Ultrasonic Evaluation of Stiffness Tensor Changes and Associated Anisotropic Damage in a Ceramic Matrix Composite

1994 ◽  
Vol 61 (2) ◽  
pp. 309-316 ◽  
Author(s):  
B. Audoin ◽  
S. Baste
Keyword(s):  
Damage Mechanics ◽  
Damage Identification ◽  
Ceramic Matrix Composite ◽  
Processing System ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Continuum Damage Mechanics ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Anisotropic Damage

After describing the crucial role of microcracking in the behavior of ceramic matrix composites, we introduce a phenomenological model in the framework of continuum damage mechanics, where damage is defined as the change of the tensor of elasticity. For damage identification, we have developed a specific ultrasonic device. This immersion set-up was connected to a suitable data processing system for an optimum recovery of the stiffness matrix coefficients from convenient sets of velocity measurements. Linked to a tensile machine, it enabled us to measure the stiffness changes and the anisotropic damage induced by a uniaxial tensile test.

Foreign Object Impact Damage in Ceramic Matrix Composites: Experiments and Computational Predictions

2019 ◽  
Author(s):  
Rajesh S. Kumar ◽  
Matthew M. Mordasky
Keyword(s):  
Computational Modeling ◽  
Damage Mechanics ◽  
Ceramic Matrix Composite ◽  
Engine Performance ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Foreign Object ◽  
Damage State ◽  
Internal Damage ◽  
The Impact

Abstract Foreign object impact of Ceramic Matrix Composite (CMC) materials and components in a gas turbine engine environment could be detrimental to engine performance and hence must be accounted for in the design of such components. This paper is concerned with experiments and computational modeling of foreign object impact phenomenon in Silicon Carbide-based CMC. Controlled impact experiments were conducted on the CMC material using a gas-gun apparatus with spherical hardened steel projectile. The internal damage state within the CMC specimens was assessed using X-ray computed tomography scan technique. The computational modeling involved explicit dynamic finite element simulation of the impact process wherein either delamination mechanism is modeled or both ply damage and delamination mechanisms are modeled in a coupled manner. The delamination mechanism is modeled explicitly using cohesive-zone fracture mechanics approach, whereas, the ply damage mechanisms are modeled implicitly using simplified continuum damage mechanics approach. The simulation results were found to be in reasonable qualitative and quantitative agreement with the experimental results. Furthermore, it is shown that modeling both the ply damage and delamination mechanisms are essential to predict the correct delamination pattern even for intermediate velocity impacts that leads to predominantly delamination damage. The predictive nature of the modeling approach is demonstrated and approaches to enhance the models are also discussed.

A Review of Failure Models for Ceramic Matrix Composite Laminates Under Monotonic Loads

1990 ◽  
Vol 112 (4) ◽  
pp. 492-501 ◽  
Author(s):  
D. E. Tripp ◽  
J. H. Hemann ◽  
J. P. Gyekenyesi
Keyword(s):  
Matrix Composite ◽  
Composite Laminates ◽  
Damage Mechanics ◽  
Ceramic Matrix Composite ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Matrix Composites ◽  
Failure Models ◽  
Monotonic Loads ◽  
Semi Empirical

Ceramic matrix composites offer significant potential for improving the performance of turbine engines. In order to achieve their potential, however, improvements in design methodology are needed. In the past most components using structural ceramic matrix composites were designed by “trial and error” since the emphasis on feasibility demonstration minimized the development of mathematical models. To understand the key parameters controlling response and the mechanics of failure, the development of structural failure models is required. A review of short-term failure models with potential for ceramic matrix composite laminates under monotonic loads is presented. Phenomenological, semi-empirical, shear-lag, fracture mechanics, damage mechanics, and statistical models for the fast fracture analysis of continuous fiber unidirectional ceramic matrix composites under monotonic loads are surveyed.

Foreign Object Impact Damage in Ceramic Matrix Composites: Experiments and Computational Predictions

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Rajesh S. Kumar ◽  
Matthew D. Mordasky
Keyword(s):  
Computational Modeling ◽  
Damage Mechanics ◽  
Ceramic Matrix Composite ◽  
Engine Performance ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Foreign Object ◽  
Damage State ◽  
Internal Damage ◽  
The Impact

Abstract Foreign object impact of ceramic matrix composite (CMC) materials and components in a gas turbine engine environment could be detrimental to engine performance and hence must be accounted for in the design of such components. This paper is concerned with experiments and computational modeling of foreign object impact phenomenon in silicon carbide (SiC)-based CMC. Controlled impact experiments were conducted on the CMC material using a gas-gun apparatus with spherical hardened steel projectile. The internal damage state within the CMC specimens was assessed using X-ray computed tomography scan technique. The computational modeling involved explicit dynamic finite element (FE) simulation of the impact process wherein either delamination mechanism is modeled or both ply damage and delamination mechanisms are modeled in a coupled manner. The delamination mechanism is modeled explicitly using cohesive-zone (CZ) fracture mechanics approach, whereas, the ply-damage mechanisms are modeled implicitly using simplified continuum damage mechanics approach. The simulation results were found to be in reasonable qualitative and quantitative agreement with the experimental results. Furthermore, it is shown that modeling both the ply damage and delamination mechanisms are essential to predict the correct delamination pattern even for intermediate velocity impacts that leads to predominantly delamination damage. The predictive nature of the modeling approach is demonstrated and approaches to enhance the models are also discussed.

A Review of Failure Models for Ceramic Matrix Composite Laminates Under Monotonic Loads

1989 ◽  
Author(s):  
David E. Tripp ◽  
John H. Hemann ◽  
John P. Gyekenyesi
Keyword(s):  
Matrix Composite ◽  
Composite Laminates ◽  
Damage Mechanics ◽  
Ceramic Matrix Composite ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Matrix Composites ◽  
Failure Models ◽  
Monotonic Loads ◽  
Semi Empirical

Ceramic matrix composites offer significant potential for improving the performance of turbine engines. In order to achieve their potential, however, improvements in design methodology are needed. In the past most components using structural ceramic matrix composites were designed by “trial and error” since the emphasis on feasibility demonstration minimized the development of mathematical models. To understand the key parameters controlling response and the mechanics of failure, the development of structural failure models is required. A review of short term failure models with potential for ceramic matrix composite laminates under monotonic loads is presented. Phenomenological, semi-empirical, shear-lag, fracture mechanics, damage mechanics, and statistical models for the fast fracture analysis of continuous fiber unidirectional ceramic matrix composites under monotonic loads are surveyed.

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.

Accounting for frictional contact in an anisotropic damage model based on compliance tensorial variables, illustration on ceramic matrix composites

2018 ◽  
Vol 28 (8) ◽  
pp. 1150-1169 ◽  
Author(s):  
Emmanuel Baranger
Keyword(s):  
Damage Mechanics ◽  
A Priori ◽  
Damage Model ◽  
Ceramic Matrix Composites ◽  
Inelastic Strain ◽  
Ceramic Matrix ◽  
Thermomechanical Properties ◽  
Matrix Composites ◽  
Crack Network ◽  
Evolution Laws

Ceramic matrix composites have good thermomechanical properties at high or very high temperatures. The modeling of the crack networks associated to the degradation of such composites using damage mechanics is not straightforward. The main reason is the presence of a crack network mainly oriented by the loading direction, which is a priori unknown. To model this, compliance tensorial damage variables are used in a thermodynamic potential able to account for crack closure effects (unilateral contact). The damage kinematic is initially completely free and imposed by the evolution laws. The key point of the present paper is to account for friction in such cracks that can result in an apparent activation/deactivation of the shear damage. The initial model is enriched with an inelastic strain and a friction law. The plasticity criterion is expressed only using tensorial variables. The model is identified and illustrated on multiaxial data obtained at ONERA on tubes loaded in tension and torsion.

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