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Hybrid Gear Preliminary Results.pdf
NASA/TM—2012-217630
Hybrid Gear Preliminary Results—Application of
Composites to Dynamic Mechanical Components
Robert F. Handschuh, Gary D. Roberts, and Ryan R. Sinnamon
Glenn Research Center, Cleveland, Ohio
David B. Stringer
U.S. Army Research Laboratory, Glenn Research Center, Cleveland, Ohio
Brian D. Dykas
U.S. Army Research Laboratory, Aberdeen Proving Grounds, Maryland
Lee W. Kohlman
Glenn Research Center, Cleveland, Ohio
July 2012
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NASA/TM—2012-217630
Hybrid Gear Preliminary Results—Application of
Composites to Dynamic Mechanical Components
Robert F. Handschuh, Gary D. Roberts, and Ryan R. Sinnamon
Glenn Research Center, Cleveland, Ohio
David B. Stringer
U.S. Army Research Laboratory, Glenn Research Center, Cleveland, Ohio
Brian D. Dykas
U.S. Army Research Laboratory, Aberdeen Proving Grounds, Maryland
Lee W. Kohlman
Glenn Research Center, Cleveland, Ohio
Prepared for the
68th Annual Forum and Technology Display (Forum 67)
sponsored by the American Helicopter Society (AHS)
Fort Worth, Texas, May 1–3, 2012
National Aeronautics and
Space Administration
Glenn Research Center
Cleveland, Ohio 44135
July 2012
Level of Review: This material has been technically reviewed by technical management.
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NASA Center for Aerospace Information
7115 Standard Drive
Hanover, MD 21076–1320
National Technical Information Service
5301 Shawnee Road
Alexandria, VA 22312
Available electronically at http://www.sti.nasa.gov
Hybrid Gear Preliminary Results—Application of
Composites to Dynamic Mechanical Components
Robert F. Handschuh, Gary D. Roberts, and Ryan R. Sinnamon*
National Aeronautics and Space Administration
Glenn Research Center
Cleveland, Ohio 44135
David B. Stringer
U.S. Army Research Laboratory
Glenn Research Center
Cleveland, Ohio 44135
Brian D. Dykas
U.S. Army Research Laboratory
Aberdeen Proving Grounds, Maryland 21005
Lee W. Kohlman
National Aeronautics and Space Administration
Glenn Research Center
Cleveland, Ohio 44135
Abstract*
(~10 percent), many approaches have been applied to improve
the power to weight ratio of these components.
Past and current government-funded efforts for drive system
technology (Refs. 1 and 2) has used power to weight ratio as
the most critical performance metric. Through clever design
modifications, configuration arrangements, and advanced
materials, great progress has been made.
Material properties of composites make them very desirable. Having a very low density and high strength are two
important properties that directly impact power to weight
ratio. Therefore application of these materials to rotorcraft
transmission static and dynamic components can have a
drastic effect on overall drive system weight (Refs. 3 and 4).
The use of composites has been mostly limited in drive
systems to housings and shafts (Ref. 5). A number of critical
issues were identified and addressed in these applications.
These issues include metal—composite attachment, corrosion,
strength, etc. The objective of this research reported herein is
to expand the use of composite materials to gears and to
identify critical issues that may result in this application.
Several tests were performed on the composite gears to
identify the issues that need to be addressed to allow this
technology to be suitable for rotorcraft drive systems.
Composite spur gears were fabricated and then tested at
NASA Glenn Research Center. The composite material served
as the web of the gear between the gear teeth and a metallic
hub for mounting to the torque-applying shaft. The composite
web was bonded only to the inner and outer hexagonal
features that were machined from an initially all-metallic
aerospace quality spur gear. The Hybrid Gear was tested
against an all-steel gear and against a mating Hybrid Gear. As
a result of the composite to metal fabrication process used, the
concentricity of the gears were reduce from their initial highprecision value. Regardless of the concentricity error, the
hybrid gears operated successfully for over 300 million cycles
at 10000 rpm and 553 in.*lb torque. Although the design was
not optimized for weight, the composite gears were found to
be 20 percent lighter than the all-steel gears. Free vibration
modes and vibration/noise tests were also conduct to compare
the vibration and damping characteristic of the Hybrid Gear to
all-steel gears. The initial results indicate that this type of
hybrid design may have a dramatic effect on drive system
weight without sacrificing strength.
Introduction
Composite Material—Metallic
Gear Hybrid
The components used in rotorcraft applications are designed
such that the minimum weight is attained without sacrificing
reliability or safety. Since the drive system is an appreciable
percentage of the overall rotorcraft vehicle weight
Components that are lightweight and high-strength are very
important for aerospace drive systems. The composite portion
of the hybrid gear was fabricated using a triaxial braid prepreg
material made with T700SC 12K carbon fiber tows and a
350 °F epoxy matrix material. A 0/±60 braid architecture was
*
LERCIP Summer Intern at NASA Glenn Research Center
NASA/TM—2012-217630
1
TABLE 1.—MATERIALS AS USED IN THE TEST GEARS
Composite Material
Modulus of elasticity (psi)
Tensile - 6.4×106
Compression - 6.1×106
Poisson’s ratio
0.3
Density (kg/m3)
1800
9.4
Thermal conductivity (W/(m°C))
(T700 fiber – axial)
150
Useful maximum temperature (°C) as gear material
Coefficient of thermal expansion (micro-m/m)
2 (in-plane)
Failure Strain (%)
Tension - 1.89
Compression - 0.94
used so that in-plane stiffness properties would be nearly equal
in all directions. Representative composite material properties
are compared to that of the typical gear material AISI 9310,
and are shown in Table 1. Materials with these characteristics
have the potential to produce a design with a very high power
to weight ratio.
There are other reasons for using a hybrid of composite and
metallic elements in a gear. For example, gear meshing
vibration and noise should benefit from this configuration by
altering the acoustic path between the gear-mesh generating
the noise and the housing that re-radiates the vibration and
noise.
In theory it may be possible to produce a hybrid gear at
reduced cost, as a portion of the machining required to reduce
component weight would be eliminated. The manufacture
process would have to be altered when making a hybrid gear
to attain aerospace precision of the components.
Unfortunately for all the positive implications of using this
technology for dynamic drive system components, there are
also some negative aspects. Some of these include: (i) attachment to the metallic features to produce a hybrid gear (gear
teeth to web, web to shaft, and bearings to shaft), (ii) heat
conduction issues—composite material through thickness
conductivity, and (iii) operation during extreme thermal events
such as loss-of-lubrication. In current drive system component
design, the gears and shafts are one-piece and the bearing
inner raceway is typically part of the gear-shaft component.
Use of a hybrid gear would require attachment in some
manner from the composite material web-shaft to the gear
teeth.
0.29
7861
55
175
13.0
Elongation (%)
15
removed. This arrangement was chosen due to the number of
teeth (42) on the gear to be modified. By using a six-sided
feature, no sharp edge was located near a tooth fillet—root
region where the highest bending stress is reached.
TABLE 2.—BASIC GEAR DATA FOR COMPONENTS TESTED
Number of teeth ........................................................................ 42
Diametral pitch ......................................................................... 12
Circular pitch ..................................................................... 0.2618
Whole depth ......................................................................... 0.196
Addendum (in.) .................................................................... 0.083
Chordal tooth thickness (in.) .............................................. 0.1279
Pressure angle (deg) .................................................................. 25
Pitch diameter (in.) .................................................................. 3.5
Outside diameter (in.) .......................................................... 3.667
Root fillet (in.) ........................................................... 0.04 to 0.06
Measurement over pins (in.) .............................................. 3.6956
Pin diameter (in.) ................................................................. 0.144
Backlash ref. (in.)................................................................. 0.006
Tip relief (in.)..................................................... 0.0005 to 0.0007
Weight all-steel gear (lbf) .................................................. 0.8375
Weight hybrid gear (lbf) .................................................... 0.7147
Two unique ply stacks were used for this configuration. The
first ply stack was larger than the metallic portion that was
machined away and had a circular outside geometry. This
created an overlap onto the surface of the outer rim. This
overlap created a bonding surface that was critical for proper
composite to metal adhesion. The second ply stack configuration was cut to match the hexagonal region that was machined
away from the metal gear. This tight fit provided a load path
from the outer rim to the metallic inner hub.
An epoxy prepreg in conjunction with a quasi-isotropic
braided fabric was chosen as the composite material. The
fabric provides nearly in-plane isotropic properties that react
similarly to that of the metallic features.
Prior to molding, any portion of the metallic features that
were to come in contact with the composite were sandblasted
and surface primed to promote good adhesion and increase
bond-line strength.
Hybrid Gear Design and Manufacturing
The basic gear design used for this study is summarized in
Table 2. These gears have been used in the past for loss-oflubrication testing and other experimental work within NASA
(Refs. 6 to 8). Gears used were representative of aerospace
precision prior to modification to a hybrid configuration.
Turning the gears into a hybrid configuration started with a
portion of the web being machined away. The metallic teeth
and attachment regions were kept. A hexagonal region was
NASA/TM—2012-217630
AISI 9310 Gear Steel
29×106
2
A special fixture was then designed and fabricated to locate
the gear rim and the gear hub prior to composite material layup. The gear teeth outer rim was located using the “measurement over pins” (Ref. 9). The inner metallic hub was located
via its inner bore.
The first step in the lay-up process was to place the inner
metallic hub by locating it around the feature in the mold
center. During the assembly process, the larger ply stack was
created by 12 layers of the prepreg. Each layer was rotated 60°
in one direction to encourage the best isotropic behavior. With
the first ply stack positioned and debulked, a film adhesive
was added and the outer metallic ring was placed on top. The
second ply stack was created in the void between the two
metal features. The same “clocking” procedure was performed
on these plies. Another layer of film adhesive was added and
the final ply stack was added in the same fashion as the first.
The composite material lay-up process is shown in Figure 1.
This figure shows the assembly procedure used prior to curing
the finished part.
The gear mold assembly was placed into a press and subjected to a 100 psi load. The press was then heated at a ramp rate of
4 °F per minute to a temperature of 250 °F. A 1-hr dwell was
held at 250 °F to allow time for the metal and composite to
reach a consistent temperature. The temperature was then
increased to 350 °F using the same ramp rate. The temperature
was held at 350 °F to fully cure the composite prepreg. After the
cure cycle was complete the part was removed from the mold
and any excess resin flashing was removed.
The finished hybrid gear is shown in Figure 2 and Figure 3.
There was no optimization of the arrangement at this point,
but the gear produced was still on the order of 20 percent
lighter than the all-metal one.
Figure 1.—Hybrid gear assembly steps.
Figure 2.—Hybrid gear.
NASA/TM—2012-217630
3
Figure 3.—Hybrid gear manufacturing details.
mounted on the metal hub in the six o’clock position. Both the
steel gear and the composite gear were subjected to a series of
impacts in the radial direction and a series of impacts in the axial
direction. Axial impacts were concentrated at approximately the
seven o’clock position on the gear at a radius just inboard of the
teeth. For the composite gear, this location was at the edge of the
composite portion of the gear. For radial impacts, a tooth near
the ten o’clock position was impacted at the tip. A nylon bolt on
either side of the tip was used to more effectively set the standoff
distance between the tip and the gear, enabling more consistent
impacts between tests. A total of ten impacts were performed in
each of these four configurations.
Free—Free Vibration Modes
A series of experiments using a modal impact hammer was
conducted on a standard AISI 9310 steel spur gear and a hybrid
spur gear specimen. The objective was to experimentally
determine the modal properties of the hybrid spur gear and
compare them to those of its conventional steel counterpart.
Additionally, a model of the conventional spur gear was
generated using finite element software and subsequently
compared with experimental data obtained from the test
specimen. A further effort is underway to include hybrid
material parameters into the model and correlate with modal
data acquired from these experiments.
A series of modal experiments was conducted on a baseline
steel gear and the hybrid gear to identify natural frequencies
and calculate modal damping. An electric impact hammer was
used to impact the gears in multiple orientations, with an
accelerometer at the tip of hammer providing a trigger for the
acquisition of acceleration data from the gear. In all cases, the
single accelerometer was placed on the metal hub of the test
gear with the accelerometer axis parallel to the rotational axis
of the gear. This placement was chosen for convenience
because it was accessible on both test specimens. Finite
Element Analysis (FEA) demonstrated that most displacement
would be in the axial direction for the modes of interest.
Figure 4 shows the experimental configurations in which the
impact experiments were performed. The test gear was suspended on rubber bands hanging on a rubber cord, with this soft
support at the twelve o’clock position. The accelerometer was
NASA/TM—2012-217630
Impact Study
The time-domain data signal was imported into an automated
signal analysis and filtering software package. The data was
then filtered to isolate the signal associated with the natural
frequency corresponding to the first non-rigid body mode. The
log decrement was calculated for each filtered data set. From
this calculation, modal parameters of the hybrid specimen and
its steel counterpart were estimated and compared. Figure 5
depicts an example of both a raw and a filtered data set.
Additionally, the unfiltered results of each impact were
viewed in the frequency domain to compare results within
configuration groups. These are depicted in Figure 6. These
figures each show the frequency data from four of the ten
impacts for each configuration.
4
Figure 4.—Impact locations shown for hybrid gears (similar for all-steel gear).
Figure 6.—Frequency domain results, axial location impacts. All
steel gear. (b) Hybrid gear.
Figure 5.—Sample data raw. (a) Time domain signal.
(b) Filtered data.
NASA/TM—2012-217630
5
TABLE 3.—SPECIMEN MODAL PROPERTY ESTIMATES
Impact position
Axial
Gear specimen
9310-T42
Hybrid 42
Mean
0.0145
0.1296
Log decrement (δ)
Standard deviation
0.0004
0.0263
Mean
0.0023
0.0206
Damping ratio (ζ)
Standard deviation
0.0001
0.0042
General damping constant (c) (lbf-sec/in.) Mean
0.4843
2.9887
Standard deviation
0.0143
0.6053
9310-T42
7219 ± 43
Natural frequency (ωn) (Hz)
Hybrid 42
6236 ± 62
Radial
9310-T42
Hybrid 42
0.0261
0.0543
0.0028
0.0122
0.0042
0.0086
0.0004
0.0019
0.8725
1.2520
0.0928
0.2821
n=19 data samples
n=14 data samples
Using the basic log decrement relationships, modal properties of the gears were estimated. These estimates are presented
in Table 3. As expected, the hybrid gear exhibits higher
damping properties than its steel counterpart. This has the
potential to reduce transmitted vibration as compared to allsteel gears. Note, that the damping properties vary somewhat,
depending upon the impact position. The experimentally
determined mean and standard deviation of the natural frequency corresponding to the first non-rigid mode are also provided.
FEA Modal Study—Steel Gear
A modal analysis was conducted for the 42-tooth steel gear
to verify natural frequencies identified in the experiment and to
provide information on the associated mode shapes. The solid
model of the gear captures the tooth geometry to a reasonable
extent, but does not include subtle geometric features such as
tip relief. For the purposes of a modal analysis however, the
solid model is a close approximation to the test specimens.
The finite element mesh is a solid mesh consisting of 19152
linear tetrahedron elements and having a total of 31002 nodes.
The characteristic element size is approximately 0.10 in. The
gear specimens are made from AISI 9310 steel, which is
represented in the analysis as a linear isotropic material with
Young’s modulus of 29×106 psi (2.0×1011 Pa), Poisson’s ratio
of 0.29, and mass density of 0.284 lbm/in.3 (7861 kg/m3). The
analysis is conducted on the unconstrained gear (free-free).
The first six modes identified in the analysis are rigid body
translations and rigid body rotations; one mode is associated
with each translational or rotational degree of freedom. Therefore starting at mode 7 to 12 the frequencies associated with
these modes are shown in Table 4. The mode shape for mode 7
is shown in Figure 7. The mode shapes found illustrated that
the modal displacements are primarily in the axial direction for
the modes of interest, guiding accelerometer placement.
Figure 7.—All metallic gear mode shape.
FEA Modal Study—Hybrid Gear
A modal analysis was also conducted for the 42-tooth hybrid
gear to verify natural frequencies identified in the experiment
and determine the associated mode shapes. As in the case of the
steel gear, the tooth geometry is a reasonable representation but
does not include all subtle features of the teeth. The deviation
of the model geometry from the physical specimens is expected
to have a negligible effect on the modal results.
The finite element mesh is a solid mesh consisting of 25672
linear tetrahedron elements and having a total of 39166 nodes.
The characteristic element size is approximately 0.10 in. The
composite portion of the gear is constructed of prepreg. triaxial braided carbon fiber with alternating orientation between
adjacent layers, and resin. Due to the anisotropic nature of the
material, consideration was given to modeling each individual
ply with orthotropic properties. However, due to the large
number of plies, it was determined that the composite portion
of the gear could be modeled using isotropic properties.
The hub and ring portions of the gear were modeled using
properties of AISI 9310 steel, which is represented in the
analysis as a linear isotropic material with Young’s modulus of
29×106 psi (2.0×1011 Pa), Poisson’s ratio of 0.29, and mass
density of 0.284 lbm/in.3 (7861 kg/m3). The composite portion
TABLE 4.—ALL STEEL GEAR FREQUENCIES
FOR MODES 7 TO 12
Mode number
Frequency,
Hz
7
7187
8
7270
9
12304
10
12853
11
12924
12
15237
NASA/TM—2012-217630
6
of the gear is modeled as a linear isotropic material with
Young’s modulus of 6.4×106 psi (4.4×1010 Pa), Poisson’s ratio
of 0.30, and mass density of 0.055 lbm/in.3 (1522 kg/m3). The
analysis is conducted on the unconstrained gear (free-free), and
the components are treated as welded together (node-to-node
constraint at the interfaces). It is notable that the calculated
bulk modulus properties for the composite are not linear as the
tensile elastic modulus of 6.4×106 psi compares to a compressive elastic modulus of 6.1×106 psi when using bulk properties,
a difference of 5 percent. Based on the relatively minor
difference and the square root dependence of frequency on
stiffness, the bulk tensile modulus was used in this simplified
case. Based on these small differences, it was decided to use
the bulk properties to simplify the analysis.
Modes 7 to 12, identified in the analysis, are shown in
Table 5. The first 6 modes are related to the rigid body translations and rigid body rotations. The mode shape for mode 7 is
shown in Figure 8.
Figure 8.—Hybrid gear mode shape.
TABLE 5.—HYBRID GEAR FINITE ELEMENT
VIBRATION MODES AND FREQUENCIES.
Mode number
Frequency,
Hz
7
7780
8
7913
9
13745
10
14592
11
15725
12
16483
Comparison of FEA to Experiment—
Natural Frequencies
A comparison between the finite element output and the
experimental results was conducted in the first step of validating the FEA model. Figure 9 depicts a comparison between the
measured frequencies of the steel spur gear specimen and the
predicted frequencies of the finite element model. An exact
frequency match falls directly on the diagonal. The result
shows good agreement between model predictions and the
experimental results.
For the hybrid gear on the other hand, modes identified in the
experiment generally shifted to lower frequencies, whereas the
model predicted a shift to higher frequencies. In the model, this
is an expected result since the composite has a higher ratio of
elastic modulus to density than steel, and the area moment of
inertia is considerably larger for the cross section of the hybrid
gear. However, the FE model assumes adjacent surfaces in
components are bonded together.
Based on actual construction methods, the interfaces may
have a lower effective stiffness such that the experiment would
produce modes at frequencies lower than predicted. Changes to
the interfaces can be made in the model to bring the natural
frequencies within the ranges of the experiment, but this may
not provide additional physical insight to the properties of the
interface. However, such an approach may be employed to
improve the model for subsequent stress analysis.
NASA/TM—2012-217630
Figure 9.—Comparison of experimental and finite element
natural frequencies.
Unlike the steel gear, comparison between the hybrid gear
finite element results and the experimental results did not
produce similar mode frequencies as the all steel gear. From the
experiments, the hybrid gear exhibits two significant peaks at
approximately 6270 and 9743 Hz. The modes found from finite
element analysis did not compare well to the experiments. It is
expected that further model development will reduce some of
these inconsistencies with the experimental data.
Dynamic Testing
Two types of dynamic tests were conducted to determine if
gears could be considered as possible composite candidates in
future rotorcraft drive systems. The first set of tests measured
vibration and noise at four speeds and four levels of torque.
The second test was an operational endurance test.
7
The dynamic tests for noise and vibration were conducted
with four different gear arrangements at four different rotational speeds and four different levels of load. The gears were
installed in the test rig in the following configurations: (1) all
steel both sides, (2) hybrid gear left side, all steel gear right
side, (3) all steel gear left side, hybrid gear right side, and
(4) hybrid gear both sides. When the facility is operating, the
left side gear is the driving gear and the right side is the driven
gear. All vibration measurements were made on the driven side
support bearing housing as show in Figure 10.
For the four configurations mentioned above, tests were run
at 2500, 5000, 7500, and 10000 rpm and at 133, 238, 448, and
658 in.*lb torque. The vibration level in “g’s” is shown in
Figure 11. The noise level was measured via a hand-held sound
level meter at a distance of 1 in. from the test gearbox cover.
The sound level was recorded on an A-weighted scale. The
results of the sound level data are shown in Figure 12. The four
test rig configurations are shown at four speed and load
conditions.
Figure 10.—Test facility shown with cover removed.
Accelerometers are located on the right side driven gear. The
hybrid—all steel gear arrangement shown in the photograph.
Figure 11.—Vibration data taken for four speeds and four load levels.
NASA/TM—2012-217630
8
Figure 12.—Sound level measurements made for the four different test arrangements made at four different
speed and load conditions.
10000 rpm, 250 psi torque load (553 in.*lb torque) with an oil
inlet temperature of ~120 °F. The hybrid gears operated
without any problem during this extended test period. The
gears did not show any signs of fatigue during post-test
inspection.
From the vibration data shown in Figure 11, the hybrid gear
generally reduced the overall vibration level with a mixed or all
hybrid configurations. For the noise data of Figure 12 the
mixed hybrid gear arrangement and all hybrid arrangement
produced less noise for the two higher speed conditions.
Although some vibration and noise reduction was seen with
the hybrid gears, the results were not as dramatic as expected.
There are several reasons why noise and vibration had only
modest reduction. First, the manufacturing process used to
fabricate the hybrid gear did not result in aerospace quality
accuracy. The composite curing actually reduced the backlash
of the components due to stretching of the metal outside rim.
The backlash also was not consistent around the gear. Both of
these “manufacturing errors” could be corrected by postcomposite-attachment final grinding of the gear teeth. The
noise data is related to how well the teeth mesh during operation. In effect the noise measured at a small distance from the
cover is a combination of airborne and structure borne from the
meshing gear teeth being reradiated from the test facility cover.
Summary and Conclusions
Based on the results attained in this study the following
conclusions can be made:
1.
2.
3.
Long-Term Testing
An endurance test was conducted on the hybrid gears in
NASA’s Spur Gear Test Facility. The hybrid gear arrangement
was run for over 300×106 cycles (gear revolutions) at
NASA/TM—2012-217630
9
Hybrid gear arrangement shows promise as the gears were
operated for an extended period of time at a relatively high
speed and torque.
Power to weight improvement could be possible – as steel
webs could be replaced by lightweight composite material.
For the gears tested, a ~20 percent decrease in weight was
realized without optimization of the components.
Reduced noise and vibration would be expected when
manufacturing processing produces aerospace quality
gears. The hybrid gears test only show modest improvements in vibration and noise. More significant improvements are possible with improved manufacturing processes
and possible material tailoring through the composite
structure.
6. Cope, G.: Model 427 Drive System, presented at the 55th
Annual Forum, of the American Helicopter Society, May
1999.
7. Spears, S.: Design and Certification of the Model 429
Supercritical Tail Rotor Drive Shaft, presented at the 64th
Annual Forum of the American Helicopter Society, May
2008.
8. Handschuh, R. and Roberts, G.: “Patent Application –
Hybrid Gear,” 2011.
9. Handschuh, R., Polly, J., and Morales, W.: Gear Mesh
Loss-of-Lubrication Experiments and Analytical Simulation, NASA/TM—2011-217106, November 2011.
10. Handschuh, R. and Krantz, T.: Engagement of Metal Debris Into a Gear Mesh, NASA/TM—2010-216759, July
2010.
11. Dudley, D.: Handbook of Practical Gear Design,
McGraw-Hill, Inc., 1984.
References
1. Henry, Z.: Bell Helicopter Advanced Rotorcraft Transmission (ART) Program, NASA CR-195479, June 1995.
2. Anderson, N., Cedox, R., Salama, E. and Wagner, D.:
Advanced Gearbox Technology Final Report, NASA
Contractor Report CR-179625, June 1987.
3. Lenski, J.: Advanced Rotorcraft Transmission Program
(ART), NASA CR-195461, Army Research Laboratory
Report ARL-CR-224, April 1995.
4. Lin, S. and Poster, S.: Development of a Braided Composite Drive Shaft with Captured End Fittings, presented at
the 60th Annual Forum of the American Helicopter Society International, June 2004.
5. Cecil, T., Ehinger, R., and Kilmain, C.: Application and
Configuration Issues of Resin Transfer Molded Composite Transmission Housings – A Program Review, presented at the 63rd Annual Forum of the American
Helicopter Society International, May 2007.
NASA/TM—2012-217630
10
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PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS.
1. REPORT DATE (DD-MM-YYYY)
2. REPORT TYPE
01-07-2012
Technical Memorandum
3. DATES COVERED (From - To)
5a. CONTRACT NUMBER
4. TITLE AND SUBTITLE
Hybrid Gear Preliminary Results-Application of Composites to Dynamic Mechanical
Components
5b. GRANT NUMBER
5c. PROGRAM ELEMENT NUMBER
5d. PROJECT NUMBER
6. AUTHOR(S)
Handschuh, Robert, F.; Roberts, Gary, D.; Sinnamon, Ryan, R.; Stringer, David, B.; Dykas,
Brian, D.; Kohlman, Lee, W.
5e. TASK NUMBER
5f. WORK UNIT NUMBER
WBS 877868.02.07.03.01.01.01
7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)
8. PERFORMING ORGANIZATION
REPORT NUMBER
National Aeronautics and Space Administration
John H. Glenn Research Center at Lewis Field
Cleveland, Ohio 44135-3191
E-18121-1
9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)
10. SPONSORING/MONITOR'S
ACRONYM(S)
National Aeronautics and Space Administration
Washington, DC 20546-0001
NASA
11. SPONSORING/MONITORING
REPORT NUMBER
NASA/TM-2012-217630
12. DISTRIBUTION/AVAILABILITY STATEMENT
Unclassified-Unlimited
Subject Category: 37
Available electronically at http://www.sti.nasa.gov
This publication is available from the NASA Center for AeroSpace Information, 443-757-5802
13. SUPPLEMENTARY NOTES
14. ABSTRACT
Composite spur gears were fabricated and then tested at NASA Glenn Research Center. The composite material served as the web of the
gear between the gear teeth and a metallic hub for mounting to the torque-applying shaft. The composite web was bonded only to the inner
and outer hexagonal features that were machined from an initially all-metallic aerospace quality spur gear. The Hybrid Gear was tested
against an all-steel gear and against a mating Hybrid Gear. As a result of the composite to metal fabrication process used, the concentricity
of the gears were reduce from their initial high-precision value. Regardless of the concentricity error, the hybrid gears operated successfully
for over 300 million cycles at 10000 rpm and 553 in.*lb torque. Although the design was not optimized for weight, the composite gears
were found to be 20 percent lighter than the all-steel gears. Free vibration modes and vibration/noise tests were also conduct to compare the
vibration and damping characteristic of the Hybrid Gear to all-steel gears. The initial results indicate that this type of hybrid design may
have a dramatic effect on drive system weight without sacrificing strength.
15. SUBJECT TERMS
Gears; Composites
16. SECURITY CLASSIFICATION OF:
a. REPORT
b. ABSTRACT
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17. LIMITATION OF
ABSTRACT
c. THIS
PAGE
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18. NUMBER
OF
PAGES
18
19a. NAME OF RESPONSIBLE PERSON
STI Help Desk (email:[email protected])
19b. TELEPHONE NUMBER (include area code)
443-757-5802
Standard Form 298 (Rev. 8-98)
Prescribed by ANSI Std. Z39-18
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