3-D FEM Modeling of fiber/matrix interface debonding in UD composites including surface effects

Polymer composites are used in numerous industries due to their high specific strength and high specific stiffness. Composites have markedly different properties than both the reinforcement and the matrix. Of the several factors that govern the final properties of the composite, the interface is an important factor that influences the stress transfer between the fiber and matrix. The present study is an effort to characterize and model the fiber-matrix interface in polymer matrix composites. Finite element models were developed to study the interfacial behavior during pull-out of a single fiber in continuous fiber-reinforced polymer composites. A three-dimensional (3D) unit-cell cohesive damage model (CDM) for the fiber/matrix interface debonding was employed to investigate the effect of interface/sizing coverage on the fiber. Furthermore, a two-dimensional (2D) axisymmetric model was used to (a) analyze the sensitivity of interface stiffness, interface strength, friction coefficient, and fiber length via a parametric study; and (b) study the shear stress distribution across the fiber-interface-matrix zone. It was determined that the force required to debond a single fiber from the matrix is three times higher if there is adequate distribution of the sizing on the fiber. The parametric study indicated that cohesive strength was the most influential factor in debonding. Moreover, the stress distribution model showed the debonding mechanism of the interface. It was observed that the interface debonded first from the matrix and remained in contact with the fiber even when the fiber was completely pulled out.

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A thermomechanical fatigue hysteresis-based damage evolution model for fiber-reinforced ceramic–matrix composites

International Journal of Damage Mechanics ◽

10.1177/1056789518772162 ◽

2018 ◽

Vol 28 (3) ◽

pp. 380-403 ◽

Cited By ~ 7

Author(s):

Li Longbiao

Keyword(s):

Damage Evolution ◽

Ceramic Matrix Composites ◽

Peak Stress ◽

Fatigue Loading ◽

Thermomechanical Fatigue ◽

Interface Debonding ◽

Matrix Interface ◽

Cycle Number ◽

Fiber Matrix Interface ◽

Fiber Matrix

In this paper, a thermomechanical fatigue hysteresis-based damage evolution model for fiber-reinforced ceramic–matrix composites has been developed. Upon unloading and reloading, the fiber/matrix interface debonded length, interface counter-slip length, and interface new-slip length change with increasing or decreasing applied stress, which affects the stress–strain fatigue hysteresis loops and fatigue hysteresis-based damage parameters. The reloading/unloading stress–strain relationships when fiber/matrix interface partially or completely debonding are determined as a function of interface debonding/sliding, peak stress, applied cycle number, and thermal cycle temperature. The relationships between thermomechanical fatigue loading parameters (i.e. peak stress, applied cycle number, and thermal cyclic temperature), fiber/matrix interface debonding/sliding lengths, and fatigue hysteresis-based damage parameters (i.e. fatigue hysteresis dissipated energy, fatigue hysteresis modulus, and fatigue peak strain) have been established. The effects of fiber volume fraction, peak stress, matrix cracking space, and thermal cyclic temperature range on damage evolution under the out-of-phase thermomechanical cyclic loading have been discussed. The differences in damage evolution between in-phase/out-of-phase thermomechanical fatigue and isothermal fatigue loading at the same peak stress have been analyzed. The damage evolution of cross-ply SiC/magnesium aluminosilicate composite under the out-of-phase thermomechanical and isothermal fatigue loading has been predicted.

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Effect of Interface Properties on Tensile and Fatigue Behavior of 2D Woven SiC/SiC Fiber-Reinforced Ceramic-Matrix Composites

Advances in Materials Science and Engineering ◽

10.1155/2020/3618984 ◽

2020 ◽

Vol 2020 ◽

pp. 1-17

Author(s):

Longbiao Li

Keyword(s):

Fatigue Behavior ◽

Ceramic Matrix Composites ◽

Matrix Cracking ◽

Interface Debonding ◽

Interface Properties ◽

Matrix Interface ◽

Fiber Matrix Interface ◽

Fiber Matrix ◽

Stress Matrix ◽

Cracking Stress

In this paper, the effect of the fiber/matrix interface properties on the tensile and fatigue behavior of 2D woven SiC/SiC ceramic-matrix composites (CMCs) is investigated. The relationships between the interface parameters of the fiber/matrix interface debonding energy and interface frictional shear stress in the interface debonding region and the composite tensile and fatigue damage parameters of first matrix cracking stress, matrix cracking density, and fatigue hysteresis-based damage parameters are established. The effects of the fiber/matrix interface properties on the first matrix cracking stress, matrix cracking evolution, first and complete interface debonding stress, fatigue hysteresis dissipated energy, hysteresis modulus, and hysteresis width are analyzed. The experimental first matrix cracking stress, matrix cracking evolution, and fatigue hysteresis loops of SiC/SiC composites are predicted using different interface properties.

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Thermomechanical Fatigue of Ceramic Matrix Composites

Volume 6: Ceramics; Controls, Diagnostics, and Instrumentation; Education; Manufacturing Materials and Metallurgy ◽

10.1115/gt2019-90067 ◽

2019 ◽

Author(s):

Li Longbiao

Keyword(s):

Slip Length ◽

Hysteresis Loops ◽

Ceramic Matrix Composites ◽

Ceramic Matrix ◽

Interface Debonding ◽

Matrix Composites ◽

Matrix Interface ◽

Fiber Reinforced ◽

Fiber Matrix Interface ◽

Fiber Matrix

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.

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Sensitivity Analysis of Fiber-Matrix Interface Parameters in an SMC Composite Damage Model

Proceedings ◽

10.3390/icem18-05438 ◽

2018 ◽

Vol 2 (8) ◽

pp. 544 ◽

Cited By ~ 1

Author(s):

Johannes Görthofer ◽

Malte Schemmann ◽

Thomas Seelig ◽

Andrew Hrymak ◽

Thomas Böhlke

Keyword(s):

Glass Fibers ◽

Damage Model ◽

Interface Strength ◽

Strength Distribution ◽

Interface Debonding ◽

Matrix Interface ◽

Molding Compound ◽

Fiber Matrix Interface ◽

Fiber Matrix ◽

Interface Parameters

This contribution shortly introduces the anisotropic, micromechanical damage model for sheet molding compound (SMC) composites presented in the authors’ previous publication [1]. As the considered material is a thermoset matrix reinforced with long (≈25 mm) glass fibers, the leading damage mechanisms are matrix micro-cracking and fiber-matrix interface debonding. Those mechanisms are modeled on the microscale and within a Mori-Tanaka homogenization framework. The model can account for arbitrary fiber orientation distributions. Matrix damage is considered as an isotropic stiffness degradation. Interface debonding is modeled via a Weibull interface strength distribution and the inhomogeneous stress distribution on the lateral fiber surface. Hereby, three independent parameters are introduced, that describe the interface strength and damage behavior, respectively. Due to the high non-linearity of the model, the influence of these parameters is not entirely clear. Therefore, the focus of this contribution lies on the variation and discussion of the above mentioned interface parameters.

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IN SITU CHARACTERIZATION OF FIBER-MATRIX INTERFACE DEBONDING VIA FULL-FIELD MEASUREMENTS

10.12783/asc36/35899 ◽

2021 ◽

Author(s):

ROBERT LIVINGSTON ◽

BEHRAD KOOHBOR

Keyword(s):

Field Measurements ◽

Image Correlation ◽

Interface Debonding ◽

Matrix Interface ◽

Full Field ◽

Transverse Tension ◽

Fiber Matrix Interface ◽

Fiber Matrix

Macroscopic mechanical and failure properties of fiber-reinforced composites depend strongly on the properties of the fiber-matrix interface. For example, transverse cracking behavior and interlaminar shear strength of composites can be highly sensitive to the characteristics of the fiber-matrix interface. Despite its importance, experimental characterization of the mechanical behavior of the fibermatrix interface under normal loading conditions has been limited. This work reports on an experimental approach that uses in situ full-field digital image correlation (DIC) measurements to quantify the mechanical and failure behaviors at the fiber-matrix interface. Single fiber model composite samples are fabricated from a proprietary epoxy embedding a single glass rod. These samples are then tested under transverse tension. DIC is used to measure the deformation and strain fields in the glass rod, epoxy, and their interface vicinity. Initiation and propagation of the fiber-matrix debond are discussed. Full-field measurements are shown to facilitate the quantitative analysis of the traction-separation laws at the fiber-matrix interface subjected to transverse tension.

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