Effects of Curing-Induced Residual Stress on Composite Strength

2020 ◽  
Author(s):  
Haotian Sun ◽  
Dianyun Zhang
Keyword(s):  
Residual Stress ◽  
Damage Model ◽  
Matrix Cracking ◽  
Bending Test ◽  
Composite Strength ◽  
Plain Weave ◽  
The Matrix ◽  
Smeared Crack Approach ◽  
Fiber Matrix ◽  
Stress Buildup

Abstract An integrated processing-damage model was developed to predict the inter-lamina strength of a plain weave composite flange manufactured using the Resin Transfer Molding (RTM) technique. The plain weave composite flange was subjected to four-point bending test to characterize its inter-lamina strength. A Representative Volume Element (RVE) at the fiber–matrix level was established to study the effect of curing-induced residual stress on the resulting composite strength. In order to calculate the residual stress, the curing cycle of the experiment was imposed on the RVE. After fully cured, the RVE was virtually loaded and the cohesive element and Smeared Crack Approach (SCA) were employed to capture the fiber-matrix debonding and matrix cracking responses, respectively. Due to the nature of stress history dependency, the SCA was formulated in the incremental form to reflect the stress buildup. The result shows that both fiber-matrix debonding and matrix cracking can be captured during the virtual loading. However, the load drop in the simulation mainly depends the matrix cracking. As the stress buildup in the matrix is dramatic, it demonstrates that the residual stress has large impact on the composite inter-lamina strength. The numerical methods in this paper can be used as an efficient tool in optimizing the curing process of composite material.

The Matrix Cracking Stress and Residual Thermal Stress of 2D SiC/SiC Composite Fabricated by PIP Process

2018 ◽  
Vol 281 ◽  
pp. 375-381
Author(s):  
Hai Peng Qiu ◽  
Shan Hua Liu ◽  
Ling Wang ◽  
Bing Yu Zhang ◽  
Ming Wei Chen ◽  
...  
Keyword(s):  
Residual Stress ◽  
Regression Line ◽  
Strain Curve ◽  
Thermal Residual Stress ◽  
Matrix Cracking ◽  
Stress Strain Curve ◽  
Sic Ceramic ◽  
The Matrix ◽  
Sic Composites ◽  
Cracking Stress

A two dimensional silicon carbide fiber reinforced SiC matrix (2D SiC/SiC) composite fabricated by precursor infiltration pyrolysis (PIP) process used a liquid SiC ceramic precursor was obtained. Two key properties including matrix cracking stress and thermal residual stress were investigated for this PIP 2D SiC/SiC composites. Three methods were applied to determine the matrix cracking stress in order to obtained a trusted value, and the value of matrix cracking stress for SiC/SiC composite was 75±4 MPa. The thermal residual stress of the composites was calculated by linear regression line according to the loading-unloading-reloading stress-strain curve of the 2D SiC/SiC composite, and the result showed that the value of thermal residual stress of SiC matrix in composite was 20MPa, which means the PIP SiC matrix in the 2D SiC/SiC composite was under the compressive stress when the composite cooling down from the fabrication temperature to the room temperature.

Effect of Fiber-Matrix Integration on the Fracture Behavior of Aluminosilicate Fiber Reinforced Clay-Kaolin Matrix Composites

2009 ◽  
Vol 417-418 ◽  
pp. 549-552
Author(s):  
Burak Özkal ◽  
Tugba Uçar
Keyword(s):  
Phase Transformation ◽  
Sintering Temperature ◽  
Matrix Material ◽  
Bending Test ◽  
Matrix Composites ◽  
Powder Packing ◽  
The Matrix ◽  
Brittle Fiber ◽  
Fiber Matrix ◽  
Clay Kaolin

Different amounts of fiber added samples were prepared by standard ceramic processing routes and sintered at different temperatures. Although powder packing characteristics of the matrix material were negatively affected with increasing fiber content; certain improvements were observed for the density, MOR and water absorption values both for green and sintered states. Fracture surfaces of the samples after three-point bending test were investigated via detailed SEM observations and phase analyses were performed by XRD measurements. It is found that phase transformation controlled fiber-matrix integration starts with increasing sintering temperature and degree of bonding between fiber/matrix interfaces can be arranged by selecting optimum sintering temperature. Aluminosilicate fiber addition was found efficient for improving mechanical properties of clay-kaolin matrix and the mechanism of the improvement can be grouped into two categories i.e. (1) brittle fiber – brittle matrix interactions via well known pulled-out, crack deflection and bridging mechanisms prior to fiber-matrix integration (2) further densification via phase transformation controlled fiber-matrix integration after high sintering temperatures.

Electromechanical Study of Carbon Fiber Composites

1997 ◽  
Vol 500 ◽  
Author(s):  
Xiaojun Wang ◽  
Xuli Fu ◽  
D.D.L. Chung
Keyword(s):  
Residual Stress ◽  
Carbon Fiber ◽  
Fiber Composites ◽  
Single Fiber ◽  
Fiber Direction ◽  
Carbon Fiber Composites ◽  
Fiber Waviness ◽  
Pull Out ◽  
The Matrix ◽  
Fiber Matrix

ABSTRACTElectromechanical testing involving simultaneous electrical and mechanical measurements under load was used to study the fiber-matrix interface, fiber residual stress and marcelling (fiber waviness) in carbon fiber composites. The interface study involved single fiber pull-out while the fiber-matrix contact resistivity was measured. The residual stress study involved measuring the resistance of a single fiber embedded in the matrix while the fiber was tensioned at its exposed ends. The marcelling study involved measuring the resistance of a composite in the through-thickness direction while tension was applied in the fiber direction.

Mechanical Property Scatter in CFCCs

1998 ◽  
Author(s):  
Marc Steen ◽  
Constantina Filiou
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Residual Stresses ◽  
Mechanical Response ◽  
Ceramic Matrix Composites ◽  
Strength Properties ◽  
Matrix Cracking ◽  
Control Mode ◽  
Residual Stress State ◽  
The Matrix

The tensile response of continuous fibre reinforced ceramic matrix composites (CFCCs) is not expected to show the large variation in strength properties commonly observed for monolithic ceramics. Results of recent investigations on a number of 2D reinforced CFCCs have nevertheless revealed a considerable scatter in the initial elastic modulus, in the first matrix cracking stress and in the failure stress. One school of thought considers that the observed variability is caused by experimental factors. Elaborate testing programmes have been set up to clarify the origins of this scatter by investigation of the effects of control mode, loading rate, specimen shape, etc.. Another school explains the scatter by the presence of (axial) residual stresses in the fibres and in the matrix. Although plausible, this hypothesis is difficult to verify because experimental determination of the residual stress state in CFCCs is not straightforward. In addition, with the available methods it is impractical to determine the residual stresses in every test specimen. This approach is indeed required for establishing the relationship between the magnitude of the residual stresses and the experimentally observed scatter. At IAM a method has been developed and validated which allows to quantify the axial residual stress state in individual CFCC specimens by subjecting them to intermittent unloading-reloading cycles. The method as well as the derived relationship between residual stress state and scatter in mechanical response will be presented.

Mechanical Property Scatter in CFCCs

1999 ◽  
Vol 122 (1) ◽  
pp. 69-72 ◽  
Author(s):  
M. Steen ◽  
C. Filiou
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Residual Stresses ◽  
Mechanical Response ◽  
Ceramic Matrix Composites ◽  
Strength Properties ◽  
Matrix Cracking ◽  
Control Mode ◽  
Residual Stress State ◽  
The Matrix

The tensile response of continuous fibre reinforced ceramic matrix composites (CFCCs) is not expected to show the large variation in strength properties commonly observed for monolithic ceramics. Results of recent investigations on a number of two-dimensional reinforced CFCCs have nevertheless revealed a considerable scatter in the initial elastic modulus, in the first matrix cracking stress and in the failure stress. One school of thought considers that the observed variability is caused by experimental factors. Elaborate testing programmes have been set up to clarify the origins of this scatter by investigation of the effects of control mode, loading rate, specimen shape, etc. Another school explains the scatter by the presence of (axial) residual stresses in the fibres and in the matrix. Although plausible, this hypothesis is difficult to verify because experimental determination of the residual stress state in CFCCs is not straightforward. In addition, with the available methods it is impractical to determine the residual stresses in every test specimen. This approach is indeed required for establishing the relationship between the magnitude of the residual stresses and the experimentally observed scatter. At IAM a method has been developed and validated which allows to quantify the axial residual stress state in individual CFCC specimens by subjecting them to intermittent unloading-reloading cycles. The method as well as the derived relationship between residual stress state and scatter in mechanical response will be presented. [S0742-4795(00)01101-7]

A micromechanics-based damage model for compressive behavior analysis of impacted composite laminates

2019 ◽  
Vol 29 (3) ◽  
pp. 369-387 ◽  
Author(s):  
Xiaofei Lou ◽  
Xuecheng Han ◽  
Hongneng Cai
Keyword(s):  
Compressive Strength ◽  
Impact Loading ◽  
Composite Laminates ◽  
Failure Mechanisms ◽  
Damage Model ◽  
Failure Criteria ◽  
Matrix Cracking ◽  
Compressive Behavior ◽  
Isotropic Composite ◽  
The Matrix

The compressive strength of composite laminates decreases seriously after being subjected to impact loading, which is an important item to be considered in the usage of composite material. In this paper, a micromechanics-based damage model is proposed to study the compressive behavior of impacted composite laminates. The micro stresses of fiber and matrix are calculated by stress amplification factors and then used to judge the failure mechanisms according to corresponding physical failure criteria. A progressive damage model based on different failure statuses of constituents is established to study the degradation of material properties. The bi-linear cohesive model is used in the research of delamination onset and propagation. The compressive behaviors of quasi-isotropic composite laminates subjected to different impact energies are investigated by this proposed method. Good agreements in terms of structure responses, failure mechanisms, and residual compressive strengths are obtained between numerical results and experimental data. The matrix cracking and delamination caused by impact loading are responsible for the initiation and propagation of buckling, which leads to the final collapse of entire laminates. Based on the numerical investigations of material parameters, the increment of mode II interlaminar fracture toughness is capable of improving the residual compressive strength significantly.

Effect of temperature on matrix multicracking evolution of C/SiC fiber-reinforced ceramic-matrix composites

2020 ◽  
Vol 39 (1) ◽  
pp. 189-199
Author(s):  
Longbiao Li
Keyword(s):  
Strain Energy ◽  
Ceramic Matrix Composites ◽  
Critical Value ◽  
Matrix Cracking ◽  
Interface Debonding ◽  
Matrix Composites ◽  
Temperature Dependent ◽  
Damage State ◽  
The Matrix ◽  
Sic Composites

AbstractIn this paper, the temperature-dependent matrix multicracking evolution of carbon-fiber-reinforced silicon carbide ceramic-matrix composites (C/SiC CMCs) is investigated. The temperature-dependent composite microstress field is obtained by combining the shear-lag model and temperature-dependent material properties and damage models. The critical matrix strain energy criterion assumes that the strain energy in the matrix has a critical value. With increasing applied stress, when the matrix strain energy is higher than the critical value, more matrix cracks and interface debonding occur to dissipate the additional energy. Based on the composite damage state, the temperature-dependent matrix strain energy and its critical value are obtained. The relationships among applied stress, matrix cracking state, interface damage state, and environmental temperature are established. The effects of interfacial properties, material properties, and environmental temperature on temperature-dependent matrix multiple fracture evolution of C/SiC composites are analyzed. The experimental evolution of matrix multiple fracture and fraction of the interface debonding of C/SiC composites at elevated temperatures are predicted. When the interface shear stress increases, the debonding resistance at the interface increases, leading to the decrease of the debonding fraction at the interface, and the stress transfer capacity between the fiber and the matrix increases, leading to the higher first matrix cracking stress, saturation matrix cracking stress, and saturation matrix cracking density.

Stochastic Aspects of Matrix Cracking in Brittle Matrix Composites

1993 ◽  
Vol 115 (3) ◽  
pp. 314-318 ◽  
Author(s):  
S. M. Spearing ◽  
F. W. Zok
Keyword(s):  
Matrix Cracking ◽  
Matrix Composites ◽  
Brittle Matrix ◽  
Tensile Response ◽  
Brittle Matrix Composites ◽  
Crack Interactions ◽  
The Matrix ◽  
Interface Slip ◽  
Bridging Fibers

A computer simulation of multiple cracking in fiber-reinforced brittle matrix composites has been conducted, with emphasis on the role of the matrix flaw distribution. The simulations incorporate the effect of bridging fibers on the stress required for cracking. Both short and long (steady-state) flaws are considered. Furthermore, the effects of crack interactions (through the overlap of interface slip lengths) are incorporated. The influence of the crack distribution on the tensile response of such composites is also examined.

Experimental Study on Testing Ni-Containing Stainless Steel Protective Coatings by Pulsed Laser Scratching

2010 ◽  
Vol 43 ◽  
pp. 651-656
Author(s):  
Ai Xin Feng ◽  
Yu Peng Cao ◽  
Chuan Chao Xu ◽  
Huai Yang Sun ◽  
Gui Fen Ni ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Power Density ◽  
Laser Power ◽  
Protective Coatings ◽  
Three Dimensional ◽  
Pulsed Laser ◽  
Laser Power Density ◽  
The Matrix ◽  
The Impact

In the experiment, we use pulsed laser to conduct discrete scratching on Ni-containing stainless steel protective coatings to test residual stress situation after the matrix is scratched; then to analyze the the impact of the impact stress wave on coating - substrate bonding strength according to the test results, finally to infer the laser power density range within which it occurs coating failure. The study shows that: after laser discrete scratching, the residual stress of the center of the laser-loaded point on matrix surface gradually reduces when the pulsed laser power density increases. The matrix produces a corresponding residual compressive stress under the laser power density reaches a certain value. The actual failure threshold values are 12.006 GW/cm2, 11.829GW/cm2 and 12.193GW/cm2 measured by the three-dimensional topography instrument testing the discrete scratch point of three groups of samples and verified by using a microscope

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