Finite-element study of C-ring fracture specimens for the determination of design strength data

To investigate the design implications of using C-ring specimens for evaluating the strength controlling flaw population(s) of ceramics when in tubular form, finite-element analysis (FEA) calculations were performed using the ANSYS code. These calculations focused on the ranges of width-to-thickness ratios required to maintain a plane stress state within the C-ring specimen during fracture. In addition, the validity of the theoretical effective-area (KA) and effective-volume (KV) relations derived during earlier analytical and experimental studies were investigated. Results of the FEA calculations indicated that a wide range of width-to-thickness ratios could be safely used to extract fracture strength design data. Moreover, the calculations confirmed the validity of the theoretical stress-area and stress-volume relations used to correlate strength defining flaw population and determine Weibull parameters. However, a tendency for the computational errors to increase with Weibull modulus was observed during the finite-element based estimations of effective-areas and -volumes.