Damage Development in SiCf/SiC Composites Through Mechanical Loading

2017 ◽  
Author(s):  
Martin R. Bache ◽  
J. Paul Jones ◽  
Zak Quiney ◽  
Louise Gale
Keyword(s):  
Acoustic Emission ◽  
Mechanical Loading ◽  
Ceramic Matrix Composites ◽  
Potential Drop ◽  
Image Correlation ◽  
Stress Concentrations ◽  
Damage Development ◽  
Macro Scale ◽  
Sic Composites ◽  
The Individual

Sophisticated mechanical characterisation is vital in support of a fundamental understanding of deformation in ceramic matrix composites. On the component scale, “damage tolerant” design and lifing philosophies depend upon laboratory assessments of macro-scale specimens, incorporating typical fibre architectures and matrix under representative stress-strain states. Standard SiCf/SiC processing techniques inherently introduce porosity between the individual reinforcing fibres and between woven fibre bundles. Subsequent mechanical loading (static or cyclic) may initiate cracking from these stress concentrations in addition to fibre/matrix decohesion and delamination. The localised coalescence of such damage ultimately leads to rapid failure. Proven techniques for the monitoring of damage in structural metallics, i.e. optical microscopy, potential drop systems, acoustic emission (AE) and digital image correlation (DIC), have been adapted for the characterisation of CMC’s tested at room temperature. As processed SiCf/SiC panels were subjected to detailed X-ray computed tomography (XCT) inspection prior to specimen extraction and subsequent static and cyclic mechanical testing to verify their condition. DIC strain measurements, acoustic emission and resistance monitoring were performed and correlated to monitor the onset of damage during loading, followed by intermittent XCT inspections throughout the course of selected tests.

Constituent and Ply Level Understanding of Electrical Resistance in Si-Containing SiC/SiC Composites

2021 ◽  
Author(s):  
Joseph El Rassi ◽  
Gregory N. Morscher
Keyword(s):  
Electrical Resistance ◽  
Ceramic Matrix Composites ◽  
Potential Drop ◽  
Matrix Composites ◽  
Damage Development ◽  
Laminate Composites ◽  
Monitoring Technique ◽  
Measured Resistance ◽  
Sic Composites ◽  
Current Potential

Abstract Electrical resistance, also known as direct current potential drop (DCPD), has been demonstrated as an enabling means to monitor damage evolution in SiC-based ceramic matrix composites. For laminate composites, it has become apparent that the location and orientation of SiC fibers, free Si and in some cases insertion of C rods can greatly affect the measured resistance. In addition, the nature of crack growth through the different plies which consist of different constituents will have different effects on the change in resistance. Therefore, both experimental and modeling approaches as to the resistance and change in resistance for different laminate architectures based on the nature of constituent content and orientation are needed to utilize and optimize electrical resistance as a health-monitoring technique. In this work, unidirectional and cross-ply laminate composites have been analyzed using a ply-based electrical model. Based on a ply-level circuit model, the change in resistance was modeled for damage development. It is believed that this can serve as a basis for tailoring the architecture/constituent content to create a “smarter” composite.

Acoustic Emission Research on Thermal Shock Behaviors of Three-Dimensional C/SiC Composites in Different Environments

2007 ◽  
Vol 546-549 ◽  
pp. 1585-1590 ◽  
Author(s):  
Peng Fang ◽  
Lai Fei Cheng ◽  
Li Tong Zhang ◽  
Hui Mei ◽  
Jun Zhang
Keyword(s):  
Acoustic Emission ◽  
Thermal Shock ◽  
Three Dimensional ◽  
Chemical Vapor ◽  
Ceramic Matrix Composites ◽  
Chemical Vapor Infiltration ◽  
Matrix Composites ◽  
Damage Development ◽  
Damage Initiation ◽  
Sic Composites

Three-dimensional (3D) carbon fiber reinforced silicon carbide matrix composites (C/SiC) were prepared by a low-pressure chemical vapor infiltration method. The thermal shock behaviors of the composites in different environments were researched using an advanced acoustic emission (AE) system. Damage initiation and propagation were easily detected and evaluated by AE. The thermal shock damage to C/SiC composites mainly occurred at the process of cooling and was limited at argon but unlimited at wet oxygen atmosphere. Also correlations have been established between the different damage mechanisms and the characteristics of acoustic emission signals obtained during thermal shock tests. In this way, the paper contributes to the development of the acoustic emission technique for monitoring of damage development in ceramic-matrix composites.

Constituent and Ply Level Understanding of Electrical Resistance in Si-Containing SIC/SIC Composites

2021 ◽  
Author(s):  
Joseph Elrassi ◽  
Gregory Morscher
Keyword(s):  
Electrical Resistance ◽  
Ceramic Matrix Composites ◽  
Potential Drop ◽  
Matrix Composites ◽  
Damage Development ◽  
Laminate Composites ◽  
Monitoring Technique ◽  
Measured Resistance ◽  
Sic Composites ◽  
Current Potential

Abstract Electrical resistance, also known as direct current potential drop (DCPD), has been demonstrated as an enabling means to monitor damage evolution in SiC-based ceramic matrix composites. For laminate composites, it has become apparent that the location and orientation of SiC fibers, free Si and in some cases insertion of C rods can greatly affect the measured resistance. In addition, the nature of crack growth through the different plies which consist of different constituents will have different effects on the change in resistance. Therefore, both experimental and modeling approaches as to the resistance and change in resistance for different laminate architectures based on the nature of constituent content and orientation are needed to utilize and optimize electrical resistance as a health-monitoring technique. In this work, unidirectional and cross-ply laminate composites have been analyzed using a ply-based electrical model. Based on a ply-level circuit model, the change in resistance was modeled for damage development. It is believed that this can serve as a basis for tailoring the architecture/constituent content to create a "smarter" composite.

scholarly journals Advances in Damage Monitoring Techniques for the Detection of Failure in SiCf/SiC Ceramic Matrix Composites

Ceramics ◽  
2019 ◽  
Vol 2 (2) ◽  
pp. 347-371 ◽  
Author(s):  
Martin R. Bache ◽  
Christopher D. Newton ◽  
John Paul Jones ◽  
Stephen Pattison ◽  
Louise Gale ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Fatigue Loading ◽  
Industrial Applications ◽  
Image Correlation ◽  
Full Potential ◽  
Matrix Composites ◽  
Monitoring Techniques ◽  
Macro Scale

From a disruptive perspective, silicon carbide (SiC)-based ceramic matrix composites (CMCs) provide a considerable temperature and weight advantage over existing material systems and are increasingly finding application in aerospace, power generation and high-end automotive industries. The complex structural architecture and inherent processing artefacts within CMCs combine to induce inhomogeneous deformation and damage prior to ultimate failure. Sophisticated mechanical characterisation is vital in support of a fundamental understanding of deformation in CMCs. On the component scale, “damage tolerant” design and lifing philosophies depend upon laboratory assessments of macro-scale specimens, incorporating typical fibre architectures and matrix under representative stress-strain states. This is important if CMCs are to be utilised to their full potential within industrial applications. Bulk measurements of strain via extensometry or even localised strain gauging would fail to characterise the ensuing inhomogeneity when performing conventional mechanical testing on laboratory scaled coupons. The current research has, therefore, applied digital image correlation (DIC), electrical resistance monitoring and acoustic emission techniques to the room and high-temperature assessment of ceramic matrix composites under axial tensile and fatigue loading, with particular attention afforded to a silicon carbide fibre-reinforced silicon carbide composite (SiCf/SiC) variant. Data from these separate monitoring techniques plus ancillary use of X-ray computed tomography, in-situ scanning electron microscopy and optical inspection were correlated to monitor the onset and progression of damage during mechanical loading. The benefits of employing a concurrent, multi-technique approach to monitoring damage in CMCs are demonstrated.

Detection of Strain and Damage Distribution in SiCf/SiC Mechanical Test Coupons

2018 ◽  
Author(s):  
Christopher D. Newton ◽  
J. Paul Jones ◽  
Louise Gale ◽  
Martin R. Bache
Keyword(s):  
Mechanical Test ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Fatigue Loading ◽  
Image Correlation ◽  
Matrix Composites ◽  
Macro Scale ◽  
Ultimate Failure ◽  
Complex Structural ◽  
Structural Architecture

The complex structural architecture and inherent processing artefacts within ceramic matrix composites combine to induce inhomogeneous deformation and damage prior to ultimate failure. Sophisticated mechanical characterisation is vital in support of a fundamental understanding of deformation in ceramic matrix composites. On the component scale, “damage tolerant” design and lifing philosophies depend upon laboratory assessments of macro-scale specimens, incorporating typical fibre architectures and matrix under representative stress-strain states. Bulk measurements of strain via extensometry or even localised strain gauging will fail to characterise such inhomogeneity when performing conventional mechanical testing on laboratory scaled coupons. The current research project has, therefore, applied digital image correlation (DIC), electrical resistance monitoring and acoustic emission techniques to the room and high temperature assessment of a SiCf/SiC composite under axial fatigue loading. Data from these separate monitoring techniques plus ancillary use of X-Ray computed tomography and optical inspection were correlated to monitor the onset and progression of damage during cyclic loading.

Damage Mechanics of Two-Dimensional Woven SiC/SiC Composites

1994 ◽  
Vol 116 (3) ◽  
pp. 403-407 ◽  
Author(s):  
Hui-Zu Shan ◽  
Philippe Pluvinage ◽  
Azar Parvizi-Majidi ◽  
Tsu-Wei Chou
Keyword(s):  
Experimental Data ◽  
Damage Mechanics ◽  
Damage Model ◽  
Ceramic Matrix Composites ◽  
Elastic Behavior ◽  
Two Dimensional ◽  
Compression Tests ◽  
Damage Development ◽  
Tension And Compression ◽  
Sic Composites

The paper reports an analysis and modeling of the damage behavior of two-dimensional woven SiC/SiC composites. The damage mechanics analysis originally developed by Ladeveze and coworkers for polymeric and C/C composites are adopted and extended for ceramic matrix composites. The experimental findings of the coauthors reported in a companion paper provides the data for analytical modeling. The damage model assumes quasi-isotropic elastic behavior of the undamaged SiC/ SiC composites as well as orthotropic damage development (e.g., matrix microcracking, interfacial debonding, and fiber fracture). The model utilize two damage variables which are determined from experimental data; and the constitutive relation takes into account the difference in damage development between tension and compression in the principal material directions. The validity of the theory is demonstrated by the prediction of damage evolution of a SiC/SiC specimen under four-point bend test based upon the experimental data of tension and compression tests. A finite element method coupled with damage is adopted for the flexural analysis. The predictions agree quite well with experimental results.

Monitoring Fatigue of SiC/SiC Ceramic Matrix Composites With Acoustic Emission and Electrical Resistance

2019 ◽  
Author(s):  
Zipeng Han ◽  
Gregory N. Morscher
Keyword(s):  
Silicon Carbide ◽  
Acoustic Emission ◽  
Electrical Resistance ◽  
Fracture Mechanism ◽  
Ceramic Matrix Composites ◽  
Matrix Composites ◽  
R Ratio ◽  
Sic Ceramic ◽  
Sic Composites ◽  
Observed Damage

Abstract Acoustic emission (AE) and electrical resistance (ER) have been effective methods to monitor damage in SiC/SiC composites for a variety of loading conditions. In this study, the change of ER and modal AE were monitored on woven silicon carbide fiber-reinforced silicon carbide (SiC/SiC) composite under cyclic loading (fatigue) conditions at room temperature. In particular, the AE activity will be emphasized in this work as it relates to ER and observed damage. Significant increase of ER and AE activities were observed during the “initial” and sometimes “final” parts of the experiments. For tests at higher fatigue frequency conditions, AE activity was significant near the end of the test which was correlated with damage predominant in the region that was ultimately the failure region. Most of these events occurred during the unload portion of the cycle, i.e., “valley” and inferred a compressive micro-fracture mechanism. Microscopy of polished sections showed increased damage very near the fracture surface, including longitudinal and shear cracking in the 90-tow region of the composite which corresponded to the “valley” AE events. For the lowest frequency fatigue condition (0.01 Hz), no valley events were observed. The compressive micro-fracture mechanism observed in this study is a new observation for progressive damage in these types of composites. More study is required to isolate the cause(s) of this behavior which are probably related to fatigue frequency, R ratio and/or porosity content.

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