CMC コンソーシアム会員の皆様
第 12 回 CMC コンソーシアムセミナーを下記のように開催いたします。
講演者：Dr. Frank Abdi、AlphaSTAR
講演タイトル ： Development of ASTM Test Standards for the Mode I-II Interlaminar
Fracture Toughness (GIc--Crack Growth Resistance) of Ceramic Matrix Composites at
RT/ET
ABSTRACT
Ceramic matrix composite (CMC) materials are targeted for high temperatureapplications in aircraft and power turbines because of their low density andhigh-temperature thermo-mechanical properties, compared to conventional
nickel super alloys. Advanced Integrated Computational Material Engineering(ICME) has been able to predict variety of CMC industry application challenges,
namely: 1) Virtual Manufacturing, Plasma spray coating, rumpling, thermal
growth oxidation (TGO); and 2) Virtual Testing, Environmental degradation,
Foreign object damage (FOD), Erosion, Creep, fatigue, retained strength, andCrack Growth Resistance (CGR).
New test methods are needed for assessment of effects of delamination cracks on the structural integrity andlife of CMC components. The ASTM C28 Fracture Toughness- CGR Working Group has drafted a standard test
method for the “Mode I -II Interlaminar Fracture Toughness (GIc -- CGR) of Fiber-Reinforced CMC. The ASTM
test standard details the scope, use, and application of the test method, interferences, test equipment,
specimen geometry and preparation, test procedures, data interpretation and calculation, and reporting
requirements for the new CMC CGR test method.
The emerging CMC materials require addressing the ASTM test standards for CMCs’ CGR concerns, eventual
qualification under service loading: Highlights in testing and modeling of CGR and derivation of simple beam
equation can be summarized as: 1) Zigzag (wavy) crack path pattern and fiber bridging, 2) Samples are verythin and difficult to machine and test; 3) Specimen initial crack, width and thickness may contribute to mixed
mode failure evolution; 4) correct measurement of interlaminar CGR and determination of critical fractureenergy 𝐺𝐼 by test or modeling; 5) Modeling to consider: (i) test observed wavy crack growth pattern due towoven architecture and/or shift in failure mode, This effort combines the test method, modeling, and DataInterpretation.
Mode I-II interlaminar fracture toughness specimens may exhibit interaction and zig-zag crack growth
behavior. CGR, ICME, and De-homogenized (fiber, matrix, interphase) Multi Scale Progressive Failure Analysis(DE-MS-PFA) based solution for CMC materials was developed which included design and test of standard test
methods for: (i) Mode I Double Cantilever Beam (DCB), Wedge Loaded DCB (WDCB); and (ii) Mode II End
Notched Flexure (ENF) and End-Loaded Split (ELS). ICME predictive methodology also used a new proposed
ASTM standard simplified CGR compliance equation to correlate the wedge load vs crack opening to 𝐺𝐼
considering geometrical anomalies and initial crack. Mode II was characterized by ENF/ELS tests where rising
R-curve behaviors were observed signifying increased toughness/resistance to crack growth. Design ofExperiment (DOE) methods were used to optimize ELS geometry and initial crack length while minimizing thecontribution of interlaminar tension (ILT) and maximizing interlaminar shear (ILS).
Prediction vs. Test Validation of an S200 Nicalon/SiNC and Oxide/Oxide Ceramic Matrix Composite (CMC) wasconducted to determine the crack growth resistance (GIc) of Mode I WDCB and Mode II ENF at Room andElevated temperatures (RT/ET) and compared with experimental tests observations. In addition, DOE
optimization determined design of specimen length, width, and initial crack length for WDCB and ENF
specimens. Note: The wedge loading method was developed to avoid the problems of high temperaturebonding of loading blocks and hinges. Wedge Loading gives proper crack path without mixed mode effects andcan be used at high temperature in a furnace.

■日 時： 2022 年 6 月 29 日（水）8：30－9：30 (予定)

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