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2020 | Buch

Time-Dependent Mechanical Behavior of Ceramic-Matrix Composites at Elevated Temperatures

verfasst von: Dr. Longbiao Li

Verlag: Springer Singapore

Buchreihe : Advanced Ceramics and Composites

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Über dieses Buch

This book investigates the time-dependent behavior of fiber-reinforced ceramic-matrix composites (CMCs) at elevated temperatures. The author combines the time-dependent damage mechanisms of interface and fiber oxidation and fracture with the micromechanical approach to establish the relationships between the first matrix cracking stress, matrix multiple cracking evolution, tensile strength, tensile stress-strain curves and tensile fatigue of fiber-reinforced CMCs and time. Then, using damage models of energy balance, the fracture mechanics approach, critical matrix strain energy criterion, Global Load Sharing criterion, and hysteresis loops he determines the first matrix cracking stress, interface debonded length, matrix cracking density, fibers failure probability, tensile strength, tensile stress-strain curves and fatigue hysteresis loops. Lastly, he predicts the time-dependent mechanical behavior of different fiber-reinforced CMCs, i.e., C/SiC and SiC/SiC, using the developed approaches, in order to reduce the failure risk during the operation of aero engines. The book is intended for undergraduate and graduate students who are interested in the mechanical behavior of CMCs, researchers investigating the damage evolution of CMCs at elevated temperatures, and designers responsible for hot-section CMC components in aero engines.

Inhaltsverzeichnis

Frontmatter
1. Time-Dependent First Matrix Cracking Stress of Ceramic-Matrix Composites at Elevated Temperatures
Abstract
In this chapter, the time-dependent first matrix cracking stress of fiber-reinforced ceramic-matrix composites (CMCs) is investigated using the energy balance approach. The shear-lag model combined with the interface oxidation model, fiber oxidation model, and fiber failure model is adopted to analyze the microstress distributions in fiber-reinforced CMCs. The relationships between the first matrix cracking stress, interface debonding and slip, fiber fracture, and oxidation time and temperature are established. The effects of the fiber volume, the interface shear stress, the interface debonding energy, the fiber Weibull modulus, the fiber strength on the first matrix cracking stress, the interface debonding length, and the fiber broken fraction are analyzed. The first matrix cracking stresses of C/SiC with strong and weak interface bonding after unstressed oxidation at 700 °C in air atmosphere are predicted for different oxidation time.
Longbiao Li
2. Time-, Stress-, and Cycle-Dependent Matrix Multicracking of Fiber-Reinforced Ceramic-Matrix Composites at Elevated Temperatures
Abstract
In this chapter, the time-, stress-, and cycle-dependent matrix multicracking of fiber-reinforced ceramic-matrix composites (CMCs) with the interface debonding, interface wear, interface oxidation, and fiber fracture is investigated. The shear-lag model combined with the interface debonding, interface wear, interface oxidation, fiber fracture models, and the fiber/matrix interface debonding criterion is adopted to determine the microstress field of the damaged fiber-reinforced CMCs. The effects of the fiber volume and interface shear stress in the debonding and oxidation region, the interface debonding energy, the oxidation temperature, and time on the matrix multicracking, interface debonding and oxidation, and fiber fracture are discussed. The experimental matrix multicracking evolution of unidirectional C/SiC, SiC/SiC, mini-SiC/SiC, SiC/CAS, SiC/CAS-II, and SiC/borosilicate composites is predicted.
Longbiao Li
3. Time-, Stress-, and Cycle-Dependent Tensile Strength of Fiber-Reinforced Ceramic-Matrix Composites
Abstract
In this chapter, the strength degradation of non-oxide and oxide/oxide fiber-reinforced ceramic-matrix composites (CMCs) subjected to multiple fatigue loading at room temperature, oxidation environment at elevated temperature, and cyclic loading at elevated temperatures in oxidative environments is investigated. Considering damage mechanisms of matrix cracking, interface debonding, interface wear, interface oxidation, and fiber fracture, the residual strength model of CMCs is established by combining the microstress field of the damaged composites, the damage models, and the fracture criterion. The relationships between the composite residual strength, fatigue peak stress, interface debonding, fiber failure, oxidation time and temperature, and applied cycle number are established. The effects of the peak stress level, initial and steady-state interface shear stress, fiber Weibull modulus, fiber strength, oxidation temperature and time on the degradation of composite strength and fiber failure are investigated. The evolution of residual strength versus oxidation temperature and time and applied cycle number curves of non-oxide and oxide/oxide CMCs is predicted.
Longbiao Li
4. Time-Dependent Tensile Behavior of Fiber-Reinforced Ceramic-Matrix Composites
Abstract
In this chapter, the time-dependent tensile damage and fracture of fiber-reinforced ceramic-matrix composites (CMCs) subjected to pre-exposure at elevated temperatures and thermal fatigue are investigated. The damage mechanisms of the interface oxidation and fiber failure are considered in the stress analysis, matrix multicracking, interface debonding, and fiber failure. Combining the stress analysis and damage models, the tensile stress-strain curves of fiber-reinforced CMCs for different damage stages can be obtained. The effects of the pre-exposure temperature and time, thermal fatigue temperature, thermal cyclic number, the interface shear stress, fiber strength, and fiber Weibull modulus on tensile damage and fracture processes are analyzed. The experimental tensile damage and fracture process of fiber-reinforced CMCs with different fiber preforms are predicted for a different pre-exposure temperature and time.
Longbiao Li
5. Time-Dependent Fatigue Behavior of Fiber-Reinforced Ceramic-Matrix Composites at Elevated Temperatures
Abstract
In this chapter, the time-dependent static fatigue and cyclic fatigue behavior of fiber-reinforced ceramic-matrix composites (CMCs) are investigated. The stress-strain relationships considering interface oxidation and interface wear in the interface debonding region under static and cyclic fatigue loading are developed to establish the relationships between the peak strain, the interface debonding length, the interface oxidation length, and the interface slip lengths. The effects of the stress-rupture time, stress levels, matrix crack spacing, fiber volume, and oxidation temperature on the peak strain and the interface slip lengths are investigated. The experimental fatigue hysteresis loops, interface slip lengths, peak strain, and interface oxidation length of C/[Si–B–C] and SiC/MAS composite at 566, 1093, and 1200 °C in air atmosphere are predicted.
Longbiao Li
Metadaten
Titel
Time-Dependent Mechanical Behavior of Ceramic-Matrix Composites at Elevated Temperatures
verfasst von
Dr. Longbiao Li
Copyright-Jahr
2020
Verlag
Springer Singapore
Electronic ISBN
978-981-15-3274-0
Print ISBN
978-981-15-3273-3
DOI
https://doi.org/10.1007/978-981-15-3274-0

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