Multi-Axial Failure of Ceramic Matrix Composite Fiber Tows

2011 ◽  
Vol 78 (3) ◽  
Author(s):  
M. Blacklock ◽  
D. R. Hayhurst
Keyword(s):  
Axial Stress ◽  
Ceramic Matrix Composite ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Composite Fiber ◽  
Woven Composites ◽  
Matrix Composites ◽  
Stress Strain ◽  
Fiber Failure ◽  
Stressed Region

This paper considers the multi-axial stress-strain-failure response of two commercially woven ceramic matrix composites. The different failure mechanisms of uni-axially stressed tows and woven composites are addressed. A model is postulated in which the local transverse and shear stressing, arising from the weave, instantaneously deactivate wake debonding and fiber pullout and initiates dynamic fiber failure; hence, triggering catastrophic failure of the axially stressed region of the tow. The model is shown to predict experimentally measured stress-strain-failure results for the woven composites considered. Simple stress-strain-failure models are also proposed for tows subjected to axial-transverse and axial-shear loadings, but due to the lack of experimental data they have not been validated.

Uni-axial stress–strain response and thermal conductivity degradation of ceramic matrix composite fibre tows

2009 ◽  
Vol 465 (2109) ◽  
pp. 2849-2876 ◽  
Author(s):  
C. Tang ◽  
M. Blacklock ◽  
D. R. Hayhurst
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Axial Stress ◽  
Ceramic Matrix Composite ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Strain Response ◽  
Matrix Composites ◽  
Stress Strain ◽  
Fibre Failure

A physical model, previously developed by one of the authors, has been extended to cover thermal conductivity degradation owing to the uni-axial stress–strain response of aligned groups of fibres or tows found in ceramic matrix composites. Both the stress–strain and thermal models, together with their coupling, have been shown to predict known composite behaviour qualitatively. The degradation of longitudinal thermal properties is shown to be driven by strain-controlled fibre failure; while the degradation of transverse thermal properties is because of the growth of fibre–matrix interface wake-debonded cracks, coupled with strain-driven fibre failure.

FINITE ELEMENT MODELING OF TRANSVERSE DEFORMATION IN REPRESENTATIVE VOLUME ELEMENTS OF CERAMIC MATRIX COMPOSITES (CMCs)

2010 ◽  
Vol 02 (01n02) ◽  
pp. 107-126 ◽  
Author(s):  
C. TANG ◽  
M. A. SHEIKH ◽  
D. R. HAYHURST
Keyword(s):  
Finite Element ◽  
Weibull Distribution ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Matrix Composites ◽  
Transverse Deformation ◽  
Stress Strain ◽  
Fiber Failure ◽  
Representative Volume ◽  
Representative Volume Elements

The paper reports the use of the finite element method to model longitudinal and transverse deformation of representative volume elements (RVE) of ceramic matrix composites subjected to uniaxial loading parallel to fibers. Cohesive elements have been used to model two forms of damage: fracture initiation and propagation both within the matrix, and along the fiber–matrix interface. From the knowledge of the constituent materials behavior, the FE technique has been used to predict the stress–strain behavior and the variation of Poisson's ratio of the RVE due to these two damage forms; but the model does not cater for fiber failure. The RVE predictions have been benchmarked against experimental results for Nicalon-CAS material and good agreement has been obtained. Comparison of the predicted behavior of the single Nicalon-CAS RVE with experimental data for unidirectional tows indicates that the stress–strain curve is predominantly controlled by the Weibull distribution of fiber failure stress, while the degradation of Poisson's ratio is determined by the Weibull distribution of interfacial strength. The same approach has been used for a HITCO C/C material for which transverse deformation behavior is unknown. The results for the HITCO C/C material, as for the Nicalon-CAS, show that the fiber behavior determines the ultimate failure of the RVE, and that interface debonding is the controlling mechanism for the variation of the Poisson ratio with axial strain.

Modeling of the Transition Layer in Ceramic Matrix Composites from Coal Wastes and Clay

2020 ◽  
Vol 299 ◽  
pp. 37-42
Author(s):  
O.A. Fomina ◽  
Andrey Yu. Stolboushkin
Keyword(s):  
Transition Layer ◽  
Raw Materials ◽  
Ceramic Matrix Composite ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Coal Waste ◽  
Matrix Composites ◽  
Carbonaceous Particles ◽  
The Core ◽  
Coal Wastes

A model of the transition layer between the shell and the core of a ceramic matrix composite from coal waste and clay has been developed. The chemical, granulometric and mineral compositions of the beneficiation of carbonaceous mudstones and clay were studied. The technological and ceramic properties of raw materials for the samples manufacturing were determined. The method of manufacturing multilayer ceramic samples from coal waste, clay and their mixture is given. The number of transition layers in the contact zone between the clay shell and the core from coal wastes is determined. The deformation and swelling phenomena of model samples from coal wastes, clay, and their mixtures were revealed at the firing temperature of more than 1000 °C. The formation of a reducing ambient in the center of the sample with insufficient air flow is shown. The influence of the carbonaceous particles amount and the ferrous form iron oxide in the coal wastes on the processes of expansion of multilayer samples during firing has been established.

scholarly journals Exposure of Ceramics and Ceramic Matrix Composites in Simulated and Actual Combustor Environments

2000 ◽  
Vol 122 (2) ◽  
pp. 212-218 ◽  
Author(s):  
Karren L. More ◽  
Peter F. Tortorelli ◽  
Mattison K. Ferber ◽  
Larry R. Walker ◽  
James R. Keiser ◽  
...  
Keyword(s):  
Ceramic Matrix Composite ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Surface Damage ◽  
Operating Conditions ◽  
Matrix Composites ◽  
Long Term Stability ◽  
Recession Rates ◽  
Combustor Liner

A high-temperature, high-pressure, tube furnace has been used to evaluate the long term stability of different monolithic ceramic and ceramic matrix composite materials in a simulated combustor environment. All of the tests have been run at 150 psia, 1204°C, and 15 percent steam in incremental 500 h runs. The major advantage of this system is the high sample throughput; >20 samples can be exposed in each tube at the same time under similar exposure conditions. Microstructural evaluations of the samples were conducted after each 500 h exposure to characterize the extent of surface damage, to calculate surface recession rates, and to determine degradation mechanisms for the different materials. The validity of this exposure rig for simulating real combustor environments was established by comparing materials exposed in the test rig and combustor liner materials exposed for similar times in an actual gas turbine combustor under commercial operating conditions. [S0742-4795(00)02402-9]

Ceramic Matrix Composite Materials for Engine Exhaust Systems on Next-Generation Vertical Lift Vehicles

2018 ◽  
Vol 140 (10) ◽  
Author(s):  
Michael J. Walock ◽  
Vann Heng ◽  
Andy Nieto ◽  
Anindya Ghoshal ◽  
Muthuvel Murugan ◽  
...  
Keyword(s):  
Ceramic Matrix Composite ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Thermal Exposure ◽  
Gas Flows ◽  
Matrix Composites ◽  
Engine Exhaust ◽  
Ir Camera ◽  
Before And After ◽  
Ceramic Components

Future gas turbine engines will operate at significantly higher temperatures (∼1800 °C) than current engines (∼1400 °C) for improved efficiency and power density. As a result, the current set of metallic components (titanium-based and nickel-based superalloys) will be replaced with ceramics and ceramic matrix composites (CMCs). These materials can survive the higher operating temperatures of future engines at significant weight savings over the current metallic components, i.e., advanced ceramic components will facilitate more powerful engines. While oxide-based CMCs may not be suitable candidates for hot-section components, they may be suitable for structural and/or exhaust components. However, a more thorough understanding of the performance under relevant environment of these materials is needed. To this end, this work investigates the high-temperature durability of a family of oxide–oxide CMCs (Ox–Ox CMCs) under an engine-relevant environment. Flat Ox–Ox CMC panels were cyclically exposed to temperatures up to 1150 °C, within 240 m/s (∼0.3 M) gas flows and hot sand impingement. Front and backside surface temperatures were monitored by a single-wavelength (SW) pyrometer and thermocouple, respectively. In addition, an infrared (IR) camera was used to evaluate the damage evolution of the samples during testing. Flash thermography nondestructive evaluation (NDE) was used to elucidate defects present before and after thermal exposure.

Investigation of Damage in Unidirectional Ceramic Matrix Composites Using a Cohesive-Shear-Lag Model

2001 ◽  
Author(s):  
B. Yang ◽  
S. Mall
Keyword(s):  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Interfacial Debonding ◽  
Matrix Composites ◽  
Fiber Reinforced ◽  
Shear Lag ◽  
Stress Strain ◽  
Unidirectional Fiber ◽  
Shear Lag Model ◽  
Lag Model

Abstract The present study develops a cohesive-shear-lag model to analyze the cycling stress-strain behavior of unidirectional fiber-reinforced ceramic matrix composites. The model, as a modification to a classical shear-lag model, takes into account matrix cracking, partial interfacial debonding, and partial breakage of fibers. The statistical nature of partial breakage of fibers is modeled by using a cohesive force law. The validity of the model is demonstrated by investigating stress-strain hysteresis loops of a unidirectional fiber-reinforced ceramic-glass matrix composite, SiC/1723. This example demonstrates the capability of the proposed model to characterize damage and deformation mechanisms of ceramic matrix composites under tension-tension cycling loading. The dominant progressive damage mechanism with cycling in this case is shown to be accumulation of fibers breakage, accompanied by increase in interfacial debonding and smoothening of frictional debonded interface.

scholarly journals Effects of Nonuniform Fiber Geometries on the Microstructural Fracture Behavior of Ceramic Matrix Composites

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Hye-gyu Kim ◽  
Wooseok Ji ◽  
Nam Choon Cho ◽  
Jong Kyoo Park
Keyword(s):  
Optimization Algorithm ◽  
Fracture Behavior ◽  
Ceramic Matrix Composite ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Shear Loading ◽  
Matrix Composites ◽  
Specific Loading ◽  
Smeared Crack Approach ◽  
Smeared Crack

Microstructural fracture behavior of a ceramic matrix composite (CMC) with nonuniformly distributed fibers is studied in the presentation. A comprehensive numerical analysis package to study the effect of nonuniform fiber dimensions and locations on the microstructural fracture behavior is developed. The package starts with an optimization algorithm for generating representative volume element (RVE) models that are statistically equivalent to experimental measurements. Experimentally measured statistical data are used as constraints while the optimization algorithm is running. Virtual springs are utilized between any adjacent fibers to nonuniformly distribute the coated fibers in the RVE model. The virtual spring with the optimization algorithm can efficiently generate multiple RVEs that are statistically identical to each other. Smeared crack approach (SCA) is implemented to consider the fracture behavior of the CMC material in a mesh-objective manner. The RVEs are subjected to tension as well as the shear loading conditions. SCA is capable of predicting different fracture patterns, uniquely defined by not only the fiber arrangement but also the specific loading type. In addition, global stress-strain curves show that the microstructural fracture behavior of the RVEs is highly dependent on the fiber distributions.

Erosion in an MI SiC/SiC Ceramic Matrix Composite (CMC)

2019 ◽  
Author(s):  
M. J. Presby ◽  
C. Gong ◽  
S. Kane ◽  
N. Kedir ◽  
A. Stanley ◽  
...  
Keyword(s):  
Ceramic Matrix Composite ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Matrix Composites ◽  
Erosion Behavior ◽  
Sic Ceramic ◽  
Material Systems ◽  
Nominal Density ◽  
Analytical Tools ◽  
Matrix Hardness

Abstract Erosion phenomenon of ceramic matrix composites (CMCs), attributed to their unique architectural configurations, is markedly different from conventional monolithic ceramic counterparts. Prior to further integration of CMCs into hot-section components of aeroengines subject to erosive environments, their erosion behavior needs to be characterized, analyzed, and formulated. The erosion behavior of a 2-D woven melt-infiltrated (MI) SiC/SiC CMC was assessed in this work as a function of variables such as particle velocity and size. The erosion damage was characterized using appropriate analytical tools such as optical and scanning electron microscopy (SEM). A phenomenological erosion model was developed for SiC/SiC CMC material systems with respect to kinetic energy of impacting particles in conjunction with nominal density, matrix hardness and elastic modulus of the SiC/SiC CMCs. The model was in reasonable agreement with the experimental data.

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