NASA Scientific and Technical Aerospace Reports

engines. Epoxy reinforced with braided carbon fibers is a candidate structural material which may be suitable for an engine
case. This paper reports flat-coupon mechanical-property experiments performed to compliment previously reported
subcomponent impact testing and analytical simulation of containment structures. Triaxial-braid T700/5208 epoxy and
triaxial-braid T700/M36 toughened epoxy composites were evaluated. Also, two triaxial-braid architectures (0 +/- 60 deg., 0
+/- 45 deg.) with the M36 resin were evaluated through tension, compression, and shear testing. Tensile behavior was
compared between standard straight-sided specimens (ASTM D3039) and bowtie specimens. Both double-notch shear (ASTM
D3846) and Iosepescu (ASTM D5379) tests were performed as well. The M36/0 +/- 45 deg. configuration yield the best
response when measurements were made parallel to the axial tows. Conversely, the M36/0 +/- 60 deg. configuration was best
when measurements were made perpendicular to the axial tows. The results were used to identify critical properties and to
augment the analysis of impact experiments.
Author
Mechanical Properties; Epoxy Matrix Composites; Carbon Fibers; Braided Composites; Impact Tests
20040112010 NASA Langley Research Center, Hampton, VA, USA
Accurate Simulation of Acoustic Emission Sources in Composite Plates
Prosser, W. H.; Gorman, M. R.; [1994]; 4 pp.; In English; 1994 ANST Spring Conference, March 1994, New Orleans, LA,
USA; Copyright; Avail: CASI; A01, Hardcopy
Acoustic emission (AE) signals propagate as the extensional and flexural plate modes in thin composite plates and
plate-like geometries such as shells, pipes, and tubes. The relative amplitude of the two modes depends on the directionality
of the source motion. For source motions with large out-of-plane components such as delaminations or particle impact, the
flexural or bending plate mode dominates the AE signal with only a small extensional mode detected. A signal from such a
source is well simulated with the standard pencil lead break (Hsu-Neilsen source) on the surface of the plate. For other sources
such as matrix cracking or fiber breakage in which the source motion is primarily in-plane, the resulting AE signal has a large
extensional mode component with little or no flexural mode observed. Signals from these type sources can also be simulated
with pencil lead breaks. However, the lead must be fractured on the edge of the plate to generate an in-plane source motion
rather than on the surface of the plate. In many applications such as testing of pressure vessels and piping or aircraft structures,
a free edge is either not available or not in a desired location for simulation of in-plane type sources. In this research, a method
was developed which allows the simulation of AE signals with a predominant extensional mode component in composite
plates requiring access to only the surface of the plate.
Author
Acoustic Emission; Plates (Structural Members); Simulation; Composite Structures; Flexural Strength
20040112022 NASA Glenn Research Center, Cleveland, OH, USA
Computation of Variability in the Average Thermal and Mechanical Properties of a Melt-Infiltrated SiC/SiC Composite
Kalluri, Sreeramesh; Brewer, David N.; Calomino, Anthony M.; [2004]; 6 pp.; In English; Fifth International Conference on
High Temperature Ceramic Matrix Composites, 12-16 Sep. 2004, Seattle, WA, USA
Contract(s)/Grant(s): NCC3-1041; 22-714-30-09; No Copyright; Avail: CASI; A02, Hardcopy
Thermal conductivity and tensile properties (elastic modulus, proportional limit strength, inplane tensile strength, and
strain to failure) of a SiC/SiC composite were experimentally determined at 816 and 1204 C. Tests were performed at room
temperature on the same material to obtain interlaminar shear and tensile strength. For each thermal and mechanical property
24 tests were conducted to capture the variation. A random sampling method was used to quantify the variability exhibited
by the mean values of the thermal and mechanical properties. The minimum number of tests required to characterize the mean
value of each thermal or mechanical property for the composite was determined by varying the group size of the random
sample.
Author
Ceramic Matrix Composites; Tensile Properties; Tensile Tests; Thermal Conductivity; Mechanical Properties;
Thermodynamic Properties; Simulation
20040112023 NASA Glenn Research Center, Cleveland, OH, USA
Ceramic Matrix Composite Vane Subelement Testing in a Gas Turbine Environment
Verrilli, Michael; Calomino, Anthony; Robinson, R. Craig; Thomas, David J.; 2004; 7 pp.; In English; ASME TURBO EXPO
2004, 14-17 Jun. 2004, Vienna, Austria
Report No.(s): GT2004-53970; Copyright; Avail: CASI; A02, Hardcopy
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