Estimate interface frictional coefficient of ceramic matrix composites from hysteresis loops

2010 ◽  
Vol 45 (9) ◽  
pp. 989-1006 ◽  
Author(s):  
Longbiao Li ◽  
Yingdong Song

An approach to estimate fiber/matrix interface frictional coefficient of ceramic matrix composites under fatigue loading is developed by means of hysteresis loops. The Coulomb friction law is adopted to describe the interface shear stress in the debonded region. The matrix crack space and interface debonded length are obtained by matrix statistical cracking model and fracture mechanics interface debonding criterion. The hysteresis loops of four different cases are derived based on the damage mechanisms of fiber sliding relative to matrix in the debonded region during unloading and subsequent reloading. The hysteresis loss energy corresponding to different cycle is formulated in terms of interface frictional coefficient. By comparing the experimental hysteresis loss energy with computational values, the interface frictional coefficient of three different ceramic matrix composites under fatigue loading is derived.

2021 ◽  
Vol 5 (7) ◽  
pp. 187
Author(s):  
Longbiao Li

In this paper, micromechanical constitutive models are developed to predict the tensile and fatigue behavior of fiber-reinforced ceramic-matrix composites (CMCs) considering matrix fragmentation and closure. Damage models of matrix fragmentation, interface debonding, and fiber’s failure are considered in the micromechanical analysis of tensile response, and the matrix fragmentation closure, interface debonding and repeated sliding are considered in the hysteresis response. Relationships between the matrix fragmentation and closure, tensile and fatigue response, and interface debonding and fiber’s failure are established. Experimental matrix fragmentation density, tensile curves, and fatigue hysteresis loops of mini, unidirectional, cross-ply, and 2D plain-woven SiC/SiC composites are predicted using the developed constitutive models. Matrix fragmentation density changes with increasing or decreasing applied stress, which affects the nonlinear strain of SiC/SiC composite under tensile loading, and the interface debonding and sliding range of SiC/SiC composite under fatigue loading.


2019 ◽  
Vol 90 (7-8) ◽  
pp. 909-924 ◽  
Author(s):  
Longbiao Li

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.


Author(s):  
Li Longbiao

In this paper, comparisons of thermomechanical fatigue hysteresis loops of fiber-reinforced ceramic-matrix composites (CMCs) subjected to different phase angles of θ = 0, π/3, π/2, and π have been investigated. The shape, location, and area of fatigue hysteresis loops are affected by the phase angle under the thermomechanical cyclic loading. The effects of fiber volume fraction, fatigue peak stress, matrix crack spacing, interface frictional coefficient, and interface debonded energy on the thermomechanical fatigue hysteresis loops and fiber/matrix interface slip of different phase angles are discussed. The fatigue hysteresis loops of cross-ply CMCs under the phase angles of θ = 0 and π are predicted for different fatigue peak stresses and cycle numbers.


MRS Bulletin ◽  
1991 ◽  
Vol 16 (4) ◽  
pp. 32-38 ◽  
Author(s):  
James A. Cornie ◽  
Ali S. Argon ◽  
Vijay Gupta

The key to controlling and predicting the properties of metal matrix composites lies in understanding and controlling the interface. When properly designed, the interface between reinforcing fibers and the matrix or protective coating can act as a mechanical fuse through a controlled delamination mechanism.Controlled delamination, in effect, results in the decoupling of fibers from early damage due to stress concentrations in the vicinity. The delamination event must precede the crack bridging and frictional pull-out mechanisms that have been so effectively demonstrated in ceramic matrix composites. The delamination event, therefore, is the necessary precondition, and so analysis of composite toughening must start with a definition of the conditions for interface debonding.This decoupling can be expressed in terms of cohesive strength of the interface, shear strength of the interface, and fiber fracture stress. In a related but alternative manner, debonding can be expressed in terms of the intrinsic work of fracture of the interface as compared to the transverse work of fracture of the fiber.


Author(s):  
Li Longbiao

Abstract In this paper, the thermomechanical fatigue (TMF) of fiber-reinforced ceramic-matrix composites (CMCs) is investigated using the hysteresis-based damage parameter. The micro stress field of the damaged CMCs of matrix cracking and fiber/matrix interface debonding is obtained considering the temperature-dependent fiber/matrix interface shear stress. The fiber/matrix interface debonded length and unloading/reloading slip length are determined using the fracture mechanics approach. Based on the damage mechanisms of fiber sliding relative to the matrix in the interface debonded region, the TMF hysteresis loops models and hysteresis-based damage parameters are developed for the partially and completely debonding to analyze the damage evolution inside of fiber-reinforced CMCs. The effects of temperature, phase angle and loading sequences on the damage development of SiC/SiC composite are discussed. When TMF temperature range increases, the fatigue hysteresis loops area, residual strain increase, and the hysteresis modulus decreases, due to the increase of the fiber/matrix interface slip length. Under TMF loading, the phase angle affects the interface debonding and sliding range, and the hysteresis loops shape, location and area of the fiber-reinforced CMCs. The experimental TMF damage evolution of 2D SiC/SiC and cross-ply SiC/MAS composites are predicted.


2021 ◽  
pp. 002199832110417
Author(s):  
Longbiao Li

Under cyclic fatigue loading, hysteresis loops appear in fiber-reinforced ceramic-matrix composites (CMCs) due to composite’s internal damage mechanisms. Loading/unloading inverse tangent modulus (ITMs) of the hysteresis loops reflect the composite’s internal damage state and can be used an effective tool to monitor composite’s fatigue damage evolution and fracture. In this paper, characterization of cyclic fatigue hysteresis loops of CMCs using ITMs are investigated. Loading/unloading ITMs are derived using a micromechanical hysteresis constitutive model considering fatigue damage mechanisms of matrix cracking, interface debonding, wear and slip, and fiber’s failure. Relationships between composite’s fatigue hysteresis loops, ITMs and interface slip state (i.e., interface reverse slip ratio (IRSR) and interface new slip ratio (INSR)) are established. Experimental fatigue hysteresis loops, ITMs, and IRSR/INSR of cross-ply SiC/CAS and SiC/MAS composites from the literature are predicted, and the effects of fiber’s volume fraction, matrix crack spacing, and interface debonding energy on composite’s fatigue hysteresis loops, ITMs, and IRSR/INSR are analyzed.


Sign in / Sign up

Export Citation Format

Share Document