Tensile testing of ceramic fibres by video extensometry

A computer-assisted video extensometer was used to measure the Young's modulus and tensile strength of commercially available alumina fibres (11.5 μm in diameter). The results showed excellent agreement with manufacturers reported values (384 ± 12 GPa and 3132 ± 296 MPa for Young's modulus and tensile strength, respectively). The machine was initially tested with 100 μm diameter SiC monofilaments to identify optimum experimental conditions. The mechanical properties of these fibres were independent of the crosshead speed and fibre length. This non-contacting extension measuring system allowed testing of fragile materials and a submicron resolution could be achieved with a high-precision CCD camera. The results in term of precision and resolution therefore meet the requirements for strain measurements in mechanical ceramic materials testing.