
Material
QTY.
1
HS
Standard Sample Holder Handle
Delrin
1
2
TM3
Medium 3 Sample Holder Top
Delrin
1
3
D10
1.0in Divider
Stainless Steel
6
4
D5
0.5in Divider
Stainless Steel
4
5
MM3
Medium 3 Sample Holder Midsection
Delrin
1
6
RM3
Medium 3 Sample Holder Rod (1/4"-20
Threaded)
Stainless Steel
1
7
BM3
Medium 3 Sample Holder Bottom
Delrin
1
8
Nut
1/4"-20 Nut
Stainless Steel
3
Draftsperson:
Subassembly Name:
Date:
Initials:
Tolerance:
Company Name:
# needed:
Scale:
Figure A.4: Medium 3 sample holder.
26 DRDC-RDDC-2016-R109
1
2
3
4
5
5
29/07/2015
7
DRDC DL(A)
Large Sample Holder
Neil Chambers
1:6
ITEM NO.
PartNo
DESCRIPTION
Material
QTY.
1
HS
Standard Sample Holder Handle
Delrin
1
2
TL
Large Sample Holder Top
Delrin
1
3
RL
Large Sample Holder Rod (1/4"-20 Threaded)
Stainless Steel
1
4
BL
Large Sample Holder Bottom
Delrin
1
5
Nut
1/4"-20 Nut
Stainless Steel
2
Draftsperson:
Subassembly Name:
Date:
Initials:
Tolerance:
Company Name:
# needed:
Scale:
Figure A.5: Large sample holder.
DRDC-RDDC-2016-R109 27
8
8
8
8
5
5
5
5
4
4
4
4
4
4
1
2
3
4
5
6
7
29/07/2015
1
DRDC DL(A)
Medium 2 and Large Sample Holder
Neil Chambers
1:9
ITEM NO.
PartNo
DESCRIPTION
Material
QTY.
1
HS
Standard Sample Holder Handle
Delrin
1
2
TL
Large Sample Holder Top
Delrin
1
3
ML
Large Sample Holder Midsection
Delrin
2
4
D18
1.8in Divider
Stainless Steel
12
5
D8
0.8in Divider
Stainless Steel
8
6
RM2
Medium 2 Sample Holder Rod (1/4"-20 Threaded)
Stainless Steel
1
7
BL
Large Sample Holder Bottom
Delrin
1
8
Nut
1/4"-20 Nut
Stainless Steel
4
Draftsperson:
Subassembly Name:
Date:
Initials:
Tolerance:
Company Name:
# needed:
Scale:
Figure A.6: Medium 2 and large sample holder.
28 DRDC-RDDC-2016-R109
8
7
10
11
6
1
4
6
5
6
59
6
6 66
30/07/2015
1
DRDC DL(A)
Sample Holder Layout
Neil Chambers
1:14
ITEM NO.
PART NUMBER
DESCRIPTION
QTY.
1
SR1
Support Rod 1
1
2
SR2
Support Rod 2
1
3
SR3
Support Rod 3
1
4
M1 SH
Medium 1 Sample Holder
1
5
M2 SH
Medium 2 Sample Holder
2
6
L SH
Large Sample Holder
7
7
M1C SH
Medium 1 Compressed Sample
Holder
1
8
SM3 SH
Small and Medium 3 Sample Holder
1
9
S SH
Small Sample Holder
1
10
M2L SH
Medium 2 and Large Sample
Holder
1
11
M3 SH
Medium 3 Sample Holder
1
Draftsperson:
Subassembly Name:
Date:
Initials:
Tolerance:
Company Name:
# needed:
Scale:
Figure A.7: Sample holder layout.
DRDC-RDDC-2016-R109 29
1 2 1043 6 75 8 9 11 12 13 14 15
30/07/2015
1
DRDC DL(A)
Full Assembly
Neil Chambers
1:17
ITEM NO.
PartNo
DESCRIPTION
Material
QTY.
1
FI
Foam Insulation
Polyurethane
1
2
Barrel
Polyethylene Barrel
Polyethylene
1
3
M1C SH
Medium 1 Compressed Sample Holder
1
4
M1 SH
Medium 1 Sample Holder
1
5
M3 SH
Medium 3 Sample Holder
1
6
M2 SH
Medium 2 Sample Holder
2
7
L SH
Large Sample Holder
7
8
M2L SH
Medium 2 and Large Sample Holder
1
9
S SH
Small Sample Holder
1
10
SM3 SH
Small and Medium 3 Sample Holder
1
11
IL
Intermediate Lid
Delrin
1
12
SR1
Support Rod 1
Stainless Steel
1
13
SR2
Support Rod 2
Stainless Steel
1
14
SR3
Support Rod 3
Stainless Steel
1
15
RMT
Rubber Mat Top
Rubber Foam
1
Draftsperson:
Subassembly Name:
Date:
Initials:
Tolerance:
Company Name:
# needed:
Scale:
Figure A.8: Full assembly.
30 DRDC-RDDC-2016-R109
Annex B: Four-point bend system draft sheets
0.472
0.394
0.965
0.555
1.509
0.125
2.854 0.555
R0.472
2 x
0.531 THRU ALL
0.936 0.313
0.811
2.638 TYP
1.427 TYP
0.571
TYP
3.844 TYP
2 x
0.201 0.787
4.594
DD
10.000
2.500
4.594 4.594
0.811
0.125
1.236
2.057
0.528
SECTION
D-D
SCALE
1 : 3
10/07/2015
1
DRDC DL(A)
Inches
Top Extension
Neil Chambers
1:3
Aluminium
Draftsperson:
Part Name:
Date:
Initials:
Units:
Company Name:
# needed:
Scale:
Material:
Figure B.1: Top extension.
DRDC-RDDC-2016-R109 31
0.965
0.472
0.394
0.555
0.125
1.509
2.854
0.555
1.150 TYP
5.276 TYP
1.427 TYP
2 x
0.531 THRU ALL
0.936 0.313
5.000
20.000
2.500
0.765 TYP
R0.500 TYP
1.000
2.375
7.500
10/07/2015
1
DRDC DL(A)
inches
Bottom Extension
Neil Chambers
1:5
Aluminium
Draftsperson:
Part Name:
Date:
Initials:
Units:
Company Name:
# needed:
Scale:
Material:
Figure B.2: Bottom extension.
32 DRDC-RDDC-2016-R109
DOCUMENT CONTROL DATA
(Security markings for the title, abstract and indexing annotation must be entered when the document is Classified or Protected.)
1. ORIGINATOR (The name and address of the organization preparing
the document. Organizations for whom the document was prepared,
e.g. Centre sponsoring a contractor’s report, or tasking agency, are
entered in section 8.)
DRDC – Atlantic Research Centre
PO Box 1012, Dartmouth NS B2Y 3Z7, Canada
2a. SECURITY MARKING (Overall security marking of
the document, including supplemental markings if
applicable.)
UNCLASSIFIED
2b. CONTROLLED GOODS
(NON-CONTROLLED GOODS)
DMC A
REVIEW: GCEC DECEMBER 2014
3. TITLE (The complete document title as indicated on the title page. Its classification should be indicated by the appropriate
abbreviation (S, C or U) in parentheses after the title.)
Accelerated ageing of composites
4. AUTHORS (Last name, followed by initials – ranks, titles, etc. not to be used.)
Underhill, R. S.; Chambers, N.
5. DATE OF PUBLICATION (Month and year of publication of
document.)
August 2016
6a. NO. OF PAGES (Total
containing information.
Include Annexes,
Appendices, etc.)
44
6b. NO. OF REFS (Total
cited in document.)
4
7. DESCRIPTIVE NOTES (The category of the document, e.g. technical report, technical note or memorandum. If appropriate, enter
the type of report, e.g. interim, progress, summary, annual or final. Give the inclusive dates when a specific reporting period is
covered.)
Scientific Report
8. SPONSORING ACTIVITY (The name of the department project office or laboratory sponsoring the research and development –
include address.)
DRDC – Atlantic Research Centre
PO Box 1012, Dartmouth NS B2Y 3Z7, Canada
9a. PROJECT OR GRANT NO. (If appropriate, the applicable
research and development project or grant number under
which the document was written. Please specify whether
project or grant.)
01ec
9b. CONTRACT NO. (If appropriate, the applicable number under
which the document was written.)
10a. ORIGINATOR’S DOCUMENT NUMBER (The official
document number by which the document is identified by the
originating activity. This number must be unique to this
document.)
DRDC-RDDC-2016-R109
10b. OTHER DOCUMENT NO(s). (Any other numbers which may
be assigned this document either by the originator or by the
sponsor.)
11. DOCUMENT AVAILABILITY (Any limitations on further dissemination of the document, other than those imposed by security
classification.)
Unlimited
12. DOCUMENT ANNOUNCEMENT (Any limitation to the bibliographic announcement of this document. This will normally correspond
to the Document Availability (11). However, where further distribution (beyond the audience specified in (11)) is possible, a wider
announcement audience may be selected.)
Unlimited
13. ABSTRACT (A brief and factual summary of the document. It may also appear elsewhere in the body of the document itself. It is highly
desirable that the abstract of classified documents be unclassified. Each paragraph of the abstract shall begin with an indication of the
security classification of the information in the paragraph (unless the document itself is unclassified) represented as (S), (C), or (U). It is
not necessary to include here abstracts in both official languages unless the text is bilingual.)
Composites have the potential to be lightweight, durable, corrosion- and cavitation-free materi-
als. The technology has been incorporated successfully into aircraft and commercial sea vessels.
The Cooperative Research Ships (CRS), Composite Propeller Working Group (COMPROP) is
investigating the feasibility of using composites for marine propellers. One aspect of the work is
to develop an understanding of how composites age when immersed in seawater for extended
periods of time. Ageing can be examined with immersion in real-time, but this is not practical for
material screening and selection purposes. One can accelerate ageing by elevating the temper-
ature of the samples, using the principle of time-temperature superposition.
This work documents the design and manufacture of an environmental immersion chamber (EIC)
for use in accelerated ageing experiments. The second part of this document reports the design
and manufacture of extensions for a four-point bend jig that would allow testing of samples up
to 455 mm long. The EIC was shown to maintain seawater at 60◦C for 24 hours at a tolerance
of ±1◦C. The four-point bend jig had sufficient capability for deflection for the longest composite
samples that will be aged.
14. KEYWORDS, DESCRIPTORS or IDENTIFIERS (Technically meaningful terms or short phrases that characterize a document and could
be helpful in cataloguing the document. They should be selected so that no security classification is required. Identifiers, such as
equipment model designation, trade name, military project code name, geographic location may also be included. If possible keywords
should be selected from a published thesaurus. e.g. Thesaurus of Engineering and Scientific Terms (TEST) and that thesaurus identified.
If it is not possible to select indexing terms which are Unclassified, the classification of each should be indicated as with the title.)
polymer matrix composite; accelerated ageing; composite propeller
www.drdc-rddc.gc.ca
