Experimental Assessment of Toughness in Ceramic Matrix Composites using the J-integral with Digital Image Correlation Part II: Application to Ceramic Matrix Composites
نویسندگان
چکیده
This paper is the second of a two-part series assessing the feasibility of using the J-integral with full-field deformation data from Digital Image Correlation (DIC) to characterize toughness in continuous fiber, SiCf/SiCc ceramic matrix composites (CMCs). In Part I, line and area integral adaptations of the J-integral were validated with analytical and experimental deformation fields. It was found that variability in experimental data and contour truncation at the crack wake introduced error and path-dependency, but this could be mitigated through data filtering. In this paper, the line and area integral methods were evaluated for cross-ply and longitudinal CMC tensile specimens. It is demonstrated that these approaches cannot be used for quantitative characterization, but can be successfully used to examine qualitative trends. For both architectures, area integral measurements of the potential energy release rate, J, were larger (and arguably more accurate) than line integral measurements. Resistance curves were characteristic of tough materials, but the stress intensity magnitudes were larger in the longitudinal laminates than the cross-ply (for equivalent crack extension). Experimentally derived bridging laws showed that fiber bridging tractions were largest in the cross-ply laminates, which was attributed to a lower volume fraction of longitudinal fibers. Quantitative, single-value measurements of fracture toughness could not be established since: (1) noise in the DIC data masked strain signals indicative of first matrix cracking, and (2) widespread matrix cracking rendered the J-integral invalid (regardless of size and position, the boundaries of the line and area contours inevitably intercepted microcracks). Rather, gross estimates of toughness and stress intensity factors were made under the assumption that the limitations in the spatial resolution of the DIC data essentially transforms regions with fine microracking along the contour into continuous regions of elastic deformation. When evaluated with the J-integral, the smoothed deformation fields manifest as resistance curves indicative of a tough material. Thus, the J-integral was valuable for qualitative assessments of toughening mechanisms in the CMCs.
منابع مشابه
Experimental Assessment of Toughness in Ceramic Matrix Composites using the J-integral with Digital Image Correlation Part I: Methodology and Validation
The complex nature of damage in ceramic matrix composites (CMCs) renders conventional methods of measuring quantitative fracture properties impractical. This paper is the first of twopart series that assesses the feasibility of using the J-integral with full-field deformation data from Digital Image Correlation (DIC) to characterize toughness in continuous fiber SiC/SiC CMC laminates. It provid...
متن کاملStudy on Iraqi bauxite ceramic reinforced Aluminum metal matrix composite synthesized by stir casting
For the past decades researchers are showing immense interest to investigate the natural advantage of preparation of composites from minerals such as bauxite particles, and proved their effectiveness as cost effective reinforcing agents in fabrication of high performance composites. This study, is a new attempt in using the Iraqi natural bauxite powder with different proportions (2wt%, 4wt%, an...
متن کاملInterfaces and interfacial mechanics : influence on the mechanical behavior of ceramic matrix composites (CMC)
The influence of fiberlmatrix interactions on the mechanical behavior of ceramic matrix composites is examined on glass matrix composites and mainly on composites made by chemical vapor infiltration (CVI) of a fiber preform by a SiC matrix. Then the relationships between interfaces and features of the stress-strain behavior are highlighted on microcomposite specimens using experimental data and...
متن کاملStrength and Toughness of Ceramic-metal Prepared by Reactive Hot Pressing Composites
William G. Fahrenholtz o 9m Ceramic Engineering Department ‘so University of Missouri-Rolls w~!!l Rolls, MO 65409 + <. +# Metal-reinforced Alz03-matrix composites were prepared using reactive hot pressing. The volume fraction of the reinforcing phase was controlled by the stoichiometry of the particular displacement reaction used. Dense Alz03-Ni and Al@3-N’b composites were fabricated using thi...
متن کاملNew Development of the ]-Based Fracture Testing Technique for Ceramic-Matrix Composites
The J-based fracture testing technique is newly extended to experimentally determine the tension-softening (a-6) relations in ceramic-matrix composites. The J-based technique originally proposed for concrete has been well established for quasi-brittle materials where the fracture process is primarily dominated by the formation of a fracture process zone and the contribution of the crack tip tou...
متن کامل