Interface Debonding Energy Research Articles

Effect of heat treatment on interface failure behavior in SiCf/PyC/SiC composites reinforced with Cansas-3 fibers

The influence of heat treatment on the correlation between interfacial mechanical properties and microstructure in CVI-SiCf/PyC/SiC composites was systematically investigated. The results reveal a progressive reduction in the average interfacial bond strength, interfacial shear stress, and interfacial debonding energy within the composites as the heat treatment temperature increases, especially beyond 1350 °C. This decline can be attributed to the attenuation of the SiCf/PyC interfacial bond strength arising from the contraction in fiber volume induced by the precipitation of Cansas-3 fibers. After push-in testing, SiCf/PyC/SiC composites heat-treated at or below 1350 °C displayed fibers in a compressed state. Conversely, composites exposed to extended heat treatment at 1400 °C or higher maintained fibers in an ejected state after push-in testing. Moreover, the composites heat-treated at 1450 °C and 1500 °C demonstrated fibers that were spontaneously ejected subsequent to cross-section polishing.

Influence of interphase type and thickness on the interface properties and tensile damage evolution of C/SiC composites

In this paper, the influence of interphase type (i.e. single-phase (PyC) and co-deposited (PyC+SiC)) and thickness (i.e. 300, 600, 1000, and 2000 nm) on the interface properties and damage evolution of mini-C/SiC composites under cyclic loading/unloading tension was investigated. The micromechanical constitutive model was adopted to derive the damage parameter of inverse tangent modulus (ITM) and perform the hysteresis analysis to estimate the interface properties of the mini-C/SiC composites with large debonding energy. Experimental damage evolution of the ITMs with unloading or reloading stress was analyzed for different interphase types and thickness. The interface properties (e.g. the interface debonding stress and interface debonding energy) were obtained through the hysteresis analysis. Relationships between the loading/unloading ITMs, interface properties, and interphase type and thickness were established.

Cracking modes in layered hyperelastic structures

Stretchable devices composed of layered hyperelastic materials are under rapid development to interact with human body, and merge the gap between human and machines. These devices are required to sustain large deformation without mechanical failure over a long time, which remains a challenge. Compared to the fast movement in functions design, the failure mechanism of layered hyperelastic structures has been much less explored. Here we study the cracking modes in layered hyperelastic structures made of relatively brittle films bonded to tougher substrates. An initial surface crack in the film is considered. It is found that the surface crack always tends to penetrate through the thickness of the film at first. With the increase of stretch, two cracking modes – crack channeling and interface debonding – are observed one after the other. The sequence is determined by the ratio of interfacial debonding energy to fracture energy of the film, and a dimensionless cracking number which depends on the film-to-substrate modulus ratio, thickness ratio and dimensionless fracture energy of the film. We establish the critical conditions for different cracking modes and build the phase diagram. This work provides a pathway to design cracking-resistant stretchable devices.

Hysteresis-based approach to estimate constituent properties of SiC/SiC ceramic matrix composites

Hysteresis loops relate with composite’s constituent properties and damage state. In this paper, a systematic approach to estimate the constituent properties of SiC/SiC composite using hysteresis-based damage parameters was developed. Four cases including small debonding energy (SDE), large debonding energy (LDE), long matrix crack spacing (LMCS), and short matrix crack spacing (SMCS) were considered for the hysteresis analysis. Closed-form solution for the unloading/reloading inverse tangent modulus (UITM/RITM), hysteresis width, interface debonding and slip ratio (IDR/ISR) were derived from the hysteresis theory. Effects of peak stress, interface shear stress (ISS), interface debonding energy (IDE), and matrix crack spacing (MCS) on the damage parameters were analyzed. Experimental hysteresis loops of unidirectional, cross-ply and 2D plain-woven SiC/SiC composites were characterized using the developed hysteresis-based damage parameters. The composite’s constituent properties of first matrix cracking stress (FMCS), ISS and IDE were estimated.

Hysteresis-based identification approach for crack opening and closure stress in SiC/SiC fiber-reinforced ceramic-matrix composites

Identification of the matrix crack opening stress (COS) and cracking closure stress (CCS) for SiC/SiC ceramic-matrix composite (CMC) is important for the reliability and durability of SiC/SiC hot-section components during operation. In this paper, a hysteresis-based identification approach for predicting COS and CCS is developed for SiC/SiC composite. First, based on the matrix cracking and interface slip damage mechanisms, the micromechanical hysteresis loop models, considering variable matrix cracking density and interface slip state, are developed for different interface debonding and slip conditions. Two damage parameters (i.e., the interface reverse slip ratio (IRSR) and interface new slip ratio (INSR)) are developed to characterize the damage state in matrix crack opening and closure upon loading/unloading. Values of COS and CCS are determined through the analysis of the hysteresis loops and related damage parameters IRSR and INSR. Experimental COS and CCS in different SiC/SiC composites are predicted using the hysteresis-based micromechanical crack opening and closure model. Effects of fiber volume fraction (FVF), interface shear stress (ISS) and interface debonding energy (IDE) on values of COS and CCS are discussed. For 1D mini and unidirectional, and 2D cross-ply and plain-woven SiC/SiC composites, the COS is much higher than CCS. The COS and CCS are the highest for the 1D mini-SiC/SiC composite and is the lowest for the 2D cross-ply SiC/SiC composite, mainly due to the transverse cracking in the 90° plies. With increasing FVF and ISS, the COS and CCS increase. However, under cyclic loading/unloading, the COS and CCS remain unchanged with increasing IDE.

Rare earth monosilicates as oxidation resistant interphase for SiCf/SiC CMC: Investigation of SiCf/Yb2SiO5 model composites

Model composites consisting of SiC fiber and Yb2SiO5 were processed by the spark plasma sintering (SPS) method. The mechanical compatibility and chemical stability between Yb2SiO5 and SiC fiber were studied to evaluate the potential application of Yb monosilicate as the interphase of silicon carbide fiber reinforced silicon carbide ceramic matrix composite (SiCf/SiC CMC). Two kinds of interfaces, namely mechanical and chemical bonding interfaces, were achieved by adjusting sintering temperature. SiCf/Yb2SiO5 interfaces prepared at 1450 and 1500 °C exhibit high interface strength and debond energy, which do not satisfy the crack deflection criteria based on He-Hutchison diagram. Raman spectrum analyzation indicates that the thermal expansion mismatch between Yb2SiO5 and SiC contributes to high compressive thermal stress at interface, and leads to high interfacial parameters. Amorphous layer at interface in model composite sintered at 1550 °C is related to the diffusion promoted by high temperature and DC electric filed during SPS. It is inspired that the interfacial parameters could be adjusted by introducing Yb2Si2O7−Yb2SiO5 interphase with controlled composition to optimize the mechanical fuse mechanism in SiCf/SiC CMC.

Characterization of cyclic fatigue hysteresis behavior of fiber-reinforced ceramic-matrix composites using inverse tangent modulus

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.

Deformation and tearing of graphene-reinforced elastomer nanocomposites

The resistance to failure through tearing is a crucial mechanical property for the application of different elastomers. In this work, graphene nanoplatelets (GNPs) were introduced into a fluoroelastomer (FKM) matrix with the aim of improving its tear resistance. The fracture energy through tearing was evaluated using the pure shear test. It was found that the tearing energy increased linearly with the volume fraction of the GNPs. At the maximum GNP content, the tearing resistance was 3 times higher, suggesting efficient toughening from the GNPs. Theoretical analysis of the micromechanics was conducted by considering debonding and pull-out of the nanoplatelets as possible toughening mechanisms. It was determined quantitatively that the main toughening mechanism was debonding of the interface rather than pull-out. The formation of cavities at flake ends during the deformation, as confirmed by scanning electron microscopy, was found to contribute to the remarkably high interfacial debonding energy (~1 kJ/m2).

Understanding the Wetting and Water-Induced Dewetting Behaviors of Bitumen on Rough Aggregate Surfaces.

The interaction of bitumen colloidal (a form of heavy oil) with inorganic solids, for example, mineral aggregates, in both air and water environments is ubiquitous in nature and engineering. However, our knowledge of the underlying physical mechanism of bitumen-/solid-wetting phenomena is still very limited. The current study aims to reveal how the mineralogy and topography of aggregate surfaces affect the wetting and water-induced dewetting of bitumen on aggregate surfaces. For this, contact angle tests were performed to measure the surface energies of bitumen and aggregate surfaces varying in both mineralogy and roughness. Based on the measurements, both qualitative and quantitative analyses were conducted for the interaction of bitumen/aggregate interface in air and water environments. Complete wetting and complete dewetting hold for the air/bitumen/aggregate and water/bitumen/aggregate interfaces, respectively. The negative interfacial adhesive energy for the air/bitumen/aggregate interface and the interfacial debonding energy for the water/bitumen/aggregate interface imply that both bitumen wetting and water-induced bitumen dewetting on flat surfaces are thermodynamically favorable. The Wenzel model approximation holds up for the rough aggregate surface interface systems. The interfacial adhesive energy and interfacial debonding energy are enhanced geometrically by the roughness factor r, which indicates that the textured aggregate surface is in favor of force-induced interfacial cracking resistance but shows an adverse effect to moisture damage resistance. The findings from the current study provide guidelines for materials design in pavement engineering.

Stress rupture of fiber-reinforced ceramic-matrix composites subjected to different stochastic loading spectrums at intermediate temperatures

In this paper, stress rupture of fiber-reinforced ceramic-matrix composites (CMCs) subjected to different stochastic loading spectrums at intermediate temperatures (600 to 1000 °C) is investigated. Under stress rupture at stress level higher than the first matrix cracking stress, multiple damage mechanisms of matrix cracking, fiber/matrix interface debonding, interphase and fiber oxidation, and fiber fracture are considered to analyze evolution of composite strain. Four different stochastic loading spectrums are considered in the analysis of damage evolution and lifetime of fiber-reinforced CMCs under stress rupture loading. Relationships between stochastic loading stress, frequency, time, interface debonding and oxidation length, fiber failure probability, and stress rupture lifetime are established. Effects of stochastic loading stress and time, fiber volume, matrix crack spacing, interface debonding energy, interface shear stress, and temperature on composite strain, interface debonding and oxidation length, and the fiber failure probability versus time are analyzed. Experimental stress rupture strain and lifetime of SiC/SiC composite under constant stress and stochastic loading spectrums are predicted. When the stochastic loading stress, frequency, and temperature increase, the stress rupture lifetime and the time for the interface complete debonding and oxidation all decrease.

A micromechanical temperature-dependent vibration damping model of fiber-reinforced ceramic-matrix composites

In this paper, a micromechanical temperature-dependent vibration damping model of fiber-reinforced ceramic-matrix composites (CMCs) is developed. Temperature-dependent damage mechanisms of matrix cracking, interface debonding and slip, and fibers fracture contribute to the vibration damping of damaged CMCs. The temperature-dependent fiber and matrix strain energy and dissipated energy density are formulated of composite constituent properties and damage related micro parameters of matrix crack spacing, interface debonding and slip length, and broken fibers fraction. Theoretical relationships between temperature-dependent composite damping, temperature and temperature-dependent damage mechanisms are established. Effects of composite constituent properties (i.e., fiber volume, interface debonding energy, interface shear stress and interface frictional coefficient) and composite damage state (i.e., matrix crack spacing) on temperature-dependent composite vibration damping of SiC/SiC composite are analyzed. When the fiber volume increases, the composite vibration damping decreases, and the temperature for the peak value of the composite vibration damping increases, mainly due to the decrease of the interface debonding and slip fraction. Experimental temperature-dependent composite vibration damping of 2D SiC/SiC composite at the temperature range of 293–1373 K are predicted using the developed micromechanical vibration damping model. Experimental vibration damping of 2D SiC/SiC composite increases with temperature, and the theoretical predicted composite vibration damping for different vibration stress of σ = 5, 6, and 7 MPa are obtained and agreed with experimental data, and the predicted interface debonding and slip fraction increases with temperature.

A micromechanical vibration damping model of fiber-reinforced ceramic–matrix composites considering interface debonding

A micromechanical vibration damping model of fiber-reinforced ceramic–matrix composites is developed considering interface debonding. The relationship between the stress-dependent composite damping and interface debonding is established. Effects of material properties and damage-related parameters on the vibration damping of fiber-reinforced CMCs are discussed. Experimental vibration damping with interface debonding of C/SiC composites is predicted. When the vibration frequency increases from f = 1–5 Hz, the vibration damping decreases due to the increasing dynamic interfacial shear stress and low frictional dissipated energy in the debonding region. The composite vibration damping decreases with increasing fiber volume, matrix crack spacing and interface shear stress, and increases with fiber radius and fiber elastic modulus. When the interface debonding energy increases, the vibration damping decreases when the interface partial debonding and approaches the same value when the interface complete debonding, and the vibration stress for complete interface debonding increases.

Correlation of nanoscale interface debonding and multimode fracture in polymer carbon composites with long-term hygrothermal effects

The correlation between nanoscale interface debonding and crack energy release rate for modes I, II, and I/II for extended exposure to hygrothermal conditions in polymer matrix composites (PMCs) needs to be understood. In this study, the effects on PMCs for two years of exposure, to a heat of 60 °C and relative humidity of 90%, were investigated. The interphase properties were studied using PF QNM. During hygrothermal treatment, the interphase region's thickness around the crack tip increases, and the morphology of the interphase changes. Nanoscale debonding of the fiber and matrix in artificially aged samples is a mix of cohesive and adhesive failure. Degradation at the nanoscale interphase and the macroscale crack initiation toughness slows after one year of aging. Interface debonding and nanoscale cracks cause intralaminar cracks, fiber bridging, and an increase in crack energy. Toughness in mode I fracture was increased in the artificially aged samples.

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

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.

Modeling stress-dependent matrix multiple fractures of fiber-reinforced ceramic-matrix composites considering fiberoxidation and fracture

ABSTRACT In this paper, the stress-dependent matrix multiple fractures of fiber-reinforced ceramic-matrix composites (CMCs) with fiber oxidation and fracture is investigated. The shear-lag model is combined with the fiber oxidation and fracture models, and the fiber/matrix interface debonding criterion is adopted to determine the micro-stress field of the damaged fiber-reinforced CMCs. The effects of the fiber volume, interface shear stress, interface debonding energy, oxidation temperature and time on the stress-dependent matrix multiple fractures, interface debonding and oxidation, and fiber fracture are discussed. When the fiber volume fraction and the interface shear stress in the debonding region increased, the matrix first cracking stress and saturation cracking stress increased, the saturation matrix cracking space decreased, and the matrix multiple fracture evolution rate increased. When the interface debonding energy and the interface shear stress in the oxidation region increased, the matrix cracking density increased. When the oxidation temperature and oxidation duration increased, the matrix cracking density decreased. The experimental matrix multiple fractures of unidirectional C/SiC, SiC/SiC, mini-SiC/SiC, SiC/CAS, SiC/CAS-II, and SiC/borosilicate composites are predicted.

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

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.

A time-dependent tensile constitutive model for long-fiber-reinforced unidirectional ceramic-matrix minicomposites considering interface and fiber oxidation

In this paper, a time-dependent tensile constitutive model of long-fiber-reinforced unidirectional ceramic-matrix minicomposites is developed considering the interface and fiber oxidation. The relationship between the time-dependent tensile behavior and internal damage is established. The damage mechanisms of time-dependent matrix cracking, fiber/matrix interface debonding, fiber failure, and the oxidation of the interface and fiber are considered in the analysis of the time-dependent tensile stress–strain curve. The fracture mechanic approach, matrix statistical cracking model, and fiber statistical failure model are used to determine the time-dependent interface debonding length, matrix crack spacing, and the fiber failure probability considering the time-dependent interface and fiber oxidation. The effects of the fiber volume, fiber radius, matrix Weibull modulus, matrix cracking characteristic strength, matrix cracking saturation spacing, interface shear stress, interface debonding energy, fiber strength, fiber Weibull modulus, and oxidation time on the time-dependent tensile stress–strain curves, matrix cracking density, interface debonding, and fiber failure are discussed. The experimental time-dependent tensile stress–strain curves, matrix cracking, interface debonding, and fiber failure of four different unidirectional SiC/SiC minicomposites for different oxidation time are predicted. The composite tensile strength and failure strain increase with the fiber volume, fiber strength, and fiber Weibull modulus, and decrease with the oxidation time; the fiber/matrix interface debonding length increases with the fiber radius and oxidation time and decreases with the interfacial shear stress and interface debonding energy; the fiber/matrix interface oxidation ratio increases with the interfacial shear stress, interface debonding energy, and oxidation time and decreases with the saturation matrix crack spacing.

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

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.

Supersoft, Stretchable, Tough, and Adhesive Elastomers with Dual Metal‐Ionic Crosslinked Double‐Network Structure

AbstractSoft, stretchable, tough, and adhesive elastomers are developed based on the metal‐ionic crosslinked double network structure, where the metal ion coordination of sulfonated poly(phenylene oxide) (SPPO) is used for the first network and the soft chemical crosslinked poly(ethyl acrylate) (PEA) is used for the second network. The influence of SPPO content on the tensile, cyclic tensile, adhesive, and rheological behavior of the elastomers is systematically investigated. It is observed that the elastomers are immensely soft and stretchable with tunable modulus from 0.038 to 0.086 MPa, fracture strain of ≈1400%, fracture stress in the range 0.20–1.2 MPa, work of extension of 0.72–5.6 MJ m−3, fast self‐recovery of 5 s after experiencing 200% strain, and robust adhesive behavior on glass substrates with interface debonding energy ≈35.2 J m−2. The mechanical behavior of the double‐network elastomers at the macroscopic scale is related to the dynamic breaking and reforming of the metal‐ion coordination at the molecular scale in the first network. This study provides a facile approach for the synthesis of elastomers with multidimensional mechanical behavior and broadens the applications of the elastomers in the field of flexible electronic devices, soft robotics, among others.

Damage evolution and lifetime of fiber-reinforced ceramic-matrix composites under stress-rupture with stochastic loading at intermediate temperatures

In this paper, the stress-rupture of fiber-reinforced ceramic-matrix composites (CMCs) with stochastic loading at intermediate temperature is investigated. There are four different stochastic loading sequences under stress-rupture are considered with different loading time and time spacing. The micro stress filed of the damaged CMCs, the damage models of the matrix cracking, fiber/matrix interface debonding, and fiber failure consider the stochastic loading and time-dependent interface and fiber oxidation. The damage evolution of the stress-rupture strain, fiber/matrix interface debonding length and interface oxidation length, and the broken fibers fraction versus the time curves of SiC/SiC composite subjected to four different stochastic loading sequences are analyzed. The effects of the fiber volume, matrix crack spacing, fiber/matrix interface debonding energy, fiber/matrix interface shear stress, and environmental temperature on the damage evolution and lifetime of SiC/SiC composite are discussed. The experimental damage evolution and lifetime of SiC/SiC composite under stress-rupture with stochastic loading are predicted. Under stress-rupture with stochastic loading, the stress-rupture lifetime decreases with the stress level, and the frequency of the stochastic loading; the stress-rupture lifetime increases with the fiber volume, and decreases with environmental temperature; and the time for the interface complete debonding increases with the fiber volume, matrix crack spacing, interface debonding energy and interface frictional shear stress in the slip and oxidation region, and decreases with the temperature.