scholarly journals Micromechanical modeling for the in-plane mechanical behavior of orthogonal three-dimensional woven ceramic matrix composites with transverse and matrix cracking

2021 ◽  
pp. 105678952110260
Author(s):  
Sota Onodera ◽  
Junpei Tsuyuki ◽  
Tomonaga Okabe
Keyword(s):  
Fiber Bundle ◽  
Mixed Mode ◽  
Damage Mechanics ◽  
Three Dimensional ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Matrix Cracking ◽  
Micromechanical Modeling ◽  
Matrix Composites ◽  
Damage Criteria

Ceramic matrix composites (CMCs) are currently being considered for applications in the hot-section components of aviation gas turbines owing to their favorable characteristics. Herein, a micromechanical modeling is presented for orthogonal 3 D woven CMCs under in-plane loading. The three-dimensional effective compliance of the 3 D woven composite was derived using three-dimensional laminate theory and continuum damage mechanics. The damage variables were used to describe the stiffness reduction due to the transverse and matrix cracking in each fiber bundle. The calculation method for the transverse and matrix cracking evolutions under in-plane loading was established by introducing mixed-mode damage criteria. The stress redistribution among the fiber bundles of 3 D woven CMCs due to the fiber/matrix interfacial debonding around matrix cracking was considered to capture the interaction between the matrix and transverse crack evolutions. Additionally, a mesomechanical model comprising finite element analysis and damage mechanics was established to evaluate the stress perturbation due to the geometry of the woven structure. The edge face of the 3 D woven CMC was experimentally observed to measure the transverse and matrix cracks that occurred in each fiber bundle. The transverse and matrix crack densities predicted by the micromechanical and mesomechanical models reasonably agreed with the experimental results up to crack saturation. Furthermore, the micromechanical model reproduced the nonlinear stress–strain response under tensile and shear loading using mixed-mode damage criteria.

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.

Durability and Damage Development in Woven Ceramic Matrix Composites Under Tensile and Fatigue Loading at Room and Elevated Temperatures

2000 ◽  
Vol 122 (4) ◽  
pp. 394-401 ◽  
Author(s):  
A. Haque ◽  
M. Rahman
Keyword(s):  
Elevated Temperature ◽  
Elevated Temperatures ◽  
Failure Strain ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Matrix Cracking ◽  
Woven Composites ◽  
Rate Equations ◽  
Matrix Composites ◽  
Damage Development

This paper investigates the damage development in SiC/SiNC woven composites under tensile and cyclic loading both at room and elevated temperatures. The ultimate strength, failure strain, proportional limit, and modulus data at a temperature range of 23°C–1250°C are generated. The tensile strength of SiC/SiNC woven composites has been observed to increase with increased temperatures up to 1000°C. The stress/strain plot shows a pseudo-yield point at 25 percent of the failure strain εf, which indicates damage initiation in the form of matrix cracking. The evolution of damage above 0.25 εf both at room and elevated temperature comprises of multiple matrix cracking, interfacial debonding, and fiber pullout. Although the nature of the stress/strain plot shows damage-tolerant behavior under static loading both at room and elevated temperature, the life expectancy of SiC/SiNC composites degrades significantly under cyclic loading at elevated temperature. This is mostly due to the interactions of fatigue damage caused by the mechanically induced plastic strain and the damage developed by the creep strain. The in-situ damage evolutions are monitored by acoustic event parameters, ultrasonic C-scan, and stiffness degradation. Rate equations for modulus degradation and fatigue life prediction of ceramic matrix composites both at room and elevated temperatures are developed. These rate equations are observed to show reasonable agreement with experimental results. [S0094-4289(00)02304-5]

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