scholarly journals Effect of Stochastic Loading on Tensile Damage and Fracture of Fiber-Reinforced Ceramic-Matrix Composites

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2469 ◽  
Author(s):  
Longbiao Li
Keyword(s):  
Fiber Strength ◽  
Ceramic Matrix Composites ◽  
Tangent Modulus ◽  
Interface Debonding ◽  
Matrix Composites ◽  
Fiber Volume ◽  
Damage And Fracture ◽  
Stochastic Loading ◽  
Composite Strain ◽  
Tensile Damage

In this paper, the effect of stochastic loading on tensile damage and fracture of fiber-reinforced ceramic-matrix composites (CMCs) is investigated. A micromechanical constitutive model is developed considering multiple damage mechanisms under tensile loading. The relationship between stochastic stress, tangent modulus, interface debonding and fiber broken is established. The effects of the fiber volume, interface shear stress, interface debonding energy, saturation matrix crack spacing and fiber strength on tensile stress–strain curve, tangent modulus, interface debonding fraction and fiber broken fraction are analyzed. The experimental tensile damage and fracture of unidirectional and 2D SiC/SiC composites subjected to different stochastic loading stress are predicted. When fiber volume increases, the initial composite strain decreases, the initial tangent modulus increases, the transition stress for interface debonding decreases and the initial fiber broken fraction decreases. When fiber strength increases, the initial composite strain and fiber broken fraction decrease.

Modeling matrix fracture in fiber-reinforced ceramic-matrix composites with different fiber preforms

2019 ◽  
Vol 90 (7-8) ◽  
pp. 909-924 ◽  
Author(s):  
Longbiao Li
Keyword(s):  
Elastic Modulus ◽  
Ceramic Matrix Composites ◽  
Interface Debonding ◽  
Matrix Composites ◽  
Multiple Fracture ◽  
Fiber Volume ◽  
Interface Shear ◽  
Interface Shear Stress ◽  
The Matrix ◽  
Fiber Preforms

In this paper, the stress-dependent matrix multiple fracture in silicon carbide fiber-reinforced ceramic-matrix composites with different fiber preforms is investigated. The critical matrix strain energy criterion is used to determine the matrix multiple fracture considering the interface debonding. The effects of the fiber radius, fiber elastic modulus, matrix elastic modulus, fiber volume, interface shear stress, and interface debonded energy on the matrix multiple fracture and the interface debonding are analyzed. The experimental matrix multiple cracking and interface debonding of minicomposite, unidirectional, and two-dimensional woven SiC/SiC composites with different fiber volumes and interphases are predicted. The matrix cracking density increases with the increasing of the fiber volume, fiber elastic modulus, interface shear stress, and interface debonded energy, and the decreasing of the fiber radius and matrix elastic modulus.

scholarly journals Modeling Temperature-Dependent Vibration Damping in C/SiC Fiber-Reinforced Ceramic-Matrix Composites

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1633 ◽  
Author(s):  
Longbiao Li
Keyword(s):  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Vibration Damping ◽  
Interface Debonding ◽  
Matrix Composites ◽  
Fiber Reinforced ◽  
Temperature Dependent ◽  
Fiber Volume ◽  
Sic Fiber ◽  
Peak Value

In this paper, the temperature-dependent vibration damping in C/SiC fiber-reinforced ceramic-matrix composites (CMCs) with different fiber preforms under different vibration frequencies is investigated. A micromechanical temperature-dependent vibration damping model is developed to establish the relationship between composite damping, material properties, internal damage mechanisms, and temperature. The effects of fiber volume, matrix crack spacing, and interface properties on temperature-dependent composite vibration damping of CMCs and interface damage are analyzed. The experimental temperature-dependent composite damping of 2D and 3D C/SiC composites is predicted for different loading frequencies. The damping of the C/SiC composite increases with temperature to the peak value and then decreases with temperature. When the vibration frequency increases from f = 1 to 10 Hz, the peak value of composite damping and corresponding temperature both decrease due to the decrease of interface debonding and slip range, and the damping of 2D C/SiC is much higher than that of 3D C/SiC at temperature range from room temperature to 400 °C. When the fiber volume and interface debonding energy increase, the peak value of composite damping and the corresponding temperature decreases, mainly attributed to the decrease of interface debonding and slip range.

scholarly journals Temperature-dependent proportional limit stress of SiC/SiC fiber-reinforced ceramic-matrix composites

2020 ◽  
Vol 39 (1) ◽  
pp. 209-218 ◽  
Author(s):  
Longbiao Li
Keyword(s):  
Ceramic Matrix Composites ◽  
Interface Debonding ◽  
Matrix Composites ◽  
Temperature Dependent ◽  
Fiber Volume ◽  
Damage State ◽  
Sic Fiber ◽  
Composite Damage ◽  
Environment Temperature ◽  
Proportional Limit Stress

AbstractIn this paper, the temperature-dependent proportional limit stress (PLS) of SiC/SiC fiber-reinforced ceramic-matrix composites (CMCs) is investigated using the micromechanical approach. The PLS of SiC/SiC is predicted using an energy balance approach considering the effect of environment temperature. The relation between the environment temperature, PLS, and composite damage state is established. The effects of the fiber volume, interface properties, and matrix properties on the temperature-dependent PLS and composite damage state of SiC/SiC composite are analyzed. The experimental PLS and interface debonding length of 2D SiC/SiC composites with the PyC and BN interphase at elevated temperatures are predicted. The temperature-dependent PLS of SiC/SiC composite increases with the fiber volume, interface shear stress and interface debonding energy, and the matrix fracture energy and decreases with the interface frictional coefficient at the same temperature.

scholarly journals Stress-Rupture of Fiber-Reinforced Ceramic-Matrix Composites with Stochastic Loading at Intermediate Temperatures. Part I: Theoretical Analysis

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3123 ◽  
Author(s):  
Longbiao Li
Keyword(s):  
Stress Level ◽  
Damage Evolution ◽  
Stress Rupture ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Interface Debonding ◽  
Matrix Composites ◽  
Matrix Interface ◽  
Stochastic Loading ◽  
Fiber Matrix Interface

Under stress-rupture loading, stochastic loading affects the internal damage evolution and lifetime of fiber-reinforced ceramic-matrix composites (CMCs) at intermediate temperatures. The damage mechanisms of the matrix cracking, fiber/matrix interface debonding and oxidation, and fiber fracture are considered in the analysis of stochastic loading. The strain, fiber/matrix interface debonding and oxidation length, and the broken fibers fraction versus the time curves of SiC/SiC composite under constant and three different stochastic loading conditions are analyzed. The effects of the stochastic loading stress level, stochastic loading time, and time spacing on the damage evolution and lifetime of SiC/SiC composite are discussed. When the stochastic loading stress level increases, the stress-rupture lifetime decreases, and the time for the interface complete debonding and oxidation decreases. When the stochastic loading time and time spacing increase, the stress-rupture lifetime decreases, and the time for the interface complete debonding and oxidation remains the same.

Comparison of prior exposure tensile damage and fracture of two-dimensional C/SiC and SiC/SiC fiber-reinforced ceramic-matrix composites

2020 ◽  
Vol 90 (23-24) ◽  
pp. 2782-2794
Author(s):  
Longbiao Li
Keyword(s):  
Tensile Strength ◽  
Fracture Strain ◽  
Prior Exposure ◽  
Interface Debonding ◽  
Fiber Volume ◽  
Damage And Fracture ◽  
Exposure Temperature ◽  
Fiber Characteristic ◽  
Sic Composites ◽  
Tensile Damage

In this paper, a micromechanical constitutive model for prior exposure tensile damage and fracture of fiber-reinforced ceramic-matrix composites is developed considering the multiple damage mechanisms of matrix multicracking, interface debonding and oxidation, and fiber fracture. The relationships between prior exposure temperature, duration time, interface debonding fraction, broken fiber fraction, tensile strength, and fracture strain of C/SiC and SiC/SiC composites are established. The experimental prior exposure tensile damage evolution and final fracture of two-dimensional (2D) C/SiC and SiC/SiC composites are predicted for different temperatures and duration times. The comparison analysis of prior exposure composite tensile strength, fracture strain, interface debonding fraction, and broken fiber fraction between 2D C/SiC and SiC/SiC composites is investigated. The effects of constituent properties and temperature on prior exposure tensile damage and fracture of 2D C/SiC and SiC/SiC composites are discussed. For 2D C/SiC and SiC/SiC composites under prior exposure at 1300℃, the fracture strain decreased with fiber volume, interface shear stress, and prior exposure temperature, and increased with fiber characteristic strength; the tensile strength increased with fiber volume and fiber characteristic strength, and decreased with prior exposure temperature; the interface debonding fraction decreased with fiber volume, and increased with prior exposure temperature; and the fiber broken fraction decreased with fiber volume and fiber characteristic strength, and increased with prior exposure temperature.

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