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.

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.

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.

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.

Multi-Lead Direct Current Potential Drop (DCPD) for In-Situ Health Monitoring of Ceramic Matrix Composites

2018 ◽  
Author(s):  
Yogesh P. Singh ◽  
Michael J. Presby ◽  
Kannan Manigandan ◽  
Gregory N. Morscher
Keyword(s):  
Damage Detection ◽  
Direct Current ◽  
Ceramic Matrix Composites ◽  
Potential Drop ◽  
Ceramic Matrix ◽  
Image Correlation ◽  
Matrix Composites ◽  
Direct Current Potential Drop ◽  
Current Potential

The method of direct current potential drop (DCPD) can be utilized as an effective, and convenient approach for in-situ damage detection, and as a non-destructive evaluation technique. We present the results from use of a multiprobe DCPD technique for in-situ damage detection in loading of a SiC/SiC composite. It is shown that in three different modes of loading (monotonic, fatigue, and cyclic load-unload), the sensing capabilities of DCPD technique compares well to the techniques of modal acoustic emission (AE) and digital image correlation (DIC). It was also found that DCPD technique provides a far earlier warning of failure under fatigue loading than the other two methods. In addition, we show that strategically placed multiple voltage leads on the specimen surface provides a promising way of qualitatively determining the crack initiation site. Therefore, the use of multiple lead DCPD method, together with other techniques, provides a viable option for sensing damage in ceramic matrix composites (CMCs) with complex geometries, and for applications at higher temperatures.

Multi-Lead Direct Current Potential Drop Method for In Situ Health Monitoring of Ceramic Matrix Composites

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Yogesh P. Singh ◽  
Michael J. Presby ◽  
Manigandan Kannan ◽  
Gregory N. Morscher
Keyword(s):  
Damage Detection ◽  
Direct Current ◽  
Ceramic Matrix Composites ◽  
Potential Drop ◽  
Ceramic Matrix ◽  
Image Correlation ◽  
Matrix Composites ◽  
Direct Current Potential Drop ◽  
Current Potential

The method of direct current potential drop (DCPD) can be utilized as an effective and convenient approach for in situ damage detection, and as a nondestructive evaluation technique. We present the results from use of a multiprobe DCPD technique for in situ damage detection in loading of a SiC/SiC composite. It is shown that in three different modes of loading (monotonic, fatigue, and cyclic load–unload), the sensing capabilities of DCPD technique compare well to the techniques of modal acoustic emission (AE) and digital image correlation (DIC). It was also found that DCPD technique provides a far earlier warning of failure under fatigue loading than the other two methods. In addition, we show that strategically placed multiple voltage leads on the specimen surface provide a promising way of qualitatively determining the crack initiation site. Therefore, the use of multiple lead DCPD method, together with other techniques, provides a viable option for sensing damage in ceramic matrix composites (CMCs) with complex geometries, and for applications at higher temperatures.

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.

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.

Sign in / Sign up

Export Citation Format

Share Document